Chapter 40

4 main categories of tissue: Epithelial, Connective, Muscle, Nervous. I. Epithelial Tissue (Epithelium): forms interactive surfaces with environment on external and internal body surfaces; functions as barriers.
Formed from continuous sheets of tightly packed cells
Covers outside of body; or lines organs and body cavities
Apical surface: the free surface exposed to air or body fluids
Basal surface: cells at base of epithelium are attached to a basement membrane (which is a dense layer of extracellular matrix)
Is avascular (no blood vessels); the blood vessels that supply nutrients and remove wastes are in the adjacent connective tissue: diffusion
Cell Shapes at APICAL surface
Squamous epithelium: flat; look like floor tiles
Their thinness allows rapid movement of substances through them by diffusion
Cuboidal epithelium: boxlike; looks like dice
Produces important secretions
Columnar epithelium: tall, pillar-like; some have cilia
Protects underlying tissue
Functions in absorption of nutrients and secretions (digestive juices)
Arrangement of Layers
Simple epithelium: 1 layer of cells
Stratified epithelium: 2 or more layers
Protect underlying tissues where the is abrasion/ wear and tear
Stratified squamous (best adapted for abrasion): covers outside of body; forms outermost layer of skin; lines mouth, esophagus, vagina, anus.
Pseudostratified epithelium (false multiple layers): 1 layer of a mixture of cell shapes; looks like multiple layers, but it isn’t. Not all cells reach the cell surface; the ones that do are either ciliated or secrete mucus. II. Connective Tissue: connects and supports other tissues; 6 major types
Characterized by few cells suspended in extracellular matrix of fibers
The extracellular matrix might be a liquid, gel or ground solid 1. Loose Connective Tissue: attaches epithelia to underlying tissues
Holds organs in place
Consists of a loose weave of 2 kinds of cells & 3 types of protein fibers
Fibroblasts: secrete the proteins (collagen and elastin) of the fibers
Macrophages: perform phagocytosis for immune system
Collagenous fibers: bundles of fibers containing 3 collagen molecules each: has great tensile strength; resists stretching
Elastic fibers: long threads of protein elastin; great resilience
Reticular fibers: branched and form a tight weave; made of collagen 2. Adipose Tissue: loose connective tissue specialized to store fat and adipose cells; insulates body; stores long-term fuel molecules (fat)
Each adipose cell ( called adipocytes) has 1 large fat droplet
Varies in size as fats are stored or utilized for energy 3. Fibrous Connective Tissue (not stretchy): dense parallel bundles of large numbers of collagenous fibers (strength/structure); imparts great non-elastic strength.
Found in tendons: attach muscle to bone
Found in ligaments; attach bone to bone at joints 4. Blood (also called vascular tissue): connective tissue made of plasma and plasma proteins; the liquid matrix allows rapid transport of blood cells, nutrients and wastes through the body.
Cellular component contains:
Leukocytes: WBC in immune function
Erythrocytes: RBC in oxygen transport
Platelets: cell fragments that function in blood clotting
Blood cells are made in red bone marrow near the ends of long bones. 5. Cartilage: connective tissue that is both strong and flexible.
Composed of collagenous fibers embedded in a rubbery matrix called chondroitin sulfate.
Avascular and without nerves
Cartilage cells: called chondrocytes
Comprises the skeleton of all vertebrate embryos
Most vertebrates replace it (ossify) with bone
Cartilage still retained in nose, ears, trachea, intervertebral discs, ends of some long bones 6. Bones: mineralized connective tissue
Bone-forming cells called osteoblasts
Bones consists of repeating units called Haversian Systems (Osteons)
In long bones, only the outer area is hard/compact
Inner are filled with spongy bone tissue called marrow III. Muscle Tissue: contracts to move parts of body
Made up of parallel bundles of long microfilaments: these are made up of contractile proteins actin and myosin
3 Types of Vertebrate Muscle Tissue 1. Skeletal (Striated) Muscle: For voluntary movement, causes body movement
Long, cylindrical cells that are striated (banded or striped across)
Multi-nucleated
Attached to bones by tendons 2. Cardiac Muscle: contractile wall of heart
Uni-nucleated
Striated and branched
Intercalated discs: ends of cells which relay contractile impulses 3. Smooth (also called visceral) Muscle
Involuntary movement; tissue in walls of internal organs
Smooth (unstriated)
Uni-nucleated
Tapered ends (spindle-shaped cells)
Contract slowly, but retains it longer (i.e. Churning of stomach) IV. Nervous Tissue: transmits nerve impulses throughout body; neuron: nerve cell
Has a cell body
Dendrites: extensions toward cell body (receives stimuli)
Axons: extensions away from cell body (send stimuli on)

Organs and Organ Systems: tissues are organized into organs
Many organs are anchored by sheets of loose connective tissue called mesenteries
Some organs have tissues in layers: Example- 4 tissue layers of stomach
In mammals, the diaphragm separates the 2 body cavities
Thoracic cavity: upper cavity (lungs and heart only)
Abdominal cavity: lower cavity

Homeostasis
Maintenance of steady state despite internal and external changes
Negative feedback: response reduces the stimulus (turns off process)
Positive feedback: amplification of a stimulus by a response, ofter bringing about a change in state. I.e. Transition from pregnancy to childbirth (continues the process)

Thermoregulation
Maintaining internal temperature within a tolerable range
Ectotherms: gain most of their heat from the environment (cold-blooded)
Ex: most invertebrates, fishes, amphibians, non-bird reptiles, snakes
Endotherms: use metabolic heat to maintain their own body temperature (warm-blooded)
Ex: birds, mammals, otter
More energetically expensive than ecothermy
Buffers the animal’s internal temperature agains external fluctuations
Enables the animal to maintain a high level of aerobic metabolism

Skin as an Organ of Thermoregulation
2 main layers: epidermis and dermis
Sweat glands function in evaporative cooling
Both endotherms and ectotherms adjust their rate of heat exchange with environment by vasodilation or vasoconstriction
Vasodilation
Increases the diameter of superficial blood vessels near the body surface
The warm blood can transfer heat to the cooler environment by radiation, conduction
Cooling mechanism for endotherms (red face, ears)
Vasoconstriction
Reduces blood flow and heat transfer by decreasing diameter of superficial blood vessels
Keeps blood closer to the core of the animal’s body
Warming mechanism (blanched extremities)

Thermostat Function of Hypothalamus
Keeps internal body temperature for humans homeostatic at 36-38 C
In response to increased body temperature; thermostat in hypothalamus activates cooling mechanisms
Sweat glands activate to increase evaporative cooling
Skin blood vessels dilate with warm blood to reduce heat by radiation (i.e. face gets red). Vasodilation; body temperature decreases.
In response to decreased body temperature: thermostat in hypothalamus activates warming mechanisms
Skeletal muscles shiver to generate heat
Skin blood vessels constrict to divert blood into deeper tissues (i.e. skin gets blanched white). Vasoconstriction; frostbite
Fever: reflects a resetting of thermostat to a higher set point in response to infection.

Chapter 41

Main Stages of Food Processing
Ingestion: eating
Digestion: breakdown (mechanical or enzymatic hydrolysis) of macromolecules into smaller monomers
Absorption: uptake of nutrients by body cells
Elimination: passage of undigested materials out of body as feces.

Anatomy of Human Digestive System
Oral Cavity: contains 3 pairs of salivary glands.
Saliva: secrete more than one liter/day
Contains 99.5% water.
Also contains salivary amylase: enzyme that helps digest starch and glycogen
Mucin (glycoprotein): protects and lubricates lining of oral cavity
Buffers: to prevent dental caries
Antimicrobial agents (lysozyme enzymes): to kill bacteria
Tongue: used to taste, help chewing, mix food with saliva to form a bolus; pushes bolus into pharynx.
Pharynx: the region we call our “throat”; an intersection which leads to both the trachea/windpipe (which is a tube in front that goes to the lungs) and the esophagus ( the tube in the back that goes to the stomach)
When we swallow, the top of the windpipe, (called the larynx: voice box) moves up so that its opening, the glottis, is blocked by a cartilaginous flap called the epiglottis. This prevents food from entering the trachea and allows food to go into the esophagus.
Esophagus: about 10 inches long, descends behind trachea; passes through diaphragm to stomach
Conducts food from pharynx to stomach
Peristaltic waves move bolus along the narrow esophagus
Muscles at top of esophagus are striated (skeletal muscle/voluntary), but then involuntary waves of smooth muscle take over
Salivary amylase continues to digest starch/glycogen (polysaccharides)
Stomach: J-shaped bag-like organ on the left side of abdominal cavity; just below diaphragm. Can stretch to hold 2 liters of food/water
Secretes mucus and gastric juice
Stomach has 2 sphincters:
Cardiac sphincter: goes into stomach; prevents back flow of acidic chyme into esophagus.
Pyloric sphincter: leads out of stomach; regulates passage of chyme into small intestine
Stomach is where proteins are first digested. Proteins are the only macromolecules that the stomach digests.
Small intestine: longest section of alimentary canal; about 20 ft. Long. First foot is duodenum; the rest is jejunum and ileum.
Duodenum (about 10 inches long): where most digestion finishes.
By the end of duodenum, most food should be monomers
Jejunum (8 ft. Long) & ileum (next 12 ft.): does nutrient absorption
Pancreas: not part of alimentary canal; it is an accessory gland that lies between the stomach and duodenum. Has 2 digestion jobs:
Discharges pancreatic enzymes into duodenum for finishing enzymatic digestion
Pancreas also secretes an alkaline solution of sodium bicarbonate into duodenum; to act as a buffer for offsetting the acidity of the chyme coming from the stomach
Liver: not part of alimentary canal; makes bile which is then stored in gall bladder.
Bile breaks down fat
Digestion of fats is difficult because fat molecules are insoluble in water
Bile salts from gallbladder are secreted into duodenum to coat the fat molecules and keep them from clumping. This is called emulsification
Large surface area is exposed to lipase which breaks it down into micelles to diffuse into epithelial lining of small intestine for absorption
Liver is first organ to receive products of digestion after absorption.
Gall Bladder: stores the bile that the liver makes
If gall bladder removed for gallstones, liver will still make bile but nowhere to store it. Must eat a low fat, not fat diet.
Large Intestine: about 4 or 5 feet long
Responsible for absorption of water, synthesis of vitamins not obtained from food (Vitamin K); absorption of vitamins/minerals, compaction, and excretion of wastes and excess salts.
Cecum: first 2 or 3 inches; blind sac; easily get polyps here
Appendix: attached to cecum, about 3 inches long; can live without ,has a minor immune function.
Colon: ascending (up): transverse (across); descending (down); sigmoid (s-shaped at the end)
Rectum: about 8 inches long; storage chamber for feces; controlled by 2 sphincters between rectum and anus; one is voluntary, other is involuntary
Anus: about 1 inch long
Large intestine contains a host of microorganisms. Most of the dry weight of feces is bacteria.

Chapter 42

Components of cardiovascular system
Heart
Atrium/atria: receive blood to heart
Top 2 chambers, thinner walled. Only pump blood to ventricles
Right atrium: receives deoxygenated blood from body
Left atrium: receives oxygenated blood from lungs
Ventricles: pump blood out of heart
Bottom 2 chambers, thicker walled
Right ventricle: pumps deoxygenated blood to lungs
Left ventricle: pumps oxygenated blood to body
Blood vessels (vasculature)
Artery: away from heart----> Arterioles ----> Capillaries ----> Venule ----> Veins to the heart.

Capillaries
Where the exchange of gases/metabolites take place.
Blood flow comes to a standstill in capillaries because of the gas exchange.

Control of Heart Beat
Initiated SA (sinoatrial) node; also called the natural pacemaker; small mass of nodal tissue on back wall of right atrium near superior vena cava
SA node: controls contraction of atria
AV node: controls contraction of ventricles

Composition of Mammalian Blood
55% Plasma
If you remove clotting factors from plasma, it becomes serum
45% Cellular elements
Erythrocytes: RBC that transport O2 and CO2
Hemoglobin
RBC circulate for about 4 months and then are destroyed in liver and spleen.
Leukocytes: WBC defense and immunity
Monocytes
Lymphocytes
Basophils
Eosinophils
Neutrophils
Platelets: blood clotting

Lymphatic System: 2 functions
Circulatory function
Collect excess fluids/plasma proteins (stranded fluid) from surrounding tissues and return them to deoxygenated blood in right atrium
Immune function
Filters lymph. Has WBC waiting in lymphatic organs and lymph nodes to trap antigens/lyse them.
Consists of the following components:
Lymphatic organs:
Thymus
Spleen
Tonsils/adenoids
Appendix
Peyers’ patch on small intestines
Lymph vessels
Return excess fluids, plasma proteins, and leukocytes from the interstitial spaces throughout the body to the blood (interstitial fluids; also called edema)
Lymphatic system drains into the circulatory system at the junction of vena cava with the right atrium
Lymph nodes: small bodies interspersed along lymphatic vessels
Act as cleaning filters and immune centers against infection
Get large with infections/cancer

Spleen
Largest lymphatic organ (5 inches long); on left side, between diaphragm and stomach
Filters the blood for immune function
Destroys old RBC/recycles Fe+2
Provides reservoir of blood
Spleen (and liver) produce RBC and WBC during fetal development (before bone takes over)

Cholesterol: white, fatty substance in blood serum
LDL: Low density lipoprotein (Bad cholesterol)
Deposits in artery walls, increasing plaque buildup
HDL: High density lipoprotein (Good cholesterol)
High levels of HDL actually good for you and lowers risk of Coronary Artery Disease because it clears cholesterol out of your system
Levels raised by exercise, eating unsaturated fats.

Chapter 43

Innate Immunity (born with): rapid non-specific responses to a broad range of microbes
External Defenses:
Skin: pH 3-5
Mucous membranes: in respiratory tract has mucus and cilia to filter/trap microorganisms. Wet tissue, anywhere there is an opening.
Secretions of skin/mucous membranes: enzymes called lysozymes in body secretions lyses pathogens’ cell wall (in saliva, tears, etc)
Symbiotic bacteria (in digestive tract, in vagina)
Outcompetes other organisms that could cause damage
Antibiotics throw this off
Internal Defenses:
Phagocytic WBC: protect us by phagocytosis, engulf and attack free-roaming germs.
Antimicrobial Proteins:
Interferons
Nonspecific, antiviral proteins. They have a broad spectrum of activity against both DNA and RNA viruses
Thought to be the cure of AIDS in the 1980s
Still used in treatment for Multiple Sclerosis, hepatitis
Complement Proteins
Group of 20 blood proteins
May team up to form a membrane attack complex (MAC) on plasma membrane and lyse pathogens’ membranes
Inflammatory Response
Body’s way to keep things local and to take care of things before they become more complex.
Nonspecific reaction to an injury to prevent spread of pathogens
Causes redness, swelling, heat, pain.
Dying cells release histamine, which increases vascular permeability. Edema occurs (accumulation of fluid in tissues)
Neutrophils arrive first, then monocytes that develop into macrophages in interstitial fluid.
Destroy invading microorganisms, dead tissue, new tissue made, fluid, fibrin, dead cells removed by leukocytes (WBC)
Fever: reaction to infection. Creates hostile environment for bacteria (too hot).

Acquired Immunity (developed, not born with): slower, specific response
Needs to be developed from previous exposure to antigen or vaccine
An antigen is an antibody-generating foreign body
Then a protein response to the foreign body occurs (called antibody or immunoglobulin)
Uses lymphocytes. One of five types of leukocytes/WBCs
4 characteristics of acquired immunity:
Specificity: specific to that pathogen
Self/non-self recognition: glycoproteins and glycolipids on surface of plasma membrane, as unique as fingerprints.
Diversity: works for many different kinds of pathogens; viruses, bacteria..
Memory: prior exposure or vaccine
Memory B cells and memory T cells remain in our bodies for later encounters
Gives us long-lasting immunity (1 year)
Vaccination induces this immunity by using dead or weakened germs

Humoral (antibody-mediated immunity) vs. Cell-mediated immunity
Humoral immunity (antibodies or Ig)
Works in blood/fluids
Uses B lymphocytes (B cells that originate in bone marrow)
Which works by using antibodies
Works on mainly bacteria
Cell-mediated immunity (cytotoxic lymphocytes)
Works in infected cells, early cancer
Uses killer T lymphocytes (T8s), killer T cells
Targets viruses inside body cells

T cells in AIDS
Helper T cells are destroyed by the virus.
Virus makes the body attack it’s own immune system. Once the T cells are knocked out, the whole thing is knocked out.

Chapter 44

Osmoregulation
Balances the uptake and loss of water and solutes
Expressed as osmolarity- total solute concentration as moles of solute/liter of solution
Higher osmolarity---more solutes (i.e. Thicker), hyper-osmotic
Lower osmolarity--- dilute, hypo-osmotic

Excretion
Animals have excess nitrogenous wastes from nitrogen-containing foods that they metabolize for energy, specifically proteins and nucleic acids. These wastes are excreted as either ammonia, urea, or uric acid.
Ammonia
Excreted by most aquatic animals, including most bony fishes
Because it is so toxic, these animals have access to lots of water to excrete it
Easily diffuses across body surface into surrounding water
Urea
Excreted by mammals, most amphibians, sharks, and some body fishes
100,000 times less toxic than ammonia
Produced in the liver by combining ammonia with carbon dioxide and then the circulatory system carries the urea to the kidneys
Uric Acid
Excreted by insects, many reptiles, and birds
Insoluble in water and excreted as a semi-solid paste called guano (bird droppings are a mixture of white uric acid and brown feces)
Allows animal to conserve its body fluid
Humans excrete mainly urea, but also a little bit of uric acid
Gout: human illness of excess uric acid in joints; mainly seen in males; alcohol and red meat makes it worse “rich man’s disease”

Key Functions of Excretory Systems
Most excretory systems start by pressure-filtering blood (and then getting a filtrate=early urine) and then modifying the filtrate’s content
Filtration: pressure-filtering blood, producing a filtrate. Lose about 20% in bowman's capsule.
Reabsorption: returning valuable solutes to blood (e.g. Glucose, vitamins, ions). “Keep the keepers”
Secretion: removes toxins, etc from blood to filtrate (get rid of the junk)
Excretion: discharging unwanted solutes as urine

Anatomy of Human Excretory System
2 kidneys
Built of compact excretory tubules (nephrons) surrounded by a dense network of capillaries
Nephrons: functional unit of kidneys (i.e. Excretory tubules)
Each kidney has about 1 million nephrons
80% are cortical nephrons (short ones)
20% are juxtamedullary (long ones), which have the Loop of Henle extending down into the inner renal medulla (long ones). These nephrons are responsible for producing urine that is Hyper-osmotic(more concentrated) to blood.
Several nephrons empty into each collecting duct, which drains into the renal pelvis.
Filter blood and restore selected amounts of water and solutes to blood
2 ureters
1 urinary bladder
1 urethra

Nephron
Bowman’s Capsule (renal capsule that surrounds the glomerulus, a ball of capillaries found inside)… where pressure filtration occurs
Proximal convoluted tubule
Reabsorption of 75% NaCl, 75 % H2O
Secretion H+, NH3 into filtrate
Loop of Henle (descending and ascending limbs)
Descending limb:
Permeable to H2O, but not salts
Reabsorption of H2O
Therefore, tip has very high osmolarity as urine becomes more concentrated.
Ascending limb:
Permeable to salt, but not to H2O
Reabsorption of NaCl
Therefore, urine becomes more dilute again
Distal convoluted tubule (backup)
If it didn’t happen in proximal convoluted tubule, it happens here.
Reabsorption of NaCl, H2O, HCO3
Secretion of K+, H+ into urine
Collecting duct
Permeable to H2O but not to salt; therefore, reabsorb lots of H2O
Urine gets more and more hyper-osmotic from urea, NaCl excreted in urine.

Flow of blood through kidneys:
Aorta, renal artery (oxygenated), afferent arteriole, glomerulus (ball of capillaries in Bowman’s Capsule), efferent arteriole, peritubular capillaries (surround proximal/distal tubules), vasa recta (capillaries surrounding Loop of Henle), (deoxygenated) renal vein, vena cavae

Hormonal Control of Kidneys
Antidiuretic Hormone (ADH); also called Vasopressin
Stimulus: high blood osmolarity; triggers osmoreceptors in hypothalamus to have posterior pituitary gland release ADH
End result: helps fluid retention by making kidneys keep more water.
Dehydration or eating salty foods (high blood osmolarity)… hypothalamus in brain… release ADH (vasopressin) stored in posterior pituitary gland… increases permeability of Collecting Duct… increases H2O reabsorption… results in lower blood osmolarity and higher blood volume/higher blood pressure.
Hypothalamus also causes thirst, drinking reduces blood osmolarity.
Renin-Angiotensin-Aldosterone System (RAAS)
Stimulus: low blood pressure or blood volume triggers JGA in kidneys to release rennin (due to dehydration of blood loss)
End result: leads to an increase in blood volume and blood pressure
Dehydration or loss of blood… JGA (juxtaglomerular apparatus)… releases renin… Converts angiotensinogen...into angiotensin II… constricts arterioles, increases BP, increases blood volume by increasing reabsorption of water, salt… increases blood pressure, volume
Angiotensin II also… stimulates adrenal cortex to release aldosterone… hormone that increases reabsorption of H2O, salt in distal tubules… increases blood pressure and volume.

Roles of Liver in Homeostasis… detoxifies harmful chemicals
Converts blood glucose into glycogen (command of insulin from pancreas); stores glycogen
Interconversion of nutrients: carbs into fats; amino acids into carbs or fats
Deaminates amino acids (removes NH2); converts NH3 into urea
Synthesizes bile, stores it in gallbladder
Produces plasma proteins and plasma lipids
Destroys old, injured RBCs
In embryo, produces RBCs (because embryo doesn’t have bone marrow yet)
Stores vitamins and iron.

Chapter 45

Pancreas: glucose homeostasis
Releases insulin (beta cells), to lower blood glucose
Converts glucose into storage polysaccharide, glycogen and stores it in liver and muscles
Protein synthesis and fat storage
Releases glucagon (alpha cells), to raise blood glucose
Gets liver and muscles to release glycogen and then breaks it down to glucose

Type I Diabetes Mellitus
Autoimmune disorder with elevated blood glucose
Pancreas makes little or no insulin
Seen in children
Insulin-dependent (must take insulin for rest of their lives)

Type II Diabetes Mellitus
Not an autoimmune disorder
Still make insulin, but target cells less responsive to insulin
Developed from poor eating habits
Seen mainly in adults over 40 years of age; although now seen more in overweight, sedentary children
Non-insulin dependent (take either medications or insulin)
Heredity involved in this predisposition
Need to change life style: diet, lose weight, exercise, low sugar/carbohydrate diet

Hormones necessary for blood calcium homeostasis
Thyroid Gland releases calcitonin
Good for you
Lowers blood calcium levels
If blood calcium levels rise too high, the thyroid gland releases calcitonin; this lowers blood calcium 3 ways: stimulates calcium deposition into bones, reduces calcium reabsorption in intestines, and reduces calcium reabsorption in kidneys
Parathyroid Glands release parathyroid hormone (PTH)
Opposite effect of calcitonin, bad for you
Raises blood calcium levels
If blood calcium levels fall too low, the parathyroid glands release PTH; this raises blood calcium levels 3 ways: by stimulating calcium release from bones, and increasing calcium reabsorption in kidneys. It also stimulates kidneys to activate vitamin D, which promotes intestinal reabsorption of calcium from food.
If you lack PTH, blood calcium drops very low, get skeletal contractions, and ultimately tetany.

Adrenal Glands:
Adrenal Medulla (inner): short-term stress response
Releases epinephrine (adrenaline) and norepinephrine (noradrenaline)
These are catecholamines that regulate “fight or flight” response
Raises blood glucose, increases metabolic activities, constricts certain blood vessels, increases heart rate, increase BP
Target organs: blood vessels, liver, heart
Adrenal Cortex (outer): long-term stress response
Releases glucocorticoids (cortisol, hydrocortisone)
These are steroids that raise blood glucose (may become diabetic)
Makes you retain fat (heart disease)
Decreases immune function
Releases aldosterone
This promotes reabsorption of sodium (increase BP), reabsorption of water (bloating, heart disease) by kidneys
Gonads:
Testes: Male gonads
Release androgens like testosterone
Promotes primary sex characteristics and secondary male sex characteristics
Ovaries: Female gonads
Release estrogens like estradiol
Stimulates uterine lining growth, and promotes secondary female sex characteristics
Releases progesterone
Promotes uterine lining growth, and pregnancy
All 3 types of sex hormones, estrogens, progestins, and testosterone, are produced in males and females but in different proportions. All are produced from the molecule cholesterol.

Chapter 46

Male reproductive tract
External genitalia:
Scrotum (scrotal sac)
Contains testes (which are the gonads)
Holds them below abdominal cavity
Body temperature too hot for sperm formation
Penis
Internal reproductive organs:
Gonads (testes) that produce gametes and hormones
Accessory glands that secrete products essential for sperm movement
Set of ducts that carry sperm and glandular secretions
Testes: Male gonads
Consist of many highly coiled tubes surround by several layers of connective tissue
The tubes are called the seminiferous tubules, where sperm are produced
Leydig cells: between seminiferous tubules, where testosterone is made
Epididymis
From the seminiferous tubules (where sperm is made) of testes, the sperm pass into coiled tubules of epididymis
Epididymis is where sperm mature and are stored for about 20 days
During passage, sperm become motile and gain ability to fertilize
Vas Deferens
During ejaculation, sperm are propelled from epididymis through muscular vas deferens
2 ducts (one from each epididymis) run from scrotum around/behind urinary bladder, where each joins a duct from the seminal vesicle; these combine to form the short ejaculatory duct
Ejaculatory duct opens into the urethra
Urethra is the tube that drains both the male excretory and reproductive systems
Urethra runs through penis and opens to outside at tip
3 sets of accessory glands
Seminal vesicles
A pair of glands behind bladder
Contributes about 60% of total semen volume
Prostate Gland
Largest gland
Secretes directly into urethra
Contains citrate, and an anti-coagulating enzyme
Slightly acidic
Source of many medical problems in men over 40
Cowper’s (Bulbourethral) gland
A pair of small glands along the urethra, below prostate
Before ejaculation, secretes a clear mucus that neutralizes any acidic urine remaining in urethra
Also carries some sperm which is released BEFORE ejaculation.
Penis
Composed of 3 cylinders of spongy, erectile tissue
Main shaft of penis covered by relatively thick skin
Head, called the glans penis, is much thinner covering

Female reproductive tract
External Genitalia
Clitoris
2 sets of labia
Internal reproductive organs
A pair of female gonads (ovaries)
A system of ducts, chambers to conduct gametes and house embryo and fetus
Ovaries (female gonads)
Lie in abdominal cavity
Follicle: consists of one egg cell surrounded by one or more layers of follicle cells
The egg cell is expelled from follicle in the process called ovulation
The remaining follicular tissue grows within the ovary to form solid mass called corpus luteum
This secretes additional estrogens and progesterone (maintains uterine lining during pregnancy)
If egg cell is not fertilized that month, the corpus luteum disintegrates and new follicle will mature next cycle
Ovarian cancer is very aggressive, difficult to diagnose early
Oviducts (Fallopian Tubes)
Leads from ovaries to uterus
Where fertilization of egg takes place
Egg cell is released into abdominal cavity near opening of oviducts
Have funnel-like opening
Uterus
The womb
Thick, muscular organ that can expand during pregnancy
Inner lining: called endometrium
Cervix
Neck, or opening of uterus. Opens into vagina
Vagina
Thin-walled chamber that forms birth canal
Also the repository for sperm during copulation
Hymen: vascularized membrane that partly covers vaginal opening
Vestibule
Area that contains vaginal opening orifice and separate urethral opening
Bordered by a pair of slender skin fold called labia minora
A pair of think, fatty ridges called the labia majora protects/encloses labia minora and vestibule
At front end of vestibule, clitoris (which is erectile tissue) consists of shaft, glans, and prepuce
During sexual arousal, the clitoris, vagina, and labia minora all engorge with blood and enlarge
Bartholin’s gland
Located near vaginal orifice
Secretes mucus into vestibule for lubrication and to facilitate intercourse
Mammary glands
Present in both sexes
Normally function only in females
Not part of reproductive tract, but important for reproduction
Small sacs of epithelia tissue that secrete milk, which drains into a series of ducts that open at nipple
Low levels of estrogen in males prevents development of secretory apparatus, development of fat deposits (so male breasts remain small); nipples not connected to ducts
Males can, however, develop breast cancer.

Estrogen
Produced by follicle monthly
Puberty for females (around age 11, 12)
Maturation of female sex organs (breast), pubic hair, curves, taller, acne, menstrual cycles, can be sexually active/pregnant
Thickening of uterine lining monthly

Progesterone
Produced by corpus luteum of ovaries
Thickens uterine lining monthly (enlargement of uterus)
Growth of placenta and further breast development, if pregnant
Inhibits uterine movement, preventing stillbirths, if pregnant

Chapter 47

4 Major Stages of Embryonic Development
Fertilization
Cleavage
Gastrulation
Organogenesis

Fertilization
Formation of zygote (diploid fertilized egg) by the fusion of haploid egg and haploid sperm; involves 4 steps
Contact/recognition between acellular egg coverings and sperm
Mammalian egg covered by zona pellucida; this is receptor for human sperm; echinoderm egg covered by vitelline envelope and jelly coat
When sperm contacts egg, undergoes acrosomal reaction; hydrolytic enzymes released to allow penetration of coverings
Sperm entry regulated to prevent polyspermy and/or interspecies fertilization
Depolarizes egg cell membrane; called fast block to polyspermy
Cortical granules are released; called cortical reaction
Formation of fertilization envelope; called slow block to polyspermy
Requires high concentration of Ca+2 in egg
Fertilization activates egg (the high Ca+2), triggering early development
Fusion of egg and sperm restores diploid condition

Cleavage
A series of rapid cell divisions that divide zygote into a many-celled embryo
Occurs in oviduct
Results in large number of blastomeres
Holoblastic cleavage: division of the entire egg
Occurs in species whose eggs have little/moderate amounts of yolk
E.g. Sea urchins, frogs, mammals
Meroblastic cleavage: incomplete division of egg
Occurs in species with yolk-rich eggs
E.g. Birds, other reptiles

Gastrulation
Blastula folds in on itself to lay down a basic body plan of 3 germ layers
3-layered embryo with a primitive digestive cavity, called a gastrula
Each germ layer gives rise to specific structures
Ectoderm: outer layer of embryo
Epidermis of skin and derivatives
Nervous/sensory systems
Germ cells
Mesoderm: middle layer
Muscular/skeletal systems
Dermis of skin
Circulatory/lymphatic systems
Endoderm: inner layer
Epithelial lining of digestive system
Epithelial lining of respiratory, excretory, and reproductive systems
Gastrulation in Humans:
The blastocyst (the name for a blastula in mammalian development) reaches the uterus, 3 days after fertilization
Outer trophoblast, gives rise to amnion and chorion
Inner cell mass called the epiblast, gives rise to the embryo itself
Blastocyst implants in endometrium of uterus, 7 days after fertilization
Extra-embryonic membranes start to form (10-11 days) and gastrulation begins (13 days)
Gastrulation has produced:
A 3-layered gastrula, which becomes embryonic tissue
4 extra-embryonic membranes, protect embryo; help it obtain food, oxygen, and eliminate wastes
Embryos of mammals, birds, other reptiles develop within a fluid-filled amnion sac either within a shell or in the uterus
Throphoblast, cells from epiblast, and endometrial tissue form placenta
After 2 months of development, the embryo is now called a fetus

Organogenesis
Process of organ development
Changes gastrula into early organs from which adult structures grow
Early events for vertebrates
Neurulation: formation of the notochord (by cells of dorsal mesoderm), will make vertebral disks in adults
Development of neural tube (from infolding of ectodermal neural plate), makes the brain and spinal cord
In humans, an error in neural tube formation results in spina bifida
Neural crest: vertebrate cells near neural tube that will make skull bones and bones of teeth

Chapter 48

Central Nervous System (CNS)
Brain
Spinal Cord
Develop from dorsal, hollow nerve cord of chordates

Peripheral Nervous System (PNS)
Cranial nerves: originating in the brain
Spinal nerves: originating in the spinal cord
Ganglia outside CNS

5 steps of vertebrate Nervous system
Detection of stimulus by sensory receptor cell
May be a neuron (nerve cell) or specialized cell
Conduction of signal by sensory neurons to CNS
Interpretation of stimulus by CNS
Conduction of signal by motor neurons effector
Response by target cell
Muscle cell or gland cell

2 Main Classes of Cells
Neurons: nerve cells that conduct nerve impulses
Consists of:
Dendrites: receive information
Cell body
Axon: Transmits away; longer/thicker and extends away from axon hillock; sends signals to other cells at synapses
Myelin sheath: supporting cells along their length that wrap around axon
Axon hillock: neuron’s integrating center
Supporting cells: provide structural reinforcement, protection, insulation, and nourishment to neurons
Called satellite cells, neuroglias or glias
3 types of neuroglias in CNS:
Astrocytes: line blood/brain barrier in brain
Microglia: serve as macrophages in nerve tissues
Oligodendrocytes: form myelin sheath in CNS
The neuroglias in PNS called Schwann cells
Form myelin sheath in PNS
Gaps between Schwann cells are called Nodes of Ranvier

Membrane potential
Resting potential: membrane potential of an unexcited neuron/muscle cell (-70 mV). More negative on the inside.
Gated ion channels: special ion channels which allow the cell to change its membrane potential in response to stimuli. Go through gates.

Action potential
Brief, all-or-none strong depolarizing stimulus which opens even more Na+ channels; even more Na+ enters cell, inside becomes at least as positive as threshold potential; triggers action potential or nerve impulse to be initiated.
“all or none” event. Size of AP not affected by strength of stimulus
After AP, there is a refractory period (neuron unable to fire for about 1-2 msec) where a 2nd AP cannot be initiated.

Propagation of AP (conduction)
Nerve impulse travels from axon hillock to synaptic terminals by propagation of a series of APs along axon
AP is generated as Na+ ions flow inward at one location
Depolarization of 1st AP spreads to neighboring region of membrane, depolarizing it, and initiating 2nd AP. At 1st AP, membrane is repolarizing as K+ flows out
Speed of conduction increases with diameter of axon, and with meylination

Saltatory conduction
The AP does not propagate along the axon in a continuous fashion. Instead, it jumps from one node of Ranvier to another. Called salutatory conduction. Faster.
This is the reason why people with nervous system (MS) that cause myelin sheaths to disintegrate (causes demyelinated axons) have poor nerve conduction.

Chemical Synapse
Synapse: juncture between 2 neurons; also found between a receptor and a neuron or between a neuron and an effector cell
Synaptic cleft: gap between terminal end of presynaptic cell (transmitting cell) and the postsynaptic cell (receiving cell)
Synaptic knob: small swelling at end of each axon of neuron
Also called synaptic terminal or bouton
Synaptic vesicles: numerous sacs within synaptic knob containing thousands of molecules of neurotransmitters.

Depolarization/repolarization
Triggers influx of Ca+2
Causes synaptic vesicles to fuse with membrane
Vesicle release neurotransmitters into synaptic cleft
Neurotransmitters bind to ligand-gated ion channels (receptors) on postsynaptic membrane
Causes either an excitatory or inhibitory postsynaptic potential (EPSP or IPSP)
AP continues in new neuron
Neurotransmitter molecules quickly degraded by enzymes, diffuse out of cleft, or taken up by surrounding cells, thus ending synaptic response.

Major known neurotransmitters
Acetylcholine
One of the most common neurotransmitters
Alzheimer’s disease (ameloid plaques) and myasthenia gravis (weakness of skeletal muscles) may be caused by a decrease
Epinephrine/Norepinephrine
Can be excitatory or inhibitory
Serotonin: derived from a.a. Tryptophan (the sleepy amino acid)
Dopamine and Serotonin are widespread in brain
Both affect sleep, mood, attention, learning, and anxiety
LSD, mescaline: produce hallucinatory effects by binding to serotonin and dopamine receptors in brain
Lack of dopamine: Parkinson’s Disease
Excess dopamine: schizophrenia
Lack of serotonin: ADHD; IED (intermittent explosive disorder/ road rage)
Excess of serotonin: schizophrenia (delusions, hallucinations, withdrawal)
Amino acids that function as neurotransmitters:
GABA (gamma amino-butyric acid)
GABA most common inhibitory neurotransmitter in brain
Drugs that increase GABA function have been used to treat epilepsy
Substance P
Excitatory for pain perception, makes pain feel worse
Met-enkephalin: an endorphin
Inhibitory for pain perception, makes pain feel less intense
Exercising regularly increases endorphins and make you feel happy =D

Chapter 49

Peripheral Nervous System (PNS)
Sensory (afferent) Division
Motor (efferent) Division

Sensory (afferent) Division
Sensing external environment
Sensing internal environment

Motor (efferent) Division
Somatic NS
Autonomic NS

Somatic NS
Voluntary control; innervates skeletal muscle

Autonomic NS
Involuntary control; innervates 12 cranial and 31 spinal cord nerves
Has 3 division:
Sympathetic Division
Parasympathetic Division
Enteric Division

Sympathetic Division
Functions in an emergency. “Fight or flight”/short-term stress
Uses adrenaline (epinephrine) and noradrenaline (norepinephrine) as neurotransmitters

Parasympathetic Division
Functions to conserve energy
Uses acetylcholine as neurotransmitter

Enteric Division
Control secretions of digestive tract, pancreas, gall bladder, peristalsis

Brain and Spinal Cord of CNS
Brain
White matter-inner region
Gray matter- outer region
Spinal Cord
White matter- outer region
Looks white from myelin sheaths on axons
Gray matter- inner region
Looks gray due to aggregate of cell bodies/synapses
Integrates simple responses and carries information to/from brain
Structural and functional areas of brain
Forebrain
Cerebrum (Cerebral Cortex): Cerebral Hemispheres
4 lobes in 2 hemispheres connected by corpus callosum: large fiber tracts not visible from surface
Most complex integrating center in CNS
Controls conscious perception, thought, and voluntary motor activity; can override most other systems; “the boss”
Frontal lobe
Personality defects, speech, aggression, motor
Parietal lobe
Speech, taste, reading, somatosensory
Occipital lobe
Vision
Temporal lobe
Smell, hearing
Thalamus
“relay station” for sensory information to cerebrum
Reticular system found here
Densely interconnected network of neurons that connect medulla, midbran, thalamus
Responsible for sensations, like pain, body temperature, touch
Hypothalamus
Regulation of homeostasis and endocrine function
Controls thirst, hunger, body temperature, water balance, reproductive functions, blood pressure, emotions, hormones
Regulates pituitary glands
Midbrain (part of brainstem)
Integration of sensory information
Pupillary and visual reflexes
Coordination of movement
Auditory pathways
Primitive functions
“Pupils are fixed and dilated”
Hindbrain
Homeostasis, data conduction, coordination of movement
Pons: reflex center (part of brainstem)
Controls respiration
Cerebellum
Balance
Muscular coordination and tone
Involved in learning motor skills/intentional movement
Medulla oblongata: junction of brain and spinal cord (part of brainstem); reflex and homeostatic functions
Heart rate, BP
Respiration/breathing
Vomiting, swallowing, digestion
Coughing, sneezing
Temperature regulation

Right vs. Left brain: connected by corpus callosum
Left Hemisphere (“nerdy”)
Calculations, math, logic
Language
Right Hemisphere (“artistic”)
Artistic ability
Spatial perceptions, pattern recognition
Emotional processing

Language and Speech
Left hemisphere contains 2 ares
Broca’s area, speech generation
Located in the primary motor cortex (frontal lobe) that controls muscles in the face
Stroke causes loss of speech
If you have a stroke here, you will understand speech, but will not be able to speak
Wernicke’s area, speech comprehension
Posterior portion of the temporal lobe
Stroke causes incomprehension of speech, but you will generally be able to mechanically speak.

Arousal and sleep
Arousal: state of awareness of external world
Sleep: not conscious of stimuli
Measured by electrical activity
EEG- electroencephalogram
Alpha waves- awake, resting
Slow, synchronous waves
Beta waves- person alert
Fast waves, spiky
Delta waves- person asleep
Slow, highly synchronous waves
Precordial jerk: large shake of body as you fall asleep; body’s way of relaxing
REM: rapid eye movement; dreaming
Loss of motor output to brain
Alternates with delta waves during sleep
90 minute cycle containing 20-30 minutes of REM sleep (this is most of your dreaming)
Arousal/sleep controlled by centers in cerebrum and brainstem (pons, medulla, midbrain)

Emotions
Complex interplay of many regions of the brain
Mediates primary emotions and attaches “feelings” to survival-related functions
Mainly the limbic system, a ring of structures around the brainstem
Consists of 3 parts of the cerebral cortex
Amygdala, Hippocampus, Olfactory bulb

Memory and learning
Short-term memory: holds information, anticipation, and goals
Location: frontal lobes… releases them if they become irrelevant
Long-term memory: holds information we wish to retain
Location: hippocampus and amygdala