Anatomy and Physiology

Cell Organelles

There are 50 trillion (50 million million) cells in the human body; they carry out chemical reactions essential to life, for example Blood cells.

Nucleus
The nucleus is the largest structure in any human cell, it contains gasps or pores, which allow protein and nucleic acid, pass through. It is the central part of the cell and it’s usually a lot darker than the rest of the cell because it absorbs stain quickly and stores the entire DNA (Deoxyribonucleic Acid) in the human body.

Cytoplasm
The cytoplasm is a semi-fluid material made up of salt and water, likened to a gel, which carries chemical reactions that take place in the body. It contains enzymes responsible for breaking down waste and aid in metabolic activity. And means cell material refers to anything inside the cell boundary and outside the nucleus.

Mitochondria
Concerned with energy release - each have a double-layered membrane and each inner layer is folded at intervals producing shelves or ridges known as cristate. They help cells to maintain proper concentration on calcium ions.

Smooth Endoplasmic Reticulum (ER)
Studded with tiny black bodies used to fill the cell interior, has a similar structure to the cell membrane. They have no attached ribosomes and are involved in the metabolism of lipids or fats.

Rough Endoplasmic Reticulum (ER)
With ribosomes attached to it’s membrane which makes it rough, it is also attached to the nuclear envelope that surrounds the nucleus, allowing movement of molecules through both membranes. It is involved with protein production and folding, quality control and dispatch.

Golgi Apparatus
Found in most cells it lies close to the main stack and it stacks up together like pancakes, they are a series of flattened filled stacks and are often known as vesicles. Although they look similar to the Rough ER, they do a completely different thing, they gather and combine simple molecules and make them more complex, packaging them into vesicles then either storing them or sending them out of the cell.

Lysosomes
Contains strong enzymes that destroy worn out organelles sometimes known as “suicide bags”. It is a specialized vesicle that holds the variety of enzymes; the purpose of this is to digest things such as food, or a cell when it dies.

Tissue Types

Tissues are a group of cells that combine together for a particular task and are similar in structure and function, for example muscles. There are 4 different types of tissue:

The epithelium tissue
Covers and lines the surfaces of the body * Used for protection, for example the skin protects us from sunlight, bacteria and physical damage. * It can absorb anything that enters the body for example the lining of the small intestine absorbs nutrients into the blood. * It filters things, for example the lining of the kidney tubules filters the waste from your blood. * It is used for secretion; different glands produce perspiration, oils, digestive enzymes and mucus. * The cuboidal epithelium is I single layer of cube shaped cells that are used within the secretion and transportation in glands and the filtration in kidneys. * The ciliated epithelium is made up of irregularly shaped cells with nuclei at different levels; they are used in secretion and absorption and secretion. They also have goblet cells that produce mucus and the cilia (larger than microvilli) on top that sweep the mucus.
Connective Tissue
Used for support, such as bones, ligaments and fat, they bind and support other tissues in the body. There are several types of connective tissue: * CT Proper – tendons and ligaments * Bones * Blood * Cartilage * Add * Adipose tissue – fat

Muscle Tissue
Used for movement in the body, it is able to contract for locomotion; there are 3 types of muscle tissue: * Skeletal – voluntary muscles with cells that are sirated and multinucleate, the muscles are attached to the bones to create the voluntary movement * Cardiac – only found in the heart * Smooth – found in the digestive system

Nervous Tissue
Has control through the body found in the brain, nerves and spinal chord, it responds to stimuli and transmits impulses. * The cells in a nervous tissue are called neurons * They are composed of cell body, axon and dendrites * A single cell may run up to several foot long

Skin Tissue * The skin is water resistant; this is because if our skin absorbed water we would expand like sponges. * It can also cool your body down and control the temperature of your body, for example when you get hot your skin opens up sweat glands which releases moisture onto your skin to help cool you down, and when you get cold your skin gets goose bumps and you start to shiver to try and help you warm up. This is called thermo-regulation. * Your skin has a protective barrier that helps to keep out infections in your body. * It holds everything in, without your skin you would just be a skeleton and all of your vital organs and muscles would be seen. * It provides UV protection, with out this people would develop skin cancer, but it absorbs the ‘good’ Vitamin D from the sun. * Protects you from friction damage, microorganisms and UV radiation. * It relays nerve impulses to inform the brain of changes in the external environment, for example if it gets hotter or colder, and if you are experiencing pain or pressure through touch. * The skin is also the largest organ in the human body.

Stomach Tissue * The layers of muscle in the stomach help to contract the stomach, mixing and propelling food through the digestive system. * The outer layer of the stomach is called the serosa – a thin membrane that’s made up of simple squamous epithelial tissue and areola connective tissue. * The inner layer is known as the mucosa – made up of mucus membrane, containing simple columnar epithelium.

Main Body Systems

Cardiovascular (the heart)
The cardiovascular system provides oxygen and nutrients to the cells in our body, as they require this to survive; these cells produce waste such as carbon dioxide, which needs to be removed from our bodies. The cells also need to fight off any infectious diseases that may enter our bodies and cause harm to our health. To provide for the cells the cardiovascular system relies on other body systems to help it such as the circulatory system and the lymphatic system.

The circulatory system transports the blood through our body; the system includes the heart, arteries, arterioles, venules and veins. The circulatory system delivers oxygen rich blood to the organs, tissues and cells, which helps them do the right job within the body. The lymphatic system helps the body and cells fight off infectious diseases in the body.

Respiratory System
The respiratory system is made up of the sinuses, throat, trachea, lungs and the bronchioles, and delivers oxygen to the cardiovascular system. Before oxygen is deposited into the blood stream is has to find its way to the lungs, and any carbon dioxide should be released out of the body.

Digestive System
The digestive system starts at the mouth where the food enters the body and is partly broken down by chewing and the chemical actions in the salivary enzymes. The food is then swallowed and enters the esophagus (the food pipe), which runs down from the mouth to the stomach using wave-like muscle movements called peristalsis to force the food through, this gives us the ability to eat or drink even when we’re upside down.

The stomach then churns the food and bathes it in gastric acid; the food is only partly digested and now mixed with stomach acids. After being in the stomach the food goes into the duodenum, the first section in the small intestine, before passing through the jejunum and the final section of the small intestine, the ileum. In this process bile - produced by the liver - pancreatic enzymes and other digestive enzymes from the wall of the small intestines help to break down the food.

In the large intestine some of the water and electrolytes are removed from the food, many microbes (bacteria) in the intestine help the process. The first section of the large intestine is the cecum, which has the appendix attached to it. Food then travels up the ascending colon, across the abdomen and in the transverse colon, going back down through the body in the descending colon and finally through the sigmoid colon. The solid waste is then stored in the rectum before exiting through the anus.

Renal System (Urinary System)
The renal system eliminates waste from the body and is able to control levels of electrolyte and metabolites. It includes the kidneys, ureter, bladder and urethra. Metabolic wastes and excess ions are filtered out of the blood, mixed with water and leave the body as urine. It also has a control of blood volume and water content called osmoregulation.

Nervous System
The nervous system is used to receive and transmit stimuli to nervous centers and get a response. The central nervous system consists of the brain and the spinal chord and is the collection point of nerve impulses. The peripheral sensory nervous system is the system and it receives stimuli, the central nervous system interprets them and then they are initiated by the peripheral motor nervous system.

Endocrine System
The endocrine system involves all the glands in the body and the hormones they produce. The glands are directly controlled by stimulation from the nervous system and chemical receptors in the blood. The glands help to maintain the body’s homeostasis by regulating the functions of the organs in the body.

Reproductive System
The reproductive or genital system is a set of organs that work together to produce offspring. Most organ systems in the human body are the same in both males and females, but not in the reproductive system; for example a female reproductive system has ovaries, whereas a male has testicles. A males reproductive system is mainly made up of external organs, for example the testes in the scrotum produce sperm, which are then ejaculated through the penis.
A females reproductive system is mainly made up of internal organs, the ovum is produced in the ovaries, and once monthly the ovum travels through the fallopian tube to the uterus to start the menstrual cycle.

Lymphatic System
The lymphatic system is made up of capillaries, vessels, nodes, and other organs that transport a fluid called lymph through the body from tissues as it returns to the bloodstream. The lymphatic tissues in these organs filter and clean the lymph of any pathogens, debris or abnormal cells. The system also transports any fatty acids to the circulatory system from the intestines.

Musculo-skeletal System
The primary function of the Musculo-skeletal system is to support to body, allowing both protection of vital organs and movement. It is made up of the skeletal bones, cartilage, muscles, tendons, joints, ligaments and any other connective tissue that supports the body, serving as a main storage system for phosphorus and calcium.

Immune System
The immune system is a bodily defense system against infections and diseases, it has an immune response, which attacks organisms and substances that invade the body systems and cause diseases. The first line of defense of your immune system is your skin, the membranes lining your respiratory, digestive, urinary and reproductive tracts and sticky mucus and fluids in your eyes, noes, ears and mouth.
The second is your immune system, the complex system of white blood cells in your body that need to work together to be effective.