Digestive and Respiratory System Worksheet

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Before answering the questions below, log in to ADAM and view the clinical animations for Peristalsis and Gas Exchange. Remember, you may use our text, our discussions, and the internet to write your answers, but be sure to write your answers in your own words and to use correct citations where appropriate! Cutting and Pasting your responses will result in a Zero for this assignment!

1. Trace the path of an oxygen molecule from the air outside you to your tissues.

Nose --> Mouth --> Pharynx --> Larynx --> Trachea --> (LUNGS: Bronchus --> Bronchioles --> Alveoli), then back out.

Air enters the body through the nose and then moves into spaces called the nasal cavities.
(Hair and cilia trap dust and debris and Air is warmed and moistened)
Some of the cells lining the nasal cavities produce mucus. This sticky material moistens the air and keeps the lining from drying out. Mucus also traps particles such as dust. The cells that line the nasal cavities have cilia, tiny hair like extensions that can move together in a sweeping motion.

Next, air enters the pharynx. The pharynx opens to two different passages. One is connected to the esophagus, wherein food and fluids are directed and the other is linked to the trachea where the air is passed through to the lungs.

From the pharynx, air enters into the larynx (the voice box). The larynx is part of the upper respiratory tract that has two main functions: a passageway for air to enter into the lungs, and a source of vocalization. The larynx is made up of the hyoid bone and cartilage, which helps regulate the flow of air. The epiglottis is a flap-like cartilage structure contained in the larynx that protects the trachea against food aspiration.

Air the moves into the trachea. The firm ridges are rings of cartilage that strengthen the trachea and keep it open. The trachea is lined with cilia and mucus. The cilia in the trachea sweep upward, moving mucus toward the pharynx. The trachea’s cilia and mucus continue the cleaning and moistening of air that began in the nose.

The Bronchi and Lungs. Air moves from the trachea to the bronchi, the passages that direct air into the lungs. The lungs are the main organs of the respiratory system. The left bronchus leads into the left lung, and the right bronchus leads into the right lung. The right main bronchus is shorter and wider than the left main bronchus. The right bronchus is subdivided into three lobar bronchi, while the left one is divided into two lobar bronchi. At the end of the smallest tubes are structures called alveoli. They are tiny sacs of lung tissue specialized for the movement of gases between air and blood. Each alveolus is surrounded by a network of capillaries.

Because the walls of both the alveoli and the capillaries are very thin, certain materials can pass through them easily. After air enters an alveolus, oxygen passes through the wall of the alveolus and then through the capillary wall into the blood. Carbon dioxide and water pass from the blood into the alveoli. This whole process is known as gas exchange.

The diaphragm is a muscular structure located between the thoracic and abdominal cavity. Contraction of the diaphragm causes the chest or thorax cavity to expand, which occurs during inhalation. During exhalation, the release of the diaphragm causes the chest or thorax cavity to contract.

2. Trace the path of food from ingestion to defecation. Briefly describe what happens at each stop on the journey. (See figs 14.11 and fig 14.13 in your text for some hints!)

1. Mouth/Pharynx
Mechanical breakdown of food by chewing. The tongue manipulates the food and the teeth grind up the food and mix it with saliva.
Chemical Breakdown thru saliva. Salivary amylase initiates the breakdown of carbohydrates.
Swallowing moves the food from the mouth to the stomach. The bolus is moved into the oropharynx --> pharynx --> esophagus.

2. Esophagus
The food is pushed through the esophagus by peristaltic action, forcing food down into the stomach.

3. Stomach
Mainly chemical breakdown of food occurs in the stomach. The stomach generates mixing waves that churns the food inside. The food mixes with gastric juices and is converted into a liquid called chyme.

4. Small intestine
Digestion of starches and absorption of some nutrients takes place in the small intestines.
A series of chemical events result in the breakdown of carbohydrates, fats and proteins using enzymes released by the pancreas and bile from the liver.
The small intestines are a passage of absorption of digested nutrients into the blood or lymph. 90% of absorption takes place within the small intestine and the other 10% occurs in the stomach and large intestine.

5. Large intestine
Absorption of water and salt, concentration of feces.
Last stage of digestion occurs in the large intestine. Bacteria ferment any remaining carbohydrates and release hydrogen, carbon dioxide and methane gas. It also converts any remaining proteins into amino acids. Finally, the absorption of any remaining water and electrolytes take place.
By the time chyme has remained in the large intestine for 3-10 hours it has become feces, which consists of water, inorganic salts, products of bacterial decomposition, and indigestible parts of food.

6. Appendix
Dead end of cecum, some bacterial action, produces vitamin K and continues to digest.

7. Rectum
Feces (undigested material and bacteria).

8. Anus
Waste leaves the body and digestive system.