1. Human Anatomy & Physiology DIGESTIVE & EXCRETORY SYSTEMS
Biology – Chapter 38

2. Primary Function
Convert foods into simpler molecules that the body can absorb and be used by cells
(Click)

3. What & why do we need to eat?
Nutrients – supply energy and raw materials for body to perform life functions
Water – all chemical reactions in your body require water
Carbohydrates – the main source of energy
Fats – helps produce membranes, myelin,
some hormones
Proteins – raw materials for growth & repair,
enzymes
Vitamins – organic molecules that help regulate
body processes
Minerals – inorganic nutrients needed for
bodily functions
When you eat foods—such as bread, meat, and vegetables—they are not in a form that the body can use as nourishment. Food and drink must be changed into smaller molecules of nutrients before they can be absorbed into the blood and carried to cells throughout the body. Digestion is the process by which food and drink are broken down into their smallest parts so the body can use them to build and nourish cells and to provide energy.

4. Anatomy of Digestion Digestive System Primary Organs: Mouth, Pharynx,
esophagus, stomach,
small intestine,
large intestine
Accessory organs (add secretions to aid digestion):
salivary glands,
pancreas, liver
Two main parts to digestive system: The primary organs & the accessory organs that add secretions to aid digestion

5. Mouth & Salivary Glands
Primary function: Break down, moisten food & start chemical digestion (mechanical and chemical digestion)
Teeth – mechanical digestion
Salivary glands – produce amylase to start chemical digestion
(Click)

6. Pathways in the Mouth Back of mouth (pharynx) leads to TWO tubes:
Esophagus (empties into stomach)
Trachea (leads to lungs)
DON’T want food to clog trachea!
Direction controller = epiglottis

7. The Esophagus Tube connecting the mouth and the stomach
Tongue and throat push chewed, moistened food (bolus) past the epiglottis into the esophagus
Bolus is moved through esophagus
by involuntary muscular contractions
(peristalsis)
(Click)

8. The Stomach The bolus is mechanically (churning)
and chemically digested in the stomach
Chemical digestion:
HCl
Pepsin
Produces Chyme
Pushed through
pyloric valve to
small intestine

9. Small Intestine Anatomy: 3 parts Duodenum Jejunum Ileum Villi
Function:
Location
where
most food is
digested &
absorbed
Bile acts as a “detergent”, helping to break down fats and allow better absorption into the small intestine
Accessory organs:
Pancreatic enzymes (Starch, protein, fat)
Liver enzymes (Bile-fat digestion, stored in gall bladder)

10. Villi
Villi greatly increase small intestine surface area for more effective absorption (can cover an area as large as a tennis court)
Undigested substances (cellulose, water, etc.) leave small intestine & move to large intestine

11. Large Intestine Anatomy: -Ascending colon -Appendix -Transverse colon
-Descending colon
Primary Function:
-Reabsorb water
Waste material passed to rectum (storage, bacterial colonies produce organic nutrients)
Excess waste released through anus

12. Digestion Summary

13. Excretory System Primary functions: Maintain homeostasis
Remove toxic chemicals
Anatomy:
Skin
Lungs
Liver
Kidneys
Know how each organ functions as an excretory organ

14. Liver
Converts excess amino acids (from protein digestion) into useful nutrients, producing nitrogen
waste products (urea)
Passed on to kidneys

15. Kidneys Two kidneys in lower back
Filter blood to remove waste products
Ureters connect to urinary bladder - removed through urethra
Kidney Anatomy:
-Nephron
-Filters out toxic waste
-Reabsorbs water, essential nutrients

16. Dialysis
If kidneys fail, a dialysis machine is required to externally maintain blood chemistry homeostasis