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Human Anatomy & PhysiologyDIGESTIVE & EXCRETORY
SYSTEMS
Biology – Chapter 381
Primary Function
2
Convert foods into simpler molecules that the body can absorb and be used by cells
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What & why do we need to eat?
3
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
Anatomy of Digestion
4
Digestive System Primary Organs:
Mouth, Pharynx, esophagus, stomach, small intestine, large intestine
Accessory organs (add secretions to aid digestion):
salivary glands, pancreas, liver
Mouth & Salivary Glands
5
Primary function: Break down, moisten food & start chemical digestion (mechanical and chemical digestion)
Teeth – mechanical digestion
Salivary glands – produce amylase to start chemical digestion
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Pathways in the Mouth
6
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
The Esophagus
7
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)
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The Stomach
8
The bolus is mechanically (churning) and chemically digested in the stomach
Chemical digestion:HClPepsin
Produces Chyme
Pushed through pyloric valve to small intestine
Small Intestine
9
Anatomy:3 parts-Duodenum-Jejunum-Ileum-Villi
Function:-Location where most food is digested & absorbed
Accessory organs:-Pancreatic enzymes (Starch, protein, fat)-Liver enzymes (Bile-fat digestion, stored in gall bladder)
Villi
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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
Large Intestine
11
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
Excretory System
13
Anatomy:SkinLungsLiverKidneys
Primary functions:Maintain homeostasisRemove toxic chemicals
Liver
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Converts excess amino acids (from protein digestion) into useful nutrients, producing nitrogenwaste products (urea)Passed on to kidneys
Kidneys
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Two kidneys in lower backFilter blood to remove waste products
Ureters connect to urinary bladder - removed through urethra
Kidney Anatomy:-Nephron-Filters out toxic waste-Reabsorbs water, essential nutrients
Dialysis
16
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