Download Comparative Vertebrate Physiology

Human Anatomy and
Physiology
Transport and mixing of food in the
alimentary tract
Food reception
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Mastication
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Teeth
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Incisors, canines (55 lb, cutting and tearing)
Premolars and molars (200 lb, grinding)
Grind and breakdown food
Stimulate saliva production
Mix food with saliva
Process of deglutition
Esophagus
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Upper sphincter
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Lower sphincter
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Ensures breathing commences
Prevents acid reflux (heartburn)
Food passage takes about 9 seconds
Stomach
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Anatomy
Cardiac sphincter
Stomach
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Motor functions
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Receptive relaxation
Food storage (1.5 L)
Gastric peristalsis
Slow emptying
Gastric motility
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Slow waves and spike potentials
Regulation of gastric motility
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1. Stomach
i. Volume of chyme
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Smooth muscle excitability
ii. Presence of protein
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Gastrin release from antral mucosa
Regulation of gastric motility
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2. Duodenum
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i. Distention of the duodenum ( )
ii. Acidity of duodenal chyme ( )
iii. Presence of protein, sugars and fats cause
hormones to be released from duodenal
mucosa (gastric inhibitory peptide GIP,
secretin)
Small intestine
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Mixing and propulsive contractions
combined (segmentation)
Control of motility in small
intestine
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Neural: slow waves
Hormonal
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Up-regulatory: gastrin, CCK, secretin, insulin
Down-regulatory: glucagon
Ileocecal valve
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Function
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Prevent backward flow
Operation
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Opens upon pressure
differences
Large Intestine
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Motility
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Rhythmical: every 30 minutes
Mass movement: coincides with ileum
contraction (follows a meal)
Large Intestine anatomy
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Tenia coli
Haustra alter their location
Defecation
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Contraction of abdominal wall musculature and lowering of
diaphragm places pressure on colon wall. External and internal
sphincters open (nervous system)