Digestion

1
Chapter 28

• Digestion

2
Digestion

• Digestion process of breaking down food into
  molecules the body can use
• Gastrointestinal tract (GI)
• Where digestion occurs
• Begins at mouth
• Ends at anus

3
(No Transcript)
4
Digestion Mouth

• Mechanical phase
• Body physically breaks down chunks of food into
  small particles
• Teeth
• Incisors sharp, flat front teeth cuts food
• Molars broad, flat back teeth grinds food
• Tongue helps keep food between chewing surfaces
• Hard palate hard part of roof of mouth
• Soft palate soft part of roof of mouth
• Uvula hangs off soft palate pushes food into
  pharynx

5
Digestion Mouth

• Chemical phase
• Saliva and enzymes begin to break down food
• Salivation mixture of water, mucus, and amylase
• Amylase helps break down carbohydrates

6
(No Transcript)
7
Digestion Esophagus

• After food is a bolus, or ball forced into
  pharynx by swallowing
• Pharynx passageway for food and air
• Epiglottis flap of tissue the covers trachea
• Food enters esophagus
• 25 cm long
• Connects pharynx to stomach
• Peristalsis muscle contractions that push bolus
  into stomach

8
(No Transcript)
9
Digestion Stomach

• Elastic bag
• Gastric pits release secretions into stomach
• Rugae folds in stomach that allow for expansion

10
Digestion Stomach Chemical Digestion

• Gastric fluid chemical digestion in stomach
• Pepsin digestive enzyme proteins
• Acid in stomach dissolves minerals and kills
  bacteria
• Mucus coating is vital to stomach survival
• Protects lining from acid
• Prevents pepsin from digesting stomach tissue
• Ulcer lesion or sore on stomach lining caused
  by bacteria

11
Digestion Stomach Chemical Digestion

• Cardiac sphincter muscle located between
  esophagus and stomach
• Food enters stomach when open
• Closes to prevent food from re-entering esophagus
• Muscle contractions churn food
• Chyme paste-like substance
• Things not broken down by pepsin
• Peristalsis forces chyme into small intestine
  where it mixes with secretions from liver and
  pancreas
• Pyloric sphincter regulates flow on chyme

12
Digestion Liver

• Large organ located just below diaphragm
• Stores glycogen and breaks down toxic substances
• Produces bile
• Bile produced by liver passes into gall bladder

13
(No Transcript)
14
Digestion Gall Bladder

• Saclike organ that stores and concentrates bile
• Releases bile into bile duct and into small
  intestine

15
Digestion Pancreas

• Organ that lies behind stomach against the back
  wall of abdominal cavity
• Secretes pancreatic fluids which break down chyme
• Changes pH of chyme from acid to base

16
Digestion Small Intestine

• 21 ft
• Duodenum first section 25 cm
• Jejunum middle section 2.5 m
• Ileum last section 4 m
• Triggers mucus glands which produce mucus

17
Digestion Small Intestine

• Absorption
• End products of digestion amino acids,
  monosaccharides, glycerol, and fatty acids
• Absorbed into blood and lymph
• Absorption when end products of digestion are
  transferred into circulatory system
• Villi finger-like projections that line small
  intestine
• Microvilli extensions on villi
• Nutrients are absorbed through diffusion and
  active transport
• Amino acids and monosaccharides enter capillaries
  and are carried to liver

18
(No Transcript)
19
Digestion Large Intestine

• After absorption, peristalsis moves remaining
  material to large intestine
• Large intestine colon final organ of digestion
• 4 parts
• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon

20
Digestion Large Intestine

• Minerals and vitamins produced by bacteria live
  here
• Peristalsis moves material toward rectum
• Absorbs water to solidify into feces
• Cells secrete mucus to lubricate intestinal wall
  which aids in passing of feces

21
Digestion Large Intestine

• http//www.northarundel.com/aniplayer/

22
Urinary System Overview

• Rids body of waste produced by cellular activity
• Filters waste from blood and passes this fluid on
  to bladder
• Regulation of blood volume
• Water regulation and excretion
• Ion concentration
• pH balance

23
Urinary System Structure

• Kidneys produce urine conserve blood-borne
  materials
• Urine leaving kidneys two tubes (ureters)
• Flow to urinary bladder
• Hollow, muscular organ
• Urination contraction of bladder that forces
  urine through urethra and out of body

24
(No Transcript)
25
(No Transcript)
26
Urinary System Structure -- Kidneys

• Nephron working unit
• Nephron tubule, blood vessels, interstitial fluid
• Nephron tubules empty into collecting duct which
  merge with other ducts into renal pelvis into
  ureter
• 4 processes
• Filtration blood plasma moves from bloodstream
  into nephron tubules
• Reabsorption water nutrients move back into
  bloodstream water retained in tubules
• Secretion hydrogen, ions, compounds move from
  capillaries into tubules
• Concentration concentration of urine is
  increased due to removal of water from loop of
  Henle collecting duct

27
Urinary System Structure Kidneys

• Filtration
• Occurs at glomerulus
• Retains large materials in blood
• Filtrate moves into Bowmans capsule
• Reabsorption
• Occurs at proximal tubules
• Secretion
• Occurs at distal tubules
• Clears body of toxins
• Concentration
• Filtrate moves forward from proximal tubules
  becomes more concentrated

28
Urinary System Hormone Control

• Urine regulation
• Regulated by ADH (antidiuretic hormone)
• Controlled by hypothalamus and released by
  pituitary gland
• LINKS
• http//www.northarundel.com/aniplayer/
• http//www.kidneypatientguide.org.uk/site/HKWanim.
  php