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1. Pharynx. cavity not involved in digesting food passageway leads to stomach connection between nasal & oral cavities to larynx & esophagus. 3 parts to pharynx. nasopharynx - connects w/ nasal cavity oropharynx - passageway food moving down & air moving into trachea

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1 pharynx
1. Pharynx
  • cavity
  • not involved in digesting food
  • passageway leads to stomach
  • connection between nasal & oral cavities to larynx & esophagus
3 parts to pharynx
3 parts to pharynx
  • nasopharynx- connects w/ nasal cavity
  • oropharynx- passageway food moving down & air moving into trachea
  • laryngopharynx- passageway to esophagus
3 stages of swallowing
3 Stages of Swallowing
  • 1st stage:
    • voluntary
    • food chewed- mixed w/ saliva
    • rolled into mass by tongue- BOLUS- forced into pharynx
2 nd stage swallowing reflex stimulated
2nd Stage- swallowing reflex stimulated
  • food is prevented entrance to nasal cavity
  • epiglottis slaps shut over larynx to keep food from going down trachea
  • tongue seals off oral cavity
  • different muscle actions open esophagus & forces food down it
slide7

epiglottis

trachea

3 rd stage
3rd Stage
  • breathing momentarily inhibited
  • peristalsis transports food down into & through esophagus
  • choking occurs when food lodges in larynx
  • Heimleich maneuver can dislodge food
2 esophagus
2. Esophagus
  • straight tube
  • ~ 25 cm long
  • food passageway from pharynx to stomach
  • goes thru opening in diaphragm
  • contains mucous glands w/ secretions that moisten & lubricate inner lining
peristalsis
Peristalsis
  • wavelike motion propels food down tubular structures
  • contraction of muscle occur above food & relaxation below it
slide14

hiatal hernia

  • acid reflux
  • Barrett’s esophagus
3 stomach
3. Stomach
  • j-shaped, pouched organ
  • ~ 1 L capacity
  • fxns: receives food from esophagus, mixes food w/ gastric juices, begins protein digestion, limited absorption, moves food into small intestines
regions of stomach
Regions of stomach:
  • cardiac-
  • fundus- temp storage area
  • body- main part
  • pylorus- approaches small intestines
slide21

inner lining contains gastric glands w/ 3 types secretory cells:

    • mucous cells- secrete mucus w/ other secretions keeping stomach from digesting itself
    • chief cells- secrete digestive enzymes- pepsinogen
    • parietal cells- release HCl & intrinsic factors

all these form GASTRIC JUICE (2-3 L/day)

slide24

inner lining= RUGAE- disappears when stomach is distended

ulcer is open sore in the lining of stomach

may be caused by presence of H pylori bacteria

slide25

pepsinogen is released & when hits HCl forms PEPSIN which digests almost ALL types of protein

  • intrinsic factors aid in vitamin B12 absorption in small intestines
  • mostly digestion occurs in stomach, but some absorption of water, salts, and drugs does occur
slide26

mechanical & chemical digestion begin here

resulting in a semi-paste called CHYME

rate at which this enters sm intestine depends of type of food

liquids pass thru quickly

fatty foods 3-6 hours

proteins & carbs pass thru more quickly

vomiting
Vomiting
  • medulla oblongata- vomiting center
  • body prepares for the process by closing off nasal cavity, trachea, contraction of diaphragm, contraction of abdominal muscles, etc
4 pancreas
4. Pancreas
  • dual fxn- endocrine gland & digestive gland
  • closely associated w/ small intestine in the curve of duodenum
  • fxn: release pancreatic juice
  • juice contains enzymes that digest carbs, fats, nucleic acids, proteins
slide30

PANCREATITIS- condition where there is a blockage in release of juice

  • essentially pancreas digests itself
5 liver gallbladder
5. Liver & Gallbladder
  • largest internal organ in body
  • inferior to diaphragm on right side of body (under ribs)
  • 4 lobed organ (2)
  • connected to sm intestines by ducts
  • main fxn: manufacture bile salts
functions
Functions:
  • imp role in carb metabolism
    • regulates glucose in bld
  • imp in lipid metabolism- converting subst into fats (bile salts)
  • imp in protein metabolism
slide37

produce plasma proteins

  • destroy bacteria/old rbc & wbc
slide38

produce enzymes that break down poisons that are harmful to body

  • stores certain vitamins/minerals needed by body
  • also stores poisons that can’t be broken down & excreted
  • activates vitamin D
diseases of liver
Diseases of Liver
  • cirrhosis
  • hepatitis
  • cancer
slide42

gallstones

  • gallbladder attacks
6 small intestine
6. Small Intestine
  • major digestive organ
  • ~ 21 feet long
  • 3 subdivisions:
    • duodenum- ~10” long (25cm)

diameter: ~ 2” (5cm)

C-shaped around the pancreas

B. jejunum- ~ 8’ long

greater diameter

thicker walls, more vascularized

slide44

C. ileum- ~ 12’ long

hard to distinguish between jejunum & ileum

slide45

mesentery- thin membrane that suspends the portions of the intestines from walls

  • contains blood vessels, nerves, lymphatic vessels
slide47

only processes small amount of food at a time so pyloric sphincter muscle considered gatekeeper

  • produces enzymes to digest food (w/ help of pancreatic enzymes & bile)
slide48

enzymes secreted by mucosal cells break down proteins, carbs, fats

  • wall of intestine has many tiny projections called villi
  • microvilli project off the villi
  • the epithelial lining is replaced every 3 to 6 days
  • food absorption occurs thru these structures
slide50

carries on mixing movements & peristalsis

  • chyme moves slowly; 3-10 hours
  • if wall becomes distended/irritated, a peristaltic rush pushes contents to large intestine so quickly that water, nutrients, & electrolytes aren’t absorbed - diarrhea
8 large intestine
8. Large Intestine
  • ~ 5’ length
  • greater diameter than small int
  • fxns:

1. dry out indigestible food residue by absorbing water

2. eliminate residues from body as feces

slide53

little or no digestive fxns

  • no secretions except mucus by goblet cells in wall
    • protects inner wall
    • binds fecal matter
  • normally absorbs water & electrolytes
  • many bacteria, intestinal flora, inhabit organ (100 trillion)
  • help break down substances that aren’t by our digestive system
slide54

4 principle regions:

    • cecum- beginning; dilated pouchlike

contains appendix (appendicitis)

    • colon- subdivided into 4 parts:

a. ascending colon- right side

b. transverse colon- across

c. descending colon- left side

d. sigmoid colon- s-shaped

3. rectum

4. anal canal

slide56

mixing & peristalsis occurs but slower

  • 2-3 mass movements happen per day
  • forces feces into lower 2 regions until eliminated
  • if feces stay in too long leads to constipation