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Physiology > Digestive System > Flashcards

Digestive System Flashcards

0
Q

Gastric Secretions will stop due to?

A

Food in duodenum, causes stretching effect, causes hormones to be released, to slow down gastric secretions

  • no protein present-HCL’s purpose it’s to convert pepsinogen to pepsin.
  • duodenal feedback
  • somatostatin release - released by duodenal cells, slow gastric secretion
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1
Q

Phases that control Gastric Secretions

A
  1. Cephalic - Thinking about food, causes stomach to release gastrin. Hormone that produces HCL & mucous. Prepares body for food arriving in the body - stomach grumbling. Increase secretions
  2. Gastric - release of gastrin, gastrin increases HCL. Stretching of stomach. Continues breakdown of proteins. Increase secretions
  3. Intestinal-duodenal feedback - slow gastric phase (secretions). Stretching effect sends message back to stomach to slow down release of chyme. Gives duodenum time to do its job. Decrease secretions
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2
Q

Factors that effect duodenal activity

A
  1. Presence of fat in chyme-bile from liver or gb & lipase (pancreatic/exocrine juice) breakdown & emulsifies fats. The amount of fat affects the amount of time is needed to get through the duodenum
  2. Hypertonicity of chyme-amount of solutes. Chyme is more viscous than than H2O. Need time to break down large proteins, carbs, & lipids
  3. Acidity of chyme-time is needed to neutralize acidity. The more acidic, the slower the process.
  4. Distention of the duodenum-stretching effect, releases hormones & slows down gastric emptying
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3
Q

Duodenal hormones

A

Effect digestion

Slow gastric secretion; speeds up release of bile & pancreatic juice, Na+ bicarbonate

  1. Secretin
  2. Somatostatin
  3. Cholecystokinin (CCK)
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4
Q

Absorption features

Of

Small Intestine

A

All 3 are only found in the small intestines-because absorption primarily happens in the small intestines

Main function - increase surface area for digestion & absorption

  1. Micro villi - cytoplasmic extensions of the cell - columnar cell, extends upward
  2. Villi - folds in mucosa similar to rugae in stomach
  3. Circular folds - folds in submucosa
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5
Q

Absorption of

Carbs & amino acids

In small intestines

A
  1. Active transport- Na+/K pump
    • cell to blood capillaries
  2. Secondary active transport - glucose (carbs) & amino acids co-transport with Na+
    • intestine to cell
  3. Diffusion-glucose & amino acids
    • cell to blood capillaries
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6
Q

Absorption of

Lipids

In small intestine

A

-Triglycerides broken down by lypase to glycerol & fatty acids.
-bile is released from liver or gall bladder
-bile salts surround the fat molecule, which are called miceles
When bile salt surround fat molecule, it becomes water soluable.
-by diffusion glycerol & fatty acids move into the cell
Bile salts stay in the small intestine & can be re-used

  • glycerol & fatty acids reform to become triglycerides again
  • cell creates a protein coating around triglyceride. This structure is called chylomicron. This make it water soluble
  • blood identifies chylomicron as protein, not fat surrounded by protein.
  • chylomicron moves into lymphatic system, then into blood circulatory system
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7
Q

Fructose (carb)

Absorption in

Small intestine

A

By simple diffusion -uniport-a carrier protein helps fructose to move into the cell

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8
Q

Functions

Of the

Digestive System

A
  1. Ingestion - process of physically putting food in the body. Carbs, lipids, proteins.
  2. Digestion - start breakdown foods into smaller components.
    Mechanical-chewing & grinding (muscle contractions)
    Chemical-HCL (hydrochloric acid) & mostly enzymes
  3. Secretion - mucous & hormones. HCL & enzymes. Helps overall process
  4. Movement - smooth muscle contractions. Parastalisis-alternating waves of muscle contractions
  5. Absorption - carbs & amino acids absorbed directly into the bloodstream.
    Fats (lipids) absorbed into lymphatic system, then into the blood stream (circulatory system)
  6. Excretion - deification reflex. Bowel movement. We don’t absorb everything we eat
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9
Q

Names & description

Of

Digestive System

A

One long tube in the body

Holding tank, tube, canal

  • digestive tract
  • gastrointestinal tract
  • alimentary canal

Food does not become a part of us unless we physically absorb the nutrients in the lymphatic system or blood

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10
Q

Layers

Of the

Digestive Tract

A

4 Layers are the foundation, but may change based on where it is in the digestive tract.

  1. Mucosa - epithelium (inner lining)
  2. Submucosa - blood vessels, lymphatic vessels, glands, nerves
    *absorption happens here
  3. Muscularis Externa - smooth muscle
    Creates peristalsis - movement of fluid thru the digestive tract
    • inner muscle layer (circular)-changes diameter
    • outer muscular layer (longitudinal)
  4. Serosa - connective tissue that holds other 3 layers together
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11
Q

Features of the

Oral Cavity

A

Teeth & tongue-mechanical digestion
3 salivary glands in submucosa-chemical digestion

Saliva: H2O, mucous (moistens & protects),
Salivary amylase (starts digestion of carbs pH6),
Antibacterial enzymes

Stratified squamous epithelium - multiple layers for more protection

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12
Q

Features of the

Esophagus

A

10 inches in length
Stratified squamous epithelium
Pathway to stomach
Does NOT release anything

  • muscularis Externa
    • top 3rd - skeletal muscle
    • middle 3rd - skeletal & smooth muscle
    • bottom 3rd - smooth muscle

Swallowing we control skeletal muscle

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13
Q

Features of the

Stomach

A

PH2
Simple columnar epithelium-we replace stomach lining every 20 days. Goes thru mitosis because acid in stomach will eat the cells up.
Rugae-folds in the mucosa. Function-expansion & surface area
* Muscularis Externa-3 smooth muscle layers. Churns & grinds food. Only place in the body that has 3 muscle areas
Proteins begin to digest in the stomach

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14
Q

Cells

Of the

Stomach

A
  1. Mucous cells - secrete mucous; protects cells from acid environment & helps protect intestinal lining
  2. Chief cells - secrete pepsinogen (inactive enzyme), which interacts with HCL->pepsin (active enzyme that breakdown peptide bonds)
  3. Parietal cells - secrete HCL, which produces acidity
  4. Entero endocrine cells - release hormones.
    Thinking about food causes gastrin to be released. Gastrin increases stomach activity
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15
Q

What is chyme?

A

Liquid formed in stomach that moves into the small intestines.

Contents: H2O, churned food, enzymes

16
Q

Features of the

Small Intestines

A

21 ft. Long
Simple columnar epithelium

3 sections:
Duodenum-digestion thru enzyme action (1 ft)
Jejunum-digestion & begins absorption (8 ft)
Ileum-absorption (12 ft)

17
Q

Accessory Organs

Of the

Digestive tract

A
  1. Liver - produces bilirubin. Bilirubin converts to bile salts. Bile makes fats water soluble (emulsifies)
  2. Gall bladder - stores bile salts
  3. Pancreas - very important for homeostasis in the body
    a. Exocrine portion-whatever it secretes goes thru a duct or tube system
    -enzymes: pH6.
    Amylase-breakdown carbs
    Protease-breakdown protein
    Lypase-breakdown lipids
    -sodium bicarbonate - neutralize the acidic chyme (pH2). Raise to pH6, so enzymes can work
    b. endocrine portion (islet cells)
    - release hormones
    - beta cells: release insulin (lower blood sugar)
    - alpha cells: release glucagon (raise blood sugar)
18
Q

Define diabetes mellitus

A

Type 1 - little or no insulin. Aka: juvenile diabetes
Type 2 - insulin is not working

  • Insulin picks up sugar, the dump sugar into diff cells of he body (fat cells, liver cells, muscle cells).
  • Sugar reacts with with receptors on the cells.
  • Receptor sites are clogged or shut down, so sugar doesn’t have contact with receptor sites
  • Body releases more insulin to try to rectify the problem
19
Q

Solution to

Diabetes Mellitus

A

Diet & Exercise

Body brings in less food (sugars), then can use stored glucose & fat cells for energy. The fat cells stop releasing enzymes that block receptor sites

20
Q

Define insulin dependent diabetes

A

Initially Type 2, used up all insulin. So it turned into Type 1

21
Q

Functions of the

Large intestines

A

Compaction of un digested food
Absorption of H2O (minerals, vitamins, & amino acids)

Has E. Coli present, keeps bad bacteria out. Also helps breakdown proteins, which release amino acids, & cause gas

22
Q

Where do compaction problems primarily occur?

A

Sigmoid colon

23
Q

Define diverticulitis

A

Intestinal wall has gotten weak, so it bulges out. Fecal matter gets stuck in there & becomes infected or inflamed, it could rupture.

Solution: can give bacteria to shrink & heal or colon re-section

Insoluable fiber creates framework (creates skeletal system) for fecal material, which will create less strain on intestinal wall.

If intestines go into shock, it shuts down.

24
Q

Action of Secretin

A

Intestinal hormone that stimulates the release of bicarbonate & pepsin

Inhibits gastric acid

25
Q

Action of

Cholecystokinin CCK

A

Intestinal hormone that regulates digestive function & may play a role in appetite

26
Q

Action of

Somatostatin

A

Hypothalamic hormone that inhibits growth hormone release & gastric paracrine that inhibits gastrin secretion

27
Q

Action of

Gastrin

A

Secreted by stomach that stimulates gastric secretion

Physiology (13 decks)

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