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Life sciences for paramedics > Gastro-intestinal system > Flashcards

Gastro-intestinal system Flashcards

1
Q

Anatomy of GI tract

A

-from mouth to anus, 8 metre long tube
-passes through thoracic and abdominopelvic cavities
-this tube consists of 4 layers that are specialised for specific functions (mucosa, submucosa, muscular layer, serosa)

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2
Q

Mucus membrane
-what is it, structure (2), function, clinical relevance

A

Mucosa
-surface epithelium
-some regions it is folded with projections which increases absorption
-also patches lymphatic tissue called mucosa-associated lymphoid tissue (MALT)
-carries out secretion and absorption
-in contact with food
-no sensory nerves, damages easily

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3
Q

Ulceration-
1. In mucosa
2. In submucosa
3. muscular layer

A

1.mucosa damage causing discomfort
2. bleeding occurs
3. causes extensive bleeding (fatal)

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4
Q

Submucosa
what is it, what it contains, function (2)

A

-loose connective tissue
-contains glands, blood vessels, lymphatic vessels and nerves
-nourishes surrounding tissue
-carries away absorbed material

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5
Q

Muscular layer
function, structure (detail)

A

-moves the tube
-constructed of 2 smooth muscle tissue coats
1. circular fibres on inner coat cause contraction
2. longitudinal fibres run length ways and cause shortening

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6
Q

Serous layer
structure(2), function(2)

A

Serosa
-visceral peritoneum on outside
-connective tissue beneath
-protects underlying tissues
-secretes serous fluid

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7
Q

4 layers of GI tract from deep to superficial

A

-mucosa
-submucosa
-muscular layer
-serosa

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8
Q

Peritoneum
what is it, 2 layers and gap between them

A

-largest serous membrane of the body
-parietal peritoneum lines wall of abdominopelvic cavity
-visceral layer covers organs
-space between them is where serous fluid is

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8
Q

Ascites-

A

where fluid accumulates in the abdomen

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9
Q

Retroperitoneal organs
Examples and what they are

A

-kidneys, pancreas
-covered by peritoneum only on anterior surfaces

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10
Q

Mesentery
what is it, structure (3)

A

-fold of peritoneum
-fan shaped
-binds small intestine to the posterior abdominal wall
-extends from posterior abdominal wall wraps around small intestine and returns to origin

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11
Q

Mesocolon

A

-fold of peritoneum binds large intestine to posterior wall
-carries blood and lymphatic vessels

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12
Q

Functions of GI tract

A

-ingestion
-mechanical processing
-digestion
-secretion
-absorption
-excretion

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13
Q

Ingestion

A

-food enters GI tract through mouth
-starts process with mechanical and chemical actions

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14
Q

Mechanical processing
what is it, what has main influence on chewing, numbers

A

-mastication- chewing, crushing and breaking into smaller fragments
-pressure changes in mouth have main influence on chewing, teeth are secondary
-not chewing properly reduces digestion by 50%
-pressure changes of 37psi are achieved by the mouth

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15
Q

Digestion

A

-chemical breakdown of food into small particles that can be absorbed by epithelium
-simple molecules stay intact while others are broken down before being absorbed

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16
Q

Secretion

A

-release water, acids, buffer enzymes and salts by epithelium and glandular organs

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17
Q

Absorption

A

-movement of molecules acted upon by enzymes, electrolytes, vitamins and water across epithelium into interstitial fluid

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18
Q

Excretion

A

-removal of waste products
-becomes faeces eliminated by defecation

19
Q

Nervous control of GI tract
specific NS, types neurone and what they do, branch of NS

A

-enteric NS= brain of gut
-consists of 100 million neurones
-motor neurone- control motility and secretion by epithelial cells
-sensory neurones- chemo and stretch receptors
-ANS- sympathetic decreases digestion, parasympathetic increases digestion

20
Q

Mouth
proper name, structure, function

A

-oral/ buccal cavity
-oral cavity= space extends from gums to fauces
-salivary glands- secrete just enough to keep mouth and pharynx moist

21
Q

Salivary glands
branches ANS, 3 gland names

A

-parasympathetic increases secretion, sympathetic decreases salivation
-3 pairs major glands secrete most saliva
1. parotid- watery texture
2. submandibular- mucus rich
3. sublingual- mucus rich

22
Q

Composition of saliva

A

99.5% water
0.05% solutes eg. ions and salivary amylase

23
Q

Tongue

A

-accessory digestive organ
-skeletal muscle covered by mucus membrane
-manoeuvres food for chewing, swallowing
-lingual glands secrete salivary lipase (triglycerides)

24
Q

Oesophagus

A

-secrete mucus, transports food
-purely for transportation, no enzymes of absorption
-mucosa for protection of wear and tear
-muscularis divided into 3
1. superior= skeletal muscle
2. middle= skeletal and smooth
3. inferior= smooth muscle
-2 sphincters:
1. upper oesophageal sphincter- reg movement in oesophagus
2. lower oesophageal sphincter- reg movement in stomach

25
Q

Deglutition
what is it, facilitated by, 3 stages

A

-act of swallowing
-facilitated by saliva and mucous
-3 stages:
1. voluntary- bolus passed oropharynx
2. pharyngeal- involuntary passage through pharynx to oesophagus
3. oesophageal- involuntary passage through oesophagus to stomach

26
Q

Stomach
what is it, capacity, structure, absorption, vomiting

A

-muscular bag
-1.5l capacity
-higher portion= fundus
-lower portion= pylorus (thickest muscle)
-small amount of absorption
-when vomiting, pylorus contracts first
-pylorus is more liquefied, fundus has more undigested chunks

27
Q

Digestion in stomach
2 types and how they work

A

Mechanical digestion
-mixing waves, rippling peristaltic movements
Chemical digestion
-digestion by saliva continues until deactivated by acid
-parietal cells secrete H+ and Cl- which create HCl
-pepsin secreted by chief cells digests proteins. secreted as pepsinogen which is inactive
-gastric lipase splits triglycerides into fatty acids and monoglycerides

28
Q

Adrenaline and drugs/ alcohol effect on stomach

A

Adrenaline
-suppress mucus production
Alcohol/ drug misuse
-causes pepsinogen malfunction
-pepsin is produced and causes digestion of the own stomach

29
Q

Pancreas
location, structure, function

A

-posterior to greater curvature of stomach
-has head, body and tail
-connects duodenum via pancreatic duct and accessory duct
-endocrine islets secrete hormones
-exocrine acini secrete pancreatic juice

30
Q

Liver
structure, composition

A

-left and right lobes
-composed of hepatocytes (cells) and hepatic sinusoids
-sinusoids= permeable capillaries receive oxygenated blood from hepatic artery and deoxygenated nutrient rich from hepatic portal vein

31
Q

Functions liver and gallbladder

A

-carb metabolism- glycogen to glucose
-fat metabolism
-protein metabolism
-breakdown erythrocytes
-detoxification drugs etc
-secretion bile
-storage- glycogen, iron, water etc.

32
Q

Gallbladder

A

-smooth muscle contracts which ejects contents into cystic duct
-stores bile produced by liver until needed by SI
-absorbs water and ions to concentrate bile up to ten-fold

33
Q

Liver blood flow

A

-ox blood hepatic artery
-HPV deoxy blood from digestive system
-this flows into sinusoid which absorbs nutrients then flows into hepatic vein

34
Q

Composition bile

A

-mostly water, salts, cholesterol, lecithin, bile pigments
-bilirubin= principal bile pigment, derived from haeme of recycled RBCs

35
Q

Small intestine
3 regions

A

-duodenum
-jejunum
-ileum

36
Q

Structures in GI tract increase SA

A
  1. circular folds
    -ridges mucosa and submucosa
    -causes chyme to spiral
  2. villi
    -finger-like projections of mucosa
    -contain lots blood vessels
  3. microvilli
    -protects of apical membrane of absorptive cells
37
Q

Mechanical digestion

A

-governed by myenteric plexus
-divided into segments which are localised and cause mixing contractions
-peristalsis keeps food moving from the lower portion of the stomach

38
Q

Absorption in SI

A

Electrolytes:
-from GI secretions of food
Vitamins:
-fat soluble eg. A, D, E and K
Water:
-most absorbed SI some in LI
-all absorbed by osmosis

39
Q

Large intestine
function, 4 regions, sphincter, division of colon

A

-completes absorption, produces vitamins, forms and expels faeces
-4 regions: caecum, colon, rectum, and anal canal
-ileocaecal sphincter between SI and LI
-colon divides into ascending, transverse, descending and sigmoid
-internal anal sphincter= smooth muscle
-external anal sphincter= skeletal muscle

40
Q

Digestion of LI

A

Mechanical
-haustral churning
-peristalsis
Chemical digestion
-final stage digestion through bacterial action
-mucous no enzymes

41
Q

What does metabolism use nutrients to do

A

-provide energy by chemical oxidation of those nutrients
-make new or replace body substances

42
Q

Anaerobic respiration

A

-glycolysis
-glucose + insulin= pyruvic acid + lactic acid

43
Q

Aerobic respiration

A

-krebs cycle
-pyruvic acid + oxygen -> CO2 + H2O + ATP

44
Q

Absorptive state

A

period in which the GI tract is full and anabolic (build) processes exceed catabolism (break)

45
Q

Post absorptive state

A

period where GI tract is empty of nutrients and body stores must supply required energy

Life sciences for paramedics (23 decks)

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