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Digestion System > Digestion System > Flashcards

Digestion System Flashcards

1
Q

What is digestion?

A

Breakdown of food to a useful form that can be absorbed and used by cells

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2
Q

Why do the cells use the absorbed ‘food’

A

Creation of energy

‘cellular respiration’ – ‘catabolism’
Production of ATP

pair / building

Production of ‘building blocks’ ‘anabolism’

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3
Q

What is mechanical digestion?

A

Physical breakdown

mastication / churning

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4
Q

What is chemical digestion?

A 
Chemical breakdown (catabolic)
acids / surfactants / ENZYMES
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5
Q

What does mechanical and chemical digestion do?

A

Liberating ‘useful’ components

amino acids, fatty acids, glucose, nucleotides

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6
Q

What are the major organs of the digestive system? (7) And accessory organs? (3)

A 
The major parts of the digestive system:
Salivary glands.
Pharynx.
Esophagus.
Stomach.
Small Intestine.
Large Intestine.
Rectum.
Accessory digestive organs: liver, gallbladder, pancreas.
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7
Q

What are the digestive system processes? (5)

A 
Ingestion
Propulsion
Digestion
- Mechanical breakdown
- Chemical breakdown
Absorption
Defecation
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8
Q

Recipe for saliva?

A

Water (~99%)

Amylase
Lingual lipase
Antibodies
Lysozyme
Defensins
‘Friendly bacteria
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9
Q

What are the four layers of the GI tract wall?

A

Serosa
Muscularis
Submucosa
Mucosa

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10
Q

Gastrointestinal tract layers

A
  1. serosa (adventitia)
  2. muscularis which includes longitudinal muscle and circular muscle.
  3. submucosa
  4. mucosa

Chyme in lumen

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11
Q

Function of the mucosa?

A
  1. Mucous membrane (protects, secretes, absorbs)
  2. Lamina propria (blood vessels, lymphoid tissue)
  3. Muscularis mucosa (provides infoldings)
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12
Q

Function of muscular layer

A

2 layers of smooth muscle
(circular & longitudinal)
Provides peristalsis and mixing
Onward movement regulated by sphincters

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13
Q

Function of the submucosa?

A 
Loose connective tissue
Blood vessels
Nerves
Lymph vessels
Lymphoid tissue
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14
Q

Function of the adventitia/serosa?

A

Outermost layer
In abdomen = peritoneum
Barrier to spread of infection
Anchors GI tract

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15
Q

What is the mesentery?

A

The mesentery is a fold of membrane that attaches the intestine to the abdominal wall and holds it in place.

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16
Q

What are Mesenteric lymph nodes (MLNs)?

A

Mesenteric lymph nodes (MLNs) are an important site of T-cell activation for both the SI and colon. DCs continually migrate from intestinal tissues to the MLNs where they present antigen and control the development, migration, and functional differentiation of cells of the adaptive immune system

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17
Q

What is peristalsis?

A

Peristalsis, involuntary movements of the longitudinal and circular muscles, primarily in the digestive tract

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18
Q

What is the enteric nervous system?

A

The enteric nervous system (ENS) is a large division of the peripheral nervous system (PNS) that can control gastrointestinal behaviour independently of central nervous system (CNS) input.

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19
Q

Five facts about the oesophagus

A

Conveys food oropharynx → stomach

Mucosa subject to considerable friction

Thick protective stratified squamous epithelium

Passage of food facilitated by:
Flattening of mucosal folds
Mucous glands (G)
Loose and elastic submucosa (SM)

Muscularis externa
Upper ⅓: skeletal muscle (initiation of swallowing voluntary)
Lower ⅔ : smooth muscle only (peristalsis)

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20
Q

Glands of the stomach fundus and body

A
  1. Surface mucous cells
  2. Mucous neck cells simple columnar
    Secrete acidic mucus
  3. Parietal cells secrete HCl & intrinsic factor
  4. Chief cells secrete pepsinogen, lipases
  5. G –cells Secrete gastrin
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21
Q

Three parts of the small intestine

A

Duodenum
Jejunum
Ileum

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22
Q

Function of the small intestine

A

Glands secrete intestinal juice
Completes chemical digestion
Absorption of nutrients

23
Q

What are the mucosal folds made up off and what is the function?

A

villi and microvilli increase surface area for digestion and absorption

24
Q

Name the cells in the small intestine.

A
  1. Absorptive cells
  2. Goblet cells
    (Mucus)
  3. Intestinal crypt
    (crypt of Lieberkuhn)
  4. Paneth cells
    Defensins
    Lysozyme
  5. Secretory cells
    Intestinal juice
  6. Entero-endocrine cells
    Secretin
    Cholecystokinin
25
Q

Specialist cells and function of duodenum

A

Brunner’s glands (G)

Secrete alkaline mucus
neutralize chyme
protect mucosa

CCK production

26
Q

Specialist cells and function of jejunum

A

2nd section of small intestine
Main absorptive region
(glucose, vitamins, amino acids, fats)

Very few Brunner’s glands
pH – neutral to alkaline

Mucosal folds – large and numerous
Rapid absorption

Longest villi found here

27
Q

Specialist cells and function of ileum

A

Distal part of small int.

Peyer’s patches
in lamina propria

Huge domes of
lymphoid tissue

28
Q

What does Secretin stimulates?

A

stimulates liver cells to release bile & pancreatic secretion

29
Q

What does CCK stimulate?

A

stimulates gallbladder contraction & pancreatic secretion

30
Q

Colon: what is the teniae coli?

A

Teniae coli

Bands of longitudinal smooth muscle

31
Q

Colon: what is the epiploic appendage?

A

Fat-filled pouch

32
Q

Colon: what is the haustra?

A

Pocket-like sacs

33
Q

Three features of the oesophagus

A

Conveys food oropharynx → stomach

Mucosa subject to considerable friction

Thick protective stratified squamous epithelium

34
Q

How is the passage of food facilitated in the oesophagus? (3)

A

Flattening of mucosal folds
Mucous glands (G)
Loose and elastic submucosa (SM)

35
Q

Where is bile produced?

A

Liver

36
Q

Why does the gallbladder contract?

A

To release bile into gut.

37
Q

What does CCK stimulate?

A

CCK stimulates gallbladder contraction & pancreatic secretion

38
Q

What does secretin stimulate?

A

Secretin stimulates liver cells to release bile & pancreatic secretion

39
Q

Structure of the colon (6)

A
  1. Thick mucosa:
    Simple columnar epithelium (except anal canal)
  2. Many crypts
  3. Absorptive cells
  4. Goblet cells (mucus)
  5. No circular folds
  6. No villi
40
Q

What does the bacteria in the colon do?

A
  1. Synthesize vitamins B and K
  2. Metabolize molecules e.g. heparin, mucin
  3. Ferment indigestible carbohydrates; produce 500ml flatus daily
41
Q

Rectal valve function?

A

Allows gas but not fetal matter to pass (higher life forms only)

42
Q

Anal canal function?

A

Protective Stratified squamous epithelium against fetal matter.

43
Q

Anal sinuses function?

A

Produces mucus to allow fetal matter to leave body.

44
Q

What is the defecation reflex

A
  1. Impulse from cerebral cortex (conscious control)

Sensory nerve fibers stretch the receptors in the wall

  1. Voluntary motor nerve to external anal sphincter.
  2. External anal sphincter (skeletal muscle)
45
Q

Six functions of the liver.

A
  1. Detoxification of metabolic waste
  2. Destruction of spent RBC
  3. Secretion of bile
  4. Synthesis of plasma proteins
  5. Processing and storage of nutrients absorbed from gut tube (B12)
  6. Storage of fat-soluble vitamins
46
Q

What is a hepatocytes? (liver)

A

Hepatocytes are the chief functional cells of the liver and perform an astonishing number of metabolic, endocrine and secretory functions.

47
Q

What is the liver lobule?

A

Filter cells and the cells that make up the bulk of the liver lobule are hepatocytes.

48
Q

What is in the Portal triads (what separates the connective tissue with portal tracts in the liver lobules)

A 
arteries 
nerves (vagus) 
Sinusoid
Central vein
Hepatic portal  vein
Hepatic artery
Bile duct

Efficient 2-way exchange between blood in sinusoids
and hepatocytes. To create a filter bed.

49
Q

What are Kupffer cells?

A

are macrophages found in the sinusoids of the liver.

50
Q

What are the contents of bile?

A 
Bile salts – emulsify fats
Bile pigments – chiefly bilirubin (haem waste product). Broken down into stercobilin
Cholesterol
Triglycerides
Phospholipids - lecithin
Electrolytes
51
Q

What is the function of bile?

A

To emulsify fats

52
Q

Three features of the gall bladder

A
  1. Muscular sac, stores and concentrates bile 5-10 X
  2. Tall columnar epithelium with brush border
  3. Lymph / blood vessels in submucosa to transport H2O away
53
Q

Features of the pancreas. (5)

A
  1. Exocrine organ (alpha cells insulin) component forms 80% gland
  2. Secretes alkaline fluid, rich in enzymes
  3. Neutralises acid chyme from stomach
  4. Trypsin / chymotrypsin secreted in inactive form (prevents autodigestion)
  5. Activated in duodenum
54
Q

What are the three steps bile and pancreatic secretion?

A
  1. Presence of acidic chyme in intestine stimulates production of intestinal juice
  2. Secretin stimulates liver cells to release bile & pancreatic secretion
  3. CCK stimulates gallbladder contraction & pancreatic secretion

Digestion System (1 decks)

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