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Human Physiology in Health and Disease > Chapter 24.1-24.6 > Flashcards

Chapter 24.1-24.6 Flashcards

1
Q

list the major digestive organs

A

oral cavity
pharynx
oesophagus
stomach
small intestine
large intestine
rectum
anus

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2
Q

list the accesory digestive organs

A

salivary glands
liver
gall bladder
pancreas

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3
Q

name the 3 regions of the small intestine

A

duodenum
jejunum
ileum

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4
Q

what are the six major functions of the digestive system

A

ingestion and mastication
propulsion and mixing
secretion
digestion
absorption
elimination

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5
Q

why is it important for solid foods to be mechanically broken down by mastication

A
  • digestive enzymes only effective on outer surface of food particles
  • to increase total surface area for digestion
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6
Q

define propulsion

A

the movement of food from one end of the digestive tract to another

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7
Q

define mixing

A

the movement of food back and forth in the digestive tract without forward movement

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8
Q

what is the correct order of propulsive movement

A

swallowing
peristalsis
mass movements

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9
Q

what are peristaltic waves

A

muscular contractions
- wave of relaxation of the circular muscles in front of the mass of undigested food (chyme)
followed by
-wave of strong contraction of the circular muscles behind the chyme forcing bolus along the digestive tract

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10
Q

what are mass movements

A

contractions that move material in the distal parts of the large intestine to the anus

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11
Q

what are mixing waves

A

gentle stomach contractions that churn food with gastric secretions
then released to small intestine as chyme

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12
Q

what are segmental contractions

A

mixing of food particles with digestive secretions in the small intestine

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13
Q

describe the process of segmental contraction

A

-mass of chyme begins at one location
-segments of digestive tract alternate between contraction and relaxation
-mass of chyme spreads out in both directions

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14
Q

what is the role of secretions

A

-lubricate (food)
-liquefy (food)
-buffer (food)
-digest (food)

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15
Q

Define digestion

A

the breakdown of large organic molecules into their individual components

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16
Q

Define absorption

A

the movement of molecules out of the digestive tract and into the blood or lymphatic system
-depending on molecule, they may pass out by diffusion, facilitated diffusion, active transport, symport or endocytosis

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17
Q

Define elimination

A

the process by which the waste products of digestion are removed from the body

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18
Q

What are the 3 major types of glands associated with the digestive tract?

A
  • unicellular mucus glands in mucosa
  • multicellular glands in mucosa and submucosa
  • multicellular glands outside digestive tract
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19
Q

What is the innermost tunic of the GI tract (in contact with the lumen)

A

the mucosa

20
Q

What does the mucosa consist of

A
  • mucous epithelium
  • lamina propria
  • muscularis mucosae
21
Q

Describe the structure and function of the mucous epithelium

A
  • non-keratinised stratified squamous epithelium in mouth, pharynx, oesophagus and anal canal
  • simple columnar epithelium in remainder of GI tract
  • layer of epithelial cells- absorbs material into capillaries/lymph lacteals
  • protects from gut abrasion and exocrine/endocrine and enteroendocrine secretions
22
Q

Describe the structure and function of the lamina propria

A
  • loose connective tissue
  • contains Peyer’s patches
  • contains capillaries and lymph vessels
  • involved in inflammatory response
23
Q

Describe the structure and function of the muscularis mucosae

A
  • thin outer layer of smooth muscle
  • controls folding of GI wall
24
Q

What are the 2 types of specialised cells in the mucosa

A

-mechanoreceptors
-chemoreceptors

25
Q

List the tunica of the GI tract from innermost to outermost

A

-mucosa
-submucosa
-muscularis externae
-serosa/adventitia

26
Q

Describe the structure and function of the submucosa

A
  • thick layer of connective tissue
  • network of neurons and glial cells form submucosal plexus of the ENS (directly in contact with mucosa)
  • oesophagus and stomach lack submucosal plexus
  • sensory function and regulation of secretory activity
27
Q

Describe the structure and function of the muscularis externae

A

-inner layer of circular smooth muscle
-outer layer longitudinal smooth muscle
-between 2 layers : myenteric plexus
-myenteric plexus: more extensive than submucosal and controls GI tract motility
-exceptions: upper oesophagus (skeletal) and stomach (3 layers)
-responsible for peristalsis and segmentation

28
Q

Describe the structure and function of the serosa/adventitia

A

-outermost layer
-loose connective tissue
-forms visceral peritoneum and is continuous with parietal peitoneum
-simple squamous epithelium
-protects GI tract when it moves

29
Q

How is most nervous regulation of the GI tract controlled

A

-by the enteric nervous system (ENS)
-submucosal and myenteric plexuses
-also autonomic (ANS) innervation (mostly parasympathetic) through vagus nerves

30
Q

What is the ENS capable of controlling in the digestive tract?

A
  • peristaltic and mixing movements
  • blood flow to tract
31
Q

What is Hirschprung disease?

A

-painful developmental disorder
-caused by absence of enteric neurones in distal large intestine
-loss of function mutation in RET gene
-results in poor intestinal motility and severe constipation

32
Q

Describe the chemical regulation of the digestive system

A

-acetylcholine (stimulates GI activity)
-norepinephrine (inhibits GI activity)
-serotonin (stimulates GI motility)
-95% body serotonin found in GI tract
-gastrin and secretin (regulates GI function)
-local chemical regulators eg. histamine

33
Q

What is the peritoneum

A

-continuous serous membrane
-lining the walls and organs of the abdominal cavity

34
Q

Describe the structure of the peritoneum

A

-serous membrane: smooth and secretes lubricating serous fluid
- membrane and fluid reduce friction as organs move
-portion that covers organs: visceral peritoneum
-portion that covers interior surface of abdominal cavity wall: perietal peritoneum

35
Q

What is peritonitis?

A

-potentially life-threatening inflammation of the peritoneum
-resulting from chemical irritation (bile escape from damaged GI tract or infection

36
Q

What are the main symptoms of peritonitis?

A

-acute abdominal pain and tenderness worsened by movement
-ascites can occur (accumulation of excess serous fluid in peritoneal cavity)
-ascites also present in starvation, alcoholism and liver cancer

37
Q

Describe the regions of the oral cavity

A

-vestibule (space between lips or cheeks and teeth)
-oral cavity proper (lies medial to teeth)

38
Q

Which type of epithelium is present in the oral cavity?

A
  • non-keratinised stratified squamous
  • protects against abrasion
39
Q

Name the 2 dental arches

A

-maxillary arch
-mandibular arch

40
Q

Describe the protective functions of saliva

A
  • large volume of saliva (continually washes oral surface preventing bacterial infection)
  • HCO3- (acts as buffer to neutralise acids produced by oral bacteria)
  • lysozyme and immunoglobulin A (prevents bacterial infection)
    -mucus protects GI tract from physical abrasion
41
Q

Describe the action of salivary amylase

A

breaks covalent bonds between glucose molecules in starch and other polysaccharides to produce disaccharides maltose and isomaltose

42
Q

Name the secretions released from the oral cavity

A

-serous saliva
-salivary amylase
-mucus
-lingual lipase

43
Q

Name the salivary glands

A

-submandibular gland
-sublingual gland
-parotid gland

44
Q

Identify the structures of the digestive tract that are lined with stratified squamous epithelium

A
  • oropharynx
  • mouth
  • oesophagus
  • anal canal
45
Q

Name the structures through which a bolus enters and exits the stomach

A
  • enters through lower oesophageal sphincter
  • exits through pyloric sphincter
46
Q
A

Human Physiology in Health and Disease (5 decks)

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