Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology Module 4 > Digestive > Flashcards

Digestive Flashcards

1
Q

Functions of Digestive System

A

Supply body with
Water
Electrolytes
Vitamins
Nutrients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Processes of Digestive System

A

Movement
Secretion
Digestion
Absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

List the functions of the digestive system

A

the function of the digestive system is to supply the body with water , electrolytes , vitamins , and nutrients . This is conducted through the processes of motility , digestion, secretion and absorption . Food travels through the body beginning in the mouth , pharynx , then down the esophagus . It then enters the stomach , small intestine /duodenum. jejunum , ileum), large intestine (ascending , transverse, descending, sigmoid colon) to the rectum and lastly the anus. Accessory organs include salivary glands ,liver , pancreas , and gal bladder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Tissue Layers of GI Tract

A

Mucosa
Submucosa
Smooth muscle
Circular layer
Longitudinal layer
Serosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Give the layers of the gastrointestinal (GI) tract and explain their functions.

A

The mucosa is the innermost layer of the GI tract , facing the lumen. Mucosa is several epithelial cells thick in the beginning of the
trait to handle abrasion , and 1 cell thick later in the trait, designed for absorption.
The mucosa also has a thin muscle layer to help in
changing shape.
The submuwsa_ contains lots of vasculature ,nerves , lymph ,
and glands to aid in secretion and blood supply to the intestines.
Layers of smooth muscle assist in peristalsis :
-
The circular layer runs in circles around the submucosa
-
The longitudinal layer is the more superficial layer and runs in long lines
the serosa is the most superficial layer, consisting of connective tissue.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Accessory Organs
of Digestive System

A

Salivary glands
Pancreas
Liver
Gall bladder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

GI Smooth Muscle

A

Unitary (single unit) smooth muscle
Functions as a syncytium (gap junctions)
Electrical Activity
Slow waves
Fixed frequency
Interstitial Cells of Cajal (pacemakers)
Variable amplitude
Affected by nervous/hormonal stimuli
Spike Potentials
True action potentials
When threshold reached

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Spike Potentials

A

Contraction due to Ca++ levels
Enters through calcium – sodium channels
Slow to open & close
Long action potential duration
Frequency influenced by neural/hormonal stimuli
Increased frequency -> increased contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Endocrine (hormones)

A

All GI hormones are peptides
Released into blood → act on distant target cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Paracrines

A

Some are peptides (somatostatin), some are not (histamine)
Endocrine cells release → diffuse to target cells
Can act on endocrine cells (+ or -)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Neurocrines (neurotransmitters)

A

Some are peptides (VIP), some are not (Ach, NE)
Nerves release → diffuse to target cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Parasympathetic

A

Vagus nerve
Sacral/pelvic nerves
Generally excitatory (Ach)
More innervation near mouth/anus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Neural Control of GI Function

A

Enteric Nervous System
Myenteric plexus
(Auerbach’s plexus)
GI movements
Submucosal plexus (Meissner’s plexus)
GI secretion & local blood flow
Can function independently or be influenced by autonomic system
NT: excitatory and inhibitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Sympathetic

A

T5-L2 (NE)
Innervation throughout GI tract
Generally inhibitory (NE)
Inhibition mostly by inhibiting ENS neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Sensory Nerves from Gut

A

80% of fibers in vagus nerve are afferent
Other afferents, too
Can be excitatory or inhibitory
Stimulated by
Irritation of mucosa
Distention of GI tract
Chemicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Local: ENS reflexes

A

Secretion, mixing, peristalsis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Long Loop: Gut to prevertebral sympathetic ganglia & back

A

Gastrocolic reflex
Enterogastric reflex
Colonoileal reflex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Long Loop: Gut to CNS & back

A

Stomach/duodenum to control secretion
Pain reflexes
Defecation reflexes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Integration of Control

A

Nervous and endocrine systems work together
Neurons stimulate hormone release
Hormones stimulate neural activity
Simultaneous effects

Stimuli for both can be internal or external

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Peristalsis

A

propulsive movements
Stimulated by distention
Myenteric plexus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Segmentation

A

mixing movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Splanchnic Circulation

A

Blood to
GI tract
Spleen
Pancreas
Liver
25-30% of CO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Control of Gut Blood Flow

A

Blood flow proportional to local activity
Meal → ↑ blood flow (2-3 fold) for 3-6 hr
Causes of activity-induced blood flow
Vasodilating hormones
gastrin, secretin, CCK
Low oxygen
Nervous control of blood flow
PNS - ↑ gut activity → ↑ blood flow
SNS - Directly ↓ blood flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

GI Movements

A

Mastication (chewing)
Deglutition (swallowing)
Esophageal motility
Gastric motility
Small intestine motility
Large intestine motility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Mastication (Chewing)

A

Purpose of Chewing
Breaks apart indigestible cellulose
Increases surface area by decreasing particle size
Mixes food with saliva
Begins digestion of starches (α-amylase)
Begins digestion of lipids (lingual lipase)
Lubricates food for swallowing
Control of chewing
Nervous (cranial nerve/brain stem)
Mastication reflex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Deglutition (Swallowing)

A

Stages of Deglutition
Voluntary
Initiates swallowing process
Pharyngeal
Passage of food through pharynx into esophagus
Reflex controlled
Esophageal
Passage of food from pharynx to stomach
Reflex controlled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Esophageal Motility

A

Muscle composition
Upper 1/3 is skeletal muscle
Lower 2/3 is smooth muscle
Peristalsis
Primary peristalsis
Continuation of swallowing reflex
Secondary peristalsis
In response to distention
ENS and brainstem control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Gastric Motor Functions

A

Store food until processing complete
Mix food with gastric secretions to form chyme
Empty chyme into small intestine at appropriate rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Storage Function of Stomach

A

Food entering causes stretch
Leads to vagovagal reflex
Relaxation of muscle tone to accommodate more food

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Stomach Tissue Modifications

A

Smooth muscle
3 layers
Circular
Longitudinal
Oblique
Rugae
Allow for expansion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Mixing/Propulsion in Stomach

A

Most of stomach
Mixing (constrictor) waves due to slow waves
Can have contraction just from slow waves
Don’t need spike potentials
Antrum
Peristalsis
Few ml get into duodenum
through pyloric sphincter
Retropulsion of remainder

32
Q

Regulation of Gastric Emptying

A

Signals from stomach & duodenum
Gastric factors that promote emptying
Food volume
Gastrin

33
Q

Regulation of Gastric Emptying

A

Gastric factors that inhibit emptying
Reflexes from food in duodenum
Prevent too much chyme in duodenum
Controlled by 3 routes that inhibit stomach contraction & increase pyloric sphincter tone
ENS
Duodenum to stomach
Vagus afferents to brainstem
Sympathetic
Extrinsic afferent nerves to sympathetic inhibitory efferents
Gastric factors that inhibit emptying
Due to
Duodenal distention
Irritation of duodenal mucosa
Low pH in duodenum
High osmolality of chyme in duodenum
Chyme from proteins & fats

34
Q

Small Intestine Motility

A

Spike waves required for contraction
Mixing contractions/Segmentation
Due to slow waves
Surface of small intestine contains ridges
that move food through small intestine in
circular motion (and slower than if smooth)
Propulsive movements/Peristalsis
Enhanced by
Gastroenteric reflex (distention of stomach)
Gastrin, CCK, insulin, motilin, serotonin
Inhibited by
Secretin, glucagon, epinephrine

35
Q

Large Intestine Motility

A

Mixing Movements (Haustrations)
Like segmentation in sm. intestine
Propulsive Movements (Mass Movements)
Modified peristalsis from cecum to sigmoid
1-3X/day for most people, for 10-30’
Large areas contract as a unit & propel feces
When feces reaches rectum: defecation reflex
Initiated by gastrocolic and duodenocolic reflexes

36
Q

Defecation Control

A

Intrinsic
Can be local, entirely within ENS using myenteric plexus to initiate peristalsis
Spinal Control
Higher CNS can also control

37
Q

Defecation Reflex – Spinal/Parasympathetic

A

Stimulus
Stretch
Receptor
Stretch receptors
Afferent nerves
Integrating center
Spinal cord
Efferent
Sacral Parasympathetic
Somatic (Pudendal)
Target
Smooth muscle of descending colon, sigmoid, rectum, anus
External anal sphincter
Response
Intense peristalsis
Relaxation of external sphincter - VOLUNTARY

38
Q

Migrating Motor Complex

A

Housekeeping function”
Sweeps undigested residue toward colon to maintain low bacterial counts in upper intestine
Periods of intense, rapid peristaltic contractions
~90 min to go from stomach to colon
Mediated by motilin and ENS

39
Q

Secretion

A

Digestive enzymes
From all along tract
In response to food presence/type
Regulatory peptides and modulators
Mucus
From mucous glands

40
Q

Secretory Gland Types

A

Single cell (produce mucus)
Mucous glands, mucous cells,
goblet cells
Pits
Crypts of Leiberkühn
Tubular glands
Oxyntic gland that secretes acid
Complex glands
Many throughout tract
Salivary, pancreas

41
Q

Control of Secretion

A

ENS
In response to
Distention
Tactile stimulation
Chemical irritation
ANS
Parasympathetic – increases most secretion
Sympathetic – dual effect, but decreases most secretion
Causes vasoconstriction

42
Q

Mechanism of Secretion

A

Secrete organic substances
Secrete water and electrolytes to carry substances

43
Q

Functions of Mouth

A

Secretion – saliva
Motility – chewing, swallowing
Digestion
Mechanical digestion
Chemical digestion
Immune
Saliva
Tonsils

(Minimal absorption of ions and very small things sublingually)

44
Q

Saliva

A

Secreted into mouth by salivary glands
Functions
Lubricate food
Digest food
Immune function
Contents include
α- amylase (digests starches)
Mucus (lubricates)
Ions
Enzymes (destroy bacteria)
Also secreted into oral cavity
Lingual lipase (digests lipids)

45
Q

Pharynx/Esophagus

A

From mouth, bolus of food goes into pharynx, followed by esophagus
Most secretion here is mucus to help lubricate food & protect mucosa

46
Q

Functions of Stomach

A

Store food
Motility – already discussed
Liquefy food into chyme
Release chyme into small intestine slowly
Secretion (modified mucosa w/deep glands)
HCl, pepsinogen, gastric lipase, mucus, bicarbonate, gastrin, histamine
Digestion – limited to proteins (fats minimal)
Limited absorption (lipid-soluble)

47
Q

Mucus and Bicarbonate

A

Secreted by mucous cells
Tonic secretion and in response to irritation
Protect stomach lining from acid

48
Q

Gastrin

A

Secreted by G cells
In response to Ach, AAs, and peptides
Causes acid production
(by stimulating ECL and parietal cells)

49
Q

Histamine

A

Secreted by ECL cells (enterochromaffin-like)
In response to Ach, gastrin
Causes acid production
(by stimulating parietal cells)

50
Q

Pepsinogen

A

Secreted by chief cells
In response to gastrin, acid
When converted to pepsin, helps digest proteins

51
Q

Gastric lipase

A

Secreted by chief cells
In response to gastrin, acid
Digests lipids

52
Q

Gastric acid

A

Secreted by parietal cells
In response to Ach, gastrin, histamine
Activates pepsinogen into pepsin
Kills bacteria

53
Q

Intrinsic factor

A

Secreted by parietal cells
In response to Ach, gastrin, histamine
Allows for absorption of vitamin B12 in the small intestine

54
Q

Somatostatin

A

Secreted by D cells
In response to acid
Inhibits acid secretion by inhibiting
G cells from producing gastrin
ECL cells from producing histamine
Parietal cells from producing HCL

55
Q

Gastric (oxyntic) Glands

A

Neck cells
Mucus
Chief Cells (peptic cells)
Pepsinogen
Parietal cells
HCl
Intrinsic factor

56
Q

Pyloric Gland

A

G-cells
Gastrin
Mucous neck cells
Mucus
Pepsinogen (small amounts)

57
Q

Phases of Acid Secretion and Digestive Regulation

A

Cephalic Phase
Gastric Phase
Intestinal Phase

58
Q

Acid Secretion

A

Basal secretion ~10% of response after meal

59
Q

Cephalic Phase

A

Seeing, smelling, thinking about, and/or tasting food
Stimuli
Central pathway (thought)
Hypoglycemia
Chemoreceptors (smell/taste)
Mechanoreceptors
~30% of acid response (after a meal)

60
Q

Gastric Phase

A

When food enters stomach
Stimuli
Distention (local and vagovagal)
Increased pH
Peptides/amino acids
~60% of acid response after a meal

61
Q

Intestinal Phase

A

When food enters small intestine
Stimuli
Distention
Peptides/amino acids
~10% of acid response after a meal

62
Q

Acid Response to a Meal

A

Duration of gastric acid response to meal is a function of
Intra-gastric pH
Nature of chyme entering duodenum
Acid secretion before a meal is suppressed due to low pH
Acid stimulates somatostatin release (which decreases gastrin secretion)
Acid has direct effect to suppress parietal cell secretion

63
Q

Stomach is Protected from Acid

A

Mucus layer protects stomach epithelium
Bicarbonate keeps pH at stomach mucosa ~pH 7.0
Lumen is ~pH 2.0
pH gradient between epithelium and lumen

64
Q

Pancreatic Secretion

A

Exocrine
To handle chyme
Digestive enzymes
Bicarbonate

Endocrine
Metabolic hormones
Insulin
Glucagon

65
Q

Pancreatic Digestive Enzymes

A

Help digest
Proteins
Carbohydrates
Lipids

66
Q

Pancreatic Enzymes for
Protein Digestion

A

Trypsin
Proteins to polypeptides

Chymotrypsin
Proteins to polypeptides

Carboxypolypeptidase
Polypeptides into amino acids

67
Q

Pancreatic Enzymes for Carbohydrate Digestion

A

Pancreatic amylase
Complex carbohydrates into disaccharides

68
Q

Pancreatic enzymes are stored and secreted in

A

inactive forms called zymogens
Not activated until enterokinase from intestinal cell converts trypsinogen to trypsin

69
Q

Trypsin converts

A

Chymotrypsinogen into chymotrypsin

Procarboxypeptidase into carboxypeptidase

Procolipase into colipase

Prophospholipase into phospholipase

70
Q

Pancreatic Bicarbonate Secretion

A

Neutralizes acidic chyme
Creates optimal pH (7-8) for digestive enzymes

71
Q

Regulation of Pancreatic Secretion

A

Released throughout phases (mostly intestinal phase)

Digestive enzymes
In response to protein/fat content of chyme

Bicarbonate
In response to acid of chyme

72
Q

Bile Secretion of the Liver

A

Helps digest fats
Emulsification
Aids absorption
Helps excrete wastes

Gall bladder stores & concentrates bile
CCK stimulates gall bladder contraction

73
Q

Small Intestine Secretions

A

Mucus
Brunner’s glands of duodenum
Protects mucosa
Stimulated by Ach and irritation
Inhibited by NE
“Digestive Juices”
Crypts of Leiberkühn throughout small intestine
Most regulation by local ENS reflexes

74
Q

Crypts of Leiberkühn

A

Secrete watery fluid

Active secretion of Cl-
Active secretion of HCO3-
Electrical drag of Na+
Osmotic movement of H2O

75
Q

Large Intestine Secretions

A

Also contains crypts of Leiberkühn
Mucus
Some bicarbonate
Stimulated by
ENS reflexes (irritation)
Parasympathetic activation

Physiology Module 4 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions