Intro to GI tract Flashcards by Rachel Muxlow

What are the general components of the GI tract?

Mouth
Esophagus
Stomach
Small intestine
Large intestine/colon

How well did you know this?

Not at all

Perfectly

What are the four parts of the stomach?

Cardia
Fundus
Body
Antrum

How well did you know this?

Not at all

Perfectly

What are the 3 parts of the small intestine?

Duodenum
Jejunum
Ileum

How well did you know this?

Not at all

Perfectly

What are the 6 parts of large intestine/colon?

Cecum
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Rectum

How well did you know this?

Not at all

Perfectly

What are the four general processes found in the GI system?

Digestion
Absorption
Motility
Secretion

How well did you know this?

Not at all

Perfectly

What is the definition of digestion?

The chemical and mechanical breakdown of food

How well did you know this?

Not at all

Perfectly

What are the general functions of the liver?

Glucose and fat metabolism
Protein synthesis
Bile production
Hormone production
Urea production
Detoxification
Glycogen storage

How well did you know this?

Not at all

Perfectly

What are the plasma proteins made in the liver?

Albumin
Fibrinogens
Apoliproteins

How well did you know this?

Not at all

Perfectly

What are the hormones made in the liver?

Angiotensinogen
Insulin like growth factor

How well did you know this?

Not at all

Perfectly

What are the two general functions of the pancreas?

Exocrine - digestive enzymes
Endocrine - hormones

How well did you know this?

Not at all

Perfectly

What hormones are produced by the pancreas?

Insulin
Glucagon
Somatostatin

How well did you know this?

Not at all

Perfectly

What are the 4 general structures of the GI tract?

Mucosa
Submucosa
Muscularis externa
Serosa/adventitia

How well did you know this?

Not at all

Perfectly

What are the general sections of the mucosa of the GI tract?

Epithelium
Lamina propria
Muscularis mucosae

How well did you know this?

Not at all

Perfectly

What are the special cells of GI epithelium?

Transporting cells
Exocrine and endocrine secreting cells
Stem cells

How well did you know this?

Not at all

Perfectly

What generally makes up the lamina propria?

CT
Small blood and lymph vessels
Nerve fibers
Wandering immune cells

How well did you know this?

Not at all

Perfectly

What generally makes up the submucosa?

CT with lymphatics and blood vessels
Submucosal plexus

How well did you know this?

Not at all

Perfectly

What are the two sections of the muscularis externa?

Longitudinal layer of smooth muscle
Circular layer of smooth muscle (myenteric plexus)

How well did you know this?

Not at all

Perfectly

What are the two main ways to categorize smooth muscle?

By their communication with neighboring cells
By contraction pattern

How well did you know this?

Not at all

Perfectly

What are the two groups of smooth muscle under the category of communication?

Single unit/unitary
Multi-unit

How well did you know this?

Not at all

Perfectly

What are the characteristics of single unit smooth muscle?

Connected by gap junctions
Cells contract as single unit
In walls of most hollow organs

How well did you know this?

Not at all

Perfectly

What are the characteristics of multi-unit smooth muscle?

Not electrically linked
Each cell stimulated indepently

How well did you know this?

Not at all

Perfectly

Where can you find multi-unit smooth muscle?

Iris and ciliary body of eye
Male reproductive tract
Piloerector muscles

How well did you know this?

Not at all

Perfectly

What are the two types of the contraction pattern category of smooth muscle?

Phasic
Tonic

How well did you know this?

Not at all

Perfectly

Where is tonic contraction found in the GI tract?

Gastroesophageal sphincter
Ileocecal sphincter
Internal anal sphincter

How well did you know this?

Not at all

Perfectly

What is slow wave potential?

Slow, regular oscillations of membrane potential in GI smooth muscle

What maintains slow potential and their location?

Interstitial cells of Cajal in the myenteric plexus

What ions cause slow waves?

Influx of Ca - depolarize Efflux of K - repolarize

What is the response to AP called in GI smooth muscle?

Spike potential

What is the frequency of slow waves in the stomach?

4 waves/min

What is the frequency of slow waves in the duodenum?

12 waves/min

What is the frequency of slow waves in the distal ileum?

8 waves/min

What is the frequency of slow waves in the cecum?

9 waves/min

What is the frequency of slow waves in the sigmoid colon?

6 waves/min

What does Ca bind to in smooth muscle cells during contraction?

Calmodulin

What activates myosin light chain kinase in smooth muscle cells?

Ca bound to calmodulin

What is the function of activated myosin light chain kinase?

Phosphorylates light chains in myosin head and increases myosin ATPase activity

How is cytosol concentration of free Ca decreased?

Pumped back into the SR by sER-Ca-ATPase Pumped out of the cell by primary active transport

What is the function of myosin phosphatase in smooth muscle cells?

Removes phosphate from myosin light chains which decreases myosin ATPase activity

What are three patterns of motility in the GI tract?

Migrating motor complex Peristaltic contractions Segmental contractions

How does smooth muscle differ from other muscle types?

No cross striations Poorly developed SR Elongated, single nucleus, spindle shape Sarcotubular system not as developed - very shallow dip Calmodulin instead of troponin - no troponin Low calcium storage and pump Involuntary control - ANS Low excitability - very slow contraction speed

What is the general PNS innervation of the GI tract?

Vagus nerve ENS

What is the general SNS innervation of the GI tract?

Thoracolumbar nerves

What is the intrinsic ANS of the GI tract?

ENS

What is the two general parts of the extrinsic ANS of the GI tract?

PNS and SNS

What are the NTs and neuromodulators of the GI tract?

Acetylcholine Norepinephrine Vasoactive intestinal peptide Nitric oxide Gastrin releasing peptide Enkephalins Neuropeptide Y Substance P

What is the receptor for Ach in the GI tract?

Cholinergic

What 5 functions does ACh have in the GI tract?

Contraction Relaxation of sphincters Increase salivary secretion Increase gastric secretion Increase pancreatic secretion

What is the receptor for norepinephrine in the GI tract?

Adrenergic

What are the 3 functions of norepinephrine in the GI tract?

Relaxation Contraction of sphincter Increase salivary secretion

Where does NO act in the GI tract?

Neurons of ENS

What is the function of NO in the GI tract?

Relaxation

Where does GRP act in the GI tract?

Vagal neurons of gastric mucosa

What is the function of GRP in the GI tract?

Increase gastrin secretion

Where is VIP released from and what is it receptor in the GI tract?

ENS neurons Peptidogenic

What are the 3 functions of VIP in the GI tract?

Relaxation Increase intestinal secretion Increase pancreatic secretion

What substance effects enkaphalin secretion and where?

Opiates ENS neurons

What are the 2 actions of enkaphalins in the GI tract?

Contraction Decrease intestinal secretion

Where is neuropeptide Y released?

ENS neurons

What are the 2 actions of neuropeptide Y in the GI tract?

Relaxation Decrease intestinal secretion

Where is substance P secreted from?

ENS neurons

What are the 2 actions of substance P in the GI tract?

Contraction Increase salivary secretion

What NT is substance P secreted with?

ACh

What are the steps of a reflex arc?

Stimulus Sensory receptor Input signal Output signal Target/effector Response

What is a long reflex?

Sends signals to CNS

What is a short reflex in the GI tract?

Sensed by receptors in GI tract and processed entirely in ENS

What are the hormones of the GI tract?

Gastrin CCK Secretin Motillin Incretins Ghrelin Leptin Insulin Amylin

What secretes gastrin?

G cells

What is the function of gastrin?

Stimulates gastric acid secretion and mucosal growth

What secretes CCK?

I cells

What are the functions of CCK?

Stimulates gallbladder contraction and pancreatic enzyme secretion Inhibits gastric emptying and acid secretion

What secretes secretin?

S cells

What is the function of secretin?

Stimulates bicarbonate secretion Inhibits gastric emptying and acid secretion

What secretes motillin?

Endo M cells

What is the function of motillin?

Stimulates migrating motor complex

What are the two incretins of the GI tract?

Gastric inhibitory peptide Glucagon-like peptide-1

What is another name for gastric inhibitory peptide?

Glucose dependent insulinotropic peptide

What secretes gastric inhibitory peptide?

K cells

What are the functions of gastric inhibitory peptide?

Stimulates insulin release Inhibits gastric emptying and acid secretion

What secretes glucagon-like peptide-1?

L cells

What are the functions of glucagon-like peptide-1?

Stimulates insulin release Inhibits glucagon release and gastric function

What secretes ghrelin and when?

Gastric mucosal cells Fasting state

What is the function of ghrelin?

Stimulate orexigenic and inhibit anorexigenic neurons hypothalamus to increase appetite

What secretes leptin?

Fat cells of adipose tissue

What is the function of leptin?

Stimulates anorexigenic and inhibit orexigenic neurons in hypothalamus to decrease appetite

How may ghrelin activity effect the result of gastric bypass procedures?

May result in decreased/loss of ghrelin activity - decreasing appetite

How may leptin may be affected by obesity?

Secretion may be lost

What is the general pathway of stimulating insulin secretion in response to GI tract distension?

Distension of GI tract wall Stimulates stretch receptors Increases sensory neuron input to CNS Parasympathetic output to beta cells of pancreas Stimulates insulin release

What is the general pathway of stimulating insulin secretion in response to carbohydralase in GI lumen?

Presence of carbohydralase in GI lumen stimulate endocrine cells of small interesting to release GLP-1 and GIP which stimulate beta cells of pancreas to release insulin

What is the general pathway of stimulating insulin secretion in response to nutrient digestion and absorption?

Nutrient digestion and absorption increases AAs and plasma glucose which stimulates beta cells of pancreas to release insulin

What is the function of Amylin?

Prevent spike after ingestion by slowing gastric emptying - improves glycemic control