IOP exam 3

3 regions of the stomach

1. fundus

2. body

3. antrum

3 regions of the small intestine

1. duodenum

2. jejunum

3. ileum

What are the accessory organs?

pancreas and liver

2 regions of large intestine

colon and rectum

pH of oral cavity

6.8 - 7.5

pH of stomach cavity

1.5 - 2.0

pH of duodenum

5.6 - 8.0

pH of small intestine

7.2 - 7.5

pH of colon

7.9 - 8.5

In the stomach, surface area is increased by invaginations called

gastric glands

intestinal surface area is enhanced by fingerlike villi and invaginations called

crypts

mucosa is created from?

mucosal epithelium, lamina propria, and muscularis mucosae

What are the modifications that increase surface area of the digestive system?

• rugae (stomach)

• plicae (intestine)

• villi

• gastric glands

• crypts

• submucosal glands

layers of GI tract

1. mucosa

2. submucosa

3. muscularis externa

4. serosa

what does the submucosa contain?

• connective tissue

• submucosal plexus of the enteric nervous system

what does the muscularis externa consist of?

• two layers of smooth muscle

• myenteric plexus of the enteric nervous system

what does the serosa consist of?

peritoneal membrane

what does the serosa form?

sheets of mesentry

4 basic processes of digestive

1. digestion

2. absorption

3. secretion

4. motility

secretion is the movement of material from ____ into _____ or ____

cells

lumen

ECF

absorption is the movement of material from _______ to _____

GI lumen

ECF

mucous cells are located in

stomach

serous cells located in

salivary glands

goblet cells are located in

intestine

2 main types of contractions for GI motility

1. tonic

2. phasic

Tonic contractions occur where?

some smooth muscle sphincters and anterior portion of the stomach

Where do phasic contractions occur?

posterior region of the stomach and in the small intestine

Slow wave potentials originate from?

interstitial cells of cajal

peristalsis moves bolus

forward

Extrinsic Neurons

autonomic neurons that bring signals from CNS to digestive system

Short reflexes are integrated in the

enteric nervous system

Long reflexes integrated in

CNS

Long reflexes originate from?

• some outside of the GI tract

• others in ENS

short reflexes originate in the

ENS

Short reflexes are mainly carried out in within?

the wall of the gut

Parietal cells

HCl

Chief cells

pepsinogen and gastric lipase

surface mucous cells

mucus and bicarbonate

gastrin

G cells

Histamine

ECl cells

GI hormones

• G cells

• cholecystokinin (CCK)

• secretin

• motilin

• Gastric Inhibitory peptide (GIP)

• Glucagon - like peptide 1 (GLP-1)

Primary target of G cells

ECl cells and parietal cells

Primary target of CCK

gallbladder, pancreas, and stomach

Primary target of secretin

pancreas and stomach

Primary target of motilin

gastric and intestinal smooth muscle

Primary target of GIP

beta cells of pancreas

Primary target of GLP-1

endocrine pancreas

Cephalic phase

chemical and mechanical digestion begins in the mouth

when you see or smell food

3 functions of the stomach

1. storage

2. digestion

3. defense against swallowed pathogens

Gastric Phase

gastric secretion

( food is now in stomach)

2 Secretory Glands

1. oxyntic glands

2. Pyloric glands

sequence cephalic phase

1. see or smell food

2. medulla oblongata

3. preganglionic parasympathetic neuron in vagus nerve

4. long vagal reflex

Sequence Gastric Phase

1. food or cephalic reflexes initiate gastric secretion of gastrin, histamine, and acid

2. gastrin stimulates acid secretion by direct action on parietal cells or indirectly through histamine

3. acid stimulates short reflex secretion of pepsinogen

4. somatostatin release by H+ is the negative feedback signal that modulates acid and pepsinogen release

Dual role of pancreas

1. exocrine

2. endocrine

what is the endocrine role of the pancreas?

secretes insulin and glucagon

What is the exocrine role of the pancreas

secretes digestive enzymes and bicarbonate

Intestinal phase

goblet cells secrete mucus for protection and lubrication

• isotonic NaCl solution

Bile secreted from liver contains?

1. bile salts

2. bile pigments

3. cholesterol

sequence isotonic NaCl secretion

1. Na+, K+, Cl- enter by cotransport

2. Cl- enters lumen through CFTR channel

3. Na+ is reabsorbed

4. Negative Cl- in lumen attracts Na+ by paracellular pathway. Water follows

what converts trypsinogen into trypsin?

enteropeptidase

The largest internal organ?

liver

common hepactic duct

takes bile made in the liver to storage to the gallbladder for storage

common bile duct

takes bile from the gallbladder to the lumen of the small intestine

hepatic artery

brings oxygenated blood containing metabolites from peripheral tissues to the liver

hepatic portal vein

blood is rich in absorbed nutrients from the gastrointestinal tract and contains hemoglobin breakdown products from the spleen. blood leaves the liver in hepatic vein

sphincter of oddi

controls release of bile and pancreatic secretions into the duodenum

hepatocytes of liver are organized into units called?

lobules

each lobule is centered around a

central vein

the branches associated with the lobules form

sinusoids into which the blood flows

bile canaliculi

small channels into which bile is secreted.

zone 1 on the liver lobule

has the highest oxygen and performs oxidative metabolism

zone 3 on liver lobule

lowest oxygen and most susceptible to hypoxia and toxin damage

liver functions

• metabolic

• storage

• excretory/secretory

• protective

• circulatory

• coagulation

Metabolic functions of liver

• carbohydrate metabolism

• synthesis of fatty acids, lipoproteins, cholesterol

• ketogenesis

• protein metabolism

• synthesis of plasma proteins

• urea synthesis

• hormone metabolism

• RBC production

Storage functions of liver

• glycogen

• vitamins (A,D,E,K —> lipid soluble B12—> water soluble)

• iron

• copper

Excretory/secretory functions of liver

• bile

• insulin like growth factor 1 (IGF-1)

• most blood proteins

• cholesterol, fatty acids

protective function of liver

• purification, transformation, and clearance (endogenous and exogenous drugs and chemicals)

• kupffer cells (residential macrophages)

Coagulation function of liver

Production of coagulation factors

• fibrinogen I

• prothrombin II

• Factors (V,VII,IX,X,XI)

• Protein C and S

• antithrombin

2 types of liver enzymes

1. transaminases

2. cholestatic

Transaminases enzymes

1. AST, ALT, SGOT, SGPT

2. from damaged/dead hepatocytes (liver cells)

Cholestatic Enzymes

1. ALP and GGT

2. From injured biliary epithelial cells (bile ducts)

In the intestinal phase what vitamin is absorbed?

B12

Enterocytes transport

nutrients and ions

capillaries transport

most absorbed nutrients

lacteals transport

fats to the lymph

crypt cells secrete

ions and water

endocrine cells secrete

hormones

Free amino acid absorption

Uptake of individual amino acids into intestinal cells via Na⁺ dependent transport and their movement into the bloodstream.

Peptide absorption

Protein —> peptide —> amino acid

via H+ transporter

intestinal phase: large intestine

• concentrates waste for excretion

• defecation reflex

• digestion and absorption

sequence immune functions of the GI tract

1. M cells scan by sampling stuff in the guts, they detect something sus

2. immune cells secrete cytokines

3. cytokines attract additional immune cells, trigger inflammatory response

4. increase in Cl-, fluid, and mucus secretion

5. pathogen flushed out

what does lipase do when released from pancreas?

breaks down fatty acids

what does protease do when released from pancreas?

splits up protein

what does amylase do when released from pancreas?

divides carbohydrates to create rich-energy sugar

six functions of the kidneys

1. regulation of extracellular fluid volume and blood pressure

2. regulation of osmolarity

3. maintenance of ion balance (Na+, Ca2+, K+)

4. homeostatic regulation of pH

5. excretion of waste

6. production of hormones

T cells develop in?

thymus

T cells make up most of?

• Circulating lymphocytes

• helper and cytotoxic cells

B cells develop in?

bone marrow

What do B cells produce?

antibodies

activated B lymphocytes develop into?

plasma cells