Gastrointestinal

Question 1

Layers of GI tract

Answer 1

Mucosa-endothelial cells specialised for absorption
Sub Mucosa-collagen, elastin and blood vessels
Longitudinal smooth muscles-motility
Serosa-faces blood

Question 2

Roles of the stomach

Answer 2

Kills bacteria
Releases acid and pepsin and delivers it to duodenum at rate for secretion of enzymes and bile salts and movement of food.

Question 3

What is gastric juice made of

Answer 3

HCL- Denatures proteins
Pepsinogen-proenzyme which is converted to pepsin (protease)
Mucus-protects wall against acid
Bicarbonate-to buffer acid

Question 4

Where is gastric juice produced and secreted

Answer 4

Gastric mucosa pits at the base of stomach, glands called oxynitic pyloric glands.

Question 5

Cephalic phase

Answer 5

Taste and smell—->Medulla—->activates para SNS—-> Vagal nerve releases ACh—-> releases Gastin—->produces gastric acid

Question 6

Gastric Phase

Answer 6

Ingested food stimulates gastric activity bu stretching stomach and stimulating mucosa

Question 7

Intestinal phase

Answer 7

Semi digested FA and ph2 inhibits gastric secretion

enterogastic response

Question 8

Small intestine during intestinal phase

Answer 8

Releases gastric juice and bile through duodenal papillary secreted through glands along the SI

Question 9

Types of epithelial cells in the small intestine

Answer 9

Goblet cells-secrete mucosa
Enterocytes-secrete CO3-
Endocrine cells-secrete gut hormones
Paneth cells-secrete anti-bac proteins

Question 10

Function of Large intestine

Answer 10

Stores and releases faecal matter and produces mucosa substance to lubricate. Absorbs water and is an environment for bacteria which produce vitamins.

Question 11

Secretagogue

Answer 11

Substance that stimulates secretory cells

Question 12

Neurocrine neurotransmitters

Answer 12

Innervate secrete cells 
Acetyl Choline 
Nitric Acid 
GABA
G1 Peptides

Question 13

Pancrine

Answer 13

Released in same neighbourhood and reaches cell by diffusion
Histamine

Question 14

Endocrine

Answer 14

Released by distant cells and transported by bloodstream to activate secretion
G1 PEPTIDES

Question 15

Acetyl Choline

Answer 15

Released by post-ganglionic neurones
Direct-M3 receptors on pariental cells
Indirect-M2&M4 receptors on D-Cells which inhibit somatostatin secretion

Question 16

Endocrine hormone- Cholecystokinin

Answer 16

Secreted by I-cells of small intestine in response to Fatty Acids and small peptides
1, contraction of gall bladder
2, secretion of pancreatic enzymes
3, growth of pancreas and gall bladder

Question 17

Endocrine hormone- Secretin

Answer 17

Secreted S-Cells of duodenum in response to H+
Stimulates secretion of HCO3-
Neutralises H+ so enzymes can digest fats

Question 18

Pancrine hormone- Histamine

Answer 18

Produced by ECL cells
Decarboxylation of L-Histidine AA
Stimulates H+ secretion

Question 19

Pancrine hormone- Somatostatin

Answer 19

*Inhibitor of GI Secretion* 
Secreted by D-Cells 
Stomach and pancreas- somatostatin 14
Intestine- somatostatin 28
1/2 life = 2-3 mins

Question 20

Somatostatin act on

Answer 20

CNS- Inhibits gratin release from pituitary
Liver- Decreases blood flow, inhibits bile secretion, inhibits gall bladder contraction
Pancreas- Inhibits endocrine and exocrine secretion
Gastrointestinal- Slows GI motility, Inhibits absorption, inhibits gastric acid secretion

Question 21

Defence mechanisms

Answer 21

1st level- Bicarbonate, mucus, immunoglobulins
2nd level- Epithelia that are resistant to acids
3rd level- mucosal microcirculation
4th level- mucosal immune system

Question 22

Ulcerative Colitis and IBS

Answer 22

Mucus layer is thinner than usual

Reduction in goblet cells

Question 23

Intestinal immune system

Answer 23

Largest reservoir of immune cells in body 60% of Tcells
Peyers patches-defined t and B cell sites
M-cells uptake antigens into immune inductive sites leading to maturation of T cells

Question 24

4 major activities

Answer 24

Secretion absorbtion digestion and motility

Secretagogue- secretory activator
Somatostatin- GI inhibitor

Question 25

Liver lobes

Answer 25

Right- largest Left Quadrate Caudate

Question 26

Blood flow to kidney

Answer 26

Supplied by portal vein and artery. Carried away by hepatic vein Connected to diaphragm by 5 ligaments

Question 27

Gall bladder

Answer 27

Muscular sack for storage, concentration and release of bile to small intestine

Question 28

Liver lobules

Answer 28

Hexagonal structures consisting of hepatocytes which radiate around central vein Each 6 corners of a lobule is a portal triad

Question 29

Bilary Anatomy

Answer 29

Hepatocytes produced bile Bile flows through canals called bile canaliculi to bile duct Bile ducts leave the liver via the common hepatic artery

Question 30

Hepatocytes

Answer 30

``` Functional unit of the liver Cuboidal cells Bile secretion and production Numerous mitochondria Catabolism of endogenous substances ```

Question 31

Main liver functions

Answer 31

Anabolism-Local (glycogen) Distant (FA and glycerol) Catabolism Glycogenolysis and Glyconeogenesis

Question 32

Storage and synthesis in liver

Answer 32

Hepatocytes absorb and store excess nutrients from blood Protein synthesis- Albumin which transports Cholesterol synthesis- Produced by hepatocytes used for bile production

Question 33

Breakdown of erythrocytes-RBCs and Haemoglobin

Answer 33

When RBCs die haemoglobin is released by phagocytosis Kupfer cells in liver

Question 34

Breakdown of haemoglobin

Answer 34

Iron is removed leaving bilirubin Iron is moved to marrow to renew RBCs Bilirubin is component of bile Globulins are hydrolysed to AA and returned to blood

Question 35

Bile

Answer 35

Consists of Bile salts, Bilirubin, cholesterol and proteins | Is secreted into small intestine via the bile duct

Question 36

Bilirubin

Answer 36

Principle constituent in Bile Is then conjugated by UDP glucuronyl transferase Broken down in gut to form urobillogen which is resecreted into bile or excreted into urine

Question 37

Hepatitis

Answer 37

Inflammation of liver and damage of liver cells

Question 38

Cirrhosis

Answer 38

Increased fibrosis and obstruction of bile flow

Question 39

Hepatic bilirubinemia

Answer 39

Unconjugated- caused by conjugation defects within the liver (UDP glycuronyl transferase) Bilirubin has t remain uncongugated to pass placenta and shorter 1/2 life of RBCs and less albumin leads to babies having jaundice

Question 40

Paracetamol overdose

Answer 40

Most common acute liver failure 10% of paracetamol is metabolised into toxic metabolites Paracetamol—p450 enzyme—->NAPQI—with no GSH->Hepatic and renal damage Low GSH levels can also encourage overdose (alcohol) Treatment with N-acetyl-cystine as replenishes NAC

Question 41

Excitation of contraction coupling of skeletal muscle

Answer 41

1, influx of Ca2+ to presynapse 2, release of neurotransmitter 3, binding of ACh to nicotinic receptors 4, influx of Na+ at motor end 5, propagation of AP 6, activation of T-tubules DHPR 7, release of calcium from SR 8, binding of ca to troponin 9, cross bridge formation with actin and myosin 10, power stroke and release of ADP + Pi