W1: organs of the abdomen- liver, pancreas and kidney

Question 1

components of urinary system

Answer 1

suprarenal adrenal gland
kidney
ureter
bladder
urethra

Question 2

functions of urinary system

Answer 2

regulator: water, inorganic ion balance (acid base balance)
excretor: removal of metabolic waste (removal of foreign chems from body)
producer: gluconeogenesis, production of hormones (renin, erythropoietin)

Question 3

the kidney

Answer 3

• 25% of cardiac output and functional units called nephrons

Question 4

the nephron flowage

Answer 4

1. blood enters nephron via afferent arteriole: AA carries o2 blood into glomerulus inside renal corpuscle. pressure in glomerulus forces water, small molecules and waste products out of blood and into Bowman’s capsule, forming glomerular filtrate
2. filtrate enters PCT and most filtered stuff is reabrosbed back into bloodstream thru active and passive transport
3. filtrate moves into LOH, in desc limb h20 is re absorbed ion blood stream (conc increases) and in asc limb, ions are actively re absorbed into surrounding interstitial space but h30 remains in tubule
4. filtrate enters the DCT where na and ca are reabsorbed but k and h are secreted into filtrate
5. filtrate enters collecting duct that regulates water balance (permeability of CD is controlled by ADH). in presence of ADH, more water is reabasorbed (urine is conc). CD further adjusts the composition and eventually becomes urine
6. urine is formed and collected in renal pelvis. from renal pelvis, urine moves to ureter then to bladder and eventually exists thru urethra

Question 5

feature of nephron

Answer 5

peritubular capillaries surround nephrons tubule for reabsorption and secretion

Question 6

different nephrons

Answer 6

cortical: 80%
juxtameduallary nephron: 20%

Question 7

reabsorption and secretion

Answer 7

reabsorption: movement of substances from tubule into interstitial space/ peritubular capillaries

secretion: movement of substances from interstitial space/ peritubular capillaries to the tubule

Question 8

glomerulus

Answer 8

filtration: filters out 105-125ml of fluid from blood to capsular space
includes: water + all solutes present in blood
doesnt include: proteins (apart from v small), rbc

filtration occurs due to pressure gradient
filtration membrane is made up of glomerular cells and podocytes
smaller diameter than afferent arteriole

Question 9

proximal tubule

Answer 9

re absorbed: 65% of filters na, cl, k ions , bicarbonate and h20
100% glucose and amino acids

secretion of h+, organic acids and bass

Question 10

loop of henle

Answer 10

thin descending loop:
- permeable to h20, leaves down osmotic gradient
- slightly permeable to na+
- tubule fluid increases in osmolarity

thin ascending loop:
- impermeable to h20
- moderately permeable to na+
- na+ moves from table to interstitial space
- h20 doesnt follow even tho there is osmotic gradient smaller diameter
- osmolarity decreases

thick ascending loop:
- impermeable to h20
- highly permeable to na+
- actively pumps out na, cl, k, ca and mg ions from tubule to interstitial space
- lowering osmolarity within tubule
- increases osmolarity within the interstitial space
- 20% of the tubular h20 is reabsorbed

Question 11

distal convoluted tubule

Answer 11

• same characteristics as thick ascending
• tubular fluid becomes more dilute
• up to this point 85% of the h20 and 90% of nacl reabsorbed

Question 12

late distal tubule and cortical collecting duct

Answer 12

• hormones dictate the final urine concentration
• na+ reabsorption and k+ secretion

Question 13

hormone (ADH)

Answer 13

ADH
- produced by posterior pituitary gland
- insert aquaporind in the luminal membrane of collecting ducts
- increase permeability to h20- more water reabsorbed
- urine more concentrated

Question 14

water reabsorption by ADH

Answer 14

loop of henle- creation of hyper-osmotic interstitium which create the gradient for osmosis

more ADH= small volume of concentrated urine
less ADH= large volume of dilute urine

Question 15

hormones (aldosterone)

Answer 15

released from adrenal cortex
increase reabsorption of na+ = increasing h20 reabsorption
urine become ore concentrated (lower volume)
increase bp

Question 16

renin angiotensin- aldosterone system (RAAS)

Answer 16

1. trigger when bp falls, kidneys detect the change
2. kidney realise renin into blood from granulosa cells
3. renin acts on angiotensinogen, a protein produced by liver, converts it into angiotensin I
4. angiotensin I - > angiotensin II by the angiotensin- converting enzyme, primary in lungs
5. angiotensin II has 2 effects: vasoconstriction and aldosterone release from adrenal gland
6. aldosterone promote reabsorption of na+ and h20 into bloodstream from kidney DCT and collecting ducts -> increase blood volume which helps raise bp
7. combination of vasoconstriction and increased blood volume raises bp

Question 17

regulation of glomerular filtration rate

Answer 17

1. macula densa cells located in distal tubule, they monitor na+ concentration in filtrate, and single charges in na+ levels to adjust GFR
2. granular cells located in afferent arteriole, they form modified smooth muscle cells, and secret renin which activates RAAS

GFR regulation mechanisms:
myogenic: stretch receptors in afferent arteriole detect changes in bp

increase bp stretches the arteriole= vasoconstriction = reduce GFR
decrease bp relaxes the arteriole= vasodilation = increase GFR

tubuloglomerular feedback: macula densa detects changes in na concentration in filtrate

high na levels indicate high GFR= vasoconstriction of the afferent arteriole to reduce GFR

low na levels indicate low GFR= vasodilation and renin realise to increase GFR

Question 18

hormones (atrial natriuretic peptide)

Answer 18

released from atrial tissue

inhibits reabsorption of na+ - inhibit h20 reabsorption
urine becomes more dilute
decreases blood pressure

Question 19

accessory organs of digestive system

Answer 19

liver
gall bladder
pancreas

Question 20

what does the duodenum do

Answer 20

the beginning of small intestine

receives secretions from liver, gall bladder and pancreas

Question 21

the liver, lobule

Answer 21

LIVER: heaviest organ in body
2nd largest
completely covered by dense irregular connective tissue

LOBULE: lobes of liver are mad of functional units called lobules
hepatic sinusoid: highly permeable blood capillaries
hepatocyte: epithelial cells (main functioning unit) that secrets bile
bile canaliculi: small ducts that collect bile from hepatocytes
interlobular bile duct, vein and artery
central vein in centre

Question 22

path of bile

Answer 22

hepatocytes secrete bile
enter narrow canals (bile canaliculi)
canaliculi enter into small ducts at the edges of the lobules

Question 23

describe the path of bile

Answer 23

bile ducts merge to form right and left hepatic ducts
unite to form common hepatic duct
joins cystic duct from gall bladder to form common bile duct
enter duodenum at sphincter of oddi

Question 24

gall bladder

Answer 24

8cm sac on the under surface of liver
stores and concentrates the bile produced by the liver
delivers bile to duodenum when you eat

Question 25

carbohydrate, lipid and protein metabolism

Answer 25

C: vital in maintaining the normal glucose levels in blood stores glucose as glycogen and lipids and triglycerides can concert amino acids and other sugars into glucose L: synthesis of lipoproteins, cholesterol and bile salts P: deaminates amino acids (convert to urea for excretion) synthesis of plasma proteins

Question 26

pancreas

Answer 26

pancreatic juice is secreted in duodenum (acinar cells) contains enzymes to aid digestion bicarbonate to neutralise stomach acid insulin and glucagon is secreted (regulate blood sugar)

Question 27

islets of langerhans

Answer 27

secrete insulin and glucagon insulin lower blood glucose glucagon raises blood glucose