Unit 9- Heart And Kidney

Question 1

What factors are controlled by homeostasis?

Answer 1

• body temp
• blood pH
• glucose concentration in blood
• blood water potential
• blood pressure
• blood ion concentration
• blood oxygen concentration level

Question 2

What is the artery and vein called that carries blood to the kidneys and away

Answer 2

Toward - renal artery

Away - renal vein

Question 3

What 5 sections make up the nephron?

Answer 3

Bowmans capsule
Proximal convoluted tubule
Loop of henle
Distal convoluted tubule
Collecting duct

Question 4

Describe the positions of the nephrons within the mammalian kidney

Answer 4

• the bowmans capsule, glomerulus and convoluted tubules are found in the cortex
• the loops of henle and collecting ducts make up the medulla

Question 5

Describe ultra filtration and where it occurs

Answer 5

• an afferent arteriole carrying blood splits into numerous capillaries which form the glomerulus
• the afferent arteriole is wider than the efferent arterioles so blood is under pressure
• the pressure forces plasma out the capillaries by ultrafiltration through slits in podocyte cells which coat the capillaries along with all the other small components of the blood apart from large proteins and blood cells

Question 6

Where does reabsorption occur?

Answer 6

Proximal convoluted tubule

Question 7

Describe the process of selective reabsorption

Answer 7

• proximal convoluted tubule is linked with epithelial cells containing microvilli and mitochondria
• 80% of the filtrate is reabsorbed into the tissue fluid and then into the blood
• all glucose, all amino acids and most mineral ions are reabsorbed by active transport

Question 8

What is the job of the loop of henle

Answer 8

To produce a super high concentration of solutes in the medulla

Question 9

What 2 parts make up the loop of henle and what are their properties?

Answer 9

Ascending limb - impermeable to water and permeable to ions

Descending limb- permeable to both

Question 10

Describe the process of countercurrent multiplier (method behind water absorption from filtrate)

Answer 10

• in ascending limb ion transporters actively pump ions out the filtrate into the medulla increasing ion concentration in medulla
• ascending limb in impermeable to water so water cannot diffuse in
• the filtrate entering the medulla in the descending limb is permeable and due to the high concentration of ions in the medulla water moves out the filtrate by osmosis
• the conc of ions in medulla is always higher than in the filtrate so water is always diffusing out by osmosis down its water potential gradient

Question 11

What is the job of the distal convoluted tubule

Answer 11

• to actively transport certain substances into the filtrate from the blood
  Eg creatine, drugs or toxic substances
  As well as H+ ions to increase the blood pH

Question 12

What is the purpose of the collecting duct?

Answer 12

The collecting duct passes through the super medulla with a super low water potential
Water passes out the collecting duct into the medulla via aqua porin channels which are controlled by ADH

Question 13

What part of the brain controls osmoregulation?

Answer 13

The hypothalamus which contains osmoreceptor cells which detect changes in water potential of blood

Question 14

When ADH is released from the pituitary gland by the hypothalamus what happens?

Answer 14

ADH binds to channels in the collecting ducts, increasing the permeability
So water can pass into the medulla (salt bath) by osmosis

Question 15

Why might ADH get secreted?

Answer 15

If too much water has been lost from the body resulting in a low blood pressure, or a water potential in the blood that’s too high

Question 16

How does a high blood pressure link to ADH?

Answer 16

High blood pressure is detected by baroreceptors
Pituitary gland secretes less ADH
Collecting duct becomes less permeable to water
Less water is reabsorbed
Less water in blood so blood pressure decreases

Question 17

How are kangaroo rats adapted to have minimal water loss?

Answer 17

• no sweat glands
• nocturnal so active when it’s cold
• long loops of henle to produce a super low water potential in the medulla so more water is reabsorbed
• more microvilli and mitochondria in the tubules for more reabsorption
• obtain most their water from condensation reactions in the body

Question 18

What is the equation for cardiac output?

Answer 18

Cardiac output = heart rate x stroke volume

Question 19

What controls the heart rate?

Answer 19

Part of the Medulla oblongata called the cardia centre

Question 20

The cardiac centre can send an impulse to the SAN via the sympathetic or parasympathetic nervous system, what’s the difference?

Answer 20

• sympathetic neurones release noradrenaline to SAN which increase heart rate
• parasympathetic neurones release acetyl choline to SAN causing decrease of heart rate

Question 21

Describe the mechanism by which a fall in blood pH during exercise affects heart rate:

Answer 21

• muscles respire releasing CO2 into the blood, lowering the pH
• chemoreceptors in the carotid and aortic bodies detect change in pH
• an impulse is fired along sensory neurones to the cardiac centre in medulla oblongata
• increase in impulse in sympathetic nerve to SAN to release noradrenaline
• SAN depolarises more frequently increasing heart rate
• vasoconstriction of arterioles also increases blood pressure so more blood fills the heart in diastole, increasing stroke volume

Question 22

Describe the response to a fall in blood pressure

Answer 22

• baroreceptors in aortic and carotid bodies detect teh artery walls not stretching enough, so bp is too low
• a nerve impulse is sent to cardiac centre in medulla oblongata along sensory neurones
• increase in impulses in sympathetic nerve to SAN releases noradrenaline
• SAN depolarises more frequently
• heart rate increases
• arterioles contract increasing bp also

Question 23

What does the neurotransmitter noradrenaline do?

Answer 23

• excitatory neurotransmitter that causes the SAN to depolarise more frequently

Question 24

What does Acetylcholine do?

Answer 24

• an inhibitory neurotransmitter that causes teh SAN to depolarise less frequently

Question 25

What affect does the release of adrenaline from the adrenal medulla in the kidneys have on the body?

Answer 25

• the hormones gets secreted into the blood
• which affects target cells in the SAN, cardiac centre and arterioles
• resulting in increased heart rate, due to more frequent SAN depolarisation, arteriole contraction to increase blood pressure and therefore stroke volume
• this prepares the body for fight or flight

Question 26

Where are baroreceptors and chemoreceptors located?

Answer 26

In the carotid and aortic bodies (the arteries directly from the heart)

Question 27

Where does amino acid metabolism take place?

Answer 27

Liver

Question 28

Why is ammonia converted into urea? And at what cost?

Answer 28

Ammonia is very toxic, urea is less toxic, but this uses CO2 and 3 ATP

Question 29

What is deamination?

Answer 29

When the amino (NH2) group is removed from an excess amino acid with oxygen to produce a keto acid and ammonia (NH3)

Question 30

What is transamination?

Answer 30

Making scarce amino acids from abundant ones by transferring an amino acid group (NH2) to a keto acid (C=O) to make a different keto acid and new amino acid

Question 31

What are essential amino acids?

Answer 31

Only 11 amino acids can be made from transamination, the remaining 9 must be found in the diet and are therefore essential

Question 32

What happens to the products of deamination?

Answer 32

• ammonia is converted to urea

- ketoacid is put into the Krebs cycle