Lecture 30 and 31

Question 1

What are the most important Electrolytes in the body?

Answer 1

Na+, H20, K+, Ca+, H+ & HCO3-

Question 2

What is the role of Na+

Answer 2

Cell excitability, osmolarity and ECF volume

Question 3

what is the role of H20

Answer 3

osmolarity, blood volume and ECF volume

Question 4

What is the role of Ca2+

Answer 4

exocytosis, muscle contractions, bone formation

Question 5

what is the role of H+ AND HCO3-

Answer 5

pH balance and co2 transport

Question 6

What are the ways water enters the body and which is the main way?

Answer 6

Majority from food and water, a little from metabolism

Question 7

How does the body lose fluids and which is the main way?

Answer 7

Skin, Lungs, Feces but mostly urine (1.5L)

Question 8

How much water is in the human body?

Answer 8

30 L Females and 42L males

Question 9

how does osmolarity change in the nephron?

Answer 9

1) Descending loop of henle: Water is absorbed relative to the blood in the vasa recta = high osmolarity
2) Ascending loop of henle- solutes are absorbed but no water = lower osmolarity
3) Distal Tubule and Collecting Duct- water is absorbed whether is it needed or not.
4) Collecting Duct - Urine leaves with varying level of osmolarity demanding on how much was removed in previous step

Question 10

What is Vasopressin?

Answer 10

it is a neurohormone made from the hypothalamus released in the posterior pituitary gland to cause more water to be absorbed

Question 11

How is vasopressin stimulated?

Answer 11

• low blood pressure
• low blood volume
• high plasma osmolarity

Question 12

how does vasopressin increase more water intake?

Answer 12

it opens more aquaporin-2 (water channels) in the apical membrane of the collecting duct of the nephron

Question 13

What detects the 3 stimuli of vasopressin?

Answer 13

low blood pressure = carotid and aortic baroreceptors
low blood volume = atrial stretch receptors
high plasma osmolarity = hypothalamus osmoreceptors

all go to the go the the hypothalamus

Question 14

What is aldosterone?

Answer 14

is is a steroid hormone that acts on the principle cells in the distal and collecting duct of the nephrons to absorb more Na+. It is produced and released by the adrenal cortex

Question 15

what is the stimulus for Na+ reabsorption?

Answer 15

• angiotensin 2 which comes from low blood pressure and the renin-angiotensin system
• high K+ in plasma (not as important)

Question 16

What is renin and what does it do?

Answer 16

it is an enzyme that turns angiotesinogen into angiotensin 1

Question 17

How is angiotensinogen produced?

Answer 17

is it made constantly by the liver and circulates in the plasma

Question 18

What are the 3 stimulus for renin production?

Answer 18

1) low blood pressure makes granular cells in afferent arteriole produce renin
2) low blood pressure turns sympathetic activity up which makes the granular cells make renin
3) low blood pressure makes the glomerous filtration rate go down which decreases NaCl transport across the macula dense of age distal tubule which makes the paracrine produce renin

Question 19

What is angiotensin 2?

Answer 19

is it a hormone that affects the all the structures that can increase water absorption

Question 20

How is angiotensin 2 produced?

Answer 20

it is produced when angiotensin converting enzyme (ACE) changes angiotensin 1 into angiotensin 2

Question 21

What 5 structures does angiotensin affect?

Answer 21

• arterioles
• medulla oblongata
• hypothalamus
• adrenal cortex
• proximal tubule

Question 22

How does angiotensin 2 affect the 5 structures?

Answer 22

1) vasoontricts arterioles
2) makes medulla increase sympathetic activity
3) makes hypothalamus release vasopressin and increase thirst
4) adrenal cortex to release aldosterone for Na reabsorption
5) proximal tubule to absorb more Na+

all affects increases blood pressure at the end

Question 23

ph of plasma?

Answer 23

7.38-7.42

Question 24

What are the 3 mechanisms to maintain normal pH

Answer 24

1) buffers - minutes
2) regulation of ventilation - hours
3) kidneys - hours-days

Question 25

what things affect pH?

Answer 25

H+ and CO2

Question 26

How does renal system compensate for pH changes?

Answer 26

• the proximal tubule can secrete H+ and absorb HCO3
• collecting duct can use their intercalated cells to absorb and secrete H+ and HCO3-

Question 27

What are intercalated cells?

Answer 27

they contain high levels of carbonic anhydrase which can help in the secretion and absorption of H+ and HCO3-

Question 28

What do the type A intercalated cells do?

Answer 28

Respond to Acidosis- secrete H+ and reabsorb HCO3

Question 29

what do the type B Intercalated cells do?

Answer 29

responses to alkalosis - reabsorb H+ and secrete HCO3

Question 30

Functions of Calcium in extracellular matrix

Answer 30

99% -in classified in bone and teeth

Question 31

Functions of Calcium in extracellular fluid

Answer 31

• neurotransmitter release at synapse
• cofactor in coagulation cascade
• muscle contraction
• influences excitability of neurons

Question 32

Functions of intracellular Calcium

Answer 32

• muscle contraction
• signal in the second messenger systems

Question 33

structure of bone

Answer 33

• osteoblast (synthesizes bone)
• osteoclast (resorption of bone (break down))
• calcified extracellular matrix hydroxyapatite (Ca10(PO4)6(OH)2)

Question 34

the three calcium homeostasis mechanisms

Answer 34

1) parathyroid hormone
2) Vitamin D3 (calcitriol)
3) Calcitonin

Question 35

what is the parathyroid hormone

Answer 35

a peptide hormone which always produced but is released in plasma when Ca levels are low

sit behind the thyroid gland and increases
- resorption of Ca in bone (osteoclast)
- reabsorption of Ca in kidney
- absorption of Ca in GI tract

Question 36

what is Vitamin D3 (Calcitriol)and what does it do?

Answer 36

uses the vitamin D sunlight and diet in combination with lung and kidney to be produced

when signalled by the PTH causes
- resorption of Ca in bone (osteoclast)
- reabsorption of Ca in kidney
- absorption of Ca in GI tract

Question 37

Calcitoninand what does it do?

Answer 37

made in the thyroid its a peptide hormone released when Ca2+ levels are too high
- causes synthesis of Ca2+ the bone (osteoblast)
- excretion of Ca2+ in kidneys