8.2 Renal Physiology II - Fluid Balance HORMONES

Question 1

what is FLUID BALANCE

Answer 1

average INPUT of fluid per day and average OUTPUT of fluid per day

Question 2

FLUID INPUT by

Answer 2

Beverages
Foods
Metabolism (10%)

Question 3

FLUID OUTPUT by

Answer 3

Urine (60%)
Insensible losses via skin and lungs (28%)
Sweat (8%)
Faeces (4%)

Question 4

INTRINSIC FACTORS that regulate DECREASES SYTEMATIC BLOOD PRESSURE (MAINTAIN) subfactors

Answer 4

-MYOGENIV MECHANISM of AUTOREGULATION (FAST)

• TUBULOGLOMERULAR MECHANISM of AUTOREGULATION (SLOW)

(INCREASE GFR)

Question 5

EXTRINSIC FACTORS that regulate DECREASES SYTEMATIC BLOOD PRESSURE (MAINTAIN) subfactors

Answer 5

-HORMONAL MECHANISM
(SLOWER)
-NEURAL CONTROL (RAPID) (during haemorrhage)

Question 6

what triggers the RENIN-ANGIOTENSIN-ALDOSTERONE (RAAS) system

Answer 6

• Dehydration, Na+ deficiency, haemorrhage

-> DECREASE in BLOOD VOLUME

-> DECREASE in BLOOD PRESSURE
/ LOW FLUID VOLUME

Question 7

BLOOD COMPOSITION

Answer 7

44% RBC, WBC, PLATELETS

55% PLASMA

Question 8

BLOOD PLASMA consists of

Answer 8

Albumin
Fibrinogen
IgG
Clotting factors
Water
Salt
Hormones

Question 9

RENIN secreted by JUXTAGLOMERULAR CELLS which are in/next to the..

Answer 9

AFFERENT ARTERIOLE

Question 10

to trigger RAAS SYSTEM/ RENIN SECRETION DECREASED ARTERIOLE PRESSURE is DETECTED by..

Answer 10

GRANULAR (JUXTAGLOMERULAR) CELLS

• LESS PRESSURE in AFFERENT ARTERIOLE
• LESS STRETCH* of the JG CELLS (renin secretion)

Question 11

GRANULAR CELLS / JG CELLS act as ..

Answer 11

BARORECEPTORS
(detect blood pressure)

Question 12

MACULA DENSA CELLS sense composition of FLUID in the..

Answer 12

DCT

Question 13

what does DECREASED BLOOD PRESSURE result in in kidneys and how is this detected by MACULA DENSA CELLS

Answer 13

DECREASED GFR

DECREASED FLOW RATE of filtrate

therefore MORE REABSORPTION of SODIUM

-LESS SODIUM TO DCT
- DETECTED BY MACULA DENSA

Question 14

what does RENIN do to ANGIOTENSINOGEN by LIVER

Answer 14

CLEAVES to form ANGIOTENSIN I

(REMOVES 3 AMINO ACID terminals)

• further cleaved by ACE to form ANGIOTENSIN II

Question 15

ANGIOTENSINOGEN LEVELS are INCREASED by..

(/release stimulated by..)

Answer 15

• PLASMA CORTICOSTERIOD
• OESTROGEN
• THYROID HORMONE
• ANGIOTENSIN II LEVELS

Question 16

primary ROLE of ANGIOTENSIN II

Answer 16

STIMULATES ADRENAL GLANDS to produce ALDOSTERONE

Question 17

EFFECTS of ALDOSTERONE on KIDNEY
(from adrenal cortex)

Answer 17

INCREASED REABSORPTION of WATER and SODIUM

INCREASED SECRETION of HYDROGEN and POTASSIUM into urine

Question 18

ALDOSTERONE leads to INCREASED TRANSCRIPTION of which TRANSPORTERS

Answer 18

• NA-KA TRANSPORTER
• ROMK2 for K+ SECRETION
• ENaC (epithelial sodium channels) for Na+ UPTAKE (reabsorption)

Question 19

another EFFECT of ALDOSTERONE to INCREASE BLOOD PRESSURE

Answer 19

VASOCONSTRICTION of ARTERIOLES

Question 20

other actions of ANGIOTENSIN II besides stimulating aldosterone production (outside of kidney)

Answer 20

• increased inotropy (force of heart contractions)
• increased chronotropy (heart rate)
• increased catecholamine release (eg adrenaline)
• increase catecholamine sensitivity
• increased cardiac remodelling
• STIMULATION of ADH RELEASE from POSTERIOR PITUITARY

Question 21

which HORMONES secretion are STIMULATED by ANGIOTENSIN II

Answer 21

• ALDOSTERONE (adrenal)
• ADH (posterior pituitary)

Question 22

similar FUNCTION of both ALDOSTERONE and ADH

Answer 22

FACILITATE WATER RETENTION in BLOOD by action on the DCT

(ADH also acts on Collecting Duct)

(ADH: water retention in blood
Aldosterone: water reabsorption into blood, and salts)

Question 23

ADH released in dehydration and what does it do in COLLECTING DUCT

Answer 23

BINDS to G-protein coupled receptor

• AQUARPORINS in vesicles move to membrane

WATER transported OUT and REABSORBED into BLOOD