L27 Homeostasis and the kidney

Question 1

Define homeostasis

Answer 1

Maintenance of a constant internal environment

Question 2

What are the 4 most important features of our internal environment to be kept constant

Answer 2

Chemical Composittion
Blood pH (7.35-7.45)
Osmotic pressure
Temperature

Question 3

Which types of animals regulated their temperature

Answer 3

Regulated- birds and mammals (endotherms)
Not regulated- fish and amphibia (ectotherms)

Question 4

4 examples animals can regulate temperature

Answer 4

Regulation and conforming
Regional heterothermy in tuna
pre-flight warm-up in moths
Behavioral regulation in an ectotherm

Question 5

What is the control system for thermoregulation

Answer 5

Stimulus (temperature change)
Receptors (skin and hypothalamus)
Control centre (Hypothalamus)
Effectors (skin blood vessels, sweat glands, hair, muscles)
Response mechanisms (vasoconstriction/dilation, sweat production, piloerection, shivering)

Question 6

define hyperosmotic

Answer 6

Contains more solutes and less water

Question 7

Define hypo-osmotic

Answer 7

contains less solutes and more water

Question 8

which way does water move by osmosis

Answer 8

High to low concentration
hypo-osmotic to hyperosmotic

Question 9

Osmolarity/solute conc.=

Answer 9

no. of osmoles solute per litre of solution

Question 10

what are 3 functions of the kidney

Answer 10

1 Removal of nitrogenous waste
2 Regulation of water content of body (osmoregulation)
3 Regulation of salt balance (ionic regulation)

Question 11

where does the ammonia excreted in waste come from

Answer 11

When amino acids are metabolised, the amino group is removed and forms ammonia (NH3)

Question 12

How can ammonia be excreted

Answer 12

Ammonia
Urea
Uric acid

Question 13

Toxicities of nitrogenous waste

Answer 13

Ammonia- high
Urea- low
Uric acid- very low

Question 14

metabolic cost of nitrogenous wastes

Answer 14

Ammonia- none
Urea- some
Uric acid- high

Question 15

Shape and location of the kidneys

Answer 15

Two bean shaped organs. Located against the back wall of the abdomen on either side of the body

Question 16

Revise structure of kidneys

Answer 16

:)

Question 17

What are the kinds or nephrons are there

Answer 17

Juxta-medullary = very concentrated urine
Cortical = less concentated urine

Question 18

Revise nephron structure

Answer 18

:)

Question 19

what is the ratio of cortical and juxta-medullary nephrons

Answer 19

85% cortical
15% juxta-medullary

Question 20

How Bowman’s capsule works

Answer 20

Fluid moves by process of ultrafiltration
The hydrostatic pressure of the blood plasma forces fluid and solutes through glomerular capillaries into Bowmans capsule
Passive process- no energy

Question 21

Which molecules pass into bowmans space

Answer 21

Molecules with diameter of approx 4.2 nm do not pass out of the capillaries

Question 22

Why is blood pressure high in the glomerular capillaries

Answer 22

1 low resistance input pathway due to large diameter arteries and arterioles
2 constriction of the arteriole increasing pressure
3 high resistance due to many small thin capillaries in glomerulus, efferent arterioles and vasa recta