Homeostasis

Question 1

What is homeostasis?

Answer 1

The process of which the body maintains a relatively constant internal environment in an ever-changing external environment.

Question 2

What is the definition for thermoregulation?

Answer 2

Thermoregulation is the process of maintaning balance between heat production + heat loss

balance make heat + lose heat

Question 3

What is the formula for thermoregulation?

Answer 3

Heat (input) = heat (output)

Question 4

What is the heat input?

How is heat transferred into the body?

Answer 4

• heat from the body processes (metabolic activity) esp. respiration of liver cells
• heat from surroundings by conduction + radiation.

Question 5

Why is it important for our bodies to thermoregulate?

Answer 5

• Often during metabolic activies, such as exercise, the body produces more heat than needed + needs to be removed.
• It is characteristic to daily body temperature.

Remember META — MORE HEAT = REMOVE IT PLS — BOD TEMP

Question 6

What is the heat output?

Answer 6

• radiation, conduction, and convection to surroundings
• evaporation of water from skin + lungs
• warm air is expired from lungs
• warm feces + urine is excreted.

You need to know all these four points

Question 7

Can you distinguish the differences between central and peripheral thermoreceptors?

Answer 7

Peripheral:
* found in the skin and mucous membranes
* provide hypothalamus about external environment

Central:
* found in the hypothalamus
* detectes the internal environment

Bonus: Hypothalamus is the main temperature regulating centre.

Question 8

What is the formula for osmoregulation?

Answer 8

fluid gain = fluid loss

Question 9

What parts of the body excrete water as a byproduct?

Answer 9

• We lose water through our kidneys (by urination)
• We lose water through our skin (by sweating)
• We lose water through our lungs (by expiration)
• We lose water through our alimentary canal (by defecation)

SALK

Question 10

Can you explain how he blood vessels are integral for heat regulation?

Answer 10

• the blood vessels are located at the dermis of the skin
• Vasodilation allows more blood to be transported to the capillaries in skin
• Diameter of the blood vessels is increased
• Heat loss increases
• Vasoconstriction prevents more blood to be transported to the capillaries in the skin
• Diameter of the blood vessels is reduced
• Heat loss decreases

Question 11

How does the skin regulate temperature?

Answer 11

• Important organ in body temp regulation.
• Heat lost by conduction, convection, radiation + evaporation.
• Sweat glands secrete sweat and periodic contraction of cells surrounding ducts pump sweat to surface.
• Evaporation of sweat from skin has cooling effect.
• Continual loss of water (sweating aside) from surfaces + respiratory passages contributes to lots of daily heat loss.

Question 12

How is water intake regulated?

Answer 12

• As water is lost from body (sweat, urine, faeces, exhaled, etc):
• Plasma becomes concentrated and has lower water content/high osmotic pressure.
• Water moves from intercellular fluid into plasma by osmosis
• Intercellular fluid more concentrated and water diffuses out of cells + cells start to shrink.
  *

Question 13

What is the negative feedback loop for water restoration?

Answer 13

Restoration of water balance involves:
1. Water loss from body fluids ↓ plasma volume and ↑ osmotic conc. of extracellular fluid.
2.Osmoreceptors in hypothalamus detect rising osmotic conc. Other stimuli such as dry mouth also involved.
3. Stimulation of thirst centre makes person feel thirsty.
4. Conscious feeling of thirst stimulates person to drink
5. Fluid consumed is absorbed into the plasma from alimentary canal.
6. As blood circulates, it enables intercellular fluid and intracellular fluid to return to proper osmotic conc.
7. After drinking, thirst centre no longer stimulated and desire to consume water stops. Negative feedback has occurred.

Question 14

What happens when there is a small increase of CO2 gas in the blood?

Answer 14

Small increase in CO2 (and H+ conc.) can cause marked increase in breathing rate.
1. Increases in both CO2 and H+ in the blood detected by central chemoreceptors (in medulla) and peripheral chemoreceptors (in carotid + aortic bodies).
2. Chemoreceptors transmit nerve impulses to the respiratory centre (in the medulla).
3. Nerve impulses sent to respiratory muscles via phrenic and intercostal nerves and stimulate increase in breathing rate.