Physiology 2 week 6

Question 1

When does the body temperature rise?

Answer 1

When heat production exceeds heat loss

Question 2

When does the body temperature decrease?

Answer 2

When heat loss surpasses heat production

Question 3

What is heat a by product of?

Answer 3

Metabolism

Question 4

Name 3factors heat is influenced by?

Answer 4

• Basal metabolic rate of body cells
• Increased metabolism from muscle activty
• Effects of hormones like throxyine, growth hormones and testtosterone

Question 5

Name and describe the 2 steps heat transfer occurs

Answer 5

1. Conducting heat from internal organs to the skin.

2.Transferring heat from the skin to the surroundings

Question 6

Name insulators in the insulator system and their role

Answer 6

• Skin, subcutaneous tissues and fat
• They reduce the heat loss

Question 7

What is the role of insulation system

Answer 7

It allows skin temperature to mach the surroundings while maintaining stable internal core temperatures

Question 8

Explain how the blood vessels in the skin work

Answer 8

-Skin has a venous plexus beneath it, recieving blood from the capillaries
- In hands, feet and ears arteriovenous anastomes direclty supply bood to the plexus.

Question 9

What is the role of High blood flow?

Answer 9

• It effectively conducts heat from the body core to the skin

Question 10

What is the function of reduced blood flow

Answer 10

• Minimizes heat transfer

Question 11

What is the blood flow to the skin regulated by and controlled by?

Answer 11

-It is regulated by vasoconstriction of arterioles and arteriovenous anastomoses.
Controlled by the sympathetic nervous system in response to changes in body core and environmental temperature.

Question 12

Name the 3 methods of heat loss

Answer 12

• Radiation
• Conduction
• Evaporation

Question 13

What happens in Radiation?
When does heat loss occur ?

Answer 13

• Heat radiates as infrared rays
• Heat loss occurs if the bodys temperature is higher than its surroundings ?

Question 14

What happens in conduction?

How is heat transferred ?
When does heat transfer stop?

Answer 14

• Heat transfers via direct contact
• Heat transfer stops when air temperature equals skin temperature unless the heated air is replaced

Question 15

What happens in convection?

How is heat transferred?

Answer 15

• Heat is transferred from the skin to air and carried away by moving air currents

Question 16

Compare SHC, heat loss and insulating layers in water and air

Answer 16

• Water has a higher SHC than air
• Heat loss in water is greater than in air
• Both have not insulating layers

Question 17

What is insensible evaporation?

Answer 17

• When water evaoprates insensibly from the skin to the lungs even when a person is not sweating

Question 18

When is evaporation neccessary

Answer 18

When the surrounding air temperatures exceeds the skin temperature , so then heat is gained from the environment via conduction and radiation

Question 19

What happens to individuals with an absence of sweat glands

Answer 19

They cannot loose heat effecitvely leading to heatstroke risks

Question 20

What is the effect of clothing on heat loss

Answer 20

• Clothing traps the air near the skin, reducing heat loss by conduction and convection

Question 21

What does coating clothes in reflective metals do?

Answer 21

• Enhances insulation by reflecting radiant heat back to the body

Question 22

Does wet clothes reduce or increase heat loss

Answer 22

increases heat loss

Question 23

What is the role of the Anterior hypothalamus preoptic area

Answer 23

• Stimulates sweating in response to heat

Question 24

Explain the Autonomic pathway for sweating

Answer 24

• The sweating signals travel through cholinergic sympathetic nerve fibers, which release acetylcholine

Question 25

Explone the hormonal influence in response to sweating

Answer 25

- Epinephrine and Norepinephrine frome the adrenal medulla can also stimulate sweat glands indirectly during exercise

Question 26

Describe the structure of a sweat gland and its functions

Answer 26

- Coiled secretory protein( produces percursor fluid) -Duct portion ( modifies fluid)

Question 27

What happens to Na and Cl at low sweating rates

Answer 27

- They are reabsorbed, reducing their concentrations -

Question 28

What happens to Na and Cl at high sweating rates

Answer 28

-There is less reabsorption, resulting in higher Na and Cl concentrations

Question 29

What is the body temperature regulated by?

Answer 29

- The nervous feedback mechanisms and these mechanisms operate via the temperature regulating centers in the hyopthalamus

Question 30

What does the anterior hypothalamic preoptic area contain?

Answer 30

- Heat senesitive nerons - Cold sensitive neurons

Question 31

What happens when the anterior hypothalamic preoptic area is heated?

Answer 31

- Profuse sweating occurs across the body - The skin blood vessels dilate

Question 32

What receptors does the skin have?

Answer 32

Cold and warmth receptors

Question 33

Where are the deep body receptors found?

Answer 33

- Spinal cord, abdominal viscera around great veins in upper abdomen

Question 34

What is the role of deep body detectors

Answer 34

- They detect core body temperature , focusing in cold detection to prevent hypothermia

Question 35

Name the 3 reflex responses to chilling(cold)

Answer 35

- Shivering- increase heat production -Sweating- reduce heat loss -Vasconstriction- minimise heat loss from the skin

Question 36

What does the Posterior hypothalamus integrates?

Answer 36

- Peripheral temperature signals -central signals from the anterior hypothalamic preoptic area

Question 37

What are the mechanisms that take place to decrease the body temperature when it is too high

Answer 37

- Vasodilation: - Sweating -Decrease in heat production: - inhibiting shivering and chemical thermogenesis

Question 38

What happens in vasodilation

Answer 38

- The blood vessels in the skin dilate due to the inhibition of sympathetic vasoconstrictor centres in the posterior hypothalamus

Question 39

What are the mechanisms that take place to increase the body temperature when it is too cold

Answer 39

- Vasoconstriction - Pilo erection - Increase in heat production: stimulating shivering and thyroxine secretion

Question 40

What is the function of vasoconstriction and what is it caused by

Answer 40

-Reduces heat loss Caused by the stimulation of the posterior hypothalamus sympathetic centers

Question 41

What is the function of throxyine in increasing the body temperature

Answer 41

- Boosts cellular meabolism, enhancing heat production

Question 42

What is shivering controlled by

Answer 42

- Primary Motor center for shivering

Question 43

# critical body What is the set point

Answer 43

- Critical body temperatures that the temperature control mechanisms aim to maintain

Question 44

What happens at temperatures above the set point

Answer 44

- Heat loss exceeds heat production causing a decress in body temperature

Question 45

# measure of What is the feedback gain

Answer 45

- A measure of the effectiveness of temperature regulation

Question 46

What influence does the skin receptors have on the set point

Answer 46

-Signals from the skin receptors can modify the hypothalamic set point

Question 47

Give 2 examples of psychological behavioural adjustments

Answer 47

- Feeling cold- move to a warmer area - Feeling warm- Move to a cooler area

Question 48

What is the most effective mechanism for maintaining body heat

Answer 48

- Behaviour control

Question 49

What is a fever

Answer 49

- Elevated body temperature beyond the normal range

Question 50

What is a fever caused by

Answer 50

- Brain abnormalities,Toxic substances,infections,brain tumours

Question 51

What is the mechanism of a fever- when does it occur

Answer 51

- When the hypothalamic set point is raised dye to pyrogens

Question 52

Where do pyrogens originate from

Answer 52

- Toxins

Question 53

What is the role of pyrogens

Answer 53

- They act directly on the hypothalamus to increase the set point o - They act indirectly through intermediates like (cytokines)