Homeostasis blood sugar + temp - Chapter 5

Question 1

Homeostasis

Answer 1

process whereby body’s internal environment is maintained in a steady state.

Question 2

Properties of tissue fluid maintained by homeostasis:

Answer 2

• core body temperature (normal range 37ºC)
• pH and concentration of dissolved substances in body fluids
• fluid concentrations
• concentration of nutrients, metabolic waste and gases

Question 3

Tolerance limits

Answer 3

conditions which body can function - if conditions change beyond tolerance limits the body systems don’t function properly.
- blood pressure 120/180mm Hg
- blood glucose 3.5-8mmol/L

Question 4

Feedback systems

Answer 4

a circular situation in which body responds to change or stimulus

negative - response decreases original stimulus
positive - response increases original stimulus

Question 5

Feedback loop

Answer 5

involves a stimulus, receptor, modulator, effector, response and feedback

Question 6

Role of the liver

Answer 6

• largest gland in the body, and involved in blood glucose regulation
• converts glucose to glycogen for storage (glycogenesis)
• converts glycogen to glucose for release (glycogenolysis)
• most of livers blood supply comes from the hepatic portal vein which carries blood from the stomach, spleen, pancreas and intestines

Question 7

Glycogenesis

Answer 7

glucose –> glycogen

Question 8

Glycogenolysis

Answer 8

glycogen –> glucose
(breakdown of glycogen)

Question 9

Gluconeogenesis

Answer 9

fats/proteins –> glucose

Question 10

Role of the pancreas

Answer 10

• is an endocrine and exocrine gland
• contains clusters of hormone secreting cells called islets of langerhans

Question 11

Alpha cells

Answer 11

secrete glucagon

Question 12

Beta cells

Answer 12

secrete insulin

Question 13

Role of the adrenal glands

Answer 13

• situated above the kidneys
• composed of an adrenal medulla and an adrenal cortex

(outer) cortex - cortisol [sstimulates conversion of glycogen to glucose, stimulate movement of amino acids from cells to liver, and some may be converted to glucose]

(inner) medulla - noradrenaline/adrenaline [breakdown of glycogen to glucose, stimulates production of lactic acid from glycogen which is then used to form glucose]

Question 14

Glands involved in glucose regulation

Answer 14

• liver
• pancreas
• adrenal glands

Question 15

Optimum core body temperature

Answer 15

36.8ºC
- this temp is achieved when heat lost = heat gained (thermoregulation maintains this)

Question 16

Metabolic rate

Answer 16

the rate at which energy is released by the breakdown of food.

Question 17

When does metabolic rate increase

Answer 17

• during exercise, stress or rising body temperature
• during exercise, metabolic rate increases for muscle contractions producing more energy
• stress stimulates sympathetic nerves releasing noradrenaline raising metabolic rate of the cells
• 1ºC increase in body temp increases metabolic rate by 10%

Question 18

Peripheral thermoreceptors

Answer 18

detect changes in external temperature.
- found in skin and some mucous membranes
- send info to hypothalamus

Question 19

Central thermoreceptors

Answer 19

detect changes in internal temperature.
- found in hypothalamus

Question 20

Two types of thermoreceptors

Answer 20

cold receptor - stimulated by lower temperatures

heat receptors - stimulated by higher temperatures

Question 21

Role of the skin

Answer 21

skin has a large surface area and separates the internal and external environments.

initiates heat loss through conduction, convection, radiation and evaporation.

Question 22

Conduction

Answer 22

transfer of heat via direct contact of particles.

Question 23

Convection

Answer 23

transfer of heat by movement of liquid or gas

Question 24

Radiation

Answer 24

transfer of heat through emission of electromagnetic radiation

Question 25

Evaporation

Answer 25

process of liquid absorbing heat and transforming into a gas

Question 26

Role of blood vessels

Answer 26

blood vessels located in dermis of skin carry heat to skin from core

autonomic nerves control the diameter of blood vessels.

Question 27

Vasodilation

Answer 27

increased diameter allows higher blood flow to capillaries in the skin and greater heat loss.

Question 28

Vasoconstriction

Answer 28

decreased diameter allows less blood to be transported to the capillaries of the skin and decreases heat loss.

Question 29

Role of sweat glands

Answer 29

sweating: alive secretion of fluid by sweat glands

-sweat is transported to the skins surface where it absorbs heat and evaporates
- only occurs once blood vessels are already at max dilation

Question 30

Evaporation of sweat as a cooling effect:

Answer 30

• sweat absorbs latent heat from skin as it evaporates
• this leaves the skin cooler which results in the cooling of blood passing through

Question 31

Role of the muscles

Answer 31

shivering: rhythmic tremors (small contractions) occurring at a rate of 10-20 per second
- no work occurs, so the heat produced is released as heat

Question 32

Heat exhaustion

Answer 32

the collapse of a person after heat exposure during which their body’s heat regulating mechanism continue to function normally.

Question 33

Heat stroke

Answer 33

failure of temperature regulation mechanisms when exposed to excessive heat.

Question 34

Hypothermia

Answer 34

abnormally low body temperature (below 35ºC)

• causes speech failure, mental processes become irrational, lack of insulation, heart and organs fail if body temp drops too low.
• treated through passive rewarming (using own body heat + dry warm clothes), active external warming (hot bottles, warm bath), active internal core warming (warm, moist air and drinks).