Homoeostasis of body temperature and body fluids

Question 1

what is core body temperature?

Answer 1

36.8 degrees

Question 2

why does body temperature need to be kept around an optimum range?

Answer 2

for cellular respiration

Question 3

what is thermoregulation?

Answer 3

the balance between heat production and heat loss

Question 4

what are the risks of increased body temperature?

Answer 4

nerve malfunction, enzyme denaturing, changing structures of proteins, death

Question 5

what is energy used for?

Answer 5

muscle contractions, active transport, building compex molecules, heat production

Question 6

what is metabolic rate?

Answer 6

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

Question 7

what are peripheral thermoreceptors and where are they located?

Answer 7

skin and mucous membranes; procide hypothalamus with info about external environment

Question 8

where are central thermoreceptors located?

Answer 8

in the hypothalamus

Question 9

what are the four ways heat is lost in the body?

Answer 9

conduction, convection, radiation, evaporation

Question 10

how does sweating cool the body?

Answer 10

evaporation has a cooling effect

Question 11

which nervous system stimulates sweating?

Answer 11

sympathetic

Question 12

what types of substances are dissolved in sweat?

Answer 12

urea, lactic acid, salt, potassium ions

Question 13

what is vasoconstriction?

Answer 13

constriction of blood vessles if the body is exposed to cold temperatures; reduces heat loss, increases heat production

Question 14

what is secreted as a result of vasoconstriction?

Answer 14

adrenaline and noradrenaline (adrenal medulla)

Question 15

what controls shivering?

Answer 15

the hypothalamus –> sends stimuli to increase skeletal muscle tone
cerebral cortex –> conscious imput

Question 16

why would an increased amount of thyroxine increase heat?

Answer 16

increases metabolic rate (by-product = heat)

Question 17

what is an example of a behavioural response to cold temperatures?

Answer 17

put on a jumper, put the heater on, curl up into a ball

Question 18

what is vasodilation?

Answer 18

dilation of blood vessels to increase heat loss

Question 19

why is sweating important and when is it effective?

Answer 19

above 28 degrees, in dry environments (to allow sweat to evaporate)
due to high specific heat capacity of water

Question 20

why would a decreased metabolic rate decrease heat production?

Answer 20

less heat produced as a by-product of respiration

Question 21

what are some examples of behavioural responses to cool down>

Answer 21

turn on aircon, remove clothing, reduce physical activity

Question 22

what is heat stroke?

Answer 22

rise in body temp = cease of regulatory mechanisms

Question 23

how is heat stroke treated?

Answer 23

cooling body as quickly as possible

Question 24

what is heat exhaustion?

Answer 24

occurs as a result of extreme sweating and vasodilation; loss of water in plasma + vasodilation = reduces resistance to blood flow = reduced output of blood from heart = collapse

Question 25

what is hypothermia?

Answer 25

low metabolic rate, body unable to replace heat lost causing body temp to continue to fall

Question 26

what is considered the max and min temperatures before death?

Answer 26

33 degrees or below and 42 degrees or above

Question 27

what is metabolic water?

Answer 27

water obtained as a by-product of chemical processes

Question 28

what are some examples of where fluid can be lost from?

Answer 28

kidneys, surface of lungs, alimentary canal, sweating

Question 29

what is excretion and why can’t faeces be considered excretory products?

Answer 29

excretion: removal of metabolic wastes.

faeces is not metabolic wastes (it is undigested food matter)

Question 30

what do the lungs excrete?

Answer 30

CO2

Question 31

what do the sweat glands exrete?

Answer 31

water containing by-products of metabolism

Question 32

what does the alimentary canal excrete?

Answer 32

bile pigments

Question 33

what do they kidneys excrete?

Answer 33

urea

Question 34

what is the basic process for filtration in the kidneys?

Answer 34

1. Blood enters glomerulus; high pressure
2. Filtration: high pressure forces small dissolved molecules from blood (large molecules remain)
3. Filtrate collected in glomerular capsule
4. Reabsorption: filtrate passes through proximal convoluted tubule, loop of Henle, distal convoluted tubule, collecting duct (water and other useful substances absorbed)
5. Secretion: wastes are secreted into kidneys
6. Urine: carried by collecting ducts to the ureters then bladder

Question 35

what is the role of ADH in fluid balance?

Answer 35

increased ADH = high permeability to water (increased water absorption)

Question 36

what is the role of aldosterone in fluid balance?

Answer 36

increases amount of sodium reabsorbed + increases amount of potassium excreted in urine

Question 37

what are osmoreceptors responsible for?

Answer 37

stimulating the thirst centre of they hypothalamus

Question 38

what is dehydration?

Answer 38

loss of more than 2% of water (sweating, vomiting, diarrhea)

Question 39

what are symptoms of dehydration?

Answer 39

severse thirst, low blood pressure, dizziness, headache

Question 40

why do elederly people get dehydrated?

Answer 40

their thirst reflex is less effective

Question 41

what is water intoxication?

Answer 41

body fluids become diluted and cells take on extra water by osmosis

Question 42

when does water intoxication occur?

Answer 42

when the person has lost a lot of water and salts through sweating then replaces this with plain water

Question 43

what are symptoms of water intoxication?

Answer 43

light-headedness, collapse, vomiting

Question 44

what are the four responses to a decreased core body temperature?

Answer 44

1. vasoconstriction of skin blood vessels
2. shivering
3. increased BMR
4. behavioural reponses

Question 45

what are the four responses to an increaesd core body temperature?

Answer 45

1. vasodilation
2. sweating
3. decreased BMR
4. behavioural responses