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Life Sciences > Homeiostasis > Flashcards

Homeiostasis Flashcards

1
Q

what is homeostasis

A

defined as ability of organism to maintain stability of internal conditions despite change in environment.

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2
Q

what is included in homeostasis

A 
blood concentration 
water concentration 
CO2/O2 concentration
blood pH 
body temp 
salt concentration 
waste
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3
Q

explain the sequence of a negative feedback system

A
  1. Imbalance occurs
  2. receptors detect change and stimulate control centre.
  3. control centre responds to stimuli
  4. control centre send messenge to target organ.
  5. target organ responds
  6. target organ corrects imabalance
  7. Balance restored
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4
Q

where is thyroxine produced and secreted

A

thyroid

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5
Q

explain how thyroxin levels are maintained

A
  • amount of thyroxin in blood is kept constant by - feedback mechanism between hypophysis/ pituitary and the thyroid.
  • when thyroxin levels decrease
  • pituitary is stimulated to secrete more TSH
  • TSH released into blood to reach target organ (thyroid gland)
  • higher levels of TSH in blood stimulate thyroid gland to secrete more thyroxin
  • thyroxin levels increase (return to normal)
  • when thyroxin levels increase
  • secretion of TSH by hypophysis is inhibited
  • hypopyhysis secretes less TSH into blood.
  • lower TSH in blood results in decreased thyroxin production by thyroid
  • levels decrease and return to normal
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6
Q

name the 2 substances that manage BG levels

A

insulin and glucagon

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7
Q

what type of hormones are insulin and glucagon, what does this mean?

A

antagonistic

  • have opposite effects
  • stimulated/inhibited
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8
Q

describe what happens when BG levels are high

A

pancreas releases INSULIN
converts glucose
glycogen in liver
lowers BG levels

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9
Q

describe what happens when BG levels are low

A

pancreas releases GLUCAGON
converts glycogen in liver and muscles to glucose
levels increase

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10
Q

what is the product of CR

A

ATP

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11
Q

byproduct of CR

A

CO2

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12
Q

what happens when there is an excess of CO2 in blood

A

pH of bodily fluids too acidic (lowers pH)

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13
Q

what happens when there is insufficient CO2

A

pH of bodily fluids too alkaline (increases pH)

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14
Q

name the receptor that is sensitive to change in CO2 concentration of blood

A

chemoreceptors in aorta.

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15
Q

name the hormone that is secreted that regulates water balance

A

ADH

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16
Q

explain how body regulates blood water content on a hot day

A
  • sweats a lot
  • osmoreceptors stimulated
  • hypothalamus sends impulses to pituitary to secrete MORE adh
  • more ADH in kidney
  • increased permeability to DCT making walls more permeable.
  • more water reabsorbed
  • less water lost due to low volume of concentrated urine.
  • osmorereceptors stimulate thirst centre in brain
  • water content returns to normal.
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17
Q

name the hormone that regulates salt concentration

A

aldosterone

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18
Q

explain the process that occurs when there is an increased salt concentration in blood

A
  • salt levels rise above normal
  • receptors in afferent and efferent arterioles detect high salt level
  • adrenal gland is inhibited
  • less aldosterone secreted into blood.
  • decreased reabsorption of sodium ions from renal tubules into surrounding blood capillaries.
  • more soidum ions excreted in urine.
  • concentration returns to normal.
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19
Q

explain the process that occurs when there is an decreased salt
concentration in blood

A
  • salt levels drop below normal
  • receptors in afferent and efferent arterioles of kidney detect low salt level
  • adrenal gland stimulated.
  • aldosterone secreted into blood
  • stimulates reabsorption of more sodim ions from renal tubules.
  • fewer sodim ions excreted in urine
  • concentration returns to normal.
20
Q

what is thermoregulation

A

the regulation of body temperature.

21
Q

explain the difference between ectothermic and endothermic species

A

ecto - cold blooded

endo - warm blooded

22
Q

explain ectothermic animals

A
  • body temp varies according to environmental temperature
  • dependent on external heat sources
  • low MR
23
Q

list 4 things that ectothermic animals do to ensure thermoregulation.

A
  • dark colour
  • increases SA
  • dig holes
  • hibernation
24
Q

name 4 ways that heat is transfered to ectothermic animals

A

radiation
evaporation
convection
conduction

25
Q

exaplin endothermic animals

A
  • maintain constant body tep irrespective of environment
  • heat produced by cellular resp
  • 37*c
26
Q

importance of maintaing temp

A
  • enzympe activity
  • prevents denaturing
  • prevents inactivity
27
Q

name the 2 components that make up the skin

A

epidermis

dermis

28
Q

name the 3 layers made up in the epidermis

A

cornified
granular
basal

29
Q

name 2 areas in the body that have thicker cornified layers

A

palsm of hands

soles of feet

30
Q

describe the cornified layer

A

outermost
dead, flaky
shred and replace

31
Q

describe the granula layer

A

under cornified
living cells
granules in cytoplasm

32
Q

describe the basal layer

A

living cells that divide continuesly.

contains melanin

33
Q

function of the epidermis

A

protects underlying tissue

waterproof barrier

34
Q

describe the areolar connective tissue

A 
thicker 
BV 
LV 
Nerves 
Sensory organs
35
Q

describe the adipose tissue

A

fatty tissue that connects skin to underlying parts

insulation

36
Q

function of blood vessels in skin

A
  • transports nutrients and O2 to cells as well as waste out

- distribution of blood effects body temp.

37
Q

name the corpuscle that maintains heat and falls under sensory organs

A

ruffini’s corpuscle

38
Q

describe hair follicles

A
  • extention of epidermis

* grows from a follicle (extends into dermis) (lined with epidermal cells that divide rapidly)

39
Q

name the fatty acid that is secreted to prevent dehydration of skin and hair

A

sebum.

40
Q

what is the formal name for ear way

A

cerumen

41
Q

function of glands

A

excretes waste

sweat helps to cool body down.

42
Q

state the thermoneutral zone

A

36.5-37.5

43
Q

explain how temperature is regulated on a cold day through the skin

A

heat loss reduced through skin:

  • Krause’s corpuscles detect temperature change in skin and converted into nerve impuleses that stimulate the heat regulation centre in hypothalalmus
  • hypothalamus sends nerve impulses to INVM layer in walls of the BV in skin
  • muscles contract and BV constrict (vascoconstriction)
  • blood is directed to blood vessels in depper skin layers
  • less blood flow to skin means less heat loss
  • less sweating as vasconstriction occurs.
  • Erector muscles cause hair to contract and hairs to stand.
44
Q

explain how temperature is regulated on a hot day through the skin

A
  • rise in temp detected by ruffini’s corpuscles in the skin and converted into nerve impulses that stimulate the heat regulating centre in the hypothalamus.
  • HYPO send nerve imuples to involuntary muscle layer in walls of BV in skin.
  • muslces relax and BV dilate in vasodilation.
  • more blood flows to skin
    causing more heat loss
  • vasodilation causes more sweating therefore cooled down.
  • erector muscles not stimulated and hair lies flat (heat loss)
45
Q

explain how temperature is regulated on a hot day through the body

A
  • muscle tone of voluntary muscles decreases and the person becomes less active, muscle cells require less energy, respiratory rate decreases and less heat is produced.
  • decreased thyroxin production results in lowered MR - respiratorry rate decreases and less heat is produced.
  • behavioural activities include colour of clothes, drinking cool drinks and moving to a cooler environment

Life Sciences (16 decks)

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