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2019 - Biology > HOMEOSTASIS IN HUMANS > Flashcards

HOMEOSTASIS IN HUMANS Flashcards

1
Q

body fluids

A

the fluid that body cells consist of and are surrounded by; forms the internal environment of the body

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2
Q

factors to be constant for cells to function optimally

A
  • glucose
  • salt
  • water
  • oxygen/c02
  • temperature
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3
Q

organs that help to maintain a constant int env

A

liver, kidneys, skin, lungs, pancreas

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4
Q

homeostasis

A

maintenance of a constant internal environment in the body

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5
Q

negative feedback mechanism

A

when a deviation from the normal is detected, which results in a reaction that counteracts the change and returns it to normal

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6
Q

how negative feedback system works

A
  • change occurs in normal levels
  • receptors detect and transmit info via hormones or nerve impulses to the effectors
  • effectors respond and correct the deviation
  • normal is detected and corrective action is switched off
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7
Q

control of CO2

A
  • chemoreceptors send impulses to resp and cardio centres in the brain as soon as co2 conc changes
  • resp centre sends impulses to diaphragm and intercostal musc to acc contract/relax
  • breathing rate and depth inc, more CO2 exhaled
  • cardio centre send impulses to heart musc to inc heart rate + blood flow
  • co2 transported faster to lung for exhalation = normal
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8
Q

control of water

A
  • change in normal
  • osmoreceptors in hypothalamus detect
  • thirst centre stimulated / ADH secreted into blood = transport to kidneys
  • walls of tubules become permeable
  • more water reabsorbed
  • water content rises
  • normal
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9
Q

control of salt

A
  • sodium conc is low = more aldosterone is secreted and more sodium ions are reabsorbed from the convoluted tubes into the blood in surrounding capillaries
  • sodium conc in blood inc, less excreted in urine
  • normal
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10
Q

thermoregulation

A

regulation of body temp in an organism

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11
Q

ectothermic animals eg

A

fish, amphibians, reptiles

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12
Q

ectothermic animals

A
  • body temperatures vary according to environmental temp

- reptiles use color (dark) and body orientation to regulate body temp

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13
Q

endothermic animals

A

birds, mammals

  • constant body temp, irrespective of env temp
  • heat produced inside the body via resp
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14
Q

why humans need to be 37

A

optimum temp for enzyme action, too high = denature, too low = inactive

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15
Q

heat production in human body

A
  • resp is main source

- heat can be absorbed from environment by consuming warm food/fluid/exposing body to sun

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16
Q

adrenalin + thyroxin in heat prod

A

increased secretion of the two results in inc metabolic rate. resp increases bc of this and more heat is released

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17
Q

heat loss in human body

A

radiation
convection
conduction
evaporation

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18
Q

radiation

A

loss of heat from warm body to cold env via rays + waves

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19
Q

convection

A

distribution of heat in fluids or gas

20
Q

conduction

A

transfer of heat energy from warm to cold objects that are in contact w each other

21
Q

evaporation

A

when a fluid absorbs heat energy to convert to a gas

22
Q

two layers of skin

A

dermis

epidermis

23
Q

epidermis three lyers

A

cornified, granular, malpighian

24
Q

cornified layer

A
  • outermost layer, dead flattened cells
  • contain keratin
  • continuously replaced by the underlying tissue
25
Q

keratin functions

A

protects skin from water, light and infection

26
Q

granular layer

A

directly under cornified layer and consists of living cells w granules in the cytoplasm

27
Q

malpighian layer

A

lower layer, consists of living cells that continuously divide to replace cells in upper layers

  • contains melanin
  • receives oxygen + nutrients from the dermis
28
Q

melanin

A

protects skin from UV rays from sun + gives skin color

29
Q

epidermis function

A

protects underlying tissues

30
Q

dermis

A

thicker layer than the epidermis and consists of areolar connective tissue

31
Q

dermis contains…

A

blood + lymph vessels, nerves, sensory organs, hair follicles, tiny erector musc, glands

32
Q

beneath the areolar connective tissue

A

a layer of adipose (fatty) tissue that connects skin to underlying body parts; serves an insulator

33
Q

blood vessels in d

A
  • transports nutrients in the blood to cells and waste products to sweat glands for excretion
  • helps w body temp reg
34
Q

lymph vessels in d

A

drain excess tissue fluid

35
Q

nerves in d

A
  • sensory fibres - conduct impulses from sense organs in skin to CNS
  • motor fibres - conduct impulses from thalamus to blood vessels in the skin
36
Q

sensory organs

A

various corpuscles which detect heat, cold pressure, touch and pain

37
Q

hair follicles

A
  • an extension of epidermis, all over body except palms and soles
  • hair grows from follicle
38
Q

sebum

A

fatty substance, secreted by sebaceous glands, which helps to prevent dehydration of skin and hair

39
Q

erector muscle

A

connects base of hair follicle to the epidermis (contracts when it is cold, causes hair to stand up)

40
Q

glands

A

sebaceous, wax, mammary, sweat

41
Q

wax glands

A

occur in ext auditory canals of ear and secrete cerumen which prevents insects from entering the auditory canals

42
Q

mammary glands

A

secrete milk after birth for babies

43
Q

sweat glands

A

long coiled ducts in the dermis which extend to sweat pores = excretes harmful waste products in a water medium + play a role in regulation of body temp by cooling the body

44
Q

heat regulation centre

A

in hypothalamus is resp for maintaining body temp
stimulated by nerve impulses from receptors in skin which detect changes in temp + by changes in temp of blood that flows through it

45
Q

regulation of body temp on a cold day

A
  • drop in temp is detected by Krause and converted into impulses that stimulate HRC
  • thalamus sends impulses to the involuntary musc layer in the skins blood vessels
  • circular musc contracts and blood vessels narrow in vasoconstriction
  • blood is redirected to vessels in deeper skin layers and less blood flows to skin surface = less heat lost
  • less blood flows to the sweat glands / reduced sweat secretion

2019 - Biology (13 decks)

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