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Biology - Module 5 > Communication And Homeostasis > Flashcards

Communication And Homeostasis Flashcards

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1
Q

what is homeostasis

A

regulation of the internal conditions of a cell or organism to maintain optimum conditions for function

in response to internal and external changes

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2
Q

two types of communication system

A

endocrine + nervous

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3
Q

describe the effect of high pH on enzymes

A

Hydrogen + ionic bonds hold the tertiary structure together

solutions with an excess of H+ / OH– ions = cause these bonds to break

alters shape of active site

enzyme-substrate complexes form less easily

eventually, enzyme-substrate complexes can no longer form at all

complete denaturation

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4
Q

purpose of cell signalling

A

allows multicellular organisms to control and coordinate their bodies and to respond to their environments

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5
Q

describe the stages of cell signalling

A

A stimulus is received by a receptor cell

stimulus is converted to a signal - e.g chemical - that can be passed on

(this process = transduction)

signal is transmitted to target cell that can detect it via receptors in its cell membrane

An appropriate response is made

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6
Q

what is paracrine signalling

A

signalling between cells that are close together

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7
Q

what is endocrine signalling

A

signalling between cells that are far apart

being transported in the circulatory system

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8
Q

examples of paracrine signalling molecules

A

amino acids / lipids / phospholipids / glycoproteins

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9
Q

examples of endocrine signalling molecule

A

hormone

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10
Q

what is negative feedback

A

reduces initial effect of the stimulus

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11
Q

what is positive feedback

A

enhances the effect of original stimulus

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12
Q

state three examples of positive feedback

A

clotting cascade

childbirth

bone repair

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13
Q

describe the clotting cascade as a positive feedback cycle

A

Blood vessel damaged + platelets stick to region

Release factors that initiate clotting + that attracts more platelets

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14
Q

describe childbirth as an example of positive feedback

A

Head of baby pressed against cervix

Production of oxytocin

stimulates uterus to contract + baby head pushes even harder against cervix

more oxytocin – until baby born

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15
Q

describe bone repair as an example of positive feedback

A

involving special cells - osteoblasts and osteoclasts

osteoblasts secrete a hormone - inactive osteocalcin

osteoclasts secrete acid = causes the inactive osteocalcin to become active

active form of osteocalcin binds to a receptor on beta cells in pancreas

stimulates them to release insulin

Osteoblast possess insulin receptors + when stimulated causes them to release more inactive osteocalcin

osteoblast cells enhance the effect of the original stimulus (insulin) - positive feedback

Insulin is known to have anabolic effects, promoting the building of tissues, including bone

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16
Q

what is an endotherm

A

an animal that possess physiological mechanisms to control their internal body temperature

17
Q

what is an ectotherm

A

animals that rely on behavioural adaptations to control temp

18
Q

example of endotherm

A

mammals + birds

19
Q

example of ectotherms

A

reptiles and amphibians

20
Q

what is radiation, convection and conduction

A

radiation – transmission of EM waves

convection – heating + cooling by currents of air / water

conduction – heating by collision of molecules

21
Q

state the ways an animal can gain + lose heat

A
22
Q

how do endotherms detect temperature

A

detect external temperatures via peripheral receptors / thermoreceptors

hypothalamus monitors temp of blood flowing through it

23
Q

where are thermorecpetors found

A

skin and mucous membranes

24
Q

state the cooling mechanisms of an endotherm

A

Vasodilation / Sweating / Flattening of hairs

25
Q

state the warming mechanisms of an endotherm

A

Vasoconstriction / Boosting metabolic rate / Shivering / Erection of hairs

26
Q

what is vasodilation / vasoconstriction caused by

A

caused by the relaxing and contracting of muscles in the arterioles, not capillaries

Capillaries do not have muscles in their walls

27
Q

describe vasoconstriction + vasodilation

A

vasoconstriction - muscles in arteriole walls contract + more blood is directed through the shunt vessel

vasodilation - muscle in arteriole wall relax + more blood flow through capillaries near skin surface

28
Q

how are hairs risen

A

hair erector muscles contract

29
Q

how does shivering generate heat

A

Rapid / involuntary contracting + relaxing of large muscles

Metabolic heat from exothermic reaction

30
Q

how does rising hair generate heat

A

insulating layer of air formed

31
Q

how does sweating loose heat

A

latent heat of vaporisation

32
Q

structure of hypothalamus

A

heat loss centre

heat gain centre

33
Q

what happens when the heat loss / gain centre is activated

A

Sends impulses via autonomic nervous system to effectors in skin / muscles

34
Q

state the difference between thermoregulation of ectotherms in water vs on land

A

ectotherms in water – don’t need to thermoregulate because of high heat capacity of water = temp stable

35
Q

types of responses that ectotherms carry out

A

behavioural

physiological

36
Q

what are the behavioural responses of ectotherms to cool down

A

seek shade or water

digging burrows

pressing bodies against cool ground

minimise SA

37
Q

what are the behavioural responses of ectotherms to warm up

A

seek out the sun / bask – increase SA

pressing bodies against ground – conduction

contract muscles / wings – exothermic metabolic reactions

38
Q

what are the physiological responses of ectotherms to warm up

A

dark skin – absorb more radiation

alter heart rate

39
Q

what are the issues with ectotherms

A

environmental temps vary a lot – seasons / in a day

need more energy to maintain body temp

= metabolic rate + food requirement is higher

survival weaker

Biology - Module 5 (8 decks)

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