Co-ordination and response Flashcards

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1
Q

What is homeostasis

A

Maintaining a constant internal environment

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2
Q

What is a hormone

A

Chemical messengers that are secreted by glands and carried in the bloodstream

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3
Q

How is a change in core body temperature detected

A

By the thermoregulatory centre in the hypothalamus

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4
Q

Why is it important that core body temp remains constant

A

For enzymes at work at their optimum temp and not denature

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5
Q

How does the body respond to an increase in temp

A

sweating- sweat glands produce sweat which cools the body upon evaporation
Hair lies flat- increases heat loss
Vasodilation- arterioles become wider, blood flow closer to the skin and increases heat loss from radiation

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6
Q

How does the body decrease blood sugar levels

A

Brain sends signal to pancreas
Pancreas releases insulin into bloodstream
Glucose is stored as glucagon in the liver from the bloodstream

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7
Q

How does the body respond to a decrease in temp

A

Shivering- muscular contractions require respiration which releases heat
Hair stands on end- insulation, traps air
Vasoconstriction- arterioles become narrower, blood flow further from skin and reduces heat loss from radiation

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8
Q

How does the body increase blood sugar levels

A

Brain send signal to pancreas
Pancreas releases glucagon into bloodstream
Glucagon splits up into individual glucose molecules again from liver into bloodstream

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9
Q

Identify glands and the hormones they release

A

Adrenal glands- adrenaline
Testes- testosterone
Pituitary glands- ADH
Pancreas- insulin
Ovaries- oestrogen

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10
Q

what 2 structures make up the central nervous system

A

Brain
Spinal cord

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11
Q

What is a stimulus

A

A change in the environment

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12
Q

What is a receptor

A

A special type of cell that detects changes in the environment

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13
Q

what is an effector

A

produce a specific response to a detected stimulus
muscle or glands

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14
Q

what makes reflex actions involuntary and faster responses

A

they bypass the brain to minimise damage to body and be quicker

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15
Q

why are fast reflex actions important

A

essential for survival and avoiding damage

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16
Q

why is the iris reflex important

A

prevents the bright light from damaging the receptor cells in the retina

17
Q

Iris reflex in bright light

A

circular muscles contract
radial muscles relax
pupil constricts
less light can enter eye

18
Q

iris reflex in dim light

A

radial muscles contract
circular muscles relax
pupil dilates
more light can enter eye

19
Q

how do electrical impulses move from one neurone to another

A

nervous impulses arrive at end of neurone causing vesicles to move towards membrane
neurotransmitters (chemicals) released from vesicles and diffuses from one side of synapse to the other
neurotransmitters attaches to receptor causing new electrical impulses to move down the neurone

20
Q

what is accomodation

A

ability to focus on objects which are at different distances from the eye

21
Q

what happens when you focus on a near object

A

ciliary muscles contract
suspensory ligaments loosen
lens shape thickens

22
Q

what happens when you focus on a far object

A

ciliary muscles relax
suspensory ligaments tighten
lens shape thins

23
Q

what is a tropism

A

a growth in response to a stimulus

24
Q

what effect does auxin have in the roots and shoots of plants

A

roots- inhibits growth
shoots- stimulates growth

25
Q

how do the roots respond to gravity

A

auxin gathers in bottom side due to gravity
as auxin inhibits cell elongation in roots, this causes the roots to grow downwards

26
Q

how do the shoots respond to gravity

A

auxin gathers in bottom side due to gravity
auxin stimulates cell elongation in shoots, causing the shoots to grow upwards

27
Q

how does a plant shoot respond to light

A

shoot grows towards light
auxin builds up on shaded side, so cell elongates faster on this side
this causes shoot to bend so they can absorb more light for photosynthesis