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IGCSE Biology > coordination and response > Flashcards

coordination and response Flashcards

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1
Q

what are the parts of the nervous system

A
  • central nervous system

- peripheral nervous system

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2
Q

what is the central nervous system

A

Central nervous system (CNS) consisting of the brain and spinal cord, which are the areas of coordination

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3
Q

what is the peripheral nervous system

A

Peripheral nervous system (PNS) made up of nerves and neurones, which coordinate and regulate bodily functions.

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4
Q

what are involuntary actions

A

not under conscious control e.g. reflex action

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5
Q

what are voluntary actions

A

are done if we decide to carry them out

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6
Q

what are nerve impulses

A

an electrical signal that passes along nerve cells called neurones

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7
Q

types of neurones

A
  • motor neurone
  • sensory neurone
  • relay (connector) neurone
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8
Q

what is a reflex action

A

A reflex action is an involuntary, quick action to respond to a stimulus, in order to protect the body from danger
means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)

E.g. quickly removing your hand from hot metal surface

They involve three neurones: a sensory neurone, relay neurone and motor neurone.

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9
Q

what is a synapse

A

The gap between neurones is called a synapse. a junction between two neurones, consisting of a gap across which impulses pass by diffusion of a neurotransmitter

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10
Q

how the reflex arc works

A

A stimulus affects a receptor (cell or organ that converts a stimulus into an electrical impulse)

A sensory neurone carries impulse from the receptor to the CNS

Connector/relay neurone carries impulse slowly (because it has no myelin sheath) across the spinal chord

Motor neurone carries impulse from the CNS to the effector

Effector (either a muscle or a gland) carries out the response

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11
Q

what is a synaptic cleft

A

small gap between each pair of neurones

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12
Q

describe diffusion of a neurotransmitter (synapses)

A

Inside the neurones axom, there are 100s of tiny vacuoles (vessicles each contain a chemical called neurotransmitter)

When an impulse arrives, the vessicles move to the cell membrane and empty their content into the synaptic cleft

The neurotransmitter quickly diffuses across the tiny gap and attaches to receptor molecules in the cell membrane of the relay neurone

This can happen because the shape of the neurotransmitter molecules is complimentary to the shape of the receptor molecule

Many drugs e.g. heroin act upon synapses

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13
Q

what are antagonistic muscles

A

A muscle that opposes the action of another; e.g. biceps and triceps are antagonistic muscles or circular and radial muscles in the eye

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14
Q

what is an agonist muscle

A

a muscle that contracts while another relaxes; e.g. when bending the elbow, the biceps are the agonist

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15
Q

what is an antagonist mucsle

A

a muscle that relaxes while another contracts; e.g. when bending the elbow, the triceps are the antagonist

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16
Q

what are sense organs

A

groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals.

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17
Q

what is the eye

A

The sense organ responsible for sight

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18
Q

parts of the eye

A

Cornea: refracts light

Iris: controls how much light enters pupil

Lens: focuses light onto retina

Retina: contains light receptors, some sensitive to light of different colours

Optic nerve: carries impulses to the brain

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19
Q

what is (sensory) accomodation

A
  • adjusting for near and distant objects
  • light rays from distance objects are parallel so do not need much refraction to focus properly
  • light rays from closer objects diverged and need much refraction to focus properly
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20
Q

what happens to the eye when viewing a near object

A
  • ciliary muscles contract
  • ligaments relax
  • lens becomes short nd fat
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21
Q

what happens to the eye when viewing a distant object

A
  • ciliary muscles relax
  • ligaments are tight
  • lens becomes long and thin
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22
Q

what is pupil reflex

A

-adjusting for high and low light intensity

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23
Q

pupil reflex in low light intensity

A

Radial muscles (straight lines) contract and become shorter to pull the pupil (black dot) making it wider, to let more light enter, to form a clear image on retina

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24
Q

pupil reflex in high light intensity

A

Circular muscles (circular lines) contract and become shorter to reduce the size of the pupil to protect retina from bleaching.

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25
Q

what are rods

A
  • Provide low detail, black & white images, good for seeing in low intensity light (at night).
  • Packed most tightly around edge of retina so you can see things most clearly when not looking directly at them.
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26
Q

what are cones

A
  • Provide detailed, coloured images; they work in high light intensity.
  • Most tightly packed at centre of retina, so objects are seen most clearly when being directly looked at.
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27
Q

what is the fovea

A

Part of the retina where the receptor cells are pushed most closley together

Where light is focused when you look straight at an object

has the highest concentration of light sensitive cells and gives the most detailed image

28
Q

what are hormones

A

A chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver.

29
Q

what is adrenaline

A

A hormone secreted by the adrenal gland.

It increases pulse rate, makes the glycogen in muscles get converted to glucose, and released into blood, makes you breath deeper and more rapidly, airways become wider, and makes skin become pale as blood is diverted away.

Increases conc. of glucose in the blood for respiration.

Adrenaline is secreted for example: while bungee jumping or riding a rollercoaster

30
Q

function of adrenal gland

A
  • secretes adrenaline

- Prepares body for vigorous action

31
Q

function of pancreas

A
  • secretes insulin

- Reduces conc. of glucose in blood

32
Q

function of testis

A
  • secretes testosterone

- Causes development of male sexual characteristics

33
Q

function of ovary

A
  • secretes oestrogen

- Causes development of female sexual characteristics

34
Q

comparison of nervous and hormonal system speed of action

A
  • nervous: rapid

- endocrine: can be slow

35
Q

comparison of nervous and hormonal system nature of message

A
  • nervous: Electrical impulses, travelling along nerves

- endocrine: Chemical messenger (hormones) travelling in bloodstream

36
Q

comparison of nervous and hormonal system duration of response

A
  • nervous: Usually within seconds

- endocrine: May take years (puberty)

37
Q

comparison of nervous and hormonal system area of response

A
  • nervous: Localized response (only one area usually)

- endocrine: Widespread response (in many organs)

38
Q

comparison of nervous and hormonal system example of process controlled

A
  • nervous: Reflexes such as blinking

- endocrine: Reflexes such as blinking

39
Q

use of hormones in food production advantages and disadvantages

A

Hormones are used in food production, for example oestrogen is used to boost growth rate of chickens.

Advantage: chickens grow quickly meaning more profit.

Disadvantages: this may cause human males to develop feminine characteristics, and it is unnatural.

40
Q

what is homeostasis

A

The maintenance of a constant internal environment.

Homeostasis is the control of internal conditions within set limits

41
Q

what is negative feedback

A

Feedback controls the production of hormones – the hormones regulate their own production.

A negative feedback control is when the change in hormone level acts as a signal to cancel out that change, so when blood hormone level is low, hormone production is stimulated, when it is high, it is inhibited.

42
Q

what is glucoregulation

A

Blood glucose levels are monitored and controlled by the pancreas

The pancreas produces and releases different hormones depending on the blood glucose level

Insulin is released when blood glucose levels are high – the liver stores excess glucose as glycogen

Glucagon is released when blood glucose levels are low – the liver converts stored glycogen into glucose and releases it into the blood

43
Q

what is type 1 diabetes

A

When the control of blood glucose does not work, a person is said to have diabetes

Type 1 diabetes is caused by the death of the cells that secrete insulin

44
Q

symptoms of type 1 diabetes

A

hyperglycaemia (feel unwell, dry mouth, blurred vision and feel thirsty) or hypoglycaemia (tired, show confusion and irrational behaviour)

45
Q

treatment of type 1 diabetes

A

eating little and often and avoiding large amount of carbohydrates, injecting insulin to reduce blood glucose concentration

46
Q

thermoregulation of insulation

A

provided by fatty tissue retains heat. Hairs become erect to trap warm air by contracting erector muscles and vice versa.

47
Q

thermoregulation of vasodilation

A

when it is hot, arterioles, which supply blood to the skin-surface capillaries, dilate (become wider) to allow more blood near to skin surface to increase heat loss (face redder)

48
Q

thermoregulation of sweating

A

the water evaporates giving a cooling effect

49
Q

thermoregulation of skin receptors

A

sense heat and sensory neurons send impulses to the hypothalamus

50
Q

thermoregulation of shivering

A

muscular activity generates heat

51
Q

thermoregulation of thermoregulatory centre

A

in the hypothalamus, it controls the use of corrective mechanisms (e.g. sweating and shivering).

52
Q

homeostasis of cells

A

change composition of blood as they remove nutrients and O2 and add wastes and CO2

53
Q

homeostasis of heart

A

keeps blood pressure constant to deliver oxygen and nutrients around body

54
Q

homeostasis of skin

A

to maintain heat exchange with external environment

55
Q

homeostasis of kidneys

A

regulate water and salt levels (osmoregulation) and the removal of wastes like urea (excretion)

56
Q

homeostasis of lungs

A

regulate gas exchange

57
Q

homeostasis of intestines

A

Intestines: supply soluble nutrients and water to blood

58
Q

homeostasis of liver

A

regulates blood solutes and removes toxins

59
Q

homeostatic organs

A
  • cells
  • heart
  • skin
  • kidneys
  • lungs
  • liver
60
Q

what is auxin

A

Plant hormones or growth substances

Controls tropisms

It is produced by cells at the tip of roots and shoots of plants

61
Q

what is gravitropism

A

a response in which a plant grows towards (positive) or away (negative) from gravity.

62
Q

auxins role in gravitropism

A

Tend to settle at the bottom end of the root.

However, this does not make the cells of the tip of the root grow longer; auxins prevent cells at bottom tip of root from growing, making cells at top of root grow faster.

When cells of top of the root grow faster, they push root deeper into soil and root gets longer.

The root grows in direction of the gravitational pull.

63
Q

what is phototropism

A

a response in which a plant grows towards (positive) or away (negative) from the direction from which light is coming.

64
Q

auxins role in phototropism

A

If sun shines on right side of a plant’s shoot, auxins will accumulate on dark opposite left side.

Auxins accumulating makes cells on left side grow faster than cells on right side.

When left side of shoot starts growing faster than right side, shoot will start to bend to right side towards sunlight.

65
Q

use of hormones as weed killers

A

Hormones can be used as weed killers: spraying with high concentrations of hormone (2,4-D) upsets normal growth patterns. It affects different species differently so might only kill one species not the other (this is good).
2,4-D is a weedkiller / AW ;
sprayed on crops / applied to leaves ;
specific to broadleaved weeds ;
does not affect, cereals / narrow-leaved crop plants ;
causes uncontrolled growth

66
Q

structure of neurones

A

Neurones have a long fibre (axon)
This means that less time is wasted transferring the impulse from one cell to another
The axon is insulated by a fatty sheath with small uninsulated sections along it (called nodes)
This means that the electrical impulse does not travel down the whole axon, but jumps from one node to the next
Their cell body contains many extensions called dendrites
This means they can connect to many other neurones and receive impulses from them, forming a network for easy communication

67
Q

advantages of coordinating endocrine and nervous system

A

4(d) nervous system, responds quickly / immediately ; ora
idea that (nerve) impulses travel to, (specific) muscles / (adrenal) glands
/ effector(s) ;
effects of endocrine system are long lasting ; ora
hormones / adrenaline, travels throughout the body / allows multiple
(target) organs to respond (to same signal) ;
idea that less energy required than to have nerves going to every, cell / tissue ;
stimulate both voluntary and involuntary responses (simultaneously) ;
more effective / enhanced, response (than using one system alone) ;

IGCSE Biology (21 decks)

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