stimuli and response 3.6

Question 1

what is a stimulus

Answer 1

a detectable change in the internal or external environment of an organism that leads to a response

Question 2

function of receptors
(3)

Answer 2

detect stimuli
specific to one type of stimulus
detect information from inside body and the surroundings

Question 3

function of coordinator

Answer 3

formulates a suitable response to stimulus

Question 4

function of effector

Answer 4

produces a response
muscle or gland

Question 5

how do hormones differ as an effector to muscles

Answer 5

relatively slow
found in both plants and animals

Question 6

how do muscles differ as an effector to hormones

Answer 6

more rapid
found only in animals

Question 7

summary of sequence of response

Answer 7

stimulus > receptor > coordinator > effector > response

Question 8

what is taxis

Answer 8

a simple response whose direction is determined by the direction of the stimulus

Question 9

what is positive taxis

Answer 9

moves towards stimulus

Question 10

what is negative taxis

Answer 10

moves away from stimulus

Question 11

what is kinesis

Answer 11

response where
organism does not move towards or away from a stimulus
changes the speed at which it moves
and the rate that it changes direction

Question 12

what is a tropism

Answer 12

direct stimuli that contribute to plant survival are responded to by positive or negative tropisms.

Question 13

light tropism

Answer 13

phototrophic

Question 14

gravity tropism

Answer 14

gravitropic

Question 15

water tropism

Answer 15

hydrotropic

Question 16

how does IAA bring about phototropism in plants

Answer 16

controls plant cell elongation

Question 17

how does IAA affect root growth in response to light

Answer 17

high conc of IAA inhibits cell elongation in roots
cell elongation is greater on light side
roots are negatively phototropic

Question 18

how does IAA affect root growth in response to gravity

Answer 18

IAA produced in root tip
greater conc of IAA builds up on the lower side of the root
cells on lower side elongate less causing root to bend downwards

Question 19

how do shoots respond to gravity

Answer 19

greater conc of IAA on lower side increases elongation on lower side
shoots grow upwards away from gravity

Question 20

IAA roots vs shoots

Answer 20

inhibits root elongation
stimulates shoot elongation

Question 21

what is a sensory neurone

Answer 21

provides a sensory input
carries signals to the CNS from sensory organs

Question 22

what is a motor neurone

Answer 22

provide a motor output
carry signals from the CNS that control activity of muscles and glands

Question 23

what is the voluntary nervous system

Answer 23

controls involuntary movements by activating skeletal muscles

Question 24

what is the autonomic nervous system

Answer 24

controls involuntary responses
by influencing
organs, glands, and smooth muscle

Question 25

what is a reflex action

Answer 25

an involuntary response very rapid not under control of the brain protective, prevents damage to the body

Question 26

order in reflex arc (8)

Answer 26

stimulus receptor sensory neurone intermediate neurone spinal chord motor neurone effector response

Question 27

difference between kinesis and taxis

Answer 27

kinesis is non directional taxis is directional

Question 28

difference between kinesis and tropism

Answer 28

kinesis in animals tropism in plants

Question 29

what is a traducer (sensory receptor is an example of a traducer)

Answer 29

detect one form of energy and convert it into electrical energy

Question 30

what is a pacinian corpuscle made of

Answer 30

a single sensory neurone in the centre of a layer of tissues, each separated by gel

Question 31

what happens when pressure is applied to skin around a pacinian corpuscle

Answer 31

changes the shape of the pressure sensitive sodium channels causes them to open

Question 32

name of the sodium channel in a pacinian corpuscle

Answer 32

stretch mediated sodium channel

Question 33

what happens when sodium channels (in pacinian corpuscle) are opened

Answer 33

sodium ions diffuse in membrane is depolarised therefore produces a generator potential creates an action potential passed along the neurone

Question 34

what are the two main light receptor cells

Answer 34

rods and cones

Question 35

cone cells distribution

Answer 35

higher concentration in the fovea

Question 36

rod cells distribution

Answer 36

spread evenly across retina but none in fovea

Question 37

cone cells visual activity and why

Answer 37

high each cone cell has a single connection to optic nerve

Question 38

rod cells visual activity and why

Answer 38

low several rod cells share a connection to the optic nerve

Question 39

light intensity cone cells

Answer 39

sensitive to high light intensity

Question 40

light intensity rod cells

Answer 40

sensitive to low light intensity

Question 41

how many types of rod cells

Answer 41

1

Question 42

how many types of cone cells

Answer 42

3

Question 43

how many connections do rod cells have to bipolar cells

Answer 43

3:1

Question 44

how many connections do cone cells have to bipolar cells

Answer 44

1:1

Question 45

what pigment is broken down leading to a generator potential in cone cells

Answer 45

idopsin

Question 46

how is an action potential produced in a rod cell

Answer 46

light shines on rhodopsin pigment breaks down creates a generator potential this stimulates an action potential

Question 47

why are multiple rod cells connected to a single bipolar cell

Answer 47

a threshold value has to be exceeded before a generator potential is made in bipolar neurone 3:1 makes this more likely

Question 48

what is the consequence of many rod cells linking to a single bipolar cell

Answer 48

even if many rods detect light single impulse sent to brain brain cannot distinguish between separate sources of light results in poor visual activity

Question 49

consequence of each cone cell being attached to a single bipolar cell

Answer 49

if 2 cone cells stimulated brain receives 2 separate impulses brain is able to distinguish between the 2 able to resolve two dots close together

Question 50

sympathetic nervous system

Answer 50

most dominant during stress and excitement stimulates effectors to speed up activity

Question 51

parasympathetic nervous system

Answer 51

most dominant during rest and sleep inhibits effectors to slow down activity

Question 52

define myogenic

Answer 52

contraction of heart is initiated within the muscle itself rather than by nerve impulses

Question 53

what are the 2 nodes involved in heart contraction

Answer 53

sinoatrial node atrioventricular node

Question 54

where is the sinoatrial node located

Answer 54

wall of right atrium

Question 55

where is the atrioventricular node located

Answer 55

wall that separates the two atria

Question 56

describe how heartbeats are initiated and coordinated

Answer 56

SAN initiates wave of depolarisation atrial systole impulse delayed AVN conveys impulse along bundle of his branches into purkinje fibres along ventricles causes ventricles to contract from apex upwards

Question 57

formula for cardiac output

Answer 57

stroke volume x heart rate

Question 58

how does the body respond to a decrease in blood pressure

Answer 58

baroreceptors send more impulses to cardioacceleratory centre more impulses to SAN via sympathetic nervous system stimulates release of noradrenaline increases heart rate and strength of contraction

Question 59

how does the body respond to an increase in blood pressure

Answer 59

baroreceptors send more impulses to the cardioinhibitory centre more impulses to SAN via parasympathetic nervous system stimulates release of acetylcholine decreases heart rate