5.1 Neuronal communication & sensory receptors Flashcards Preview

A Level Biology > 5.1 Neuronal communication & sensory receptors > Flashcards

Flashcards in 5.1 Neuronal communication & sensory receptors Deck (49):
1

what must all organisms do?

respond to changes in their internal and external environment

2

how do animals respond to their environment?

neuronal and hormonal

3

how do plants respond to their environment?

chemical communication including hormones e.g. auxin

4

what factors do we respond to in our environment?

humidity
temperature
sound
light intensity
blood glucose levels
internal temperature
cell PH
water potential

5

why is coordination needed?

few body systems can work in isolation
all cells have specialised functions so must coordinate the function of different cells and systems efficiently

6

(Coordination) give an example of body systems needing to work together? (animals)

muscles contract and need O2
O2 transported in RBCs
RBCs made in bone marrow my haematopoietic stem cells

7

(coordination) give an example of plant cells needing to coordinate? and how they do it?

flowering plants need to coordinate with the seasons to know when to flower, light sensitive chemicals enable this to happen

8

(Homeostasis) in multicellular animals different organs have different functions....

....so must be coordinated

9

(Homeostasis) give examples of a system in which organs must work together:

digestive organs must work together to maintain blood glucose levels

10

what does nervous and hormonal control rely upon?

communication at cellular level through cell signalling

11

where can cells transfer signals?

locally - between neurones at synapses
over large distances using hormones

12

what is AUTOCRINE cell signalling?

where the call targets itself

13

what is PARACRINE cell signalling?

where cell targets nearby cell

14

what is ENDOCRINE cell signalling?

where the cell targets a distant cell through the bloodstream

15

What does cell signalling across gap junctions involve?

a cell targeting another cell which it is connected by gap junctions

16

what is the nervous system responsible for?

detecting changes in the internal and external environment

17

what is the pathway a nerve impulse follows?

receptor -> sensory neurone -> relay neurone -> motor neurone-> effector

18

what are some axons covered in?

a myelin sheath (many layers of plasma membrane)

19

what sort of cells produce the myelin sheath? how do they do it?

schwann cells
by growing around the axon many times adding a double layer of phospholipid bilayer each time

20

what is the function of the myelin sheath?

insulation which leads to conducting electrical impulses at faster speeds

21

what is the function of a motor neurone?

transmitting electrical impulses from the relay neurone (in the CNS) to the effector producing a response

22

what is the function of a sensory neurone?

transmitting the electrical impulse from receptor cells to a relay neurone, motor neurone or the brain

23

what is the function of the axon?

to carry nerve impulses away from the cell body

24

what is multiple sclerosis?

autoimmune disease which affects nerves in the brain and spinal chord

25

what does multiple sclerosis involve and what does it result in?

thinning of myelin sheath and axon, slow impulses, results in problems with muscle movement and vision

26

what are sensory receptors?

groups of specialised cells located in sense organs such as the eyes and ears

27

what do sensory receptors do?

convert the stimulus they detect into nerve impulses called a GENERATOR POTENTIAL which is transmitted to the CNS

28

what are the two main features of sensory receptors?

specific to a single type of stimulus
acts as a transducer converting a stimulus to a nerve impulse

29

what are the 4 types of sensory receptors?

photoreceptors
chemoreceptors
mechanoreceptors
thermoreceptors

30

what stimulus does a mechanoreceptor detect? give an example of a mechanoreceptor and the sense organ:

pressure and movement
pacinian corpuscle (detects pressure)
organ: skin

31

what stimulus does a chemoreceptor detect? give an example of a chemoreceptor and the sense organ:

chemicals
olfactory receptor (detects smells)
organ: nose

32

what stimulus does a thermoreceptor detect? give an example of a thermoreceptor and sense organ:

heat
end bulbs of Krause
tounge

33

what stimulus does a photoreceptor detect? give an example of a photoreceptor and sense organ:

light
cone cell (detects different wavelengths of light)
eye

34

what are pacinian corpuscle's?

sensory receptors that detect mechanical pressure

35

where are pacinian corpuscle's located?

in the joints and deep within skin

36

what does the centre of the pacinian corpuscle contain?

the end of the sensory neurone surrounded by layers of connective tissue with each layer being separated by gel

37

the neurone ending in a pacinian corpuscle has a...

...stretch mediated sodium ion channel

38

1. In resting state the stretch mediated sodium ion channels in the sensory neurones membrane are too narrow to?

allow sodium ions to pass through - it has resting potential

39

2. when pressure is applied to the pacinian corpuscle what does it do?

it changes shape causing the membrane to stretch

40

3. When the membrane stretches what happens to the sodium ion channels?

sodium ion channels widen and sodium can diffuse into the neurone

41

4. what does the influx of positive ions do to the membrane?

changes the potential of the membrane, it becomes depolarised resulting in a generator potential

42

5. what does the generator create?

an action potential that passes along the sensory neurone to the CNS

43

what do rod cells allow? what is this due to?

vision in dim light
due to the presence of a pigment called RHODOPSIN found in membrane bound vesicles

44

what happens to rhodopsin when it absorbs light?

Bleaching - it is split into opsin and retinal.
Low levels of light are enough to cause this breakdown

45

what effect does opsin have on the rod cells permeability to sodium?

changes its permeability to sodium, initiating a generator potential

46

what are cone cells sensitive to? what is this due to?

high light intensities
due to the presence of the pigment IODOPSIN

47

what happens to iodopsin in bright light?

broken down into its constituent parts, generating an action potential in the ganglion cell

48

what does the cell body consist of?

nucleus surrounded by the cytoplasm, which contains large amounts of ER & mitochondria involved in the production of neurotransmitters

49

what are dendrons?

short extensions from the cell body which divide into dendrites. They transmit electrical impulses toward the cell body.

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