Sensory Receptors

Question 1

What are sensory receptors?

Answer 1

specialised cells that detect changes in surroundings, energy transducers that convert one form of energy to form of electrical energy: nerve impulse

Question 2

What are the sensory receptors in the eye?

Answer 2

light sensitive rods and cones in retina, detect light intensity and range of wavelengths

Question 3

What are the sensory receptors in the nose?

Answer 3

olfactory cells line inner surface in nasal cavity, detect presence of volatile chemicals

Question 4

Where are taste buds? What do they detect?

Answer 4

in tongue, hard palate, epiglottis and first part of oesophagus, presence of soluble chemicals

Question 5

What are the sensory receptors in the skin?

Answer 5

pressure receptors (Pacinian corpuscles), detect pressure

Question 6

What are the sensory receptors in the ear?

Answer 6

sound receptors in inner ear (cochlea), detect vibrations in ear

Question 7

How are muscle spindles sensory receptors?

Answer 7

proprioceptors, detect length of muscle fibre

Question 8

What is a polarised membrane?

Answer 8

membrane that has a potential difference across it (the resting potential)

Question 9

What is depolarisation?

Answer 9

loss of polarisation across membrane, when sodium ions are entering cell making inside less negative

Question 10

What are sodium/potassium pumps?

Answer 10

actively transport sodium ions out of cell and potassium ions into cell, more Na+ out than K+ in

Question 11

How are the inside of nerve cells charged?

Answer 11

more negative in respect to outside

Question 12

How is a nerve impulse created?

Answer 12

altering the permeability of a nerve cell membrane to sodium ions, Na+ channels open and Na+ in down diffusion gradient, movement changes charge

Question 13

What is a generator potential?

Answer 13

small depolarisation caused by sodium ions entering the cell

Question 14

How does the size of a stimulus affect movement of sodium ions?

Answer 14

large stimulus (change in energy level) = more gates Na+ channels open

Question 15

What causes an action potential?

Answer 15

when membrane depolarised to +40mV (threshold level), all or nothing response

Question 16

What are the 3 different types of neurone?

Answer 16

sensory: carry action potential (AP) from sensory receptor to central nervous system (CNS), motor: carry AP from CNS to effector, relay: connect sensory and motor neurones

Question 17

What is the general structure of a neurone?

Answer 17

long to transmit AP, membrane lots gated ion channels, Na+/K+ pumps, maintain potential difference, surrounded by myelin sheath: Schwann cells, gaps = nodes of Ranvier, cell body with nucleus, many mitochondria and ribosomes, numerous dendrites

Question 18

Where do motor neurones have their cell body?

Answer 18

in CNS, long axon which carries AP to effectors, start-shaped cell body at top of neurone, transmission direction = down from cell body

Question 19

How do sensory neurones look?

Answer 19

long dendron, carries AP from sensory receptor to cell body, just outside CNS, cell body smaller and just to side of axon, direction of transmission direction: up to cell body