Nervous System 4- Senses and Reflex Flashcards Preview

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Flashcards in Nervous System 4- Senses and Reflex Deck (34):
1

Describe the components of Physiological Control Systems

SENSOR (RECEPTOR) -> Afferent Pathway -> CONTROL CENTRE -> Efferent pathway -> EFFECTOR

2

What connects the afferent and efferent neurone

An interneurone

3

Which parts of the neurones are located in the CNS

The interneurone and the cell body of the efferent neurone

4

Describe a reflex arc (Sophie Assults Sam Every Normal Monday)

Sense organ -> Afferent neurone -> Synapse -> Efferent neurone -> Neuromuscular junction -> Muscle

5

What are reflex arcs?

"In-built" responses which are present from birth. Not under voluntary control

6

What can generator potentials be stimulated by

Sensory stimulus (e.g. mechanical stimulation)

7

What does EPSP stand for

Excitatory Postsynaptic Potential

8

What happens is small transient depolarisations are big enough

They evoke an action potential if they reach the threshold

9

How do cells communicate with each other

Via synapses

10

Describe the components of a synapse

Pre-synaptic neurone -> synapse -> post-synaptic neurone

11

What is convergence

When lots of neurones send signals to one individual neurone

12

What is divergence

When one neurone sends signals to lots of neurones

13

What is summation

When signals combine

14

What are the three types of summation

1. Temporal 2. Spatial 3. EPSP-IPSP cancellation

15

What is temporal sumation

Related to time. Same stimulus over period of time

16

What is spatial summation

Related to space. If close together only need a few signals from each to reach the threshold

17

What is EPSP-IPSP cancellation

One causes hyperpolarisation, the other caused depolarisation. They cancel eachother out resulting in no action potential.

18

What are the two characteristics of receptors

They have high specificity and high sensitivity

19

What does receptors having high specificity mean

They respond more readily to one particular stimulus (e.g. pressure, temperature)

20

What does receptors having high sensitivity mean

They are extremely sensitive to a determined stimulus (e.g. olfactory stimulus can respond to a few odour molecules the air)

21

There is only one type of skin receptor- true/ false

False, there are many different types of skin receptors each with detecting different things and adapting at different rates

22

What are two effectors

Muscles and glands

23

What are the two types of effector glands

Exocrine and endocrine

24

What do exocrine effector glands do

Secrete into the bloodstream

25

What do endocrine effector glands do

Secrete into a specific place (e.g. salivary)

26

What does a stimulus do

It causes action potentials along a sensory axon

27

What is an example of a somatic reflex

The stretch reflex

28

Describe the stretch relex

Receptors in quadriceps -> CNS -> motor neurones -> flexor contracts and knee moves flicking leg up/ extensor contracts and knee moves flicking leg down

29

What are the characteristic of a somatic reflex arc

Via the spinal chord, fast

30

What are the characteristics of a autonomic reflex arc

More interneurones so not as quick as the somatic reflex

31

What is an example of a autonomic reflex arc

The light reflex

32

Describe the light reflex arc

1. Optic nerve receptors in the retina detect light. 2. Info travels via optic nerve fibres to brain 3. Cranial nerve III from brain to papillary sphincter 4. Papillary sphincter = either contract or dilate iris

33

What does an increase in arterial pressure result in

increase in firing of baroreceptors -> increase in parasympathetic outflow to heart & decrease in sympathetic outflow to heart, arterioles, veins

34

Reflexes are under voluntary control- true/ false

FALSE, reflexes are not under voluntary control and most are present from birth