Lecture 5- Structure of the PNS Flashcards Preview

Physiology > Lecture 5- Structure of the PNS > Flashcards

Flashcards in Lecture 5- Structure of the PNS Deck (47)
1

What is the PNS divided into?

Afferent (receptors, sense organs)

Efferent -autonomic, somatic

2

What is a receptor?

cell allowing the body to get information about the outside/inside conditions

3

What types of photoreceptors are there?
1
2
3
4
5
6
7

1 photo
2 mechano
3 thermo
4 osmo
5 chemo
6 pain = nociceptors
7 electro

4

What is receptor potential?

When receptor stimulated (thermo by temp etc) it changes the permeability to a selective ion-
-the local depolarising change in potential in case of a separate receptor cell

5

What is the generator potential?

as receptor potential but when the receptor is a specialised afferent neuron

6

What type of potential is involved in the receptors?

graded potential= the stronger the stimulation the greater the permeability and the larger the receptor potential. If receptor potential large enough= action potential can be triggered in the afferent neuron

7

What are the two main physiological types of receptors and how does action potential flow in those?

-specialised afferent neuron-
local current flows between the activated receptor and the trigger zone
-cell closely associated with the afferent neuron
=such as retina= the receptor potential triggers the release of a neurotransmitter

8

What is a tonic receptor?

-don't adapt or very slowly, when maintained info about stimulus is needed
-stop when stimulus stops

9

What is a phasic receptor?

-adapts rapidly
-more receptive to changes
-receptor potential rises quickly and stops quickly
(clothes wearing wouldn't want to know all the time)

10

How does the size a receptive field affect acuity?

The smaller the receptive field= the greater the acuity= like on your fingertips.= higher density of receptors

11

How does the size of receptive fields differ in the body?

Greatly, fingertips, palms, teeth, muzzle= really sensitive
back= can't even tell if one or two fingers very easily

12

What is lateral inhibition?

-enhances contrast
-the most stimulated port enhanced stimulation and the immediate areas inhibited
-helps telling where the stimulus is
-occurs in the CNS

13

Name the layers through which light must go to get to the back of the eye.

-cornea
-aqueous humour
-iris
-lens
-vitreous humour
-retina= rods and cones
then optic nerve

14

What is the cornea for?

refracts the entering light
-living but no blood supply

15

What is the aqueous humour for?

to keep the cornea inflated

16

What is the iris for?

- it's controlled by autonomic muscles
- contract/relax= determines how much light passes through and focuses the light onto the retina

17

What is the lens for?

-semi solid
-can focus light
- muscles are attached to it= change its length
-only humans and small mammals have it
-- cattle and horses don't! needed for detail!

18

What is the vitreous humour for?

transfers light through to the retina

19

How many types of retinal cells do we have/other animals?

-we have 3
-most animals 2 = that's why they can't tell red

20

What is a binocular field of view and which animals have it?

-cats and dogs
-good for depth perception
-seeing to the front

21

What is monocular field of view and which animals have it and what are it advantages?

-to the sides and extended behind
-blind spot directly at front
-herbivores (cattle, horses)
-so they can see approaching predators when eating grass

22

What is opsin?

A protein in retinal cells
-detects change in light = if light is not hitting it= sends electrical signal= so light decreases the potential

23

What is the structure of the ear?

-pinnae
-middle ear (eardrum, ossicles, Eustachian tube)
(also gutteral pouch in horses)
-cochlea (hair cells)

24

What is sound?

Change in air pressure

25

How can we hear?

The change in air pressure causes mechanical movement of the hairs in the cochlea which opens up ion channels- if enough stimulation = AP

26

What is the vestibular apparatus for?

Balance and co-ordination of head and eye movements.

27

What are semi-circular canals and what do they do?

-part of the vestibular apparatus, hairs
-detect head movements, rotation, acceleration etc.
-

28

What are the Otolith organs?

-part of the vestibular apparatus
-tell gravitational info
-hair hang down because of gravity = that's how you tell where is up

29

What is proprioception?

-know where my legs are
-awareness of one's body in space

30

What is cutaneous output?

Pressure on my feet on the ground

31

What part of the brain processes the stimuli relating to balance?

Cerebellum

32

What are the four main taste buds?

1. salt
2. sour
3. sweet
4. umami

33

What is the olfactory mucosa?

- in smelling
- has special receptor cells responsive to particular chemicals (often the ones released by individuals of other species)

34

What is the vomeronasal organ?

-in vertebrates' nose
-"sexual nose"
- detects pheromones in animals

35

What is the Flehmen response?

-in horses, horses laugh, curl their lips and cover nostrils, breaths in deeply carrying pheromones into the vomeronasal organ and can determine if mare is sexually receptive

36

What are mechanoreceptors for?

Touch + pressure

37

How are mechanically-gated dendrites activated?

Mechanically, when moves= AP

38

What are Pacinian corpuscles for?

Detecting deep pressure. reflect the magnitude of the stimulus.

39

What are the two thermoreceptors involved in cold environment?

-CMR1= 28C -thermoregulatory (important for informatory role)
-AKTM1= less than 8 C (pain)
-ion gates, changing due to temperature

40

What are the three thermoreceptors involved in warm environment?

TRPV 3- 33 C = thermoregulatory
TRPV 1- 42 C= pain/spicy (not in birds the spicy)
-also triggered by chemicals, capsicain= spicy
TRPV 2- 52 C = pain!

41

What are the receptors snakes have and we don't?

infrared

42

What are the three types of nociceptors?

1.Mechanical
2. Thermal
3. Polymodal (respond to chemical from damaged tissues)

43

What chemical changes the sensitivity of nociceptors?

-prostaglandins
-chemically enhances the pain

44

How does myelination affect the speed of how fast the pain signal gets to the brain?

-myelinated fibres= fast = acute pain
-unmyelinated fibres = slow = chronic pain

45

What is substance P?

-neurotransmitter involved in pain detection
-activates pathways for higher processing

46

What bits are involved in the pain pathway?

-first have the stimulus
-then AP goes on the afferent nerve fibre to the spinal column where substance P is released
-then brainstem's reticular formation= raises awareness
-thalamus relay station
-then cortical somatosensory areas
-also hypothalamus is involved= emotional and behavioural response to the stimuli

47

What is the analgesic pathway?

- supresses pain transmission in the brain stem
- periaqueductal grey matter
-triggers interneurons in the dorsal root of spinal column to produce endogenous opiates (morphine like substances)
-block the pathway from proceeding further