Receptors

Question 1

What does a pacinian corpuscle consist of

Answer 1

Lamellae ( rings of tissue) around a sensory neurone

Question 2

Stimulation of pacinian corpuscle

Answer 2

1- pressure applied deforms lammelae opening stretch-mediated Na+ channel
2- Na+ floods into neurone making it more “positive” = depolarisation = generator potential
3- if generator potential reaches threshold = action potential produced

Question 3

Name 2 photoreceptors

Answer 3

Rod
Cone

Question 4

Features of rod cell

Answer 4

-Low visual acuity ( ability to distinguish objects from each other)
- evenly spread on retina but not on fovea
- Rhodopsin - black and white

Question 5

Features of cone cell

Answer 5

• high visual acuity
• concentrated on fovea
• Iodopsin - detects colour

Question 6

Stimulation in photoreceptors

Answer 6

1- light breaks down pigment in receptor causing Na+ to flood into sensory neurone = generator potential
2- if threshold reached = Action potential produced

Question 7

Spatial summation

Answer 7

Multiple rod cells per bipolar cell = sum of all receptors stimulated means threshold can be reached

Question 8

Retinal convergence

Answer 8

Several rod cells generate signal in a single single sensory neurone
- can be associated with poor visual acuity and blurryness

Question 9

Optic nerve

Answer 9

Axons of sensory neurones

Question 10

Heartbeat features

Answer 10

Myogenic = self stimulating/ does not require a stimulus

Question 11

Stimulation of heart ( simple)

Answer 11

1- Impulse from Sino atrial Node (SAN)
2- contraction of atria
3- transmission of impulse through atrioventricular node (AVN) to bundle of His
4- transmission of impulses along purkyne fibres
5- contraction of ventricles

Question 12

Bundle of His

Answer 12

Conducting tissue
Transmits impulse to bottom of heart + around ventricle walls along purkyne fibres

Question 13

Why is there non conducting tissue between atria and ventricle

Answer 13

Creates delay between contraction of atria and contraction of ventricles allowing ventricles to fill

Question 14

Where are chemoreceptors found

Answer 14

Wall of carotid artery and aorta

Question 15

What do chemoreceptors detect for and how are they stimulated

Answer 15

Detect CO2 concentration/ PH
1- when stimulated impulses sent to medulla oblongata
2- impulses sent from centres to Sino atrial Node(SAN) in heart

Increase in CO2 conc = heart rate increase
An increase in CO2 = lower PH due to carbonic acid

Question 16

Stimulation of heart
(complex)

Answer 16

1- Sinoatrial Node (SAN), in wall of right atria, = transmits waves along atria walls
2- Right + left atria contract together = blood forced into ventricles
3- impulse cannot pass to ventricle due to Non-conducting tissue= creates delay allowing ventricles to fill
4- impulses pass through Atrio-ventricular Node ( AVN)= bundle of his
5- as impulse pass through purkyne fibre = ventricles contract together
6- blood forced out of ventricles to artery’s

Question 17

What are purkyne fibres

Answer 17

• conducting fibres

Question 18

Affect of increase in impulses from sympathetic + parasympathetic pathways between medulla oblongata + heart

Answer 18

Sympathetic = increase in heart contraction

Parasympathetic = decrease in heart contraction

(Para Olympics for slow)