Receptors

Question 1

Receptor definition

Answer 1

Specialised cells which detect a specific stimulus and convert one form of energy into a generator potential
Generator potential may then cause an action potential in the sensory neurone

Question 2

Pacinan corpuscle

Answer 2

Found in fingers, soles of the feet and external genitalia
Pressure receptor
Increased pressure deforms stretch mediated na+ channels
Na+ channels open and na+ diffuse in
Depolarisation leads to generator potential

Question 3

Compare rods and cones

Answer 3

-Rods evenly distributed throughout the macula whereas cones densely packed in the fovea
-rods are sensitive to all wave lengths of light whereas cones are sensitive to 1 (three options)
-rods have high visual sensitivity to low levels of light intensity whereas cones sensitive to high light intensity
-rods have low visual acuity whereas cones have high visual acuity due to one cone to one bipolar neurone

Question 4

Control of heart rate

Answer 4

Sinoatrial node sends wave or electrical activity across both atria
Both atria contract
Layer of non conductive tissue prevents wave reaching ventricles
Wave of electrical activity reaches atria ventricular node
0.1 second delay allowing atria to finish contracting
Wave of electrical activity sent from the atrioventricular node
Down the bundle of his to the base of the ventricles
Up the purkinje fibres
Causing the ventricles to contract from the apex to the heart upwards

Question 5

Autonomic nervous system

Answer 5

Sympathetic - stimulates effectors , speeds up , flight or fight , neurotransmitter is noradrenaline
Parasympathetic - inhibits effectors , controls activity at rest , neurotransmitter is acetylcholine

Question 6

Acceleratory centre

Answer 6

Linked to sa node by the sympathetic nervous system

Question 7

Inhibitory centre

Answer 7

Linked to the sa node by the parasympathetic nervous system

Question 8

Pressure baroreceptors

Answer 8

Blood bp increase above normal
Detected by baroreceptors in walls of aorta and carotid arteries
More frequent impulses sent to medulla oblongata
More frequent impulses from inhibitory centre in medulla to sa node via parasympathetic nerve
Decreases frequency of impulses from sa node across atria
Heart rate decreases

Can have opposite effect

Question 9

Chemoreceptors

Answer 9

More co2 present lower ph
Blood ph decreases below normal
Detected by chemoreceptors in walls of aorta and carotid arteries
More frequent impulses sent to medulla oblongata
More frequent impulses from acceleratory center in medulla to sa node via sympathetic nerve
More frequent impulses from sa node across atria
Heart rate increases