lecture 7

Question 1

reasons for variations in senses.

Answer 1

• Genetics
  
  • Maturation
  • Circadian rhythm
  • Experience/training
  • Fatigue
• Injury/disease

Question 2

mechanoreceptors

Answer 2

function: movement.
stimuli: sound waves (hair cells) pressure (baroreceptors) touch/stretch.
location: ears, arteries and skin

Question 3

chemoreceptors

Answer 3

function: chemicals
stimuli: molecules/solutes pH
location: tongue, nose and tissues.

Question 4

thermoreceptors

Answer 4

function: temp
stimuli: heat/cold
location: skin, hypothalamus

Question 5

photoreceptors

Answer 5

function: light
stimuli: visable spectrum
location: eyes (retina)

Question 6

reception

Answer 6

ability of receptor to absorb energy of a stimulus. (receiving) detect the change in energy levels.

Question 7

transduction

Answer 7

• conversion of stimulus energy into a membrane potential, a change in permeability of a post synaptic membrane often graded = proportional to strength of stimulus may be amplified and/or may be summed may be strong enough (reaches threshold) to generate action potentials i.e. a Receptor Potential.. RP – fires an Action Potential… AP.

Question 8

Transmission

Answer 8

receptors potentials transmitted via AP’s to CNS.

Question 9

Integration

Answer 9

CNS processing of frequency of receptor potentials. Trying to make sense of it. Using the frequency to see how important something is.

Question 10

What is sensory adaptation?

Answer 10

Sensory adaptation is an attenuation (accommodation) of a stimulus, resulting in a decrease in responsiveness by receptors due to continual stimulation.

Question 11

how does sensory adaption occur.

Answer 11

Sensory adaptation occurs as senses adjust over time, becoming less sensitive to stimuli that are repeatedly experienced. A uniformly maintained stimulus of constant intensity is perceived as progressively weaker, while a variable intensity stimulus of shorter durations is perceived as progressively stronger over time.

Question 12

what is the homounculus

Answer 12

is a representation of the human body within the brain, particularly in the somatosensory and motor cortices. topograhical.

Question 13

lesions of these sensory areas

Answer 13

Defective Localization - cannot distinguish different touch sense.
Loss of proprioception -
Tactile Agnosia (trouble identifying an object by touch alone).

Question 14

interceptors

Answer 14

states of our internal organs (not so relevant for this course). (hungry)

Question 15

proprioceptors

Answer 15

nformation about or own movements (AKA kinesthesis). Where our body is in space and in time.
Includes
- Muscle receptors (spindles and Golgi).
- Joint receptors.
- Cutaneous receptors.
- Vestibular system.

Question 16

Exteroceptors

Answer 16

Information about the movement of objects in the environment. Avoid objects in life because we see them.
- Vision and audition.

Question 17

Proprioception

Answer 17

= the sensation and perception of the position and movement of limbs, head and trunk.

Question 18

muscle spindles

Answer 18

are parallel to muscle fibres - most important proprioceptors. They fire when the muscles is stretched.
- Mechanical deformation in the receptor, spindles send signals via motor neurons to spine and up (afferent). Changes in length (type) and velocity.

Question 19

what communicates through spnindles.

Answer 19

Alpha and gamma talk through spindles to tell us about the tension and length. Rich information.

Question 20

Golgi tendon organs (GTO)

Answer 20

Give feedback of tendon stretch. Are with tendons. Response opposite to muscles: when muscle contracts, GTO fires.
Allow us to estimate weights of objects, and forces applied to objects.
Stretch. Fire when our muscles contract. Can tell us how heavy smth is because of the change in this tendons. Has a small loop with the spinal cord to respond fast without the brian. Sensing environment and responding fast.

Question 21

Joint receptors

Answer 21

Sensory endings in the joint. Provide information of the joint angle. Useful to tell when body is approaching not-so-useful position!
Approaching a not so useful position.

Question 22

Cutaneous receptors

Answer 22

Receptors in skin. Mechanoreceptors measure deformation of skin, e.g., information about touch, pressure, displacement. Other cutaneous receptors for temperature & pain.
When we are picking a hot object we do. Rough or the touch of the object. Bake a cake and not burn ourselves.

Question 23

Proprioception: Vestibular system

Answer 23

Signals balance: information about the position & movement of head Location: middle inner ear deep within the temporal bone Sensors triggered by linear and angular acceleration of the head.

Inner ears, smallest bones. Fluid circulates around these small bones. Brushing on small hairs when our head position moves.