Lecture 10: the nervous system part II: sensory input Flashcards
(48 cards)
What is signal transduction?
The conversion of environmental factors into neural information
Why are the five classic senses not well-considered?
They measure the same thing encompassed by different types of stimuli (i.e. different modalities)
What are the 5 types of signal modalities?
Mechanoreception Thermoreception Photoreception Chemoreception Nociception
What are 5 things measured by mechanoreception?
Pressure, body position, sound, acceleration and gravity
Where are hair cells involved in mechanoreception found?
The organ of Corti
Semicircular canals
The utricle and saccule
Where does thermoreception take place?
Free nerve endings in skin and core temp sensors in hypothalamus
What cell types are involved in photoreception?
Rod and cone cells
Name receptors involved in chemoreception
Olfactory receptors in nose
Gustatory receptors in taste buds
What does nociception measure?
Cellular damage (e.g. NK1 receptor for Substance P)
What are lamellar corpuscles also known as?
Pacinian corpuscles
What is the structure of lamellar corpuscles?
Dendrites surrounded by layers (lamellae) of connective tissue
How do lamellar corpsucles work?
When lamellae are distorted by physical pressure, dendrite membrane stretches, opening special sodium ion channels
What is the charges of a lamellar corpuscle when at resting potential?
Positive outside, negative inside
What happens when sodium rushes into the lamellar corpuscle?
Voltage-gated ion channels open and the signal travels down to the myelinated dendrite to soma and axon hillock, triggering AP down axon
What is proprioception?
perception or awareness of the body position or movement of the body
What do spindles respond to (and inform the brain of)?
Muscle length
Rate of change of length
What happens when muscles stretch to propriceptors?
They stretch and activate. There is an increased rate of action potential in the fibers
Pacinian corpuscles and muscle spindles are examples of _____ stimulation of sensory neurons
Direct
What is the magnitude of depolarisation of the membrane called?
The receptor potential or generator potential
Why is lamellar corpuslces considered an example of direct stimulation of sensory neurons?
Connective tissue sheath is not a cell
Where are pressure waves transmitted to inside the ear?
Vestibular duct
Hearing is an example of what type of sense?
Mechanoreception
What do sound waves cause to vibrate within the ear?
Connective tissue fibres in the tectorial membrane
When do sound waves cause connective tissue fibres in the tectorial membrane to vibrate?
When they match resonant frequency of the fibres
