WEEK 3 Flashcards
What is an exteroreceptor?
A receptor that transduces information we receive from the world around us
What is an interoceptor?
A receptor that transduces information we receive from the world inside us (eg. baroreceptors)
What is the result of a stronger stimulus?
Larger depolarisation, more APs (response is graded by stimulus strength)
Do sensory receptors respond to all stimuli or are they selective?
They are selective transducers that convert energy from specific stimuli to another form of energy
What is sensory modality?
The type of stimulus (eg. touch, taste, smell, sight, balance) which is carried on dedicated pathways called labelled lines-only one type of nerve will take one type of sensation. Can have sub-modalities (sight-colour, distance etc)
What is adequate stimulus?
The type of energy to which a receptor is most sensitive
What are the classifications of sensory receptors?
Mechanoreceptors (mechanical energy) Photoreceptor (electromagnetic, light) Chemoreceptor (chemical) Thermoreceptor (temperature) Nociceptor (noxious-chemical/thermal/mechanical)
How are stimuli detected by receptors?
Region of sensory receptor surface is stimulated which causes a change in the membrane potential of that neurone
What is the role of proprioceptors?
Sense of position
What is receptor adaptation?
The lessoning of receptor potential with maintained stimuli (can be rapidly/slowly adapting)
What are the mechanoreceptors of the somatic sensory system?
Merkel’s receptors (slowly adapting free nerve endings embedded between epithelial cells) and Meissner’s corpuscles (rapidly adapting nerve endings that are coupled to surrounding epithelium by strands of connective tissue)
How do Pacinian corpuscles work?
Pressure applied, concentric rings of connective tissue surrounding neurone are deformed and stretch, activating stretch-mediated Na+ ion channels, generator potential, AP, if stimulus is maintained, concentric rings slide over one another, effectively dampening stimulus energy and activity abates
What is a motor unit?
A somatic efferent (motor neurone) plus all the muscle fibres it supplies (minimal functional unit of motor system)
What are the three types of muscle?
Skeletal (striated, voluntary/neurogenic), Cardiac (striated, involuntary/myogenic) and Smooth (non-striated, involuntary/myogenic) muscle
What does neurogenic mean?
Stimulation by nerves
What does myogenic mean?
Spontaneously discharges electrical potentials causing depolarisation and muscle contractions
Functions of skeletal muscles
Movement
Stability of joints
Posture (muscle tone)
Heat generation (maintenance of body temp)
What is a myocyte?
A single cell of muscle (muscle fibre), formed by myoblast
What is a fasciculus/fascicle?
A collection of myocytes