L20 Flashcards
what is sensation and what does it sensation require
- Conscious or subconscious awareness of changes in the external/internal environment
- Require
○ Stimulation
§ Within a sensory receptors receptive field
○ Transduction of a stimulus
§ Change in mechanical/chemical energy, into electrical graded potential
§ Receptors are selective
○ Generation of a action potential
§ In a sensory neiron
§ Intensity of sensations determiend by frequency of action potentials + no. Of receptors activated
○ Integration of sensory input
§ Need spinal cord, brains tem, cortex involvement, + decision making (motor output)
- Require
what is perception
Conscious interpretation of sensations, performed by cerebral cortex
3 different types of sensory receptors
○ Free nerve endings
§ Detect pain, temp., tickle, itch
○ Encapsulated nerve endings
§ Detect pressure, vibration, touch
○ Separated cells
§ E.g. Gustatory receptor cells in taste buds
§ Photoreceptors in retina of eye
Hair cells in inner ear for hearing
define exteroceptors, intereoreceptors, proprioceptors
○ Exteroceptors
§ Hearing, vision, smell, taste
○ Intereoreceptors
§ Bodies internal environment
○ Proprioceptors
- Info about body position muscle length + tension, position + movement of joints
explain thermoreceptors
- Can detect heat or cold
- Both types of receptors adapt quickly upon stimulus, but have low frequency to prolong stimuli
Temp. Above 48 degrees and below 10 degrees stimulate pain receptors rather then temp. receptors
- Both types of receptors adapt quickly upon stimulus, but have low frequency to prolong stimuli
explain cold receptors
○ Linked to small fast type A nerve fibres in epidermis
○ Some free nerve endings attached to C nerve fibres
Detects 10 degrees to 40 degrees
explain heat receptors
○ Free nerve endings attached to slow C nerve fibres in dermis
○ NOT as abundant as cold receptors
○ Detects 32 degrees to 48 degrees
what are the 2 types of nocioreceptors (pain)
○ Fast
§ acute, sharp, pricking, percieved in 0.1 seconds
○ Slow
chronic, burning, aching, throbbing, percieved in a second or more after stimuli
deep vs superficial vs visceral pain
○ Deep
§ Skeletal muscles, joints, tendons, fascia
○ Superficial
§ From skin receptors
* Visceral pain
○ Stimulation of pain sensors in visceral organs
○ Presents deep in skin that overlies stimulated organ
Can be distant to site- reffered pain
what is referred pain
- For example
○ Heart attack, signified by shooting pain in left arm
○ Because sensory nerves in arm project to the same spinal nerve as the heart, so attached that way
So pain in heart shows up on left arm
explain proprioceptors and hows its involved with muscle spindles + tendon organs
- Is the position of body positions
- Found in muscles + tendons
○ Muscle spindles
§ In skeletal muscles, monitors their length
§ Involved in stretch reflexes○ Tendon organs
§ Junction of a tendon + a muscle
Protects muscles from overstretching
- Found in muscles + tendons
explain join kinaesthetic receptors
○ Exists within or around the joint capsule of synovial joints
○ Respond to pressure and acceleration/deceleration during movement
Joint ligament contain receptors to protect against excessive strain
explain the somatic sensory pathways + the 3 orders
- Carry info from somatic sensory receptors to the primary somatosensory area in the cerebral cortex and to the cerebellum
- Pathways to the cortex consists of thousands of sets of 3 neurons
○ 1st order
§ Impulses form somatic receptors to BRAINSTEM/SPINAL CORD○ 2nd order
§ Impulse from brainstem/spinal cord to THALAMUS○ 3rd order
Impulse from thalamus to PRIMARY SOMATOSENSORY AREA OF CORTEX
- Pathways to the cortex consists of thousands of sets of 3 neurons
explain the somatic nervous system
- Sensory info processed in brain
- Response generated through motor neurons
- Movement is complex involves coordination of a range of muscles
E.g. When movement is smooth, input from cerebellum and basal nuclei (Parkinsons disease, Huntington’s disease)
what are the 2 motor neurons in the somatic nervous system
○ Input to Upper motor neurons
§ Movement due to contractions of skeletal muscles
1. Local circuit neurons in brainstem/spinal cord
2. Upper motor neurons from cerebral cortex
3. Basal nuclei neurons
4. Cerebellar neurons
Lower motor neurons
