Nervous System Flashcards
(103 cards)
Key characteristics of general sensory organs
-Widespread throughout body
-Detect touch and temperature
-Role in proprioception
Key characteristics of special sensory organs
-Localised to a small area
-Highly specialised
Encapsulated sensory receptor
-Mechanoreceptor
-Sensitive to touch, pressure, vibration, temperature
-Located in dermis and pancreas
Examples of encapsulated sensory receptors
-Meissner’s corpuscles
-Pacinian corpuscles
-Ruffini’s corpuscles
-Merkel’s discs
Free sensory receptor
-Nociceptors, mechanoreceptors and chemoreceptors
-Detects pain and other noxious stimuli
-Located in high sensitivity areas (intestines, tooth pulp, skin, oral cavity, cornea)
Associated sensory receptor
-Sensitivity relies on association with another structure eg hair, muscle spindle
-Detects mechanical or proprioceptive stimuli
Functions of proprioception
-Automatic postural adjustment
-Pre-activates muscles in preparation (for a fall, landing etc)
Muscle spindle proprioceptors
-Intrafusal muscle fibres and associated sensory receptors
-Measure muscle length and rate of muscle length change
-Responsible for stretch reflex
Stretch reflex
Spinal reflex which regulates resting muscle tone according to muscle length detected by muscle spindles
Golgi tendon organs
-Detect tension within tendons
-Located in tendons attached to skeletal muscle
Gustatory cells
-Primary chemoreceptors
-Located in taste buds
-Have no axons
-Impulses relayed by 3 cranial nerves
Vomeronasal organ
-Detects pheromones
-Separate and parallel to main olfactory pathway
-Connected to mouth and nose by nasopalatine canal
-Animals exhibit mouth/lip movements to actively draw air over the organ
Fovea
Area of high cone cell density within the retina
Pineal complex
Primitive light-sensing organ within the brain. Conserved by turtles, which use it to detect day/night and seasonal variations in sunlight
Magnetoreception
Some migrating animals are able to navigate by sensing minute variations in Earth’s magnetic field, used as an “internal compass”
Neuromast organ
-Common mechanoreceptor setup
-Consists of hair cells and support cells covered by a gelatinous cap
-Used in lateral line system
How do animals use hair cells to detect changes in their environment?
-Fish use hair cells as part of their lateral line system to measure water flow and detect objects at a distance
-Mammals use hair cells as part of their vestibular system to detect their own movement
-Mammals use hair cells in the cochlea to detect sound
Function of corticospinal pathway in mammals
Fine control of hands, particularly individual finger movements
Function of tectospinal pathway in mammals
-Co-ordinated locomotor and feeding movements
-Head turning reflex
-Postural movement reflexes (in response to visual stimuli)
Function of rubrospinal pathway in mammals
-Motor function
-Flexor muscle activity
-Extensor muscle inhibition
Function of vestibulospinal pathway in mammals
-Extensor muscle activity
-Postural reflexes
-Equilibrium maintaining reflexes (in response to vestibular input)
Function of reticulospinal pathway in mammals
-Gross movement (locomotion, posture, reaching)
-Proximal and axial muscle control
Which descending pathway would a person use when carrying out complex surgery?
Corticospinal pathway
Three layers of the eye
Retina, choroid, sclera