Topic 5: Nervous System 3 Flashcards
Describe reflexes
Rapid automatic, response to stimuli
Stimulus causes consistent response
Protective
Involve 2 or more neurons
What is the pathway of impulses that leads to a reflex?
Stimulus
Receptor
Integration center (CNS)
Motor neuron
Effector
What are reflexes categorized into?
Effector: SOMATIC or VISCERAL
Which side of body neurons are located: IPSILATERAL or CONTRALATERAL
Number of synapses (& neurons) in arc: MONOSYNAPTIC or POLYSYNAPTIC
This is an automatic muscle contraction in response to sudden or excessive stretching.
What is it?
Provide an example
How does it work?
Stretch reflex
Eg. Knee jerk reflex
stimulus: tap on patellar ligament stretches quadriceps femoris muscle
receptor: muscle spindle (in quads)
effector: skeletal muscle contracts ipsilateral and monosynaptic
What is the flexor (Withdrawal) reflex?
Automatic contraction of flexor muscles that moves part of the body away from the painful stimulus
Describe the cerebrum
-Interprets sensory info from senses
-Initiates & controls skeletal muscle movement
-Higher functions (memory, intellect, etc)
-Relaying info between different parts of the brain
What are the main parts of the brain stem?
MIDBRAIN: auditory/visual reflexes
PONS: regulates breathing (with medulla)
MEDULLA OBLONGATA includes:
-decussation (crossing) of sensory/motor tracts
-autonomic vital reflex centre (respiratory & cardiovascular centres)
-non-vital areas (coughing, sneezing, etc)
What does the hypothalamus regulate?
ANS (glands, smooth/cardiac muscle)
Parts of endocrine system
Temperature
Food/water intake
Parts of limbic system
Part of reticular activating system (RAS)
What is the difference between somatic and visceral (autonomic) reflexes?
It categorizes the EFFECTOR
Somatic: effector is skeletal muscle
Visceral: effector is smooth muscle, cardiac muscle, or glands
What is the difference between ipsilateral and contralateral reflexes?
It categorizes WHICH SIDE of the body
Ipsilateral: sensory & motor neurons are the SAME side
Contralateral: sensory & motor neurons are on opposite sides of the body
What is the difference between monosynaptic and polysynaptic reflexes?
Categorizes the # of SYNAPSES (and neurons) in a reflex arc
Monosynaptic: 1 synapse between 1 sensory & 1 motor neuron
Polysynaptic: 2+ synapses between 3+ neurons
If you step on something sharp, the painful stimulus on the bottom of your foot will trigger a withdrawal reflex to pull the foot away. How does the body insure that you don’t fall over?
The crossed extensor reflex causes the automatic contraction of the extensor muscles in the opposite limb
What is reciprocal inhibition during a spinal reflex?
The inhibition of somatic lower motor neurons to antagonistic muscles during the contraction of the agonist muscles, which ensures smooth and coordinated movement
eg. in a stretch flex
- quads (agonist) contracts
- hamstrings (antagonist) contraction is inhibited
What are autonomic spinal reflexes? Provide an example
Reflexes where the effector is smooth muscle, cardiac muscle, or glands (ie. visceral reflex)
eg. Micronutrition Reflex - urinary bladder
- stimulus = stretch of bladder
- receptor = stretch receptors in wall
- CNS = sacral segment of spinal cord
- effector = destrusor muscle (bladder wall): contracts
The ______ controls all major homeostatic functions, so if it is damaged, it can can cause loss of homeostasis
hypothalamus
What is the Rinne test and what is it for?
Test for middle-ear deafness
Tuning fork on mastoid process. Once sound is gone, move fork to outside ear. Sound should normally be heard by air conduction
What is the Weber test?
Test to determine whether there is any form of hearing loss
Tuning fork on middle of forehead. There should be no difference in intensity in each ear
