integration and control (brain + spinal cord)

Question 1

overview

Answer 1

• sensory (afferent) division “inputs” info into brain + spinal cord (control centers)
• brain + spinal cord integrates info and control effectors through motor (efferent) division (“output”)

Question 2

spinal cord reflexes

Answer 2

• rapid automatic response to stimuli
• stimulus always causes the same motor responses
• usually protective
• involve 2 or more neurons \
• reflex pathway or arc = pathway of impulses

Question 3

what are reflexes categorized into

Answer 3

a. effector:
- somatic reflex=effector is skeletal muscle
- visceral (autonomic) reflex=effector is smooth muscle, cardiac muscle or glands

Question 4

which sides of the body the sensory + motor neurons are located

Answer 4

a. ipsilateral reflex=sensory + motor neurons are on the same side
b. contralateral=sensory + motor are on opposite sides

Question 5

what are the number of synapses in arc

Answer 5

a. monosynaptic reflex=one synapse between 1 sensory + 1 motor neuron
b. polysynaptic reflex= 2 or more synapses - 3 or more neurons

Question 6

stretch reflex

Answer 6

e. g. knee jerk reflex
- extensor muscle contracts
- stimulus=tapping patellar ligament, which stretches the quads
- receptor= muscle spindle ( in quad)
- effector = skeletal muscle
- ipsilateral, monosynaptic

Question 7

flexor (withdrawal) reflex

Answer 7

e,g. in leg

• stimulus: stepping on nail
• receptor: touch, pressure, pain
• effector: hamstrings (=flexors) - contract
• ipsilateral, polysynaptic

Question 8

reciprocal inhibition

Answer 8

skeletal muscle (or group) contracts

• at the same time antagonist prevented from contracting
• in stretch reflex

Question 9

autonomic spinal reflexes

Answer 9

• effector: smooth m. cardiac m. or glands
• micturition reflex - urinary bladder
• stimulus=stretch of the bladder
• receptor: stretch receptors in bladder wall
• CNS=sacral segment of spinal cord (PSNS)
• effector= detrusor muscle (wall of bladder)

Question 10

brain: cerebrum

Answer 10

• interpreting sensory info from general and special senses
• initiating and controlling skeletal muscle movement (motor areas and basal nuclei)
• memory intellect

Question 11

brain: brain stem

Answer 11

• controls life-sustaining processes e.g. breathing, circulation
• if brain stem functional but higher centers damaged=alive but not aware

Question 12

what are the parts of the brain stem

Answer 12

a. midbrain
- auditory and visual reflexes
b. pons
- functions with medulla to regulate breathing
c. medulla oblongata
- many functional regions

Question 13

functional regions

Answer 13

a. decussation (crossing) of sensory + motor tracts
- e.g. left brain controls right skel. muscles
b. autonomic vital reflex centres
- respiratory area: drives breathing rate
- cardiovascular centre: cardiac area modifies heart rate
c. other, non-vital areas - control swallowing, vomiting coughing sneezing

Question 14

hypothalamus

Answer 14

major functions:

a. regulates ANS (smooth & cardiac muscle, glands)
b. regulates parts of endocrine system
c. regulates temperature
d. regulates food + water intake
e. part of limbic system = emotional brain.
f. part of the reticular activating systems (RAS) with the reticular formation in the brain stem, cortex, thalamus