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List the 5 components of a reflex arc
- 1. The receptor is the site of stimulus action
- 2. The sensory neuron transmits afferent impulses to the CNS
- 3. The integration center consists of one or more neurons in the CNS
- 4. The motor neuron conducts efferent impulses from the integration center to the effector organ
- 5. The effector muscle fibers/glands responds to efferent impulses by contracting (muscles) or secretion (glands)
When do stretch reflexes occur?
- 1. When maintaining balance
- 2. When maintaining posture
- 3. During locomotion
- **Initiated by tapping a tendon which leads to stretching the muscle
Describe the patellar stretch reflex
- 1. Tapping the muscle excites muscle spindles in the quads
- 2. Afferent impulses travel to the spinal cord
- 3. Motor neurons send activating impulses to quads causing extension of the knee
- 4. At the same time, interneurons make inhibitory synapses preventing the antagonist muscle (hamstrings in this case)
- -this is called reciprocal inhibition
Golgi tendon reflex
- protects skeletal muscles from excessively heavy
- loads by causing muscles to relax and dropping the heavy load.
- **occurs in the withdrawal reflex
- Stimulus produces the excitation of one muscle, but the inhibition of the antagonistic muscle.
- Ex: If you touch a hot stove, you’ll pull your hand back. This motion occurs because the biceps are excited and the triceps (antagonist to biceps) is inhibited. If the triceps was not inhibited, you would not be able to pull your arm back.
Crossed Extensor reflex
- **occurs in withdrawal reflex
- Consists of a flexor or withdrawal reflex followed by extension of the opposite limb.
- Ex: If you step on glass, you’ll pull your foot up. In order to not fall over after lifting your foot, you need to contract the muscles in the opposite leg.
- Ex2: If someone grabs your arm, you’ll pull that arm away. In addition, you’ll usually push out your other arm, trying to push the person away.
An action that is performed without conscious thought as a response to a stimulus.
- eye's response to light
- receptor - the retina
- afferent - optic nerve (II)
- efferent - oculomotor nerve (III)
- effector - iris smooth muscle
- a reflex elicited when the sole of the foot is stimulated with a blunt instrument.
- The reflex can take one of two forms: 1. In normal adults the plantar reflex causes a downward response of the hallux (flexion). 2. An upward response (extension) of the hallux is known as Babinski response
- also known as the blink reflex
- is an involuntary blinking of the eyelids elicited by stimulation of the cornea (such as by touching or by a foreign body), or bright light, though could result from any peripheral stimulus.
- Stretch reflex
- knee-jerk reflex
- patellar ligament is tapped for a reaction
- asses L2-L4 level of spinal cord
Which was the fastest reflex tested
- a. vision—slowest
- b. hearing—faster
- c. touch-fastest
Be able to identify the 5 brachial plexus nerves
- a. Musculocutaneous
- b. Median
- c. Ulnar
- d. Axillary
- e. Radial
flexor muscles of anterior arm (biceps brachii, brachialis)
flexor groups of anterior forearm (flexor carpi radialis, flexor digitorums, pronators)
flexor muscles of anterior forearm (flexor carpi ulnaris and digitorum profundus)
deltoid and teres minor
posterior muscles of arm, forearm and hand (triceps brachii, supinator, brachioradialis, extensor carpi radialis longus and brevis, extensor carpi ulnaris)
Spinal cord (will be pictures or descriptions, not actual spinal cord)
- 1. cervical enlargement—upper limbs (between shoulders)
- 2. lumbar enlargement—lower limbs (before/above horse tail)
- 3. rootlets (branches - dorsal/ventral roots)
- 4. caudate equine (horse tail)
- 5. filum terminale (very end, cocyxx)
- 6. dura mater (most outer membrane of cord)
What would happen is a person had their spinal cord severed above the lumbar enlargement?
- Paraplegic - Complete paralysis of the lower half of the body including both legs, usually caused by damage to the spinal cord.
- (spastic paralysis)
What would happen is a person had their spinal cord severed above the cervical enlargement?
Quadriplegic - paralysis caused by illness or injury to a human that results in the partial or total loss of use of all their limbs and torso