Lecture 7

Question 1

• characterized by the gradual degeneration and death of motor neurons.
– Affects both the upper and the lower motor neurons
– degenerate and stop sending messages to muscles.
– Over time muscles weaken, waste away (atrophy), and
have very fine twitches (called fasciculations).
– Eventually, the ability of the brain to start and control voluntary movement is lost.

What type of disease is this?

Answer 1

Motor Neuron Disease

Question 2

What are 4 causes of motor neuron disease?

Answer 2

1. Gene mutation. Various genetic mutations can lead to inherited ALS, which appears nearly identical to the non-inherited form.
2. Chemical imbalance. People with ALS generally have higher than normal levels of glutamate, a chemical messenger in the brain, around the nerve cells in their spinal fluid. Too much glutamate is known to be toxic to some nerve cells.
3. Disorganized immune response. Sometimes a person’s immune system begins attacking some of his or her body’s own normal cells, which may lead to the death of nerve cells.
4. Protein mishandling. Mishandled proteins within the nerve cells may lead to a gradual accumulation of abnormal forms of these proteins in the cells, eventually causing the nerve cells to die.

Question 3

1. Resting membrane potential
2. Depolarization
3. Repolarization
4. Hyperpolarization

What are these the 4 basic steps of?

Answer 3

Action potential (specifically in skeletal muscle)

Question 4

What is the charge of the chemical signal that crosses synaptic cleft? Is it excitatory or inhibitory?

Answer 4

• Chemical signal which crosses the synaptic cleft can be + or –

Thus the impulse can be excitatory or inhibitory

Question 5

What are 3 differences between excitatory and inhibitory neurons?

Answer 5

• Excitatory Neuron: Na+ channels open, cell depolarizes, AP

* Inhibitory Neuron: Cl- channels open, cell hyperpolarizes, AP much less likely

Question 6

• (blank) is the net sum of both excitatory and inhibitory synapses
• When enough of a change is generated an action potential will be triggered

What is the answer?

Answer 6

Spatial summation

Question 7

• An action potential can also be triggered by frequent, close together firing of synapses
• When firings are far apart membrane potential recovers between
• When firings are close together they can SUM to elicit an action potential

What is this type of summation?

Answer 7

Temporal summation

Question 8

How does neural integration relate to spatial and temporal summation?

Answer 8

It requires more than 1 synapse “firing” to cause enough of a local potential to generate an AP
– Spatial and temporal summation

Question 9

What are the 3 components of the brain stem?

What are the 4 types of lobes in the brain?

Answer 9

Midbrain, Pons and Medulla oblongata

Frontal, Parietal, Temporal and Occipital

Question 10

What part of the brain is notified when one primary cortex has decided to perform movement?

What are the 2 tracts of nerve fibers that permit two-way conduction of nerve impulses?

Answer 10

Cerebellum(responsible for coordinating movements)

– Ascending afferent (sensory) fibers
– Descending efferent (motor) fibers

Question 11

• Connects to brain and spinal cord via
– 12 pairs of cranial nerves 
• connect to brain
– 31 pairs of spinal nerves 
• connect to spinal cord
– Both types directly supply skeletal muscles

What section of the nervous system is this?

Answer 11

Peripheral nervous system

Question 12

What do sensory nerves do? What are the 5 major families of sensory receptors?

Answer 12

Transmits information from periphery to brain

– Mechanoreceptors: 
– Thermoreceptors: 
– Nociceptors: 
– Photoreceptors: 
– Chemoreceptors:

Question 13

What does each family of sensory receptors react to?

Answer 13

– Mechanoreceptors: physical forces
• mechanical stimuli (touch, pressure, vibration, proprioception, hearing and Eq, and stretching of blood vessels and internal organs
– Thermoreceptors: temperature
– Nociceptors: pain
– Photoreceptors: light
– Chemoreceptors: chemical stimuli

Question 14

What does proprioception mean? What are 3 types of special proprioceptive receptors?

Answer 14

Proprioception means “sense of self”

• kinesthetic joint receptors
• Muscle spindles
• Golgi tendon organs

Question 15

What do motor nerves do? What are the 2 main types and what do they do?

Answer 15

Transmits information from brain to periphery

– Autonomic: regulates visceral activity
– Somatic: stimulates skeletal muscle activity

Question 16

• Controls involuntary internal functions
• Exercise-related autonomic regulation
– Heart rate, blood pressure
– Lung function

• Two complementary divisions
– Sympathetic nervous system
– Parasympathetic nervous system

What section of the nervous system is this?

What response is the sympathetic nervous system responsible for?

What response is the parasympathetic nervous system responsible for?

Answer 16

Autonomic nervous system

Fight or Flight

Rest and digest

Question 17

Sensory motor integration

• Can be integrated at many points in CNS
• Complexity of (blank) increases with ascent through CNS
– Spinal cord (simplest)
– Lower brain stem
– Cerebellum
– Thalamus
– Cerebral cortex (primary sensory cortex)

What is blank?

Answer 17

integration

Question 18

What is the purpose of motor spindles?

What is a practical benefit of having muscle reflexes?

1. Neuron from golgi tendon fires
2. Motor neuron is inhibited
3. Muscle relaxes
4. Load is dropped

These are the 4 steps of what reflex?

Answer 18

• Muscle spindles monitor muscle length and prevent overstretching

Muscle Reflexes Help Prevent Damage

Golgi tendon reflex

Question 19

CNS responds to minimize (blank) after your finger is cut
– Reflexes generated by spinal cord
– Voluntary movement generated in the brain

Answer 19

Pain

Question 20

Muscle spindles are a group of specialized fibres called (blank) fibres, found within extrafusal fibres, that have (blank) nerves wrapped around them.

Respond to (blank)
Controlled by specialized gamma motor (blank)

Answer 20

intrafusal

sensory

stretch

neurons

Question 21

Encapsulated sensory receptors located at the junction of a (blank) and a muscle.
Protect tendons and their associated muscles from damage due to excessive (blank). Protective- inhibit agonist and excite (blank)

Answer 21

tendon

tension

antagonist