*****SOME ANSWER REQUIRES DRAWING. PLEASE DRAW ON A PAPER, SNAP USING YOUR PHONE

Question

*****SOME ANSWER REQUIRES DRAWING. PLEASE DRAW ON A PAPER, SNAP USING YOUR PHONE, EMAIL TO YOUSELF, COPY FROM EMAIL TO PC and upload here. DRAWINGS ARE REQUIRED TO RELEASE ALL 1500 POINTS******

Muscular Dysgeny

A case study nervous and muscular physiology

You are a research scientist interested in finding the cause of the cellular defect associated with the genetic disease Muscular dysgeny. You already know it is a lethal recessive, genetic disease of mice that is caused by a mutation in the mdg gene. Animals with this mutation die shortly after birth. You are interested in finding the exact defect associated with this mutation.

You surgically remove a single motor unit from a normal mouse fetus and a dysgenic mouse fetus. You place the neuron/muscle fiber unit in an experimental chamber in order to study abnormalities.

1. Define each of the following:

motor neuron

synapse

synaptic knob (endbulb)

sarcolemma

t-tubules

sarcoplasmic reticulum

motor end plate.

2. Place the following steps for an action potential in the correct order:        

            1. Voltage gated Na+ channels open

               2. Na+ rushes in

               3. Potential moves toward and above zero to + 30 mV

               4. Voltage gated K+ channels open

               5. K+ rushes out

               6. Na+/K+ pump restores RP

               7. Graded potential reaches TP

               8. Potential moves toward RP and past to

Explanation / Answer

1).

Motor neuron: a nerve cell forming part of a pathway along which impulses pass from the brain or spinal cord to a muscle or gland.

Synapse: a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.

Synaptic knob (endbulb): this knob is adjacent to a tiny cleft or synapse (s). When a nerve impulse reaches this knob, a drug called a neurotransmitter is released from vesicles into the synapse. The neurotransmitter diffuses across the gap and binds to receptors on the membrane of the adjacent neuron or muscle cell.

Sarcolemma: It is the smallest contractile unit where contractile proteins are organized in a specific arrangement.

T-tubules: A T-tubule (or transverse tubule) is a deep invagination of the sarcolemma, which is the plasma membrane of skeletal muscle and cardiac muscle cells. These invaginations allow depolarization of the membrane to quickly penetrate to the interior of the cell

Sarcoplasmic reticulum: the endoplasmic reticulum of cardiac muscle and skeletal striated muscle that functions especially as a storage and release area for calcium.

Motor end plate: The neuromuscular junction connects the nervous system to the muscular system via synapses between efferent nerve fibers and muscle fibers, also known as muscle cells. As an action potential reaches the end of a motor neuron, voltage-dependent calcium channels open allowing calcium to enter the neuron.

2).

7. Graded potential reaches TP

1. Voltage gated Na+ channels open

2. Na+ rushes in

3. Potential moves toward and above zero to + 30 mV

10. Voltage gated Na+ close

4. Voltage gated K+ channels open

5. K+ rushes out

8. Potential moves toward RP and past to

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.