4.1 Neuromuscular Function

Question 1

Outline the purpose of the nervous system

Answer 1

• Purpose: To regulate the body’s internal environment as well as respond to the external environment. - Controls voluntary movement of skeletal muscle, involuntary regulation of cardiac and smooth muscle and glands.

Question 2

The nervous system consists of:

Answer 2

-The Central Nervous System (CNS) (Brain and Spinal Cord) - The Peripheral Nervous System (PNS) (Nerves extending from the spinal cord to the body.)

Question 3

Explain the nervous system pathway

Answer 3

Sensory receptors detect changes inside or outside the body and send signals via sensory neurons to the central nervous system (CNS) where this information is processed. If a response is required, the CNS sends an electrical signal via motor neurons to the effector (muscle and glands).

Question 4

Name the 3 types of neurons

Answer 4

1. Sensory (afferent) 2. Motor (efferent) 3. Interneurons/Relay Neurons.

Question 5

Name the 3 skeletal muscle fiber types

Answer 5

Type 1: Slow Oxidative: Maintain posture (anti-gravity muscles), endurance running. Back and neck muscles. Type 2a Fast Oxidative: Middle distance running. Leg muscles. Type 2b Fast Glycolytic: Rapid, intense movements of short duration. Ball throwing, weight lifting. Arm muscles.

Question 6

What are the 3 types of skeletal muscle fibers based on?

Answer 6

1. How fast a muscle will twitch. 2. Pathway used to generate ATP/Energy (anaerobic (glycolytic) or aerobic (oxidative).

Question 7

Explain the role of acetylcholine and cholinesterase in stimulating tricep muscle contraction.

Answer 7

Acetylcholine

Changes electrical signals from the neuron to a chemical stimulus to cross the synapse.

Spreads the impulse over the entire muscle fiber.

Allows the muscle to contract.

Cholinesterase

Breaks down Acetylcholine within 5 milliseconds.

Repolarizes the membrane.

It allows the muscle to relax.

Question 8

Explain how an action potential travels from the brain or spinal cord, until the point of the synaptic cleft.

Answer 8

The brain or spinal cord sends an impulse to the muscle.

The impulse travels down the motor neuron and reaches a neuromuscular junction where it releases acetylcholine, to transfer the electrical signal to a chemical signal. This allows the action potential to cross the synaptic cleft.

Question 9

Explain the sliding filament theory after acetylcholine (ACh) increases muscle membrane permeability.

Answer 9

The sarcoplasmic reticulum (SR) surrounding the T tubules release calcium ions (Ca2+) into the sarcoplasm

The Ca2+ binds to troponin located on the actin filament, causing tropomyosin to move and expose binding sites for myosi

The myosin head now binds to actin and forms a cross-bridge.

ADP and Pi are released from myosin, which causes the myosin to move. This movement is called the power stroke.

ATP binds to myosin causing it to release the actin and reverting ATP into ADP and Pi.

Question 10

Label the Structure of a Neuron

Only need to know

(Dendrites, Axon Terminal, Myelin Sheath, Axon, Nucleus, Cell body, Action Potential/Impulse

Answer 10