Muscle Contraction Process Overview

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What is a distinguishing feature of smooth muscles compared to skeletal muscles?

Presence of troponin

Responds only to excitatory stimulus

Calcium source from extracellular fluid (correct)

Highly developed sarcoplasmic reticulum

Where is actin bound in smooth muscles?

Sarcomeres

Z lines

Dense bodies (correct)

Myosin filaments

How are neurons connected to smooth muscles?

Through neuromuscular junctions

Not directly connected (correct)

Via the bloodstream

Direct physical connection

What type of nerves connect to smooth muscles?

Autonomic nerves Signup and view all the answers

How do contractions of smooth muscles differ from skeletal muscles?

Slow sustained contractions Signup and view all the answers

What neurotransmitters do autonomic nerves release?

Norepinephrine and acetylcholine Signup and view all the answers

Which system is norepinephrine associated with?

Sympathetic Signup and view all the answers

What two processes can smooth muscle, like the uterus, undergo?

Mitosis and hypertrophy Signup and view all the answers

What are the two major types of smooth muscles?

Multi unit or single unit Signup and view all the answers

How do single unit smooth muscles contract?

They contract as a unit due to gap junctions Signup and view all the answers

What is the primary action of alpha 2 receptors in the body?

Vasodilation Signup and view all the answers

Which neurotransmitters do beta 2 receptors primarily respond to?

Epinephrine and norepinephrine Signup and view all the answers

What is the difference between muscarinic and nicotinic receptors in terms of their response mechanism?

Muscarinic are ligand-gated, while nicotinic are second messengers Signup and view all the answers

Where are beta 1 receptors primarily located in the body?

Heart Signup and view all the answers

Which neurotransmitters equally stimulate alpha 1 receptors?

Epinephrine and norepinephrine Signup and view all the answers

What is the mechanism that activates myosin ATPase during smooth muscle contraction?

Binding of Ca to calmodulin Signup and view all the answers

What is the significance of the latch bridge cycle in smooth muscle contraction?

It helps to maintain tension for an extended period. Signup and view all the answers

In adrenal innervation, which neurotransmitter is released from the presynaptic neuron?

Acetylcholine (ACH) Signup and view all the answers

What is the main neurotransmitter released from the adrenal glands in adrenal innervation?

Epinephrine (EP) Signup and view all the answers

Where does sympathetic innervation release Acetylcholine (ACH) instead of Epinephrine (EP) and Norepinephrine (NE)?

Sweat gland innervation Signup and view all the answers