What is the key difference between an isotonic and an isometric muscle contraction?

In an isotonic contraction the muscle changes length and moves a load; in an isometric contraction the muscle develops tension but does not change length and the load does not move.

Why is calcium (Ca²⁺) essential for skeletal muscle contraction?

Ca²⁺ binds to troponin, which moves tropomyosin away from actin’s binding sites, allowing myosin heads to attach and perform the cross-bridge cycle.

Functionally, what is the main difference between the somatic nervous system and the autonomic nervous system?

The somatic system controls voluntary movements of skeletal muscle; the autonomic system regulates involuntary functions such as cardiac muscle, smooth muscle, and glands.

How does myelin affect the speed of nerve impulse conduction?

Myelin allows saltatory conduction, where impulses “jump” between nodes of Ranvier, greatly increasing conduction speed compared with unmyelinated fibers.

What is the main functional difference between pulmonary and systemic circulation?

Pulmonary circulation carries blood between the heart and lungs to exchange gases; systemic circulation carries blood between the heart and the rest of the body to deliver oxygen and nutrients.

What is the primary distinction between innate (nonspecific) immunity and adaptive (specific) immunity?

Innate immunity provides a rapid, general defense against many pathogens; adaptive immunity is slower to develop but is specific to particular antigens and has memory.

What is the main role of B lymphocytes (B cells) in adaptive immunity?

Activated B cells differentiate into plasma cells that secrete antibodies and memory B cells that provide long-term protection.

What is the main function of bile in the digestive process?

Bile emulsifies fats in the small intestine, breaking large fat globules into smaller droplets to increase surface area for lipase action and improve fat digestion and absorption.

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Week 13: Assignment

Week 13: Assignment - StudyStack Set 2

Question	Answer
What is the primary muscle responsible for abducting the arm at the shoulder joint from 15° to about 90°?	The deltoid muscle.
What is the key difference between an isotonic and an isometric muscle contraction?	In an isotonic contraction the muscle changes length and moves a load; in an isometric contraction the muscle develops tension but does not change length and the load does not move.
Why is calcium (Ca²⁺) essential for skeletal muscle contraction?	Ca²⁺ binds to troponin, which moves tropomyosin away from actin’s binding sites, allowing myosin heads to attach and perform the cross-bridge cycle.
Functionally, what is the main difference between the somatic nervous system and the autonomic nervous system?	The somatic system controls voluntary movements of skeletal muscle; the autonomic system regulates involuntary functions such as cardiac muscle, smooth muscle, and glands.
How does myelin affect the speed of nerve impulse conduction?	Myelin allows saltatory conduction, where impulses “jump” between nodes of Ranvier, greatly increasing conduction speed compared with unmyelinated fibers.
What is the main functional difference between pulmonary and systemic circulation?	Pulmonary circulation carries blood between the heart and lungs to exchange gases; systemic circulation carries blood between the heart and the rest of the body to deliver oxygen and nutrients.
During which phase of the cardiac cycle is blood actively ejected from the ventricles: systole or diastole?	During ventricular systole.
What is the primary distinction between innate (nonspecific) immunity and adaptive (specific) immunity?	Innate immunity provides a rapid, general defense against many pathogens; adaptive immunity is slower to develop but is specific to particular antigens and has memory.
What is the main role of B lymphocytes (B cells) in adaptive immunity?	Activated B cells differentiate into plasma cells that secrete antibodies and memory B cells that provide long-term protection.
What is the main function of bile in the digestive process?	Bile emulsifies fats in the small intestine, breaking large fat globules into smaller droplets to increase surface area for lipase action and improve fat digestion and absorption.

Created by: martin8010

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