What is a motor unit, and how does the size principle help control force?

A motor unit = one motor neuron + all its fibers. Size principle: small, fatigue-resistant units are recruited first; larger, stronger units join as force demands increase → smooth, graded contractions.

A synapse is the gap between two nerve cells where messages pass through using chemical messengers called neurotransmitters

What is the anatomical position and why is it important?

It’s the standard body position—standing upright, facing forward, arms at sides, palms out. It’s used as a reference point so everyone describes body parts the same way.

What is smooth muscle?

Smooth muscles are involuntary and found in organs like the stomach and blood vessels. They move automatically to help with digestion and blood flow.

What are enzymes and why are they important?

Enzymes are proteins that speed up reactions so the body can function fast enough to survive—like digesting food or repairing tissue.

Define osmosis and explain hypotonic vs isotonic vs hypertonic solutions.

Osmosis is water movement across a semipermeable membrane toward higher solute. Hypotonic ECF → cells swell; isotonic → no net water shift; hypertonic → cells shrink.

What is Cell Membrane Structure?

Phospholipid bilayer with embedded proteins. Hydrophobic core limits ion movement; channels/carriers provide selective pathways; cholesterol modulates fluidity; glycocalyx aids recognition.

What are the phases of an action potential?

Threshold reached → depolarization (voltage-gated Na⁺ open) → repolarization (Na⁺ inactivate, K⁺ open) → after-hyperpolarization (K⁺ efflux). Absolute/relative refractory periods ensure one-way propagation and rate limits.

What structures define the sarcomere, and what shortens during contraction?

A band (myosin length) stays constant; I band and H zone narrow as actin slides over myosin (sliding filament theory).

: A tissue is a group of similar cells working together for a specific job, such as muscle tissue for movement or nervous tissue for communication.

How do negative and positive feedback differ?

Negative feedback reverses a change to restore set point (sweating lowers body temp). Positive feedback amplifies a change to drive a rapid outcome (oxytocin intensifies uterine contractions during labor).

What do mitochondria do?

They produce ATP through cellular respiration and act as the “powerhouse” of the cell.

What is cardiac muscle?

An involuntary muscle found only in the heart that contracts rhythmically to pump blood.

What does metabolism mean?

It’s the sum of all chemical reactions in the body, including building (anabolism) and breaking down (catabolism)

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Toni-Ann Brown

Study Stack 1 Physiology WEEKS 1-6

Questions/Terms	Answers/Definition
What is a motor unit, and how does the size principle help control force?	A motor unit = one motor neuron + all its fibers. Size principle: small, fatigue-resistant units are recruited first; larger, stronger units join as force demands increase → smooth, graded contractions.
Synapse	A synapse is the gap between two nerve cells where messages pass through using chemical messengers called neurotransmitters
What is the anatomical position and why is it important?	It’s the standard body position—standing upright, facing forward, arms at sides, palms out. It’s used as a reference point so everyone describes body parts the same way.
What is smooth muscle?	Smooth muscles are involuntary and found in organs like the stomach and blood vessels. They move automatically to help with digestion and blood flow.
What are enzymes and why are they important?	Enzymes are proteins that speed up reactions so the body can function fast enough to survive—like digesting food or repairing tissue.
Define osmosis and explain hypotonic vs isotonic vs hypertonic solutions.	Osmosis is water movement across a semipermeable membrane toward higher solute. Hypotonic ECF → cells swell; isotonic → no net water shift; hypertonic → cells shrink.
What is Cell Membrane Structure?	Phospholipid bilayer with embedded proteins. Hydrophobic core limits ion movement; channels/carriers provide selective pathways; cholesterol modulates fluidity; glycocalyx aids recognition.
What are the phases of an action potential?	Threshold reached → depolarization (voltage-gated Na⁺ open) → repolarization (Na⁺ inactivate, K⁺ open) → after-hyperpolarization (K⁺ efflux). Absolute/relative refractory periods ensure one-way propagation and rate limits.
What structures define the sarcomere, and what shortens during contraction?	A band (myosin length) stays constant; I band and H zone narrow as actin slides over myosin (sliding filament theory).
What is a tissue?	: A tissue is a group of similar cells working together for a specific job, such as muscle tissue for movement or nervous tissue for communication.
How do negative and positive feedback differ?	Negative feedback reverses a change to restore set point (sweating lowers body temp). Positive feedback amplifies a change to drive a rapid outcome (oxytocin intensifies uterine contractions during labor).
What do mitochondria do?	They produce ATP through cellular respiration and act as the “powerhouse” of the cell.
What is cardiac muscle?	An involuntary muscle found only in the heart that contracts rhythmically to pump blood.
What does metabolism mean?	It’s the sum of all chemical reactions in the body, including building (anabolism) and breaking down (catabolism)

Created by: Osharule

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