Human Physiology Notes

What is Physiology?

The study of the normal functioning of a living organism and its component parts.

What are the key concepts/themes in Physiology?

Structure & function, Biological energy, Informational flow, Homeostasis.

Name the levels of organization in living organisms.

Chemical, Cellular, Tissue, Organ, Organ system, Organism.

What are the four primary tissue types in the human body?

Epithelial, connective, muscle, and neural.

What is homeostasis?

The maintenance of a relatively stable internal environment.

What are graded potentials?

Localized changes in membrane potential that can be depolarizations or hyperpolarizations.

Define action potentials.

All-or-nothing electrical signals that travel along axons without decreasing in strength.

What is muscle contraction?

The process by which muscle fibers shorten and generate force.

Describe the sliding filament theory of muscle contraction.

Muscle contraction occurs as thick and thin filaments slide past each other, causing the sarcomere to shorten.

What is the role of Ca2+ in muscle contraction?

Ca2+ binds to troponin, causing tropomyosin to move and exposing binding sites on actin for myosin interaction.

What is a motor unit?

A motor neuron and all the muscle fibers it innervates.

Differentiate between isotonic and isometric contractions.

Isotonic contractions result in movement, while isometric contractions create force without changing muscle length.

What is the neuromuscular junction?

The synapse between a motor neuron and a skeletal muscle fiber.

What neurotransmitter is released at the neuromuscular junction?

Acetylcholine (ACh).

What are the three types of muscle?

Skeletal, smooth, and cardiac muscle.

What do adrenergic receptors respond to?

Norepinephrine and epinephrine.

What is the function of gap junctions in tissues?

To facilitate direct cell-to-cell communication.

How is action potential conduction affected by axon diameter and myelination?

Larger diameter and myelination increase conduction speed.

What does the ECG measure?

The electrical activity of the heart during the cardiac cycle.

What are the phases of the cardiac cycle?

Systole (contraction) and diastole (relaxation).

What causes the 'lub' sound in the heart?

Closure of the AV valves.

What are the main functions of the cardiovascular system?

Transporting nutrients, gases, hormones, and wastes throughout the body.

What is the result of vasodilation?

Widening of blood vessels, leading to decreased blood pressure.

What is the role of the pacemaker cells in the heart?

They initiate and regulate the heartbeat.

What is the effect of sympathetic stimulation on heart rate?

It increases heart rate.

What factors influence stroke volume?

Sympathetic stimulation, end-diastolic volume, and contractility.

What is the significance of the refractory period in cardiac muscle?

It prevents tetanus and ensures the heart has time to relax between beats.

What initiates muscle action?

The contraction process is initiated by a signal from the motor neuron at the neuromuscular junction.

What is the role of ATP in muscle contraction?

ATP provides the energy needed for muscle fibers to contract and relax.

Define hypertrophy in muscle physiology.

Hypertrophy is the increase in muscle cell size due to strength training.

What changes occur in the heart during exercise?

Heart rate increases, stroke volume increases, and cardiac output increases.

What is the role of the coronary arteries?

To supply blood to the heart muscle itself.

What effect does aging have on the cardiovascular system?

Aging can lead to stiffening of blood vessels and decreased cardiac efficiency.

How does regular exercise benefit the cardiovascular system?

Regular exercise improves heart efficiency, lowers blood pressure, and enhances circulation.

What is diastolic blood pressure?

The pressure in the arteries when the heart is at rest between beats.

What is the primary role of platelets in the cardiovascular system?

To aid in blood clotting and repair damaged blood vessels.

Explain the significance of stroke volume.

Stroke volume is the amount of blood ejected by the heart with each beat, influencing cardiac output.