Human Anatomy and Physiology

Heart

Muscular organ that pumps blood throughout the body.

Atria

The two upper chambers that receive blood returning to the heart.

Ventricles

The two lower chambers that pump blood out of the heart.

Right Atrium

Receives deoxygenated blood from the body through the vena cava.

Left Atrium

Receives oxygenated blood from the lungs through the pulmonary veins.

Right Ventricle

Pumps deoxygenated blood to the lungs through the pulmonary artery.

Left Ventricle

Pumps oxygenated blood to the rest of the body through the aorta.

Valves

Structures that prevent backflow of blood within the heart.

AV Valves

Include the tricuspid and bicuspid (mitral) valves; separate atria from ventricles.

Semilunar Valves

Include the pulmonary and aortic valves; control flow out of the ventricles.

Systole

Contraction phase of the heart; blood is pumped out of the ventricles.

Diastole

Relaxation phase; chambers fill with blood.

SA Node

The heart's natural pacemaker that starts each heartbeat.

AV Node

Slows the signal from the SA node before it moves to the ventricles.

Cardiac Cycle

One full heartbeat including both systole and diastole.

Systemic Circulation

Carries oxygenated blood from the left ventricle to the body and back to the right atrium.

Pulmonary Circulation

Carries deoxygenated blood from the right ventricle to the lungs and back to the left atrium.

Arteries

Carry blood away from the heart; usually oxygen-rich.

Veins

Carry blood toward the heart; usually oxygen-poor.

Capillaries

Tiny blood vessels where gas and nutrient exchange occur.

Blood

Fluid that carries oxygen, nutrients, hormones, and waste.

Plasma

The liquid portion of blood that transports nutrients and waste.

Red Blood Cells

Carry oxygen using hemoglobin.

White Blood Cells

Fight infection and disease.

Platelets

Help blood clot when vessels are damaged.

Cardiac Output (CO)

Amount of blood the heart pumps per minute (CO = HR × SV).

Heart Rate (HR)

Number of beats per minute.

Stroke Volume (SV)

Amount of blood pumped per beat.

Preload

Amount of blood returning to the heart before contraction.

Afterload

Resistance the heart must overcome to pump blood out.

Contractility

How forcefully the heart contracts.

Blood Pressure (BP)

Force of blood pushing against artery walls.

Systolic Pressure

Pressure in arteries during heart contraction.

Diastolic Pressure

Pressure in arteries when the heart is relaxed.

Systemic Vascular Resistance (SVR)

Resistance in blood vessels that affects blood pressure.

Renin-Angiotensin-Aldosterone System (RAAS)

Hormone system that raises blood pressure by retaining sodium and water.

Antidiuretic Hormone (ADH)

Hormone that reduces urine output and helps increase blood volume.

Baroreceptors

Pressure sensors in arteries that help regulate blood pressure.

Respiratory System

System that brings oxygen into the body and removes carbon dioxide.

Nasal Cavity

Warms, moistens, and filters air entering the respiratory system.

Pharynx

Passageway for air from the nose and mouth to the larynx.

Larynx

Voice box that connects the pharynx to the trachea.

Trachea

Windpipe that carries air to the bronchi.

Bronchi

Two main branches that lead into each lung.

Bronchioles

Smaller branches that carry air to the alveoli.

Alveoli

Tiny air sacs in the lungs where gas exchange occurs.

Diaphragm

Muscle that contracts during inhalation to expand the lungs.

Gas Exchange

Movement of oxygen into the blood and carbon dioxide out of the blood by diffusion.

Ventilation

Process of breathing air in and out of the lungs.

External Respiration

Gas exchange between alveoli and capillaries.

Internal Respiration

Gas exchange between blood and body tissues.

Partial Pressure

The pressure of an individual gas that drives its diffusion.

CO₂ Regulation

When CO₂ levels rise, breathing rate increases to remove it.