Cardiovascular System Overview

Study Notes

Arteries carry oxygenated blood away from the heart.
Veins carry deoxygenated blood back to the heart.
Capillaries are tiny blood vessels that facilitate gas exchange between blood and tissues.

Blood pressure is the force exerted by blood against the walls of blood vessels.
It is measured using a sphygmomanometer and expressed as systolic (highest) and diastolic (lowest) pressure.

Stroke volume (SV) is the amount of blood pumped by the heart with each beat.

Inspiration occurs when the diaphragm contracts and the intercostal muscles pull the rib cage downwards, expanding the chest cavity.
Expiration happens when the diaphragm relaxes and the intercostal muscles decrease the chest cavity volume, forcing air out.

Diffusion is the movement of molecules from a high concentration to a low concentration.
Pulmonary diffusion is the exchange of oxygen and carbon dioxide between the alveoli and capillaries.
Ventilation (V) is the amount of air breathed in and out per minute.
Tidal Volume (TV) is the volume of air breathed in and out with each breath.
Respiratory rate (RR) is the number of breaths per minute.
Total Lung Capacity is the maximum volume of air the lungs can hold.

Arteries: Carry oxygenated blood away from the heart, have thick, elastic walls to withstand high pressure.
Capillaries: Tiny blood vessels that connect arterioles and venules, facilitate gas exchange between blood and tissues.
Veins: Carry deoxygenated blood back to the heart, have thinner walls than arteries due to lower pressure.
Blood pressure: The force of blood against the walls of blood vessels. Measured using a sphygmomanometer, expressed as systolic (highest) over diastolic (lowest) pressure.
Cardiac Output (Q): The volume of blood pumped by the heart per minute. Calculated as Heart Rate (HR) multiplied by Stroke Volume (SV).
Stroke Volume (SV): The volume of blood pumped by the heart per beat.
Heart Rate (HR): The number of heartbeats per minute.

Acute responses: Increased heart rate, increased cardiac output, vasodilation (widening of blood vessels), increased stroke volume.
Chronic responses: Increased stroke volume, decreased resting heart rate, increased cardiac output at maximal exercise, increased arteriovenous oxygen difference (a-V02).

Inspiration: Diaphragm contracts and moves downward, intercostal muscles contract, expanding the chest cavity and decreasing pressure, allowing air to enter the lungs.
Expiration: Diaphragm relaxes and moves upward, intercostal muscles relax, decreasing the chest cavity volume, increasing pressure and forcing air out of the lungs.
Diaphragm: The primary muscle responsible for breathing, contracts to expand the chest cavity during inspiration and relaxes to reduce the chest cavity volume during expiration.
Pulmonary Diffusion: Gas exchange in the lungs. Oxygen from inhaled air diffuses across the thin walls of the alveoli into the capillaries, where it binds to red blood cells and is transported to muscles. Carbon dioxide from the blood diffuses into the alveoli and is exhaled.
Ventilation (V): The volume of air breathed in and out per minute, calculated as respiratory rate (RR) multiplied by tidal volume (TV).
Tidal Volume (TV): The volume of air breathed in and out during a single breath.
Respiratory Rate (RR): The number of breaths taken per minute.
Total Lung Capacity: The total amount of air that can be held in the lungs after a full inspiration.