Transport in Animals and the Human Circulatory System

Comprehensive practice flashcards covering animal transport systems, cardiac anatomy, blood flow, cardiac cycle timings, and the functions of major blood vessels based on the lecture notes.

Open circulatory system

A system where blood from the heart is pumped at low pressure into a main body cavity called the haemocoel, bathing internal organs directly.

Haemocoel

The main body cavity in an open circulatory system where blood bathes all internal organs directly.

Closed circulatory system

A system where blood remains enclosed in a continuous network of blood vessels and uses a separate fluid, tissue fluid, between vessels and cells.

Cardiovascular system

Another name for the closed circulatory system in humans, derived from "cardio" meaning heart and "vascular" meaning blood vessels.

Double circulatory system

An arrangement where blood flows through two distinct circulations: the pulmonary circulation (to the lungs) and the systemic circulation (to the rest of the body).

Pulmonary circulation

The part of the circulatory system that carries deoxygenated blood from the right side of the heart to the lungs and returns oxygenated blood to the left side.

Systemic circulation

The major part of the circulatory system that carries oxygenated blood from the left heart to all body cells and returns deoxygenated blood to the right side.

Myocardial infarction

Also known as a heart attack or coronary thrombosis; it is the death of heart muscle caused by the blockage of coronary arteries starving the muscle of nutrients and oxygen.

Pericardium

A structure made of two inelastic membranes surrounding the heart, containing secreted fluid to prevent friction as the heart beats.

Mediastinum

The hollow space in the middle of the chest or thorax between the lungs where the heart is situated.

Septum

The wall that divides the heart into right and left sides, preventing the mixing of deoxygenated and oxygenated blood.

Myocardium

The layer of the heart wall made of special cardiac muscle tissue that can contract rhythmically without getting tired.

Myogenic

A term describing muscle contractions, such as those of the heart, that arise from within the muscle tissue itself rather than relying on external nerve impulses.

Atria

The two small, thin-walled upper chambers of the heart that act as receiving chambers for blood from the veins.

Ventricles

The two lower chambers of the heart with thick walls that contract to push blood out to the lungs or the rest of the body.

Tricuspid valve

The atrioventricular valve located between the right atrium and right ventricle, consisting of three flaps.

Mitral valve

Also known as the bicuspid valve, it is the atrioventricular valve between the left atrium and left ventricle, consisting of two flaps.

Tendinous cords

Cords extending from papillary muscles to atrioventricular valves that anchor the flaps and prevent them from being pushed inside out under pressure.

Semilunar valves

Three half-moon-shaped pockets located at the base of the pulmonary artery and the aorta that prevent the back-flow of blood into the ventricles.

Stroke volume

The volume of blood pumped out by each ventricle per beat, which is approximately $70\,ml/beat$.

Systole

The phase of the cardiac cycle when the cardiac muscle contracts and pressure within the heart increases to force blood out.

Diastole

The phase of the cardiac cycle when the cardiac muscle relaxes and pressure decreases, allowing blood to flow into the chambers.

Sino-atrial (SA) node

The heart's natural pacemaker located in the right atrium that generates electrical impulses to cause the atria to contract.

Purkinje fibres

A fan-like network of fibers in the ventricle walls that, when stimulated, cause the ventricles to contract in a wave from the bottom upwards.

Endothelium

The smooth membrane of endothelial tissue that lines the heart and blood vessels.

Pulse

The regular expansion and contraction of an artery caused by the heart pumping blood through the aorta.

Thrombosis

A blood clot that may form in a vein, particularly in the legs, if blood movement is restricted for a long period.

Pulmonary embolism

A potentially fatal condition where a blood clot (thrombosis) travels to the lungs and gets stuck in the lung arterioles.

Systolic pressure

The maximum pressure reached in the aorta when the ventricles contract, averaging $120\,mm\,Hg$ in a healthy adult.

Diastolic pressure

The lower pressure in the aorta when the ventricles relax, averaging $80\,mm\,Hg$ in a healthy adult.

Hepatic portal vein

The blood vessel that carries blood rich in absorbed nutrients from the small intestine and stomach to the liver.