Circulatory system

Closed Circulatory System

A system where blood circulates through closed vessels, carrying blood from the heart to the tissues and back.

Hydrostatic Pressure Gradient

The pressure gradient that drives blood flow from areas of high pressure to areas of low pressure.

Arteries

Large, thick-walled vessels that carry blood away from the heart under high pressure.

Pulse

Repeated and rhythmic surges of blood flow through arteries.

Blood Pressure Range in Arteries

Typically between 80 – 120 mmHg.

Venous Blood Flow

Blood returning to the heart from tissues under relatively lower pressure.

Valves in Veins

Structures that prevent backflow of blood towards the lower extremities.

Capillaries

Small blood vessels that connect arterial and venous circulation for nutrient and waste exchange.

Endothelium

A single layer of squamous epithelial cells that form the walls of capillaries.

Composition of Blood

Blood consists of plasma, red blood cells, white blood cells, and platelets.

Extracellular Fluid

Fluid outside the cells, including blood plasma and tissue fluid.

Tissue Fluid

Fluid that surrounds cells in tissues, also known as interstitial fluid.

Lymph

Fluid found in lymph vessels, part of the lymphatic system.

Pulmonary Circulation

The movement of deoxygenated blood from the heart to the lungs.

Systemic Circulation

The movement of oxygenated blood from the heart to the rest of the body.

Systole

The phase of the heartbeat when the ventricles contract.

Diastole

The phase of the heartbeat when the ventricles relax.

Sinoatrial Node (SA Node)

The pacemaker of the heart that initiates contraction signals.

Atrioventricular Node (AV Node)

The node that receives signals from the SA node and triggers ventricular contraction.

Bundle of His

The nerve bundle that conducts electrical impulses from the AV node to the ventricles.

Autonomic Control of Heartbeat

Control of heart rate by the autonomic nervous system, including sympathetic and parasympathetic branches.

Noradrenaline

A neurotransmitter that increases heart rate during sympathetic activation.

Acetylcholine

A neurotransmitter that decreases heart rate during parasympathetic activation.

Adrenaline

A hormone that increases heart rate and is released during physical activity.

Cardiac Cycle

The series of events that take place in the heart during a single heartbeat.

Fenestrations

Larger openings in some capillaries that allow for quicker exchange of substances.

Oxygen Transport

Red blood cells (erythrocytes) transport oxygen in the bloodstream.

Carbon Dioxide Transport

Waste product transported back to lungs for exhalation.

Nutrient Exchange in Capillaries

The process of substances like glucose and oxygen entering tissues from blood.

Fluid Balance

Maintaining equilibrium of fluid levels in the body via the lymphatic system.

Fibrillation

Irregular and uncoordinated contraction of heart muscles.

Defibrillation

Controlled electrical current used to restore normal heartbeat.

Tissue Fluid Composition

Similar to plasma but contains fewer proteins and cells.

Respiratory Waste

Carbon dioxide produced from cellular respiration that is transported in blood.

Nutrients

Substances like glucose and amino acids delivered to tissues via blood.

Heat in Blood

Important for thermoregulation and is transported by blood.

Venules

Small vessels that collect blood from capillaries and transport it to veins.

Elastic Fibres

Fibers in arterial walls that stretch and recoil, helping to maintain blood pressure.

Capillary Function

Maximizes exchange of materials due to slow blood flow and low pressure.

Lymphatic System

A subsystem of the circulatory system that maintains fluid balance and assists in immune function.

Erythrocytes

Red blood cells that transport oxygen.

Leukocytes

White blood cells that help fight infections.

Thrombocytes

Platelets involved in blood clotting.

Interstitial Fluid

Fluid surrounding cells in tissues, facilitating nutrient exchange.

Peristalsis

Involuntary contractions that help move lymph fluid through lymphatic vessels.

Subclavian Vein

Vein where lymph fluid drains back into the bloodstream.

Lymph Nodes

Structures that filter unwanted materials like bacteria from lymph fluid.

Skeletal Muscle Contraction

Helps compress veins and promote blood flow against gravity.

Nervous System Influence

The nervous system regulates heart rate via autonomic control.

Heart Chambers

The heart contains two atria and two ventricles.

Pressure Differences

Asymmetry in heart circulation necessary for different pressure requirements in pulmonary and systemic circuits.

Heart Murmur

A sound made by turbulent blood flow in the heart.

Control of Heart Rate

Regulation of heart pace by chemicals and signals from the nervous system.

Circulatory Pathway

The path of blood flow through arteries, capillaries, and veins.

Blood Pressure Regulation

Influenced by volume, elasticity, and contraction of blood vessels.

Cardiac Output

The volume of blood the heart pumps per minute.

Blood Volume Regulation

Maintained by the balance of plasma and tissue fluid levels.

Kidney Filtration

Process that helps maintain blood pressure and fluid balance.

Arterial Resistance

The resistance of arterial walls to blood flow, affecting blood pressure.

Myogenic Heart Contraction

Contraction of the heart initiated by signals within the heart itself.

Oxygen Demand

The need for oxygen in tissues, influencing heart and respiratory rates.

Blood Flow Direction

Blood flows from arteries to capillaries to veins.