Circulatory System Flashcard Set

The Circulatory system

A network of blood vessels that supply cells with nutrients and collect waste materials.

Components of circulatory system

Blood, blood vessels, and the heart.

what is blood

A collection of cells that have been specialized to perform a set of specific tasks; a connective tissue 

Functions of blood

Circulates vital materials, removes waste products, equalizes temperature, and defends against disease.

Red blood cells (erythrocytes)

Cells that transport oxygen and carbon dioxide; contain hemoglobin and have a lifespan of 120 days.

White blood cells (leukocytes)

Colorless cells that defend against disease and have nuclei; involved in phagocytosis.

Plasma

Protein-rich liquid that suspends blood cells and platelets, composed of 90% water.

Platelets (thrombocytes)

Small, irregularly shaped cell fragments responsible for blood clotting.

Blood clotting process

Begins with damage to blood vessels, leading to platelets rushing to the site, forming a temporary clot, and fibrin meshes trapping more platelets.

Blood flow path

Heart → large arteries → smaller arteries → arterioles → capillaries → venules → smaller veins → large veins → heart.

Blood pressure - systolic vs diastolic

Systolic pressure occurs when the heart contracts; diastolic pressure occurs when the heart relaxes.

Hypertension

Consistently high blood pressure causing strain on the heart and blood vessels. caused by poor lifestyle, age, medication

Arteries

Large blood vessels that carry blood away from the heart; have thick muscular walls.

Arterioles

Smallest arteries that branch off from arteries = signals nervous system to regulate diameter of arterioles to control blood flow 

Veins

Blood vessels that carry deoxygenated blood back to the heart; have thin walls and operate under low pressure.

varicose veins - what is it and why does it happen

a condition where veins, particularly those near the surface of the skin in the legs, become enlarged, twisted, and dilated

• often due to increased blood pressure in the veins, leading to weakened or damaged valves that allow blood to flow backward, causing the veins to stretch and twist. 

Capillaries

Smallest blood vessels that supply oxygen and nutrients to cells; made up of a single layer of cells.

Automatic nervous system connection to circulatory system

brain controls diameter of blood vessels (ie. vasodilation and vasoconstriction)

Vasoconstriction

Contraction of blood vessels resulting in reduced diameter and reduced blood flow.

Vasodilation

Relaxation of blood vessels resulting in increased diameter and increased blood flow.

Pulmonary circuit

Carries deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart.

Systemic circuit

Carries oxygenated blood from the heart to the body and deoxygenated blood back to the heart.

Human Heart

Muscular organ about the size of a fist, weighs about 10.5 ounces, and functions as a double pump (right pumps to lungs, left pumps to body).

Atria and ventricles of the heart

Right atrium, right ventricle, left atrium, left ventricle; blood flows from atria to ventricles.

BLOOD FLOW STEPS

1. Deoxygenated blood enters the right atrium via the superior and inferior vena cava 

2. Blood flows to the right ventricle via the tricuspid valve 

3. The right ventricle pumps the blood to the lungs via the pulmonary valve and the left and pulmonary arteries 

4. Oxygen-rich blood returns from the lungs via the pulmonary veins 

5. The blood flows into the left ventricle via the mitral valve 

6. The left ventricle pumps blood up to the aorta via the aortic valve 

function of the atrioventricular valves

prevent blood from entering the atria when the heart beats 

function of aortic valve

prevents blood from moving into the aorta when heart is not beating

function of pulmonary valve

• prevents blood from moving from the pulmonary artery to the right ventricle when the heart is not beating 

Heartbeat sounds

Lubb (atrioventricular valves closing) and Dubb (pulmonary and aortic valves closing).

what is the function for the coronary arteries and veins

provide blood circulation for the heart 

“Pacemaker” of the heart

Sinoatrial node (SA)(located in the right atrium) initiates heartbeats and sets the normal rhythm.

what do the SA signals do?

the signals reach the atrioventricular node (AV) , From AV node special conducting fibres called Purkinje fibres run down septum and throughout heart’s muscles cells

Electrocardiograph (ECG or EKG)

Device that detects the electrical activity of the heart through surface electrodes.

P wave, QRS complex, T wave

P wave = atrial depolarization; QRS complex = ventricular depolarization; T wave = ventricular repolarization.