Theย function of the circulatory systemย is to transport oxygen and nutrients throughout the body. It also carries away waste.ย
The circulatory system moves nutrients absorbed from the intestine to different parts of a bodyโs cells.ย
Parts of the Circulatory System
The main parts of the circulatory system are theย heart, blood and blood vessels
It is an organ system
The heart pumps blood through arteries
Arteries branch into smaller and smaller blood vessels.ย
The smallest blood vessels are calledย capillaries
Inside the capillaries, many substances are exchanged between the blood and surrounding tissues.ย
After this exchange is done, blood flows through the larger blood vessels calledย veinsย which eventually return to the heart.
Heart
The heart beats at a regular rate called yourย heart rate
The frequency of your heart rate can change depending on physical activity, stress, temperature, your general health and other factors
The outer and inner parts of the heart are covered with a smooth layer ofย epithelial tissue
They reduce frictionย
Protects the heart from damage as the lungs constantly expand and contract
The inner surface of the heart is lined with epithelial tissues to help blood flow freely.ย
If the inner lining hardens or roughens, it can lead to many health problems.
The heart is composed of three different types of tissue:ย cardiac muscle tissue, nerve tissue, and connective tissue.
Cardiac muscle tissue
They are a type of muscle that can only be found inside the heart
Every part of the cardiac muscle tissue contract at the same time
This causes the heart to contract and move blood around the body
Blood Flow
Veinsย bringย deoxygenatedย blood to theย rightย atriumย ย of the heartย
Theย right ventricleย of the heart pumps this blood to theย lungsย to receive oxygen
Oxygenatedย blood returns to theย left atriumย ย of the heart as it comes from the lungs
Theย left ventricleย of the heart then pumps thisย oxygenatedย blood toย rest of the bodyย through theย arteries
Blood
Components of the blood: water 92%, dissolved protein 8%, glucose, amino acids, vitamins, minerals (mainly NaCl), urea, CO2, hormones, antibodies
Red Blood Cellsย
Nearly half of the bloodโs volume is made up out of red blood cells
Containsย hemoglobin
Hemoglobin transportsย oxygenย throughout the body
It is the reason why red blood cells appear red
White Blood Cellsย
Makes up less than 1% of the bloodโs volume
White blood cells recognize and destroy bacteria and viruses
In other words, they fight infection
They are the only type of blood cell to contain aย nucleus
Plateletsย
Makes up less than 1% of the bloodโs volume
Responsible for making the blood clot
Plasma
Makes up more than half of the bloodโs volume
It is a yellow protein-rich liquid
They help carry blood cells all throughout the body
Blood Vessels
There are 3 types of blood vessels in the circulatory system:ย arteries, veins, capillaries
Arteriesย
They are very thick vessels whose job is to carry bloodย awayย from the heart.ย
Veinsย
Their job is to carry bloodย towardsย the heart. They are not as thick as arteries.ย
Capillariesย
They connect veins and arteries together
They have very thin walls.ย
Capillaries allow substances to diffuse between the blood, other body fluids and tissues. Oxygen and nutrients diffuse from the blood into surrounding tissues. Carbon dioxide and other types of wastes pass from the body tissues into the blood to be carried away for disposal.ย
All parts of the body are provided with blood through a network of capillaries.
Diseases & Disorders of the Circulatory System
Coronary Artery Disease
coronary arteries are blood vessels which provide blood to the heart muscle tissue
They can become blocked with plaque (made up from fat, cholesterol, calcium, and other substances that typically circulate in the blood).ย
The plaque buildup can be caused byย inherited genetic informationย or caused by anย unhealthy lifestyleย (high-fat diet, smoking,lack of exercise, bad oral hygiene).ย
Symptoms of coronary artery disease include tiredness, dizziness, pain/ burning sensation in the chest or arms.
It can be diagnosed with an angiogram (a type of x-ray)
In an angiogram, a fluorescent dye is injected into the bloodstream.
Heart Attack
Should the coronary arteries be completely blocked by plaque or a blood clot, a heart attack may occur
When this happens, heart muscle cells stop receiving the oxygen and nutrients they need to function, so the heart stops pumping and heart tissues start to die
Symptoms of a heart attack include:
chest pain or pressure
shortness of breath
nausea
anxiety
upper body pain
abdominal or stomach pain
sweating
dizziness
unusual fatigue
Symptoms of a heart attack may differ in men and women
Any suspicion of a heart attack requires immediate medical attention
Heart attacks can be diagnosed with aย blood testย and anย electrocardiogram (ECG)
Blood tests help identify proteins that only appear when cardiac muscle tissues die
Anย electrocardiogram (or ECG)ย measures electrical activity pattern in the heartโs beat cycle
Electrical signals in damaged heart muscles differ from those in healthy heart muscles