Circulatory System (closed system)

Circulatory System Circulatory System: The body system consisting of the heart, blood vessels, and the blood that is responsible for the transportation of material around the body and plays a major role in the regulation of body temperatures. Appears to be connected to all other systems. All cells in the body are within 2 cells of a blood cell.

Four Main Functions 1.Transportation of oxygen and carbon dioxide. 1.Distribution of nutrients and transportation of wastes. 1.Maintenance of body temperature. 1.Circulation of hormones.

Made up of 2 Systems: 1.Pulmonary Circuit: the system of blood vessels that carries deoxygenated blood to the lungs and oxygenated blood back to the heart. 1.Systemic Circuit: the system of blood vessels that carries oxygenated blood to the tissues of the body and deoxygenated blood back to the heart.

Blood Your body contains about 4 to 6 L of blood. Your blood has several functions that are essential to good health. – transports oxygen, water, nutrients, and other chemicals to your cells – removes waste products from the tissues – helps to regulate body temperature, fight infection, and heal wounds.

Components of Blood – Plasma – Red blood cells – White blood cells – Platelets

 Plasma: 90 % water remaining 10 % is made of proteins, dissolved nutrients, and wastes

 Red Blood Cells 45 % of blood volume consists mostly of red blood cells. Red blood cells carry oxygen from the lungs to all the tissues of the body. Each RBC contains about 250 million molecules of hemoglobin – Protein that binds oxygen in the lungs and releases it throughout the body. RBC transport carbon dioxide to the lungs. produced in bone marrow at the rate of two million per second in a healthy adult.

Shape: flat disk that curves inward in the middle on both the top and bottom. Mature RBC have no nucleus – it cannot grow, or divide. The typical lifespan of a red blood cell is between 100 and 120 days.

 White Blood Cells guard against infection, fight parasites, and attack bacteria. do not have to stay within the blood vessels. when infection invades your body, the number of white blood cells dramatically increases. – For example, if you get a cut, white blood cells gather at the cut to fight bacteria.

Pus is a combination of white blood cells and dead bacteria. white blood cells are produced in the bone marrow. white blood cells keep their nuclei and can live for years.

 Platelets The clotting process depends on plasma proteins and cell fragments called platelets. Each cubic millimetre of blood contains between and platelets.

Clotting begins when platelets stick to the site where the blood vessel is damaged. They break apart and release clotting factors. – The clotting factors make other nearby platelets sticky and activate a series of reactions – These reactions result in the formation of a strand-like protein called fibrin. Fibrin threads trap red blood cells and platelets. forming a patch that stretches over the torn tissue. This patch dries into a scab

Electron Micrograph of Blood

Blood Vessels 3 types of blood vessels: Arteries Capillaries veins

Arteries  Arteries are large blood vessels that carry blood from the heart to the tissues. The blood in arteries is under pressure. This pressure helps to ensure that blood flows only in one direction The arteries branch into smaller and smaller vessel called arterioles which flow into capillaries.

Veins The muscle layer in veins is thinner than that in arteries because the blood in veins is under very little pressure A series of valves allows blood to only move in one direction (towards the heart or UP) Small veins called venuoles merge together into larger veins.

Capillaries  Capillaries are microscopic blood vessels with a high surface area. The nutrients and oxygen pass out of the blood, and waste products pass into the blood here

Blood Vessels Blood vessels that carry the blood from the heart to the cells of the body and back: heart  aorta (largest artery)  other Arteries  arterioles  capillaries  venuoles  veins  vena cave (largest veins)  heart Where would blood pressure be the highest? Lowest?

Colour Vein colour is determined in large part by the color of venous blood, which is usually dark red (and not blue as is commonly believed) as a result of its low oxygen content. Veins appear blue because the subcutaneous fat absorbs low-frequency light, permitting only the highly energetic blue wavelengths to penetrate through to the dark vein and reflect back to the viewer. A recent study found the colour of blood vessels is determined by the following factors: the scattering and absorption characteristics of skin at different wavelengths, the oxygenation state of blood, which affects its absorption properties, the diameter and the depth of the vessels, and the visual perception process.venous bloodsubcutaneous fat