Circulatory System

Circulatory System

• The purpose of the circulatory system is to transport blood, hormones, nutrients, and waste throughout the body.
• It consists of the heart, arteries, veins, capillaries, and the blood.
• It carries nutrients to �the cells and waste �away from the cells

Circulatory System

• Closed circulatory system
• Partitioned heart that works as two side-by-side pumps
• Supports the high levels of activity

Circulatory System

• The heart is a four-chambered, hollow muscle used to pump blood
• It is divided into four compartments: the left & right ventricles & the left & right atria
• Ventricles pump blood into arteries
• Atrium is the chamber of the heart that receives blood
• Right side of the heart pumps deoxygenated blood (blood low in oxygen) to the lungs
• Left side of the heart pumps oxygenated blood (blood rich in oxygen) all over the body

Blood Vessels

• 3 kinds of blood vessels: arteries, capillaries, & veins
• Arteries carry blood away from the heart.
• Thick walls
• Expand to accommodate any sudden increase in blood volume that results after heart contractions.
• Deep under the skin & have no valves.
• Divide further into arterioles, which are small arteries

Blood Vessels

• Capillaries are microscopic blood vessels with a wall formed of one layer of simple squamous cells.
• Exchange with tissue fluid takes place in capillaries
• So narrow that red blood cells must pass through in single file
• Gas, nutrient, and waste exchange occur across thin walls
• Venules are vessels that take blood from capillaries & join to form a vein

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Blood Vessels

• Veins transport blood toward the heart
• Wall of a vein is much thinner than arteries - there is no blood pressure
• One-way valves open in the direction of the heart & close to prevent back-flow.

BLOOD

What is blood?

• Blood is the liquid in the circulatory system of an animal organism.
• Organisms cannot live without blood.
• All animals have blood, but its varies from one species to another.
• The amount of blood in an animal varies with the species & size of the animal.

What is blood?

• An average adult human weighing 160 pounds has about 5 quarts of blood
• Animals that live at high altitudes have more blood than those at lower altitudes because air at higher altitudes has less oxygen. More blood is needed to meet the demands of the body for oxygen

4 Major Components of Blood

• Blood consists of four major components
• Plasma is the liquid substance in which various solid materials are suspended & moved about.
• Plasma is 90 percent water
• The other 10 percent consists of dissolved substances including glucose, hormones, wastes, minerals, vitamins, & proteins

4 Major Components of Blood?

• The plasma suspends & transports the solid blood materials
• Plasma composes 50 to 60 percent of blood by volume
• Plasma has a straw color when the solid materials are removed

4 Major components of blood?

• Red blood cells are responsible for carrying oxygen from the lungs throughout the circulatory system
• oxygen is carried by a protein part known as hemoglobin
• Red blood cells have a flexible membrane that allows them to squeeze through the very smallest blood vessel
• Red blood cells do not repair themselves
• New red blood cells are made in bone marrow
• The dead red blood cells are removed by the spleen & liver.

4 Major components of blood?

• White blood cells are responsible for fighting disease & removing harmful substances from the body
• An antibody is a kind of protein that destroys bacteria, viruses, & other substances that invade the body.

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4 Major components of blood?

• Platelets are the structures in blood that are responsible for clotting.
• They are not complete cells and have a disk-like shape.
• In case of a wound, platelets stick to the edge of the skin & to each other to form a scab or cover that stops the flow of blood.
• Without platelets, an animal might bleed to death from a wound

Blood’s Functions

• 1. Transport oxygen and carbon dioxide: Blood carries oxygen to all areas of the body and acquires carbon dioxide from the respiration process in the cells.
• Blood that is being sent out passes by the lungs to give off carbon dioxide & acquire oxygen.

Blood’s Functions

• 2. Protects against disease:
• The white blood cells in blood help keep an organism healthy & fight disease.
• 3. Transport hormones: Blood carries substances known as hormones.
• A hormone is a compound that produces a response within the body of an organism.
• Hormones are produced by endocrine glands & are secreted into the blood.

Blood’s Functions

• 4. Transport nutrients & wastes: Blood carries nutrients from digested food.
• Blood that flows in the walls of the small intestine acquires nutrients as food molecules.
• As cells use the nutrients or as cells grow and die, wastes are created.
• These wastes are transported by the blood to the liver for removal & excretion.

Blood’s Functions

• 5. Heat regulation: Blood helps regulate the temperature in an organism.
• Activity by muscles in the body produces heat.
• The heat is picked up by the blood & distributed throughout the body.