The Circulatory System

continued

Practice• Now you have the opportunity to follow the path that a

red blood cell takes when it returns to the heart either from the superior vena cava or the interior vena cava.

• Copy and complete the flowchart in your notes to accurately represent the flow of blood within the heart.

• The arrows are coloured blue or red to represent the colour of blood as it moves throughout the heart.

Pulmonary Valve Mitral Valve Left Atrium

Left Ventricle Right Atrium Right Ventricle

Tricuspid Valve Aortic Valve Aorta

Left or Right Pulmonary Vein Left or Right Pulmonary Artery

Place the structures and arrows in the correct location to complete the flowchart.

• The heart is also composed of specialized tissue called the endocardium which lines the inside chambers of the heart.

• It provides a smooth surface so blood can flow without experiencing too much resistance.

• Myocardium is the muscle tissue of the heart that contracts. • It also protects the heart tissue.

Answer

Blood Vessels

• The aorta is the largest blood vessel in the body and it branches out into smaller and smaller blood vessels so that all the cells in the body can receive the nutrients from blood.

• Not all blood vessels are the same. There are three different types of vessels that carry blood throughout the body.

Arteries• All arteries carry blood away

from the heart. They have very strong walls that are formed from three layers of tissue.

• The arteries require strong walls to withstand high blood pressure caused from the contraction of the left ventricle.

• Arteries further break down into smaller vessels called arterioles.

Capillaries• Capillaries are the smallest blood vessel. They are

only one cell thick. All the exchange of materials is performed at this level. Materials such as oxygen and nutrients diffuse from the blood and into the cells. Waste materials diffuse from the cell into the capillaries. Capillaries connect arterioles to venules.

Veins• Veins are larger than capillaries

and they carry materials to the heart. Veins have thin walls that contain valves.

• Since there is no pump that forces the blood back to the heart, the contraction of muscles helps to move blood back to the heart.

• The presence of valves helps to prevent the back flow of blood.

• The largest veins are the inferior and superior vena cava.

• The smallest veins are called venules.

Blood Pressure• When ventricles contract during the cardiac

cycle, the force of the blood leaving the heart puts pressure on the blood vessels.

• This systolic pressure is necessary to push blood through the arteries.

• When the ventricles relax, the pressure on the arteries drops, this is called diastolic pressure.

• A sphygmomanometer (yeah, I can’t pronounce it either) is used to measure blood pressure.

• The normal average blood pressure reading is 120/80.

• The systolic pressure is always recorded first.

• Blood pressure can be affected by exercise, age and mass.

S-fig-mo-man-ometer

• High blood pressure is dangerous because the pressure the blood places on the vessels may cause them to burst.

• High blood pressure may result from the narrowing of the artery.

• Blood flow through the arteries may be restricted by a build up of plaque on the arterial walls.

• High blood pressure can generally be reduced by making lifestyle changes such as exercise and healthy diet.

• http://library.med.utah.edu/kw/pharm/hyper_heart1.html

• A look at blood pressure, ECG readings and heart sounds

• http://www.sumanasinc.com/webcontent/animations/content/bloodpressure.html

• Measuring blood pressure

Blood• Blood contains many vital components needed for

human survival. In addition to transporting oxygen, nutrients and wastes, blood also contains antibodies that are used to attack and destroy viruses and bacteria. Lastly, blood helps to maintain fluid levels and equilibrium throughout the cells.

• Blood is made up of a liquid phase and a solid phase. The liquid phase contains water, proteins, sugars, vitamins, minerals and waste products. The liquid phase called plasma makes up 55% of the total blood volume.

• The solid phase is made up of red blood cells, white blood cells and platelets.

• Red blood cells are manufactured in the bone marrow and are stored in the spleen. They do not have a nucleus or mitochondria.

• Recall that hemoglobin is the part of the red blood cell that is responsible for oxygen transport.

• People with the genetically inherited disease sickle cell anemia have irregularly shaped red blood cells.

• The sickle shaped red blood cells cannot pass through the tiny vessels and therefore deprive cells of oxygen.

• White blood cells help to destroy foreign particles such as bacteria and viruses. They are manufactured in the bone marrow and have a nucleus. An elevated white blood cell count is a good indication of an infection. Leukemia is a cancer of the bone marrow that results in an overproduction of white blood cells that do not function properly.

• Platelets lack a nucleus and are involved in forming clots when a blood vessel breaks. Recall that hemophiliacs do not produce a sufficient amount of platelets to clot blood properly.

• In the genetics unit, you learned about the four different blood groups; A, B, AB and O. Blood typing has been used as a means to identify people for many years.

• Forensic scientists also use the information contained within blood as evidence to identify criminals and victims.

• Remember that DNA is found within the nucleus of cells and that DNA is unique to each person.

• Only identical twins, triplets, or quadruplets will have the exact same DNA. So a drop of blood found at a crime scene contains enough evidence to identify a probable suspect.

Task• The circulatory systems of animals show great variation. Some animals

have a closed system while others have an open circulatory system. Research and describe the circulatory systems of the following animals. You may include illustrations to support your work. – Grasshopper– Earthworm– Fish

• Explain how the following terms are used to describe the circulatory system of animals.– complete and incomplete circulation– single and double circulation

• What would happen if red blood cells contained mitochondria?• Create a table to compare and contrast red blood cells, white blood cells

and platelets in terms of their function, production and genetic material.