Human Circulatory System

Importance of Circulatory System Transports nutrients to cells, wastes away from cells and chemical messengers (e.g. hormones) from cells in one part of the body to distant cells Distributes heat throughout the body Defends against invading organisms that could cause disease.

Structure of Circulatory System Composed of a four chambered heart that pumps ~5 L of blood through 96,000 km of blood vessels that come in contact with every one of the 60 trillion cells in your body

Three Types of Blood Vessels Arteries - Carry blood away from the heart to the rest of the body - Are thick-walled to withstand higher pressure, made of muscle and connective tissue - Able to stretch - Subdivide into small arteries called arterioles

Three Types of Blood Vessels Veins - Return blood from the body tissues to the heart - Are thin-walled (because pressure decreases as distance from the heart increases) - Blood pressure is very low(15-20mmHg) - Contain valves that allow a one-way flow of blood - Muscular contractions assist forward movement of blood - Subdivided into small veins called venules

Three Types of Blood Vessels Capillaries - Connect arterioles to venules - Walls are single cell thick - Exchange of O2/CO2, nutrients and wastes occur between blood and body cells through the capillary walls

ARTERY arteriole capillary venule VEIN

arteries  arterioles  capillaries  venules  veins arteriole venule capillaries

Questions from Text Read p Answer questions, p. 243 #2,3,4,5 Read p Answer questions, p. 253 #1,2,3,4

The Heart Is a double pump separated by a muscular wall called the septum the right side contains oxygen-poor blood and pumps it to the lungs the left side contains oxygen-rich blood and pumps it to the cells of the body

The Heart (con’t) * is divided into 4 chambers: - 2 upper, thin-walled atria (atrium - sing.) - 2 lower, thick-walled ventricles which pump the blood * is covered and protected by a tough membrane called the pericardium

PERICARDIUM

The Double Pump  The right side of your heart pumps oxygen- poor blood to the lungs, dumps off CO2, picks up O2 and returns it to the heart – this is called pulmonary circulation.  The left side of your heart pumps oxygen- rich blood to all your body cells, dumps off O2, picks up CO2 and returns it to the heart – this is called systemic circulation.  Coronary circulation takes oxygenated blood to and deoxygenated blood from the heart

The Path of Blood: Pulmonary Circulation 1. The right atrium collects oxygen-poor blood from the superior and inferior vena cavas 2. From the right atrium, blood flows into the right ventricle where it is pumped into the pulmonary arteries. 3. The pulmonary arteries take the blood to the lungs to dump CO2 and pick up O2. 4. This oxygen-rich blood returns to the heart via the pulmonary veins.

The Path of Blood: Systemic Circulation 1. The left atrium passes oxygen-rich blood to the left ventricle. 2. The left ventricle pumps blood into the aorta which branches into arteries and arterioles that go to all body parts 3. Arterioles connect with capillaries where O2 and nutrients are delivered and CO2 and wastes are picked up

The Path of Blood: Systemic Circulation (con’t) 4. Capillaries run into venules which run into veins, which return blood to the heart. 5. The superior vena cava collects blood from the lower body. 6. This oxygen-poor blood is emptied into the right atrium of the heart.

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Composition of Blood 55% of blood is plasma Red blood cells (erythrocytes) make up most of the rest White blood cells (leucocytes) platelets

Plasma Plasma is mostly water but also contains important proteins: -albumin – prevents water from leaving the blood and entering the cells -fibrinogen – functions in blood clotting -globulins – produces antibodies to fight against invading microbes

RED BLOOD CELLS (RBC) Also called erythrocytes; lac a nucleus Contain hemoglobin, an iron-containing pigment that gives blood its red color and metallic taste Cary O2 and CO2 5,000,000 per drop of blood Live for ~120 days produced in bone marrow Disc shaped

Red Blood Cells

RED BLOOD CELLS (RBC) Lac of RBC causes less efficient O2 exchange in lungs which results in less energy and fatigue Anemia – illness caused by low blood oxygen carrying capacity due to low hemoglobin (iron) causing extreme fatigue

People who live at high altitudes can have as many as 8 million RBC per drop of blood. Why is this advantagous?

White Blood Cell

White Blood Cells (WBC) Aka leucocytes; have a nucleus Protect the body from disease caused by pathogens Some are phagocytic, engulfing and destroying bacteria and viruses 8,000 per drop Able to move out of the blood stream closer to the cells to be destroyed

WBC chases Bacteria UhSQhttp:// UhSQ

Platelets Cell fragments so no nucleus Initiate blood clotting reactions when injury has taken place 250,000 per drop of blood Hemophilia – genetic disease in which the clotting protein cannot be produced and bleeding cannot be stopped

Platelets, WBC,RBC