The Circulatory System

http://www.brightstorm.com/science/biology/the-human-body/circulatory-system/

The Circulatory System

• A System of interconnected, one-way roads– From superhighways to back alleys– Allows the transport of materials from one place

to another• Hormones• Oxygen• Cellular Wastes• Nutrients

– Heart, Blood vessels, and Blood

The Heart

• Consists mainly of cardiac muscle that pumps blood throughout the system

• 4 Chambers– 2 upper Atria– 2 lower ventricles

• Valves keep the blood flow going in only 1 direction http://www.youtube.com/watch

?v=hCp4hVC2fnM

Heartbeat

• Cardiac muscle contracts without stimulation by the nervous system– Specialized cardiac muscle cells send out electrical

impulses that stimulate the contractions– Normally this all happens in perfect

synchronization– http://www.nhlbi.nih.gov/health/health-topics/to

pics/hhw/electrical.html

Blood Vessels

• Arteries – carry blood away from the heart– Thick walls that can withstand the pressure of the

blood being pumped– Generally carry oxygen-rich blood– Largest is the aorta which receives blood directly

from the heart• Veins – carry blood toward the heart– Lower pressure so the veins have valves that prevent

backflow of deoxygenated blood– Larges is the inferior vena cava

Blood Vessels

• Capillaries– Smallest of all the blood vessels– Connect very small arteries and veins– Exchange gases and other substances between

cells and the blood– Very thin-walled

Blood Vessels and Homeostasis

• Can either constrict (narrow) or dilate (get bigger)– These processes are signaled by the autonomic

nervous system or the endocrine system– This process controls the amount of blood flowing

to different organs

Blood Vessels and Blood Pressure

• Highest in the arteries and lowest is the veins– When they take your blood pressure they are

measuring the pressure in the arteries• High blood pressure = Hypertension• Can be controlled with diet, exercise and medication• http://www.healthcentral.com/high-blood-pressure/int

roduction-47-115.html

Pulmonary Circulation

Systemic Circulation

Cardiovascular Disease

• Atherosclerosis– Build up of plaque on

the insides of arteries• Debris, cholesterol, and

other substances

– High fat diet and smoking

– Arteries narrow and blood flow is restricted

http://www.youtube.com/watch?v=fLonh7ZesKs

Coronary Heart Disease

• A heart attack occurs when the blood supply to a part of the heart muscle is blocked or shut off

• Leading cause of death in adults in the US• Risks – smoking, lack of exercise, high-fat diet• Healthy life style choices reduce risk• Video: Heart Attack

Blood

• A fluid connective tissue• Fluid part is called plasma– Contains many dissolved substances and blood

cells• Red blood cells• White blood cells• Platelets

– http://www.apan.net/meetings/busan03/materials/ws/education/demo-los/blood-rlo/whatisblood.swf

Blood

• Red blood cells carry oxygen and contain hemoglobin a protein rich in iron that binds with oxygen

• White blood cells are generally larger than red blood cells, but fewer in number– Part of the body’s defense system

• Platelets – cell fragments involved in blood clotting – release clotting chemicals at the site of a wound

Blood Type

• ABO blood groups• Rhesus blood type• Very important when we look at blood

transfusions

http://en.wikipedia.org/wiki/Blood_type