The Circulatory and Respiratory Systems Chapter 37

The Circulatory System Components: Heart, Blood Vessels, Blood Found in multicellular organisms, because diffusion is inadequate. Similar to the transportation system of a large city.

Heart Located near the center of your chest. Almost entirely muscle. Contains all 4 tissue types Size of a clenched fist Weighs ~ 11 oz. Pumps 4,300 gallons/day

HEART STRUCTURE 2 pumps; separated by septum Right Side = pumps O 2 poor; from body to lungs Left Side = pumps O 2 rich; from lungs to body 2 upper (receiving) chambers called “atria” 2 lower (pumping) chambers called “ventricles”

Heart Structure continued Pericardium – protective membrane around the heart Myocardium – Thick layer of muscle that contracts to pump blood through the circulatory system.

HEARTBEAT Sound comes from closing of valves = “lub-dub” Bundle of nerves (pacemaker) in right atria = begins heartbeat Rate regulated by medulla oblongata in the brainstem b.p.m. at rest

BLOOD PATHWAYS Pulmonary circulation – to and from lungs Systemic circulation – to and from body –Renal – to and from kidneys –Coronary – to and from heart –Hepatic – to and from liver

BLOOD VESSELS Arteries – –carry blood away from heart –largest is aorta –muscular –elastic

Blood Vessels… Veins –carry blood to heart –Thin walled –have valves to prevent backflow of blood between heart beats Varicose Veins

CAPILLARIES Capillaries –site of blood/tissue exchange –thin –connect arteries to veins com/anim/blood.html

BLOOD PRESSURE Pressure of blood on arteries Systolic pressure. – pressure of blood when ventricles contract Diastolic pressure – pressure of blood when ventricles are filling Pulse – felt or heard at pressure points (arteries close to skin surface)

Diseases Cardiovascular diseases are one of the leading causes of death and disability in the U.S. 2 Main Types: Hypertension and Atherosclerosis.

Hypertension also called high blood pressure Forces heart to work harder which may weaken heart muscle and walls of blood vessels. Increases the risk of heart attack and stroke.

Atherosclerosis Plaque (cholesteral and calcium) build up in arteries Can restrict oxygen flow to heart (heart attack) Clots resulting from plaque build up can break loose and block blood vessels leading to the brain (stroke).

The white lining of these vessels is plaque

Before angioplasty Blocked coronary artery

After angioplasty

Circulatory System Health How to help prevent cardiovascular disease: –Exercise – strengthens the heart –Balanced diet – low saturated fat and cholesterol –DO NOT SMOKE!!!!!!!!!!!!!

Functions of Blood Collects oxygen from the lungs, nutrients from the digestive tract, and wastes from tissue. Regulates factors within the body.

Helps to fight infection Forms clots to repair damaged blood vessels

BLOOD Liquid connective tissue 4-6 liters in the body (~8% of body mass) Liquid portion - “plasma” –55% of blood –straw colored fluid –contains water, proteins, salts, sugars, enzymes, hormones, etc.

Solid portion - 45%; made of: –red blood cells –contain hemoglobin (iron & protein) –carry O 2 and CO 2 –most numerous blood cell –come from red bone marrow –have no nucleus –remain ~120 days

–White blood cells several types fight infection (parasites and attack bacteria) Not confined to the circulatory system. –Platelets cell fragments Function in blood clotting Platelets

Red Blood Cells Blood Proteins Platelets

BLOOD... Blood Types –determined by antigens (flags) on blood cells and antibodies (soldiers) in plasma –Type A - A antigens; anti-B antibodies –Type B - B antigens; anti-A antibodies Flashback: What blood type is indicated by this diagram?

Lymphatic System A network of vessels, nodes and organs (thymus & spleen). Collects fluid that has been lost from the blood and returns it to the circulatory system

Lymph – fluid lost from the blood Lymph Nodes – swellings along lymph vessels that filter lymph and house white blood cells Edema – swelling due to accumulation and backup of lymph

Any Questions?