Honor’s BiologyTopic:Circulation

What are the issues Animal cells exchange material across the cell membrane

nutrients fuels for energy oxygen waste (urea, CO2)

If you are a 1-cell organism that’s easy! If you are many-celled that’s harder

What are the issues? Diffusion is not adequate for moving material across more than 1 cell barrier

Simple diffusion Body cavity 2-cell layers think

all cells within easy reach of fluid use gastrovascular cavity for exchange

What are the solutions? Circulatory system solves this problem

carries fluids & dissolved material throughout body cells are never far from body fluid only a few cells away from blood

In circulation…– What needs to be transported

Nutritive nutrients fuels from digestive system

Respiratory O2 & CO2 from & to gas exchange systems: lungs, gills

Excretory waste products from cells water, salts, nitrogenous wastes (urea)

Protection blood clotting immune defenses white blood cells & others patrolling body

Regulation hormones

Circulatory systems All animals have:

circulatory fluid = blood tubes = blood vessels muscular pump = heart

Open circulatory system Taxonomy

Invertebrates (insects, arthropods, mollusks)• Structure

no distinction between blood & extracellular (interstitial) fluid hemolymph

Closed circulatory system Taxonomy

Invertebrates (earthworms, squid, octopuses) Vertebrates

Structure blood confined to vessels & separate from interstitial fluid 1 or more hearts

large vessels to smaller vessels material diffuses between vessels & interstitial fluid

Cardiovascular SystemComponents:

1. Heart (Pumping device)2. Blood (Fluid connective tissue)3. System of blood vessels:

Veins and venules Capillaries

1. HeartAnatomical Features:

• .• Weighs less than one pound (10 ounces).• Located just above the diaphragm.• Wall is composed of cardiac muscle covered by connective tissue.

Pericardium: Membrane that surrounds entire heart and protects heart.

Heart Chambers : divided into four separate chambers. • Right & Left Atrium :.• Right & Left Ventricle : Larger chambers. Pump blood into arteries.

Two sides of heart have different functions:• Right side :.• Left side : Pumps oxygen rich blood.

Structure of the Human Heart

Heart Valves : prevent backflow of blood as it circulates. Right & Left AV Valve: . Semilunar Valves : Close as blood leaves the ventricles and enters the

arteries.Heart murmur : Rushing, gurgling sound created by backflow of blood due to damaged or imperfect heart valves. Fairly common (10% of healthy population).

Blood Pathway in BodyRight Side of Heart :

. Right ventricle pumps oxygen poor blood to lungs.

Left Side of Heart : . Left ventricle pumps oxygenated blood to body.

Blood Pathway :Veins --> Vena cava --> Right atrium --> Right ventricle --> Pulmonary artery -->

Lungs ---> Left atrium --> Left ventricle -->Aorta --> Arteries --> Capillaries --> Veins

Heart Beat Average 70 beats per minute. 100,000 beats every day. Cardiac cycle about every 0.8 sec.

Diastole : Heart relaxes and blood flows into chambers (0.4 sec). Systole : Heart contracts.

– First atria (0.1 sec)– Then ventricles (0.3 sec)

Pumps about 8000 liters of blood/day. Pacemaker (S/A node): Controls heart rate.

Regulated by nervous and endocrine systems.

Heart Beat Two heart beat sounds (“Lub-dupp”): First sound:. Second sound: Heart relaxes, semilunar valves are closing.

*Pulse :.

The Heart’s Pace Maker: Regulation of HeartbeatSpecial tissue sets the pace S/A node (Pacemaker) Atrioventricular bundle Bundle branches

Contraction is initiated by the sinoatrial node Sequential stimulation occurs at other autorhythmic cells

Cardiac Cycle Atria contract simultaneously Atria relax, then ventricles contract Systole = Diastole = Cardiac cycle – events of one complete heart beat

Ventricular systole – blood pressure builds before ventricle contracts,

pushing out blood Early diastole – atria finish re-filling, ventricular pressure is low

Blood Pressure . “Blood pressure” usually refers to arterial pressure. Usually measured at the arm. Two measurements:

Systolic Blood Pressure : During heart contraction. Normal systolic pressure is about 120 mm Hg. (Range: 110-140 mm Hg).

Diastolic Blood Pressure : During heart relaxation. Normal diastolic pressure is about 80 mm Hg.

*(Range: 70-90 mm Hg)

2. Blood (Average Blood Volume: 4 to 6 liters.)Blood composition:

55% Plasma (containing water, salts, proteins, etc.)45% Cellular elements:

Red Blood Cells: 5-6 million RBCs/ml of blood. Contain hemoglobin to transport O2 and CO2.

White Blood Cells: 5,000-10,000 WBCs/ml of blood. Play an essential role in immunity and defense.

Platelets: .

Blood Components A. Blood Plasma Plasma = Makes up about 60% of the total blood volume.

Salts (Ions): help to maintain osmotic balance, monitor pH and the permeability of membranes Ex. Na+, Cl-, HCO3-

Metabolites & wastes: glucose, hormones, etc. Proteins: maintains osmotic balance, by ensuring an isotonic state b/w

plasma and cytoplasm of cells. Blood Cells- make up about 40% of total blood volume

B. Red Blood Cells - RBC’s Also called “erythrocytes” Hemoglobin – iron containing protein that allows oxygen to bind to RBC’s Does not have a nucleus so the shape is “concave” Anemia = a condition in which the O2 carrying ability of the blood is diminished,

and is due to blood loss or nutrient deficiency

C. White Blood Cells - WBC’s • Cells whose primary job is to defend the body against infections•• Contain nuclei, so the shape is round• There is only 1 to 2 WBC’s for every 1,000 RBC’s

*Leukemia: is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white

blood cells (leukocytes). It is part of the broad group of diseases called hematological neoplasms.

D. Platelets Play an important role in clotting blood, by forming a sticky protein plug Carry out the “clotting cascade” producing a “clot” made up of “fibrin” A mutation in one of the genes that code for one of the clotting proteins causes

“hemophilia”E. Blood Groups Letters represent protein receptors found on the outside of that cell that can act as

antigens (receptors that help trigger the immune response)E. Rh Factor People that have it are Rh+ and those who do not are Rh- If a mother is Rh- and gives birth to a Rh+ baby, than the mother makes antibodies

against it during the 1st pregnancy. If the second child is Rh+, the mother’s antibodies will attack the baby’s blood, and

harm the fetus,

3. Blood Vessels• Include arteries, arterioles, capillaries, venules, and veins.

• Double circuit, closed system:1. Pulmonary circuit :.2. Systemic circuit : Delivers oxygenated blood to tissues and organs of body (brain, liver, heart, kidneys, etc). Picks up carbon dioxide produced by tissues.

Structure of Different Blood Vessels

4. Types of Blood VesselsA. Arteries and Arterioles :

• Carry blood away from heart to body. • .• Have thick muscular walls, which make them elastic and contractile.

• Carry “oxygenated blood” (except pulmonary artery) which is oxygen rich bloodB. Veins and Venules :

• .• .

• Veins have small valves that prevent backflow of blood towards capillaries, especially when standing. C. Capillaries : walls are thin enough to permit gas exchange.Blood flow to different organs is controlled by precapillary sphincters of smooth muscle.D. Lymph Vessels

• These vessels take fluid that has leaked out of cells, called “lymph” and return it to two major veins in the neck and lymph “nodes” in certain areas of the body.•• Lymph vessels have valves to prevent backflow of fluid as well.• They contain immune cells, such as WBC’s, that are used to fight off infections and diseases.

Cardiovascular Disease Number one cause of death in the U.S. and industrialized nations .

Includes Hypertension Heart attacks & heart failure

*Most often caused by complications of: Arteriosclerosis : A condition in which arteries become blocked by calcium and lipid deposits (plaque), losing their elasticity.

Hypertension : High blood pressure. Blood pressure over 140/90. Heart must work harder to overcome resistance. Silent killer : May have few or no symptoms. May result in strokes, heart

attacks, aneurysms, and arteriosclerosis. Risk factors :.

Stroke : Third leading cause of death in U.S. after heart disease and cancer. Insufficient blood supply to the brain, caused by a blood clot or rupture of a

blood vessel. Depending on area affected may cause:

Paralysis (usually one side of body). Loss of sensation or motor control. Incontinence Loss of speech, hearing, or sight.

Heart Attack (Myocardial infarction-MI)• Decrease in blood supply to the heart, due to a clot or plaque in arteries. Heart may stop beating altogether or suffer permanent damage.• Over 1. 3 million heart attacks every year in U.S.• Heart Attacks are Caused by Blocked Coronary Arteries

Heart Attack (Myocardial infarction) Symptoms: Chest pain, pressure, or tightness, sweating, nausea, shortness of

breath, dizziness, and fainting. Risk factors :

High blood pressure High cholesterol High LDLs (low density lipoproteins) Diabetes Emotional stress Obesity Heredity