What are the issues
• Animal cells exchange material across the cell membrane
fuels for energy
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
• 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
–What needs to be transported
nutrients fuels from digestive system
O2 & CO2 from & to gas exchange systems: lungs, gills
waste products from cells
water, salts, nitrogenous wastes (urea)
white blood cells & others patrolling body
• All animals have:
circulatory fluid = blood
tubes = blood vessels
muscular pump = heart
Open circulatory system
Invertebrates (insects, arthropods, mollusks)
no distinction between blood & extracellular (interstitial) fluid
Closed circulatory system
Invertebrates (earthworms, squid, octopuses)
blood confined to vessels & separate from interstitial fluid
1 or more hearts
large vessels to smaller vessels
material diffuses between vessels & interstitial fluid
1. Heart (Pumping device)
2. Blood (Fluid connective tissue)
3. System of blood vessels:
• Veins and venules
•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:
•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
Heart murmur: Rushing, gurgling sound created by backflow of blood due to
damaged or imperfect heart valves. Fairly common (10% of healthy
Blood Pathway in Body
Right Side of Heart:
• Right ventricle pumps oxygen poor blood to lungs.
Left Side of Heart:
• Left ventricle pumps oxygenated blood to body.
Veins --> Vena cava --> Right atrium --> Right ventricle --> Pulmonary artery -->
Left atrium --> Left ventricle -->Aorta --> Arteries --> Capillaries --> Veins
• 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.
• Two heart beat sounds (“Lub-dupp”):
• First sound:.
• Second sound: Heart relaxes, semilunar valves are closing.
The Heart’s Pace Maker: Regulation of Heartbeat
Special 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
• 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” 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.)
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: .
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
• 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
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 Vessels
A. 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 blood
B. Veins and Venules:
•Veins have small valves that prevent backflow of blood towards capillaries, especially
C. Capillaries: walls are thin enough to permit gas exchange.
Blood flow to different organs is controlled by precapillary sphincters of smooth
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
• Number one cause of death in the U.S. and industrialized nations.
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:.
• 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
• Depending on area affected may cause:
Paralysis (usually one side of body).
Loss of sensation or motor control.
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 LDLs (low density lipoproteins)