Human Circulation Every organism must exchange materials and energy with its environment, and this exchange ultimately occurs at the cellular level.

Human Circulation

Every organism must exchange materials and energy with its environment, and this exchange ultimately occurs at the cellular level. Cells live in aqueous environments. The resources that they need, such as nutrients and

oxygen, move across the plasma membrane to the cytoplasm.

Metabolic wastes, such as carbon dioxide, move out of the cell.

Most animals have organ systems specialized for exchanging materials with the environment, and many have an internal transport system that conveys fluid (blood or interstitial fluid) throughout the body. For aquatic organisms, structures like gills present

an expansive surface area to the outside environment.

Oxygen dissolved in the surrounding water diffuses across the thin epithelium covering the gills and into a network of tiny blood vessels (capillaries).

At the same time, carbon dioxide diffuses out into the water.

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Diffusion alone is not adequate for transporting substances over long distances in animals - for example, for moving glucose from the digestive tract and oxygen from the lungs to the brain of mammal.

Diffusion is insufficient over distances of more than a few millimeters.

The circulatory system solves this problem by ensuring that no substance must diffuse very far to enter or leave a cell.

FUNCTIONS OF VERTEBRATE CIRCULATORY SYSTEMS

A. Nutrient and Waste Transport 1. Nutrients enter blood through wall of small intestine 2. Carried to liver for storage or metabolism-gyycogen 3. Dissolved glucose and metabolites carried to all body cells 4. Metabolizing cells release wastes into blood 5. Wastes carried to kidney for removal 6. Constitutes metabolic circuit or systemic circulation

B. Oxygen and Carbon Dioxide Transport 1. Oxygen diffuses into blood through gills or lungs 2. Oxygen accumulates in hemoglobin of red blood cells 3. Oxygen released at metabolizing cells 4. Carbon dioxide, a metabolic product, is released by cells into blood 5. Waste carbon dioxide carried back to gills or lungs and released 6. Constitutes respiratory circuit or pulmonary circulation

C. Temperature Regulation 1. Most vertebrates are poikilotherms, body temperature varies with environmental temperature 2. Mammals and birds are homeotherms, maintain constant body temperature 3. Heat distributed by circulating blood 4. Temperature adjusted by directing flow to interior or extremities a. Decrease body temperature by dissipating heat to environment b. Retain heat by directing blood from extremities to interior D. Hormone Circulation 1. Hormones transported to target tissues throughout body 2. Hormones persist only a short time, are destroyed by body enzymes

" A dream is not what you " A dream is not what you see in sleep, it is the thing see in sleep, it is the thing that does not let you that does not let you sleep."sleep."

" A dream is not what you " A dream is not what you see in sleep, it is the thing see in sleep, it is the thing that does not let you that does not let you sleep."sleep."

A. Closed system: blood enclosed within vessels– 1. Circulating fluid does not mix with other body fluids– 2. Materials pass across by diffusion through walls of vessels– 3. Annelids have a closed system – 4. Movement of fluid in vessels assisted by muscle

contraction– 5. All vertebrates have closed circulatory system– 6. Advantage of closed systems

• a. Can change diameter of individual muscle-encased vessels• b. Regulate fluid flow in specific parts of body independently

• B. Open system: no distinction between circulating fluid and body fluid– 1. Arthropods have an open system – 2. Muscular tube in body cavity pumps fluid through network

of channels– 3. Fluid drains back into central cavity

Three main circuits Pulmonary

Blood goes from heart to lungs to pick up oxygen and release carbon dioxide

Systemic Blood pumped out of heart to the rest of the body

Coronary Heart muscle itself supplied with oxygen, nutrients,

etc.

Blood flow through the body Blood vessels

Arteries--take oxygenated blood away from the heart

Thick/muscular walls Do not contain valves All carry oxygen but one. Which one? PULMONARY ARTERY Go from large diameter to small diameter Become arterioles before capillaries

Blood flow through the body• Blood vessels

• Gases diffuse across very thin wall of small vessels called capillaries

• Most are 1 cell thick

• Exchange CO2 for O2

• Nutrients for wastes

• Return to heart

•Blood flow through the body Blood vessels

Veins--take deoxygenated blood back to the heart Thin walls Have valves Prevents backflow Where are they in greatest numbers? Lower body. Why? Gravity

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are needed to see this picture.

• Metabolic rate is an important factor in the evolution of cardiovascular systems. Shift from filter feeding to active capture of prey– In general, animals with high metabolic rates

have more complex circulatory systems and more powerful hearts than animals with low metabolic rates.

– Similarly, the complexity and number of blood vessels in a particular organ are correlated with that organ’s metabolic requirements.

ALL BLOOD CIRCUITS

HEART EVOLUTION

Frogs and other amphibians have a three-chambered heart with two atria and one ventricle. The ventricle pumps

blood into a forkedartery that splits theventricle’s output intothe pulmonaryand systemiccirculations.

1. Evolution of large veins from lungs called pulmonary veins a. Altered blood flow: blood from lungs returns to heart for Repumping 2. Advantage: blood pumped to tissues

at higher pressure 3. Disadvantage: oxygenated blood mixed with unoxygenated blood

Frogs and other amphibians have a three-chambered heart with two atria and one ventricle. The ventricle pumps

blood into a forkedartery that splits theventricle’s output intothe pulmonaryand systemiccirculations.

1. Evolution of large veins from lungs called pulmonary veins a. Altered blood flow: blood from lungs returns to heart for Repumping 2. Advantage: blood pumped to tissues

at higher pressure 3. Disadvantage: oxygenated blood mixed with unoxygenated blood

The evolution of a powerful four-chambered heart was an essential adaptation in support of the endothermic way of life characteristic of birds and mammals. Endotherms use about ten times as much energy as

ectotherms of the same size. Therefore, the endotherm circulatory system needs

to deliver about ten times as much fuel and O2 to their tissues and remove ten times as much wastes and CO2.

Birds and mammals evolved from different reptilian ancestors, and their powerful four-chambered hearts evolved independently - an example of convergent evolution.

The closed circulatory system of humans and other vertebrates is often called the cardiovascular system.

The heart consists of one atrium or two atria, the chambers that receive blood returning to the heart, and one or two ventricles, the chambers that pump blood out of the heart.

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Structure of the Heart

Structure of the Heart

Covered with a sac called the pericardium

Hollow, cone-shaped structure made of muscle called myocardium

4 Chamber or Cavities 2 Atrium 2 Ventricles

4 Valves Allows blood to flow in one

direction Separates chambers-

prevents backflow of blood

Covered with a sac called the pericardium

Hollow, cone-shaped structure made of muscle called myocardium

4 Chamber or Cavities 2 Atrium 2 Ventricles

4 Valves Allows blood to flow in one

direction Separates chambers-

prevents backflow of blood

HEART STRUCTURE

Blood flow through the heart (heart pumping animation!)

Into vena cava-superior or inferior Into right atrium Thru AV valve Down to right ventricle Thru pulmonary valve Out pulmonary artery to lungs--gets 02

and dumps CO2

Back to heart through pulmonary vein Into left atrium Thru AV valve Down to left ventricle Thru aortic valve Out aorta to body

St. Joseph’s asp. animation

Trace Blood Flow in the Heart Using Pencil trace the flow of blood

through the heart (starting in the superior and inferior vena cava)

Shade the areas of the heart that contain deoxygenated blood

http://www.sumanasinc.com/webcontent/animations/content/human_heart.html

Click the Link Below to Review One More Time

Four valves in the heart, each consisting of flaps of connective tissue, prevent backflow and keep blood moving in the correct direction. Between each atrium and ventricle is an

atrioventricular (AV) valve which keeps blood from flowing back into the atria when the ventricles contract.

Two sets of semilunar valves, one between the left ventricle and the aorta and the other between the right ventricle and the pulmonary artery, prevent backflow from these vessels into the ventricles while they are relaxing.

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HEART SOUND AND REGULATION Sound of heart (lub/dub) made by valves

closing Lub is the AV valves closing-first sound Dub is the Aortic and Pulmonary valves

closing-second sound

Delivery of oxygen to the body’s organs is critical for survival.

Certain cells of vertebrate cardiac muscle are self-excitable, meaning they contract without any signal from the nervous system. Each cell has its own built in contraction rhythm. However, these cells are synchronized by the

sinoatrial (SA) node, or pacemaker, which sets the rate and timing at which all cardiac muscle cells contract.

The SA node is located in the wall of the right atrium.

The cardiac cycle is regulated by electrical impulses that radiate throughout the heart. Cardiac muscle cells are electrically coupled by

intercalated disks between adjacent cells.

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Fig. 42.7

HEART BEAT REGULATION (1) The SA node generates electrical impulses, much (1) The SA node generates electrical impulses, much

like those produced by nerves that spread rapidly (2) like those produced by nerves that spread rapidly (2) through the wall of the atria, making them contract in through the wall of the atria, making them contract in unison.unison.

The impulse from the SA node is delayed by about The impulse from the SA node is delayed by about 0.1 sec at the atrioventricular (AV) node, the relay 0.1 sec at the atrioventricular (AV) node, the relay point to the ventricle, allowing the atria to empty point to the ventricle, allowing the atria to empty completely before the ventricles contract.completely before the ventricles contract.

(3) Specialized muscle fibers called bundle branches (3) Specialized muscle fibers called bundle branches and Purkinje fibers conduct the signals to the apex of and Purkinje fibers conduct the signals to the apex of the heart and (4) throughout the ventricular walls.the heart and (4) throughout the ventricular walls.

This stimulates the ventricles to contract from the This stimulates the ventricles to contract from the apex toward the atria, driving blood into the large apex toward the atria, driving blood into the large arteries.arteries.

Contraction stimulated by membrane depolarization, reversal of electrical polarity

Contraction triggered by SA node-pacemaker Membrane of cells depolarize spontaneously with regular

rhythm Depolarization passes from one cardiac muscle cell to another Spreads because cardiac cells(myocardial) are electrically

coupled by gap junctions Ventricular wave of depolarization delayed by nearly 0.1

second Atria and ventricles separated by connective tissue Connective tissue cannot generate depolarization-SO Wave passes via atrioventricular node (AV node) Delay permits atria to completely empty before

ventricles contract Depolarization conducted over both ventricles via

bundle of His Transmitted by Purkinje fibers that stimulate ventricle

myocardial cells Right and left ventricles contract almost simultaneously

ELECTRICAL CONDUCTION http://www.youtube.com/watch?

v=zS9dEeIHE98&feature=related

VALVE SOUNDS

http://www.bostonscientific.com/templatedata/imports/HTML/CRM/heart/heart_valves.html

Blood pressure and pulse Blood pressure compares diastolic and systolic

pressures Diastole--heart relaxes and blood flows into heart

chambers Systole--ventricles contract, sending blood out of

heart

• http://www.bostonscientific.com/templatedata/imports/HTML/CRM/heart/index.html• Heart sounds http://www.youtube.com/watch?v=WXwYYsi6z7Q&feature=related• Hearts electrical system• http://www.bostonscientific

.com/templatedata/imports/HTML/lifebeatonline/summer2004/learning.shtml

• Blood in the closed circulatory systems of vertebrates is a specialized connective tissue consisting of several kinds of cells suspended in a liquid matrix called plasma.

• The plasma is about 45% of the blood volume, transparent and straw-colored.

• 90% water• Variety of ions, sometimes referred to as blood electrolytes

– Plasma is a dilute salt solution. Primarily sodium, chloride and bicarbonate

– Maintain osmotic balance of the blood and help buffer the blood.

– Proper functioning of muscles and nerves depends on the concentrations of key ions in the interstitial fluid.

• Plasma carries a wide variety of substances in transit from one part of the body to another, including nutrients, metabolic wastes, respiratory gases, and hormones.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 42.14

• The plasma proteins have many functions.– Collectively, they acts as buffers against pH changes,

help maintain osmotic balance, and contribute to the blood’s viscosity.

– Some specific proteins transport otherwise-insoluble lipids in the blood.

– Other proteins, the immunoglobins or antibodies, help combat viruses and other foreign agents that invade the body. Liver produces most plasma proteins, including albumin

– Alpha and beta globin proteins are carriers of lipids and steroid hormones

– Fibrinogen proteins help plug leaks when blood vessels are injured.• Blood plasma with clotting factors removed is called serum.

Red blood cells, or Red blood cells, or erythrocyteserythrocytes, are by far the , are by far the most numerous blood cells.most numerous blood cells. Each cubic millimeter of blood contains 5 to 6 million red Each cubic millimeter of blood contains 5 to 6 million red

cells, 5,000 to 10,000 white blood cells, and 250,000 to cells, 5,000 to 10,000 white blood cells, and 250,000 to 400,000 platelets.400,000 platelets.

There are about 25 trillion red cells in the body’s 5 L of There are about 25 trillion red cells in the body’s 5 L of blood.blood.

Carry oxygen transport, depends on rapid diffusion of oxygen across the red cell’s plasma membranes. Human erythrocytes are small biconcave disks,

presenting a great surface area. Mammalian erythrocytes lack nuclei, an unusual

characteristic that leaves more space in the tiny cells for hemoglobin, the iron-containing protein that transports oxygen.

Red blood cells also lack mitochondria and generate their ATP exclusively by anaerobic metabolism.

Contains about 250 million molecules of hemoglobin. Each hemoglobin molecule binds up to four

molecules of O2. Recent research has also found that hemoglobin

also binds the gaseous molecule nitric oxide (NO). Also CO

As red blood cells pass through the capillary beds of lungs, gills, or other respiratory organs, oxygen diffuses into the erythrocytes and hemoglobin binds O2 and NO.

The NO relaxes the capillary walls, allowing them to expand, helping delivery of O2 to the cells.

RED BLOOD CELLS

There are five major types of white blood cells, or There are five major types of white blood cells, or leukocytesleukocytes: monocytes, neutrophils, basophils, : monocytes, neutrophils, basophils, eosinophils, and lymphocytes. eosinophils, and lymphocytes.

Less than 1% of total blood cells Their collective function is to fight infection.Their collective function is to fight infection.

White blood cells spend most of their time outside the White blood cells spend most of their time outside the circulatory. circulatory. DiapedesisDiapedesis

system, patrolling through interstitial fluid and the system, patrolling through interstitial fluid and the lymphatic system, fighting pathogens.lymphatic system, fighting pathogens.

Injured cells release histamine Dilation of arterioles increases blood flow, makes area

red For example, monocytes and neutrophils are For example, monocytes and neutrophils are

phagocytes, which engulf and digest bacteria and phagocytes, which engulf and digest bacteria and debris from our own cells.debris from our own cells.

Lymphocytes develop into specialized B cells and T Lymphocytes develop into specialized B cells and T cells, which produce the immune response against cells, which produce the immune response against foreign substances.foreign substances.

Produces in the lymphatic system, bone marrow and Produces in the lymphatic system, bone marrow and the thymusthe thymus

There are five major types of white blood cells, or There are five major types of white blood cells, or leukocytesleukocytes: monocytes, neutrophils, basophils, : monocytes, neutrophils, basophils, eosinophils, and lymphocytes. eosinophils, and lymphocytes.

Less than 1% of total blood cells Their collective function is to fight infection.Their collective function is to fight infection.

White blood cells spend most of their time outside the White blood cells spend most of their time outside the circulatory. circulatory. DiapedesisDiapedesis

system, patrolling through interstitial fluid and the system, patrolling through interstitial fluid and the lymphatic system, fighting pathogens.lymphatic system, fighting pathogens.

Injured cells release histamine Dilation of arterioles increases blood flow, makes area

red For example, monocytes and neutrophils are For example, monocytes and neutrophils are

phagocytes, which engulf and digest bacteria and phagocytes, which engulf and digest bacteria and debris from our own cells.debris from our own cells.

Lymphocytes develop into specialized B cells and T Lymphocytes develop into specialized B cells and T cells, which produce the immune response against cells, which produce the immune response against foreign substances.foreign substances.

Produces in the lymphatic system, bone marrow and Produces in the lymphatic system, bone marrow and the thymusthe thymus

WHITE BLOOD CELLS

The third cellular element of blood, platelets, are fragments of cells about 2 to 3 microns in diameter. They have no nuclei and originate as pinched-off

cytoplasmic fragments of large cells in the bone marrow.

Platelets function in blood clotting.

Erythrocytes, leukocytes, and platelets all develop from a single population of cells, pluripotent stem cells, in the red marrow of bones, particularly the ribs, vertebrae, breastbone, and pelvis. “Pluripotent” means that these cells have the

potential to differentiate into any type of blood cells or cells that produce platelets.

This population renews itself while replenishing the blood with cellular elements.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 42.13

A negative-feedback mechanism, sensitive to the amount of oxygen reaching the tissues via the blood, controls erythrocyte production. If the tissues do not produce enough oxygen, the

kidney converts a plasma protein to a hormone called erythropoietin, which stimulates production of erythrocytes.

If blood is delivering more oxygen than the tissues can use, the level of erythropoietin is reduced, and erythrocyte production slows.

Recent breakthroughs in isolating and culturing pluripotent stem cells, may soon lead to treatments of problems such as leukemia. Individuals with leukemia have a cancerous line of

stem cells that produce leukocytes. These cancerous cells crowd out cells that make red

blood cells and produce an unusually high number of leukocytes, many of which are abnormal.

One strategy now being used experimentally for treating leukemia is to remove pluripotent stem cells from a patient, destroy the bone marrow, and restock it with noncancerous pluripotent cells.

BLOOD CLOTTING Blood contains a self-sealing material that plugs

leaks from cuts and scrapes. A clot forms when the inactive form of the plasma

protein fibrinogen is converted to fibrin, which collects into threads that form the framework of the clot.

The clotting mechanism begins with the release of clotting factors from platelets.

The clotting process begins when the endothelium of a vessel is damaged and connective tissue in the wall is exposed to blood.

Platelets adhere to collagen fibers and release a substance that makes nearby platelets sticky.

The platelets form a plug. The seal is reinforced by a clot of fibrin when vessel

damage is severe.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 42.16

Anticlotting factors in the blood normally prevent spontaneous clotting in the absence of injury. Sometimes, however, platelets clump and fibrin

coagulates within a blood vessel, forming a clot called a thrombus, and blocking the flow of blood.

These potentially dangerous clots are more likely to form in individuals with cardiovascular disease, diseases of the heart and blood vessels.

Blood types A,B,O dictated by the antigen that is on the

surface of the RBC’s Antigens are substances that trigger an

immune response A has A antigen B has B AB has both O has no antigens

BLOOD TYPES

Removal of wastes Blood takes CO2 back to lungs

Delivers salts, water, and nitrogenous wastes (urea) to the kidneys for excretion Urea

Main nitrogenous waste of body Produced in liver (from ammonia--NH3) Removed by kidneys