1. Blood & Heart

Function of cardiovascular system

Function of cardiovascular system

1. Transport blood throughout body

2. Pump other substances along with blood

3. Facilitates delivery of vital materials to cells and picks of cellular waste

   1. Transports nutrients and oxygen

   2. Removes carbon dioxide and waste products of cells’ metabolism

4. Parallel circulation (lymphatic system)

Major components of circulatory system

1. Heart

2. Blood

3. Blood vessels

How is blood characterized

Connective tissue

Functions of blood

1. Transportation of oxygen and nutrients

2. Clot formation

3. Fighting infection

4. Clearing waste products

5. Regulating body temperature

Blood Type A

• Very common (~41% of US population has Type A)

• A antigens found on cell membranes of RBCs

• No anti-A antibodies, but there are anti-B antibodies in plasma

Blood Type B

• B antigens

• Plasma contains anti-A antibodies (i.e. antibodies would attack Type A transfusion because they would see them as foreign material)

Effect of interaction between antibodies and foreign blood type

Agglutination resulting in serious harm and even death

Blood Type AB

• Contains both A and B antigens

• Has neither A nor B antibodies in plasma

• Universal recipients because they can accept any type of blood transfusion

Blood Type O

• Contain no A or B antigens

• Plasma contains both A and B antibodies

• Universal donor - can give blood to anyone

Components of blood

1. Plasma

2. Erythrocytes (RBCs)

3. Leukocytes (WBCs)

4. Thrombocytes (platelets)

Plasma (composition, function, proteins)

• Composition: mixture of water, sugar, fats, proteins, and salts

  • Mainly water

• Function: transportation

• Proteins: albumin

Albumin

Maintains pressure to keep water in the bloodstream

• Pulls water back into the system

Where are plasma proteins produced?

Liver

Erythrocytes (RBCs) (structure, function, proteins)

• Structure: biconcave disc (lack nucleus)

• Function:

  • Carrying oxygen from lungs to body

  • Returning CO2 to lungs

• Proteins: hemoglobin

Hemoglobin

• Protein of RBCs

• Each can carry four O2 molecules

Production of erythrocytes (RBCs) (controlled by, produced in, length of maturation, lifespan)

• Controlled by kidney hormone: erythropoietin

• Produced in bone marrow of long bones

• Takes ~7 days to mature before being released into bloodstream

• Lack of nucleus limits lifespan to ~120 days

RBC regulation: kidneys

• When kidney cells become hypoxic (decreased oxygen), there is an increase in the synthesis of erythropoietin

• Testosterone enhances production

RBC regulation: diet

• Two B vitamins:

  • Folic acid

  • Vitamin B12

• Iron

RBC destruction

• Iron is salvaged + reused

• Heme group is degraded to bilirubin and secreted in bile

Leukocytes (WBCs) (function, subdivisions)

• Function: protect against infection

• Subdivisions:

  • Granulocytes

    • Neutrophils

    • Eosinophils

    • Basophils

  • Agranulocytes

    • Lymphocytes

      • T Cells

      • B Cells

    • Monocytes

Neutrophils (subdivision + function)

• Granulocyte

• Attack bacteria

Eosinophils (subdivision + function)

• Granulocyte

• Attack parasitic worms

Basophils (subdivision + function)

• Granulocyte

• Histamine production (inflammatory response)

T Cells (subdivision + function)

• Agranulocyte + lymphocyte

• Virus and tumor cells

B Cells (subdivision + function)

• Agranulocyte + lymphocyte

• Produce antibodies

Monocytes (subdivision + function)

• Agranulocyte

• Macrophagic activity

Platelets (characteristic, function)

• Characteristic: not true cells

• Function: responsible for coagulation (clotting)

Platelets: steps

1. Vascular spasm

   1. Allows time for next steps to occur

2. Platelet plug formation

   1. Loosely knit plug

3. Coagulation (clotting)

Process of blood clotting

1. When inner wall of vessel is damaged, underlying collagen fiber becomes exposed

2. Platelets floating in blood begin to attach to rough/damaged site

3. Attached platelets release chemicals to attract more platelets, creating platelet plug

   1. Platelets secrete serotonin, causing blood vessels to spasm, decreasing blood flow to the area

   2. Within 15 seconds, clotting/coagulation begins

Effect of prothrombin on blood clotting

1. Prothrombin (produced by liver with help of Vitamin K) converted to thrombin

2. Thrombin transforms fibrinogen, dissolved in blood, into insoluble, hair-like form called fibrin

3. Fibrin forms net-like patch at injury site, snagging more blood cells and platelets

4. Clot created in 3-6 minutes

Heart structure (# chambers, right v. left)

• Four-chambered organ

• Right side = deoxygenated

• Left side = oxygenated

Layers of heart wall

1. Epicardium

2. Myocardium

3. Endocardium

Endocardium

Thin internal layer of heart also covering valves

Myocardium

Thick middle layer (cardiac muscle)

Epicardium

Thin external layer of heart

Fibrous skeleton

• Anchors cardiac muscles

• Keeps orifices patent

• Electrical insulator

Right atrium

• Receives venous blood from superior and inferior vena cava

• Discharges poorly oxygenated blood into right ventricle

Right ventricle

• Receives blood from right atrium through right AV (tricuspid) valve

• Blood exists via pulmonary valve to pulmonary artery

Valve control

• Tendinous cords arise from papillary muscles

• Contracts prior to ventricular contraction to prevent back flow

Left atrium

• Oxygenated blood enters from pulmonary vein

• Discharges blood into left ventricle

Left ventricle

• Blood enters from left atrium through mitral valve

• Exits via semilunar aortic valve

Skeletal muscles (structural elements, function, location)

• Long cylindrical fiber, striated, many peripherally located nuclei

• Voluntary movement, produces heat, protects organs

• Attached to bones and around entry/exit sites of body (mouth/anus)

Cardiac muscles (structural elements, function, location)

• Short, branched, striated, single central nucleus

• Contracts to pump blood (involuntary control)

• Heart

Smooth muscles (structural elements, function, location)

• Short, spindle-shaped, no striation, single nucleus in each fiber

• Involuntary movement, moves food, involuntary control of respiration, moves secretions, regulates flow of blood in arteries by contraction

• Located in walls of major organs and passageways

Cardiac control (actors)

1. SA (sinoatrial) node

2. AV node

3. AV bundle (bundle of His)

4. Purkinje Fibers

SA (sinoatrial) node

• Sets pace for whole heart

• ~70 BPM

Sympathetic + parasympathetic effects on SA node

• Sympathetic: increase HR

• Parasympathetic: return to basal HR

AV node

• Delays impulse from SA node by ~0.1 second

• Allows completion of atrial contraction prior to ventricular contraction

AV bundle (bundle of His)

• Only electrical connection from atria to ventricles

• Signal propagated via gap junctions in atria

  • Atria and ventricles are not connected via gap junctions

• Splits into right and left branches

Purkinje Fibers

Complete pathway of cardiac control

Cardiac cycle (definition, divisions)

• The movements of the heart

• Divided into systole and diastole

Systole

• Begins with closure of mitral or tricuspid valve

• Concludes with closure of aortic or pulmonic valve

• Ventricular contraction (forces blood into arteries)

Diastole

• Begins with closure of aortic or pulmonic valve

• Concludes with closure of mitral or tricuspid valve

• Ventricular relaxation and filling (to prepare for next ventricular contraction)

Both atria and ventricles undergo systole/diastole, but what do discussions of heart movement normally refer to?

Ventricular activity