blood

Anatomy and Physiology II

Blood & the Cardiovascular System

Chapters 14 & 15

Study Guide

 Functions of:

 Transport Oxygen and Carbon dioxide

 Transports nutrients

 Transports nutrients and cellular wastes

 Helps distribute heat evenly throughout the body

 Help maintain stability of the interstitial fluids.

 Blood – made up of formed elements (red blood cells, white blood cells and platelets)

and Plasma, which is the liquid portion of blood . A layer of formed elements and

another layer made up of plasma forms in a test tube that blood has been

transferred to and is prevented from clotting.

 Serum – plasma minus all of its fibrinogen and other clotting factors.

Formed Elements

 Red blood cells (erythrocytes) lack a nucleus, endoplasmic reticulum and

mitochondria (produce ATP through glycolysis); have a biconcave shape to increase

surface area, small in size (7.5 um)

 Hemoglobin, made up of 4 globular protein subunits, each of which contain an iron

containing heme group.

Oxyhemoglobin – Hemoglobin with oxygen lightly bound

Deoxyhemoglobin – Hemoglobin which has released its oxygen

 Hematocrit – The cellular portion of blood resulting once it has been centrifuged,

primarily containing red blood cells, but also white blood cells and platelets.

Red Blood cell origin, production and control:

 Erythropoiesis process by which formed elements produced; occurs in red bone marrow:

Red blood cells form when hematopoietic stem cells (hemocytoblast) form  Myeloid

stem cells  Proerythroblast  erythroblasts Normoblast  Reticulocyte 

erythrocytes;

 Mechanism for control of cell production: Negative feedback mechanism;

erythropoietin released from kidneys & liver stimulate red cell production in red

marrow when low O2 concentrations detected; Anemia (reduction in RBC or hemoglobin),

pernicious anemia (results from inability to absorb B12) , aplastic anemia – due to

destruction of red blood cells due to toxic chemicals/radiation

 Cyanosis – a condition that occurrs when the concentartion of deoxyhemoglobin

increases.







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 Sickle cell anemia – hemoglobin crystallizes in low oxygen environment, bending cell into

a sickle shape thereby blocking circulation in small blood vessels.

Destruction of red blood cells – worn cells removed by macrophages within liver and

spleen;

 Recycling of red blood cell components: Hemoglobin is broken down into four globin

chains with its heme group in the center. The amino acids are recycled and used in the

production of proteins. The heme is then broken into biliverdin and iron, iron

transported by combining with transferrin, 80% stored in liver as ferritin (protein), the

remaining is used in hemoglobin production in the red bone marrow , some biliverdin is

converted to bilirubin both of which enter the bile pigments and are emptied into the

intestines and excreted from body in feces. Also, some is removed by kidneys,

contributing to the color of urine.

 Jaundice – elevated blood concentrations of bilirubin in the blood. Sometimes seen in

newborns when fetal hemoglobin is being broken down and replaced with adult

hemoglobin. Also, in liver diseases that effect the livers ability to process and excrete

bilirubin.

 Red blood cell counts: Adult male – 4,600,000 – 6,200,000 cells per mm3 ; Adult female

– 4,200,000 cells per mm3; Child - 4,500,000 – 5,100,000 cells per mm3.

White blood cells (leukocytes) - develop from hematopoietic stem cells, stimulated by

interleukins & colony stimulating factors (CSF’s), blood transports to site of infection.

White blood cells are classified according to the presence of cytoplasmic granules which

are vesicles containing enzymes and other products used by the cell.

Granulocytes – granular cytoplasm, Agranulocytes – cytoplasm not granular.

Granulocytes include:

 neutrophils – 54 to 62% leukocytes, granules light purple, lobed nucleus with 2-5

sections, first arrive at infection, phagocytize bacteria;

 eosinophils – 1-3% of leukocytes, granules course & uniform, stain deep red, two lobed

nucleus, moderate allergic reactions & defend against parasitic worm infection;

 basophils – less then 1% of leukocytes, nuclei similar to eosinophils which is often

obscured by granules, have fewer, more irregularly shaped granules that appear deep

blue in color, release histamine & heparin

 Heparin - prevents clotting by inhibiting the formation of prothrombin activator and

the action of thrombin on fibrinogen.

 Agranulocytes include:

 Monocytes – 3 to 9% of leukocytes, largest blood cells, nuclei – spherical,kidney-shaped,

oval or lobed, leave blood and become macrophages that phagocytize bacteria;

 Lymphocytes – 25 to 33% of leukocytes, large spherical nucleus surrounded by thin rim

of cytoplasm, include T cells that directly attack microorganisms, dead cells, other







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debris, and B cells that produce antibodies which are proteins that attack foreign

molecules.

 Diapedesis – leukocytes squeeze between cells of smallest blood vessels.

 Leukocytosis – white blood cell count exceeding 10,000 per mm3 (may indicate

infection), Leukopenia – white blood cell count less then 5,000 per mm3 (may indicate

AIDS, typhoid fever, mumps, measles, arsenic poisoning, mercury poisoning, lead

poisoning.

 Blood platelets (thrombocytes) – arise from megakaryocytes, lack nucleus, release

serotonin which causes smooth muscle contraction, help stop blood loss.

Blood Plasma:

Liquid portion of blood in which formed elements are suspended.

About 92% water, which proteins, hormones, ions and other substances.

Plasma Proteins: Three primary proteins:

Albumins – 60% proteins by weight, produced in the liver, function in regulating

colloid osmotic pressure and bind and transport fatty acids, some hormones and

some medications.

Fibrinogen – 4% of plasma proteins, produced in the liver and functions in blood

coagulation.

Globulins – about 36% of plasma proteins, broken down into alpha, beta and gamma

globulins. Alpha and Beta globulins are synthesized by the liver, help transport

cholesterol, hormones and iron and other functions. Gamma globulins are antibodies

and are produced in lymphoid tissue.



Edema may occur if plasma protein concentrations fall, which reduces blood colloid osmotic

pressure allowing more fluid from blood to enter tissue spaces. A drop in protein

concentrations may result from liver damage.



Plasma gases: Gases are dissolved in plasma and include –

Nitrogen - makes up more then 70% of air. Nitrogen is an inert substance with no

function in the body.

Oxygen – makes up about 21% of air, is initially dissolved in plasma and then diffuses

into red blood cells that carry it to cells of the body where it is used in cellular

respiration.

Carbon dioxide – which makes up about 0.03% of air is produced as a waste by-

product of cellular respiration. Cells produce carbon dioxide that dissolves in blood

plasma and is transported to the lungs where it diffuses into the air of the lungs and

is carried out of the body.









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Plasma Nutrients: substances such as amino acids, simple sugars, nucleotides and lipids are

transported in the plasma to tissues of the body.



 Hemostasis – stoppage of bleeding, include three actions to stop bleeding –

 1.) blood vessel spasm – vasospasms, constricts blood vessel

 2.) platelet plug formation – platelets stick and collect to exposed ends of injured blood

vessels and collagen & other platelets.

 3.) Blood Coagulation – a cascade of clotting factors forms blood clot, occurs when

soluble fibrinogen is converted into insoluble threads of fibrin that sticks broken blood

vessels, trap blood cells and platelets

 Intrinsic clotting mechanism initiated by blood contacting foreign surfaces (activates

Hagman factor which is Factor XII, blood contains all clotting factors.

 Extrinsic clotting mechanisms initiated by damage to vessels or tissue, tissue damage

releases Tissue Thromboplastin (factor III).

 Blood clot fibers retract pulling edges of break closer together, platelets release

platelet derived growth factor (PDGF) which stimulates smooth muscle growth and

fibroblasts to repair tissue damage.

 Thrombus – clot abnormally forming in blood vessels; embolus – moving clot; embolism –

clot lodged in smaller blood vessel. Coronary thrombosis (heart); cerebral thrombosis

(brain);

ABO blood group: Red blood cells can have either A and/or B antigens on the surface of

there membranes or are devoid of any either antigen. The presence of surface antigens is

genetically determined. Unlike most antigens, the body produces antibodies for the

whichever antigen is not present on the red blood cells. Therefore: A (anti-B), B (anti-A),

O (anti-A and B), AB (neither anti-A or Anti-B). In addition to the ABO blood system, the

RH antigen (which is actually a group of antigens) is tested for compatibility, Rh+ has Rh

factor, Rh- does not. The body must be first exposed to the Rh factor bya Rh negative

individual prior to producing antibodies.

 Agglutination – clumping of blood; agglutinogens – antigens; agglutinins – antibodies



The Cardiovascular System

 Heart covering: Pericardium – fibrous pericardium (outer); inner double serous

membrane – inner visceral pericardium, outer – parietal pericardium; pericardial cavity –

cavity between visceral & parietal membranes filled with serous fluid.

 Heart wall: Epicardium - outer layer, corresponds to visceral pericardium; Myocardium

middle, cardiac muscle tissue; Endocardium – inner layer lines chambers of heart,

epithelium & connective tissue, contain Purkinje fibers.









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 Heart chambers – Atria: upper, Ventricles: lower, interatrial septum separate atrium,

interventricular septum separates ventricles.

 Atrioventricular valves - the valve between each of the atrium and ventricles.

Tricuspid valve found between the right atrium and right ventricle, Bicuspid valve

(mitral) - valve found between the left atrium and left ventricle

 Chordae tendineae are thin tendons that attach to the leaflets of the atrioventricular

valves extending into the ventricles and attach to the papillary muscles on the walls of

the ventricles.

 Semilunar valves – pulmonary valve found at entrance to pulmonary trunk. Aortic valves

- found at entrance to aorta; know path of blood through heart.

 Coronary arteries – first 2 branches of aorta, I. left coronary artery (2 branches)

1. circumflex artery – (travels in atrioventricular sulcus) supply walls of left atrium

& left ventricle 2. anterior interventricular artery – (travels in anterior

interventricular sulcus) walls of both ventricles. II. right coronary artery (travels in

atrioventricular sulcus) two branches 1. posterior interventricular artery (travels in

posterior interventricular sulcus) walls of both ventricles 2. Marginal artery (passes

along lower border of heart) walls of right atrium & right ventricle. Anastomoses –

blood vessel connections between arteries, alternate pathways (collateral circulation);

cardiac veins empty into coronary sinus.

 Cardiac veins – Blood from the capillaries of the heart join cardiac veins which travel

similar paths as the coronary arteries. The cardiac veins join the coronary sinus which

itself empties into the right atrium.

 Cardiac cycle – pressure within chambers rise and fall. Systole – chambers contract,

Diastole – chambers relax. During ventricle diastole ventricles start filling (70%),

during atrial systole ventricles finish filling, blood passes through atrioventricular

valves, as ventricles start to contract atrioventricular valves close, ventricles contract

sending blood out of heart through pulmonary valve (to lung) and aortic valve (to rest of

body)

 The Heart is two pumps in one: Right chambers – pulmonary circuit sending blood to

lungs; Left chambers– systemic circuit sending oxygenated blood to the rest of the

body.

 Heart sounds – lubb ventricular contraction when atrioventricular valves are closing;

dupp ventricular relaxation pulmonary and aortic valves closing; murmur abnormal sound

created as blood slips through cusps of closed valves.

 The heart has two syncytium, which are a connected network of cells which function as

a unit and include Atrial syncytium and ventricular. Both synctium are separated

fibrous heart skeleton. Since the branched cardiac muscles have gap junctions









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communicating between muscle cells, impulses pass between each muscle cell of a

syncytium,

 Cardiac conduction system – specialized cardiac cells with few myofibrils that initiate

and distribute cardiac impulses (I.) Sinoatrial node (SA) called pacemaker, in right

atrium near opening of superior vena cava, fibers continuous with atrial syncytium,

fibers reach threshold on own, rhythmic, 70-80/min, cause fibers of atrium to

contract, impulse from cell to cell of atrial syncytium via gap junctions (II.)

Atrioventricular node (AV), stimulates ventrical syncytium, located lower interatrial

septum junctional fibers carry impulses to AV, passes to AV bundle (bundle of His)

Divides into right & left branches lead to Purkinje fibers that carry impulses to distant

regions of ventricles lead to papillary muscles, to apex of heart, lateral walls of

ventricles, ventricles contract in coordinated manner, starting at apex moving up, with

twisting motion.

 Electrocardiogram – record of electrical changes in heart. P wave – atrial depolarization

(results from impulse conduction from SA node through atria); QRS complex –

ventricular depolarization & precedes ventricular contraction; T wave – ventricular

repolarization; Atrial reprolarization occurs as ventrical excitation occurs and normally

obscured by QRS complex.

 Cardiac cycle – 1. period of ventricular filling – blood passively goes into ventricles

then atria contract 2. Ventricular systole - (atria go into diastole) ventricular pressure

rises, AV valves close ( isovolumetric contraction phase – all valves to ventricles closed

for fraction of second) pressure increases & semilunar valves open and expel blood

from ventricles 3. Isovolumetric relaxation ventricles begin to relax, pressure drops

and semilunar valves close, ventricles momentarily closed (isovolumetric)

 Regulation of cardiac cycle – Parasympathetic – decrease heart rate, Sympathetic –

increase heart rate, cardiac centers in Medulla oblongata regulate autonomic impulses

to heart creating a balance between sympathetic and parasympathetic impulses.

 Bradycardia – abnormally slow heart rate.

Blood vessels:

 Blood vessels form a closed loop system that carries blood to tissues of the body,

giving up oxygen and collecting carbon dioxide and exchanging these gasses at the lungs.

This system of tubes is made up of arteries and veins, both with distinct structures.

 Arteries carry blood away from the heart, are thicker, strong and have elastic

properties. Arteries continually branch and give rise to smaller diameter arterioles.

Arteries are made up of three layers (tunics):

a) Tunica interna - innermost layer made up of simple squamouus epithelium

(endothelium) that rests on an elastic fiber rich connective tissue layer.









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b) Tunica media - middle layer made up smooth muscle fibers encircling the artery

and a thick layer of elastic connective tissue.

c) Tunica externa - outermost layer made up of connective tissue with irregularly

organized elastic and collagenous fibers.

 The middle and outer layers or arteries thin as they approach capillaries.

 Vasomotor impulses originating from the sympathetic division of the autonomic

vervous system innervate smooth muscles of arteries and veins and cause

vasoconstriction, inhibition of this stimulation causes vasodilation.









Capillaries: Include the smallest diameter blood vessels and connect smaller arterioles and

venules. Capillaries are an extension of the endothelium of the arteries and are made up

simple squamous epithelium which is semipermeable. Small pores are created by the

overlapping of simple squamous epithelium, which vary depending on the location in the

body.

Capillary Arrangement – Capillary arrangement vary depending on the part of the body and

their metabolic demands, becoming denser in areas of the body where metabolic demands

are great.

Within capillary beds, blood can either be directed through metarterioles, when metabolic

demands are low and directed through the capillaries when metabolic demands are great.

The redirecting of blood is accomplished by the use of precapillary sphincters, which can

prevent blood from flowing into capillaries.

Capillary exchange - Substances move between cells and capillaries by osmosis, diffusion

and filtration. Diffusion is the most important means of capillary exchange, lipid soluble

substances moving easily through capillary walls. Filtration predominates at the arteriole

side because of the greater hydrostatic pressure and lessons as blood approaches the

venule side of a capillary bed.

Osmotic pressure stays relatively constant throughout the capillary bed, but has greater

influence on movement of substances on the venule side of capillaries since hydrostatic

pressure is reduced. There is a net movement of water out of capillaries which is

reabsorbed by lymphatic capillaries.



Venules and Veins – carry blood back to the heart. Venules are microscopic vessels that

continue from capillaries, merge and form veins. The pathway of veins is very similar to

those of arteries. The walls of veins is composed of three layers, as arteries, except the

middle layer is not well developed.









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Many veins, particularly those of the lower and upper limbs, contain flaps that act as valves

preventing the back-flow of blood. Valves of the veins help blood move in one direction and

return to the heart. Vein also act as a blood reservoir, which allows blood to be moved

from veins to arteries in the case of blood loss.



Arteriole blood pressure: Produced by pumping of the heart. Systolic pressure occurs as

the ventricle contracts and diastolic pressure occurs when the ventricle relax.

Factors influencing blood pressure include:

heart action – Blood pressure increases as cardiac output increases ( stroke volume x heart

rate) and decreases as cardiac output decreases.

blood volume – includes plasma and all formed elements. As blood volume decreases so

does blood pressure increases as blood volume increases.

resistance to flow –dialation and constriction can either decrease or increase resistance.

Also, the elastic recoil of the artery walls also increases peripheral resistance and blood

pressure.

blood viscosity - Generally, blood viscosity stays constant, but increases when, for

instance, when blood proteins increase and decrease in the case of anemia. Increased

blood viscosity increases blood pressure and reduced blood viscosity decreases blood

pressure.



Control of blood pressure –

Blood pressure is controlled primarily by mechanisms that regulate cardiac output and

peripheral resistance.

Cardiac output depends on volume of blood discharged from the ventricle during each

contraction and the pulse rate. The more blood entering the heart, the stronger the

ventricular contraction, the greater the stroke volume and the greater the cardiac output.

The cardiac center of the medulla oblongata regulates heart rate. Vasomotor center of

the medulla oblongata regulates the diameter of arterioles and therefore peripheral

resistance.



Venous blood flow – not influenced by heart, but occurs because of skeletal muscle

contractions, breathing movements and venoconstrictions. As local pressures increase,

veins get squeezed, forcing blood in one direction toward the heart due to the valves.

Venous constriction can increase venous blood pressure and flow.









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Good web sites:



http://www.jdaross.cwc.net/heart1.htm









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