ACS NSTEMI'anaphy

8/9/2019 ACS NSTEMI'anaphy

1/19

ANATOMY AND PHYSIOLOGY

Cardiovascular System

HEART

For all its might, the cone-shaped heart is a relatively small, roughly

the same size as a closed fistabout 12 cm (5 in) long, 9 cm (3.5 in) wide at

its broadest point, and 6 cm (2.5 in) thick. Its mass averages 250 g (8 oz) in

adult females and 300 g (10 oz) in adult males. The heart rests on the

diaphragm, near the midline of the thoracic cavity. It lies in the mediastinum,

a mass of tissue that extends from the sternum to the vertebral column

between the lungs. About two-thirds of the mass of the heart lies to the left of

the bodys midline. Visualize the heart as a cone lying on its side. The pointed

end of the heart is the apex, which is directed anteriorly, inferiorly, and to the

left. The broad portion of the heart opposite the apex is the base, which is

directed posteriorly, superiorly, and to the right.

In addition to the apex and the base, the heart has several surfaces

and borders. The anterior surface is deep to the sternum and ribs. The

inferior surface is the part of the heart between the apex and the right border

and rests mostly on the diaphragm. The right border faces the right lung and

extends from the inferior surface to the base. The left border, also called the

pulmonary border, faces the left lung and extends from the base to the apex.

Layers and Coverings of the Heart


2/19

The heart is located between the lungs in the thoracic cavity and is

surrounded and protected by the pericardium (peri- around). The pericardium

consists of an outer, tough fibrous pericardium and an inner, delicate serous

pericardium. The fibrous pericardium attaches to the diaphragm and also to

the great vessels of the heart. Like all serous membranes, the serous

pericardium is a double membrane composed of an outer parietal layer and

an inner visceral layer. Between these two layers is the pericardial cavity

filled with serous fluid. The wall of the heart has three layers: the outer

epicardium (epi- _ on, upon; cardia _ heart), the middle myocardium (myo

muscle), and the inner endocardium (endo- _ within, inward). The epicardium

is the visceral layer of the pericardium. The majority of the heart is

myocardium or cardiac muscle tissue. The endocardium is a thin layer of

endothelium deep to the myocardium that lines the chambers of the heart

and the valves.

Surface Structures of the Heart


3/19

The human heart has four chambers and is divided into right and left

sides. Each side has an upper chamber called an atrium and a lower chamber

called a ventricle. The two atria form the base of the heart and the tip of the

left ventricle forms the apex. Auricles (auricle- little ear) are pouch-like

extensions of the atria with wrinkled edges. Shallow grooves called sulci

(sulcus, singular) externally mark the boundaries between the four heart

chambers. Although a considerable amount of external adipose tissue is

present on the heart surface for cushioning, most heart models do not show

this. Cardiac muscle tissue that composes the heart walls has its own blood

supply and circulation, the coronary (corona- crown) circulation. Coronary

blood vessels encompassthe heart similar to a crown and are found in sulci.

On the anterior surface of the heart, the right and left coronary arteries

branch off the base of the ascending aorta just superior to the aortic

semilunar valve, and travel in the sulcus separating the atria and ventricles.

These smallarteries are supplied with blood when the ventricles areresting.


4/19

When the ventricles contract, the cusps of the aorticvalve open to cover the

openings to the coronary arteries.

A clinically important branch of the left coronary artery is the anterior

interventricular branch, also known as the left anterior descending (LAD)

branch that lies between the right and left ventricles and supplies both

ventricles with oxygen-rich blood. This coronary artery is commonly occluded

which can result in a myocardial infarct and, at times, death.

Great Vessels of the Heart

The great veins of the heart return blood to the atria and the great

arteries carry blood away from the ventricles. The superior vena cava, inferior

vena cava, and coronary sinus return oxygen-poor blood to the right atrium.

The superior vena cava returns blood from the head, neck, and arms; the

inferior vena cava returns blood from the body inferior to the heart. The

coronary sinus is a smaller vein that returns blood from the coronary

circulation. Blood leaves the right atrium to enter the right ventricle. From

here, oxygen-poor blood passes out the pulmonary trunk, the only vessel that

removes blood from the right ventricle. This large artery divides into the right

and left pulmonary arteries that carry blood to the lungs where it is


5/19

oxygenated. Oxygen-rich blood returns to the left atrium through two right

and two left pulmonary veins. The blood then passes into the left ventricle

that pumps blood into the large aorta. The aorta distributes blood to the

systemic circulation. The aorta begins as a short ascending aorta, curves to

the left to form the aortic arch, descends posteriorly and continues as the

descending aorta.

Internal Structures of the Heart

The heart has four valves that control the one-way flow of blood: two

atrioventricular (AV) valves and two semi lunar valves (semi- half; lunar-

moon). Blood passing between the right atrium and the right ventricle goes

through the right AV valve, the tricuspid valve (tri- three; cusp- flap). The left

AV valve, the bicuspid valve, is between the left atrium and the left ventricle.

This valve clinically is called the mitral valve (miter- tall, liturgical headdress)

because the open valve resembles a bishops headdress. String-like cords
http://www.texasheartinstitute.org/HIC/Anatomy/Anatomy.cfm


6/19

called chordae tendineae (tendinous strands) attach and secure the cusps of

the AV valves to enlarged papillary muscles that project from the ventricular

walls. Chordae tendinae allow the AV valves to close during ventricular

contraction, but prevent their cusps from getting pushed up into the atria.

The two semilunar valves allow blood to flow from the ventricles to great

arteries and exit the heart. Blood in the right ventricle goes through the

pulmonary (semi lunar) valve to enter the pulmonary trunk, a large artery.

The aortic (semi lunar) valve is located between the left ventricle and the

aorta. These two semi lunar valves are identical, with each having three

pockets that fill with blood, preventing blood from flowing back into the

ventricles. The two ventricles have a thick wall between them called the

interventricular septum. Between the two atria is a thinner interatrial septum.

Coronary Circulation

There are two major coronary arteries: the right and the left. These two

arteries branch out of the aorta immediately after the aortic valve. The right

coronary artery splits into the marginal branch, which feeds blood into theright ventricle, and the posterior interventricular branch, which supplies the

left ventricle. The left coronary artery is notably larger than the right

coronary artery because it feeds the left heart, which, as a result of it's more

powerful contractions, requires a more vigorous blood flow. The left coronary

artery splits into the anterior interventricular branch and a circumflex branch.
http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23


7/19

The anterior interventricular branch runs towards the apex of the heart,

providing blood for both of the ventricles and the ventricular septum. The

circumflex branch, on the other hand, follows the groove between the left

atrium and the left ventricle, providing blood supply to both of these

chambers until it reaches and joins with the right coronary artery in the

posterior of the heart.

The coronary arteries are especially subject to blockage and narrowing

which can cause a depletion of blood to certain parts of the heart, possibly

causing a heart attack.

Blood Flow through the Heart
http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/disease/heartattack.htmhttp://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/Structure/coronary.htm#%23http://library.thinkquest.org/C003758/disease/heartattack.htm


8/19

The function of the right side of the heart is to collect de-oxygenated

blood, in the right atrium, from the body and pump it, via the right ventricle,

into the lungs (pulmonary circulation) so that carbon dioxide can be dropped

off and oxygen picked up (gas exchange). This happens through the passive

process of diffusion. The left side (see left heart) collects oxygenated blood

from the lungs into the left atrium. From the left atrium the blood moves to

the left ventricle which pumps it out to the body. On both sides, the lower

ventricles are thicker and stronger than the upper atria. The muscle wall

surrounding the left ventricle is thicker than the wall surrounding the right

ventricle due to the higher force needed to pump the blood through the

systemic circulation.

Starting in the right atrium, the blood flows through the tricuspid valve

to the right ventricle. Here it is pumped out the pulmonary semilunar valve

and travels through the pulmonary artery to the lungs. From there, blood

flows back through the pulmonary vein to the left atrium. It then travels

through the mitral valve to the left ventricle, from where it is pumped

through the aortic semilunar valve to the aorta. The aorta forks and the blood


9/19

is divided between major arteries which supply the upper and lower body.

The blood travels in the arteries to the smaller arterioles, then finally to the

tiny capillaries which feed each cell. The (relatively) deoxygenated blood then

travels to the venules, which coalesce into veins, then to the inferior and

superior venae cavae and finally back to the right atrium where the process

began.

Blood Vessels

Blood circulates inside the blood vessels, which form a closed transport

system, the so-called vascular system. Like a system of roads, the vascular

system has its freeways, secondary roads, and alleys. As the heart beats,

blood is propelled into the large arteries leaving the heart. It then moves

successively smaller and smaller arteries and then into the arterioles, which

feed the capillary beds in the tissues. Capillary beds are drained by venules,

which in turn empty into the great veins (venae cavae) entering the heart.

Thus arteries, which carry blood away from the heart, and veins, which drain

the tissues and return the blood to the heart, are simply conducting vessels.

Only the tiny hair-like capillaries, which extend and branch through the tissue

and connect the smallest arteries (arterioles) to the smallest veins (venules),

directly serve the needs of the body cells. The capillaries are the side streets

or alleys that intimately intertwine among the body cells. It is only through

their walls that exchanges between the tissue cells and the blood can occur.

Layers of Blood Vessel Walls


10/19

The walls of blood vessels have three coats, or tunics.

The tunica intima which lines the lumen or interior of the blood vessels,

is a thin layer of endothelium (squamous epithelial cells) resting on a

basement membrane. Its cells fit closely together and form a slick surface

that decreases friction as blood flows through the vessel lumen.

The tunica media is the bulky middle coat. It is mostly smooth muscle

and elastic tissue. The smooth muscle, which is controlled by the sympathetic

nervous system, is active in changing the diameter of the vessels. As the

vessel constrict or dilate, blood pressure increases or decreases, respectively.

The tunica externa is the outermost tunic; it is composed largely of

fibrous connective tissue. Its function is basically to support and protect the

vessels.

The Microcirculation


11/19

The microcirculation is that portion of the circulatory system for

exchange of water, gases, nutrients, and waste material. As such, it is the

most important part of the cardiovascular system because it is where the

exchange with tissues takes place. Although the microcirculation is

considered as a closed system, its walls are much more permeable than any

other part of the circulation.

Factors Affecting Flow of Blood

The flow of a fluid through a vessel is determined by the pressure

difference between the two ends of the vessel and also the resistance to flow. Pressure Difference. For any fluid to flow along a vessel there must

be a pressure difference otherwise the fluid will not move. In the

cardiovascular system, the pressure head or force is generated by

the pumping of the heart and there is a continuous drop in pressure

from the left ventricle to the tissue and also from the tissue back to the

right atrium.

Resistance to Flow. Resistance is a measure of the ease with which a

fluid flows through a tube: the easier it is the less resistance to flow,

and vice versa. In the circulatory system, the resistance is usually

described as vascular resistance, or also known as peripheral

resistance. Resistance is essentially a measure of the friction between

the molecules of the fluid, and between the tube wall and the fluid. The


12/19

resistance depends on the viscosity of the fluid and the radius and

length of the tube.

Radius of the Tube. The smaller the radius of a vessel, the greater is

the resistance to the movement of particles. Small alterations in the

size of the radius of the blood vessels, particularly of the more

peripheral vessels, can greatly influence the flow of blood.

Atheromatous changes in the walls of large and medium-sized arteries

cause narrowing of the lumen of the vessels and result in an increased

vascular resistance.

Length of the Tube. The longer the tube, the greater the resistance

to the flow of liquid through it. A longer vessel will require a greater

pressure to force a given volume of liquid through it than will a shorter

vessel.

Viscosity of the Fluid. Viscosity is a measure of the intermolecular or

internal friction within a fluid or in other words, of the tendency of the

fluid to resist flows. The greater the viscosity of the fluid, the greater is

the force required to move that liquid.

Blood

Blood is a specialized bodily fluid (technically a tissue) that is

composed of a liquid called blood plasma and blood cells suspended within

the plasma. The blood cells present in blood are red blood cells (also called

RBCs or erythrocytes), white blood cells (including both leukocytes and


13/19

lymphocytes) and platelets (also called thrombocytes). Plasma is

predominantly water containing dissolved proteins, salts and many other

substances; and makes up about 55% of blood by volume. Mammals have

red blood, which is bright red when oxygenated, due to hemoglobin. Some

animals, such as the horseshoe crab use hemocyanin to carry oxygen,

instead of hemoglobin.

By far the most abundant cells in blood are red blood cells. These

contain hemoglobin, an iron-containing protein, which facilitates

transportation of oxygen by reversibly binding to this respiratory gas and

greatly increasing its solubility in blood. In contrast, carbon dioxide is almost

entirely transported extracellularly dissolved in plasma as bicarbonate ion.

White blood cells help to resist infections and parasites, and platelets are

important in the clotting of blood.Blood is circulated around the body through blood vessels by the

pumping action of the heart. Arterial blood carries oxygen from inhaled air to

the tissues of the body, and venous blood carries carbon dioxide, a waste

product of metabolism produced by cells, from the tissues to the lungs to be

exhaled.

Medical terms related to blood often begin with hemo- or hemato- (BE:

haemo- and haemato-) from the Greek word "" for "blood." Anatomically

and histologically, blood is considered a specialized form of connective tissue,

given its origin in the bones and the presence of potential molecular fibers in

the form of fibrinogen.


14/19

Constituents of human blood

Blood accounts for 7% of the human body weight, with an average

density of approximately 1060 kg/m, very close to pure water's density of

1000 kg/m3. The average adult has a blood volume of roughly 5 litres,

composed of plasma and several kinds of cells (occasionally called

corpuscles); these formed elements of the blood are erythrocytes (red blood

cells), leukocytes (white blood cells) and thrombocytes (platelets). By volume

the red blood cells constitute about 45% of whole blood, the plasma

constitutes about 55%, and white cells constitute a minute volume.

Whole blood (plasma and cells) exhibits non-Newtonian fluid dynamics;

its flow properties are adapted to flow effectively through tiny capillary blood

vessels with less resistance than plasma by itself. In addition, if all human

haemoglobin was free in the plasma rather than being contained in RBCs, the

circulatory fluid would be too viscous for the cardiovascular system to

function effectvely.


15/19

Cells

4.7 to 6.1 million (male), 4.2 to 5.4 million (female) erythrocytes: In

mammals, mature red blood cells lack a nucleus and organelles. They contain

the blood's hemoglobin and distribute oxygen. The red blood cells (together

with endothelial vessel cells and other cells) are also marked by glycoproteins

that define the different blood types. The proportion of blood occupied by red

blood cells is referred to as the hematocrit, and is normally about 45%. The

combined surface area of all the red cells in the human body would be

roughly 2,000 times as great as the body's exterior surface.

4,000-11,000 leukocytes: White blood cells are part of the immune

system; they destroy and remove old or aberrant cells and cellular debris, as

well as attack infectious agents (pathogens) and foreign substances. The

cancer of leukocytes is called leukemia.

200,000-500,000 thrombocytes: Platelets are responsible for blood

clotting (coagulation). They change fibrinogen into fibrin. This fibrin creates a

mesh onto which red blood cells collect and clot, which then stops more


16/19

blood from leaving the body and also helps to prevent bacteria from entering

the body.

Plasma

About 55% of whole blood is blood plasma, a fluid that is the blood's

liquid medium, which by itself is straw-yellow in color. The blood plasma

volume totals of 2.7-3.0 litres in an average human. It is essentially an

aqueous solution containing 92% water, 8% blood plasma proteins, and trace

amounts of other materials. Plasma circulates dissolved nutrients, such as,

glucose, amino acids and fatty acids (dissolved in the blood or bound to

plasma proteins), and removes waste products, such as, carbon dioxide, urea

and lactirc acid.

Other important components include:

Serum albumin

Blood clotting factors (to facilitate coagulation)

Immunoglobulins (antibodies)

Various other proteins

Various electrolytes (mainly sodium and chloride)

The term serum refers to plasma from which the clotting proteins have

been removed. Most of the proteins remaining are albumin andimmunoglobulins.

The normal pH of human arterial blood is approximately 7.40 (normal

range is 7.35-7.45), a weak alkaline solution. Blood that has a pH below 7.35

is too acidic, while blood pH above 7.45 is too alkaline. Blood pH, arterial

oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2) and HCO3 are

carefully regulated by complex systems of homeostasis, which influence the

respiratory system and the urinary system in the control the acid-basebalance and respiration. Plasma also circulates hormones transmitting their

messages to various tissues.

Color

Hemoglobin
http://en.wikipedia.org/wiki/Immunoglobulinshttp://en.wikipedia.org/wiki/Immunoglobulins


17/19

Hemoglobin is the principal determinant of the color of blood in

vertebrates. Each molecule has four heme groups, and their interaction with

various molecules alters the exact color. In vertebrates and other

hemoglobin-using creatures, arterial blood and capillary blood are bright red

as oxygen impacts a strong red color to the heme group. Deoxygenated

blood is a darker shade of red with a bluish hue; this is present in veins, and

can be seen during blood donation and when venous blood samples are

taken. Blood in carbon monoxide poisoning is bright red, because carbon

monoxide causes the formation of carboxyhemoglobin. In cyanide poisoning,

the body cannot utilize oxygen, so the venous blood remains oxygenated,

increasing the redness. While hemoglobin containing blood is never blue,

there are several conditions and diseases where the color of the heme groups

make the skin appear blue. If the heme is oxidized, methemoglobin, which is

more brownish and cannot transport oxygen, is formed. In the rare condition

sulfhemoglobinemia, arterial hemoglobin is partially oxygenated, and

appears dark-red with a bluish hue (cyanosis), but not quite as blueish as

venous blood.

Veins in the skin appear blue for a variety of reasons only weakly

dependent on the color of the blood. Light scattering in the skin, and the

visual processing of color play roles as well.

Pancreatic Islets

The pancreas, located close to the stomach in the abdominal cavity is

a mixed gland. Probably the best-hidden endocrine glands in the body are the

pancreatic islets, formerly called the islets of Langerhans. These little masses

of hormone-producing tissue are scattered among the enzyme-producing

acinar tissue of the pancreas. Two important hormones produced by the islet

cells are insulin and glucagons.

High levels of glucose in the blood stimulate the release of insulin from

the beta cells of the islets. Insulin acts on just about all body cells and

increases their ability to transport glucose across their plasma membranes.

Once inside the cells, glucose is oxidized for energy or converted to glycogen


18/19

or fat for storage. These activities are also speeded up by insulin. Since

insulin sweeps the glucose out of the blood, its effect is said to be

hypoglycemic. As blood glucose levels fall, the stimulus for insulin release

ends (negative feedback control). Insulin is the only hormone that decreases

blood glucose levels. Insulin is absolutely necessary for the use of glucose by

the body cells. Without it, essentially no glucose can get into the cells to be

used.

Glucagons act as an antagonist of insulin; that is, it helps to regulate

blood glucose levels but is a way opposite to that of insulin. Its release by the

alpha cells of the islets is stimulated by low blood levels of glucose. Its action

is basically hyperglycemic. Its primary target organ is the liver, which

stimulates to break down stored glycogen to glucose and to release glucose

into the blood.

A. Insulin

The main function of the insulin is to participate in maintaining

homeostasis of blood glucose level and to promote other metabolic activities

that are anabolic. When absorbed nutrients, especially glucose, are in excess

of immediate needs insulin promotes storage.

It reduces high blood nutrients by:

Acting on cell membranes and stimulating uptake and utilization of

glucose by muscles and connective tissue cells;

Increasing conversion of glucose to glycogen, especially in the liver

and skeletal muscles;

Accelerating uptake of amino acids by cells, and the synthesis of

proteins;

Promoting synthesis of fatty acids and storage of fat in adipose tissue,

and;

Preventing the breakdown of protein and fat and gluconeogenesis.

B. Glucagon


19/19

The effect of glucagon is increasing blood glucose levels by

stimulating:

Conversion of glycogen to glucose (in the liver and skeletal muscle);

Gluconeogenesis, the manufacture of glucose by the body from

noncarbohydrate materials.

C. Somatostatin

The effect of somatostatin (also produced by hypothalamus) is to

inhibit the secretion of both insulin and glucagons. It delays intestinal

absorption of glucose.

Metabolism

Metabolism is a broad term referring to all chemical reactions that are

necessary to maintain life. In involves catabolism, in which substances are

broken down to simpler substances, and anabolism, in which larger molecules

or structures are built from smaller ones. During catabolism, energy is

released and captured to make ATP, the energy-rich molecule used to

energize all cellular activities, including catabolic reactions.

Just as an oil furnace uses oil (its fuel) to produce heat, the cells of the

body use carbohydrates as their preferred fuel to produce cellular energy

(ATP). Glucose, also known as blood sugar, is the major breakdown product of

carbohydrate digestion. Glucose is also the major fuel used for making ATP in

most body cells. Basically, the carbon atoms released leave the cells as

carbon dioxide, and the hydrogen atoms removed (which contain energy-rich

electrons) are eventually combined with oxygen to form water. These

oxygen-using events are referred to collectively as cellular respiration.

The overall reaction is summed up simply as:

C6H12O6 + 6 O2 => 6 CO2 + 6 H20 + ATP (energy).

Date post:	29-May-2018
Category:	Documents
Upload:	qtjheng1603
View:	219 times
Download:	0 times

ACS NSTEMI'anaphy

Documents