Cardiovascular system

Cardiovascular SystemCardiovascular System

Denise Chan "Matters of the Heart" Andrew McCaskill Andrew McCaskill

The circulatory system (scientifically known as the cardiovascular system) is an organ system that moves

substances to and from cells; it can also help

stabilize body temperature and pH (part of homeostasis).

The main components of the circulatory system

are the heart, the blood, and the blood vessels.

The human embryonic heart begins beating approximately 21

days after conception, or five weeks after the last normal

menstrual period (LMP), which is the date normally used to date pregnancy. The human heart

begins beating at a rate near the mother’s, about 75-80 beats per

minute (bpm). The embryonic heart rate (EHR) then accelerates

linearly for the first month of beating, peaking at 165-185

bpm. This acceleration is approximately 3.3 bpm per day,

or about 10 bpm every three days, an increase of 100 bpm in

the first month.

Early development

Patrick J. Lynch, medical illustrator; C.

Carl Jaffe, MD,

cardiologist

1. Arteries A. Aorta (the largest artery, carries blood out of the

heart) *Branches of the aorta, such as the carotid

artery, the subclavian artery, the celiac trunk, the mesenteric arteries, the renal

artery and the iliac artery. 2. Arterioles 3. Capillaries (the smallest blood vessels) 4. Venules 5. Veins

A. Large collecting vessels, such as the subclavian vein, the jugular vein, the renal vein and the iliac vein.

**Venae cavae (the 2 largest veins, carry blood into the heart)

They are roughly grouped as arterial and venous, determined by whether the blood in it is flowing toward

or away from the heart. The term "arterial blood" is used to indicate blood high in oxygen.

Types:There are various kinds of blood vessels

AnatomyAll blood vessels have the same basic structure. The inner lining is the endothelium and is surrounded by connective

tissue. Around this there is a layer of vascular smooth muscle, which is highly developed in arteries. Finally, there is a further

layer of connective tissue known as the adventitia, which contains nerves that supply the muscular layer, as well as nutrient capillaries in the larger blood vessels. The hollow

internal cavity in which the blood flows is called the lumen.

Capillaries consist of little more than a layer of endothelium and occasional connective tissue.

Laid end to end, the blood vessels in an

average human body will stretch

approximately 62,000 miles.

Arteries are muscular blood vessels that carry blood away from the heart.

Its proper functioning is responsible for the delivery of oxygen and nutrients to all cells, maintenance of optimum pH,

and the mobility of the elements, proteins and cells of the immune

system. In developed

countries, the two leading causes of death, myocardial

infarction and stroke each may directly

result from an arterial system that has been

slowly and progressively

compromised by years of deterioration.

Blood pressureThe arterial system is the higher-pressure portion of the circulatory

system. Arterial pressure varies between the peak pressure during heart contraction, called the systolic pressure, and the minimum, or

diastolic pressure between contractions, when the heart rests between cycles. This pressure variation within the artery produces the pulse which

is observable in any artery, and reflects heart activity.To withstand and adapt to the pressures within, arteries are

surrounded by varying thicknesses of smooth muscle which have extensive elastic and inelastic

connective tissues.

The pulse pressure, i.e. Systolic vs.

Diastolic difference, is determined

primarily by the amount of blood ejected by each

heart beat versus the volume and elasticity of the major arteries.

Over time, elevated arterial blood sugar, cholesterol, and pressure, Over time, elevated arterial blood sugar, cholesterol, and pressure, smoking, and other factors are all involved in smoking, and other factors are all involved in damaging both the damaging both the

endothelium and walls of the arteriesendothelium and walls of the arteries, resulting in , resulting in atherosclerosis or Diabetes Mellitus.atherosclerosis or Diabetes Mellitus.

Pulmonary arteriesThe pulmonary arteries carry

deoxygenated blood that has just returned from the body to the lungs, where carbon dioxide is exchanged for

oxygen.

Systemic arteriesSystemic arteries deliver blood to the arterioles, and then to

the capillaries, where nutrients and gases are

exchanged.

The AortaThe aorta is the root systemic artery. It receives blood directly from the left ventricle of the heart via the aortic

valve. As the aorta branches, and these arteries branch in turn, they become

successively smaller in diameter, down to the arteriole. The arterioles supply capillaries which in turn empty into

venules.

ArteriolesArterioles, the smallest of the true

arteries, help regulate blood pressure and deliver blood to

capillaries.

Types of Arteries

StructureThe walls of capillaries are composed of only a single layer of cells, the endothelium. This layer is so thin that molecules such as oxygen, water and lipids can

pass through them by diffusion and enter the tissues. Waste products such as carbon dioxide and urea can

diffuse back into the blood to be carried away for removal from the body.

Capillaries are the smallest of a body's blood vessels, measuring 5-10 μm. They connect

arterioles and venules, and they are the blood vessels that most closely interact with tissues.

A vein is a blood vessel that carries blood toward the heart. The study of veins and diseases of the veins is known as

phlebology.

Function:Veins serve to return blood from organs to the heart. The de-oxygenated blood is taken by veins to the right

atrium of the heart. In pulmonary circulation the

pulmonary veins return oxygenated blood from the

lungs to the left atrium, which empties into the left ventricle, completing the cycle of blood circulation.

Most veins have one-way valves called venous valves to prevent

backflow caused by gravity. They also have a thick collagen outer layer, which helps maintain blood pressure and stop blood pooling. The hollow

internal cavity in which the blood flows is called the lumen. Veins are

surrounded by helical bands of smooth muscles which help maintain blood

flow to the right atrium. Fainting can be caused by failure of the

skeletal-muscular pump. Long periods of standing can result in blood pooling in

the legs, with blood pressure too low to ascend to the heart. In these cases the smooth muscles surrounding the veins

become slack and fill with blood, absorbing a large portion of the total blood volume, keeping blood away from the brain

and causing unconsciousness.

Notable veins and vein systemsThe pulmonary veins carry oxygenated blood from the

lungs to the heart. ***The superior and inferior vena cavae carry

deoxygenated blood from the upper and lower systemic circulations, respectively.

***A portal venous system is a series of veins or venules that directly connect two capillary beds. An example of such a

system includes the hepatic portal vein.

List of important named veinsPulmonary veinsPortal vein Superior vena cava Inferior vena cava Femoral vein Jugular veins

William Harvey (April 1, 1578 – June 3, 1657) was an English medical doctor, who is credited with being

the first to correctly describe, in exact detail, the properties of blood being pumped around the body

by the heart. “I profess both to learn and to teach anatomy, not from books

but from dissections; not from positions of philosophers but from the fabric

of nature.”

Having circulated through the body, all the relatively de-oxygenated blood collects in the venous system which coalesces into two major veins: the

superior vena cava (roughly speaking from areas above the heart) and the inferior vena cava (roughly speaking

from areas below the heart). These two great vessels empty into the right

atrium of the heart. The right atrium is the larger of the two atria, although both receive the same amount of blood. The blood is then pumped

through the tricuspid valve, or right atrioventricular valve, into the right ventricle. From the right ventricle,

blood is pumped through the pulmonary semi-lunar valve into the pulmonary artery. This blood enters the two pulmonary arteries (one for each lung) and travels through the

lungs, where it is oxygenated and then flows into the pulmonary veins.

PULMONARY CIRCUIT:

This oxygenated blood then enters the left atrium, which pumps it through the bicuspid valve, also

called the mitral or left atrioventricular valve, into the left

ventricle. The left ventricle is thicker and more muscular than the

right ventricle because it pumps blood at a higher pressure.

From the left ventricle, blood is pumped through the aortic semi-

lunar valve into the aorta, a massive and thick-walled artery. The aorta arches and gives off

major arteries to the upper body before piercing the diaphragm in order to supply the lower parts of

the body with its various branches. Once the blood enters the

peripheral tissues oxygen and nutrients are extracted from it and carbon dioxide and wastes added, and it will again be collected in the

veins and the process will be repeated.

http://www.smm.org/heart/heart/pumping.htm

Systemic Circuit:

Heart Circulation: In Conclusion!

PULMONARY CIRCUIT: (De-Oxygenated Blood) From Body Superior/Inferior Vena Cava Right Atria via Tricuspid Valve Right Ventricle via Pulmonary Valve Pulmonary Arteries To Lungs (L&R)

Systemic Circuit: (Oxygenated Blood) From Lungs Pulmonary Vein Left Atria via Bicuspid Valve Left Ventricle via Aortic Semi-Lunar Valve Aorta to Body

The sinoatrial node (abbreviated SA node) is the impulse generating (pacemaker) tissue located in the right atrium of the

heart. It is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava. Although all of the Although all of the

heart's cells possess heart's cells possess the ability to the ability to generate the generate the

electrical impulses electrical impulses (or action (or action

potentials), the potentials), the sinoatrial node is sinoatrial node is

what normally what normally initiates itinitiates it, ,

sometimes called the sometimes called the primary pacemaker..primary pacemaker..

Cells in the SA node will Cells in the SA node will naturally discharge naturally discharge

(create action (create action potentials) at potentials) at about 70-about 70-

80 times/minute80 times/minute. .

The atrioventricular node (abbreviated AV node) is an area of

specialized tissue between the atria and the ventricles of the

heart, which conducts the normal electrical impulse from the atria to

the ventricles.

Acute myocardial infarction (AMI or MI), commonly known as a heart attack, is a disease

state that occurs when the blood supply to a part of the

heart is interrupted. The resulting ischemia or oxygen shortage causes damage and

potential death of heart tissue. It is a medical emergency, and the leading cause of death for both men and women all over

the world.

Important risk factors are a previous history of vascular disease such as atherosclerotic coronary heart disease and/or angina a previous heart attack or stroke any previous episodes of abnormal heart rhythms or syncope older age—especially men over 40 and women over 50 smoking excessive alcohol consumption the abuse of certain illicit drugs high triglyceride levels high LDL ("Low-density lipoprotein") and low HDL ("High density lipoprotein") diabetes high blood pressureD obesity and chronically high levels of stress in certain persons.

The term myocardial infarction is derived from myocardium

(the heart muscle) and infarction (tissue death due to oxygen starvation). The phrase

"heart attack" is sometimes used incorrectly to describe sudden cardiac death, which

may or may not be the result of acute myocardial infarction.

Classical symptoms of acute myocardial infarction include chest pain, shortness of breath, nausea,

vomiting, palpitations, sweating, and anxiety or a feeling of impending doom. Patients frequently feel

suddenly ill. Women often experience different symptoms than men. The most common symptoms of MI in women include shortness of breath, weakness, and fatigue. Approximately one third of all myocardial infarctions

are silent, without chest pain or other symptoms.

The jugular veins are veins that bring

deoxygenated blood from the head back to

the heart via the superior vena cava.

The are two sets of jugular veins: external and internal.

The internal jugular runs with the common carotid artery and vagus nerve inside the carotid

sheath. It provides venous drainage for the contents of the

skull.

The external jugular runs superficially to

sternocleidomastoid.

Both connect to the brachiocephalic veins, the

external jugular joining more laterally than the internal. The brachiocephalic veins then join the subclavian veins from both

sides then join to form the superior vena cava.

The Jugular: The Main Brain Draining Vein

In human anatomy, the common carotid artery is an artery that

supplies the head and neck; it divides in the neck to form the external and

internal carotid arteries.The common carotid artery is a paired structure,

meaning that there are two in the body, one for each

half. The left and right common carotid arteries follow the

same course with the exception of their origin. The right common carotid originates in the neck from the brachiocephalic trunk.

The left arises from the aortic arch in the thoracic

region.

Renal Artery

The renal arteries normally arise off the side of the abdominal aorta and supply the kidneys with blood. The

renal arteries carry a large portion of total blood flow to the kidneys. Up to a third of total cardiac output can pass

through the renal arteries to be filtered by the kidneys.The arterial supply of the kidneys is variable and there may be one or more renal arteries supplying each kidney. It is

located above the renal vein.

The renal veins are veins that drain the kidney. They connect the kidney to the

inferior vena cava.

Because the inferior vena

cava is on the right half of the body, the left renal vein is generally the longer of the

two.

The hepatic portal vein, a large vein that carries blood from the digestive tract to the liver.The portal venous system is responsible for directing

blood from parts of the gastrointestinal tract to

the liver. Things absorbed in the small intestine, for example, would be taken to the liver for processing before being sent to the

heart. Many drugs that are absorbed through the GI

tract are substantially metabolized by the liver before reaching general

circulation.

The subclavian artery is a major artery of the upper

thorax that mainly supplies blood to the head and arms. It is located below the clavicle,

hence the name. There is a left subclavian and a right

subclavian.

The subclavian veins are two large veins, one on

either side of the body. Its diameter is approximately

that of a man's small finger. Each subclavian drains the

extremities and upper thorax.

The axillary artery is a large blood

vessel that conveys oxygenated blood to the lateral aspect of the thorax, the axilla

(armpit) and the upper limb. Its origin

is the subclavian artery.

The axillary vein is a large blood vessel that conveys

blood from the lateral aspect of the thorax, axilla

(armpit) and upper limb toward the heart. There is one axillary vein on each

side of the body.

The common iliac arteries are two large arteries that originate

from the aorta and supply all lower extremities. There are two

divisions: the external iliac artery and internal iliac artery.

The common iliac veins are formed by the

external iliac veins and internal iliac

veins and together, in the abdomen, form the inferior vena cava. They drain blood from the

pelvis and lower limbs.

Iliac artery and vein

The femoral vein is a blood vessel that

accompanies the femoral artery. The femoral vein returns de-oxygenated

blood to the inferior vena cavae.

In anatomy, the femoral artery is a large artery in the muscles of the thigh that supplies the lower

extremities with needed oxygen.

The pulmonary arteries carry blood from the heart to the lungs. They are the only arteries (other

than umbilical arteries in the fetus) that carry deoxygenated blood.

Pulmonary hypertension occurs alone and as a

consequence of a number of lung diseases. It can be a consequence

of heart disease.

Patrick J. Lynch, medical illustrator; C. Carl Jaffe, MD, cardiologist. http://creativecommons.org/licenses/by/2.5/

Pulmonary Arteries

Pulmonary Veins

200 million RBSs 200 million RBSs are produced daily are produced daily

by the by the hematopoetic hematopoetic tissue in bone tissue in bone

marrowmarrow

About the About the same number same number of RBCs are of RBCs are broken down broken down by the spleen by the spleen and converted and converted into bilirubin into bilirubin which (along which (along with bile) help with bile) help break down break down

fats. fats.

Phenotype Genotype

A AA or AO

B BB or BO

AB AB only

O OO only

Multiple Allele TraitsTraits that are controlled by more than two alleles. Blood type in humans is controlled by three alleles: A, B, and O

www.biologycorner.com/bio2/specialgenetics.html

Blood TransfusionsBlood can only be transferred to a body of a person who's immune system will "recognize" the blood. A and B are antigens on the blood that will be recognized. If the antigen is unfamiliar to the body, your body will attack and destroy the transfused blood as if it were a hostile invader (which can cause death).O is like a blank, it has no antigens. O is called the universal donor because a person can receive a transfusion from O blood without having an immune responseAB is the universal acceptor, because a person with AB blood has both the A and B antigens already in the body, A and B blood can be transfused to the person (as well as O) and the body will recognize it and not attack.

Conclusion: Circulatory System

Blood Clotting Cascade

The circulatory system, just like any other system, is a complex,

interrelated, system with multiple parts that function as a whole. The

circulatory system exhibits “irreducible complexity” in the highest

degree. The heart without the complex arterial system would be useless. The arterial system alone

would be useless without the venous system (and its many valves) to return the blood to the heart. The complexity

of the heart alone is enough to astound anyone, let alone the system

of vessels that accompany the passage of blood to every cell of the body. Considering the relatedness to every other system of the body makes

the circulatory system the most essential system of the human body.