Chapter 8-Blood, Circulation and Vessels the Cardiovascular System

Blood makeup of the body

• average-sized adult body contains approximately 4 to 6 liters of blood

• approximately 8 percent of the total body weigh

  • varies from person to person depending on

    • person’s size

    • the amount of adipose tissue

    • concentrations of certain ions in the blood

Blood essential functions

• It carries oxygen and nutrients to tissues and carbon dioxide and wastes away from tissues.

• It also acts as the transport mechanism for hormones and helps with heat regulation of the body.

• The process of transporting blood to and from the body tissues is known as circulation.

  • The heart’s powerful muscular pump performs the task of circulation.

• primary function of blood

  • deliver oxygen and nutrients to

  • remove wastes from body cells.

• Also include

  • defense (protection)

  • distribution of heat

  • maintenance of homeostasis (regulation).

Blood as a connective tissue

• It is a connective tissue

• it is made up of cellular elements and an extracellular matrix

The cellular elements of bloods

• - termed the formed elements

• include

  • red blood cells (RBCs)

  • white blood cells (WBCs)

  • cell fragments called platelets.

The extracellular matrix of blood 

• called plasma

• makes blood unique among connective tissues because it is fluid

  • mostly water

  • suspends the formed elements

    • enables them to circulate throughout the body within the cardiovascular system.

Blood function for Transportation 

• Deliver oxygen we breathe from the lungs to the heart and nutrients from the digestive system to all body cells.

• Transport hormones from the endocrine glands into the bloodstream, which carries them to the target cells.

• Blood also picks up cellular wastes and byproducts and transports them to various organs for removal.
  

  • For instance

    • blood moves carbon dioxide to the lungs for exhalation from the body,

    • various waste products are transported to the kidneys and liver for excretion from the body in the form of urine or bile.

Blood function for Defense (Protection)

• Prevent Infection:

  • WBCs protect the body from disease-causing bacteria that have entered the bloodstream in a wound.

  • WBCs like lymphocytes seek out and destroy internal threats, such as

    • cells with mutated DNA that could multiply to become cancerous,

    • body cells infected with viruses

• Prevent Blood Loss:

  • When damage to the vessels results in

    • bleeding

    • platelets and plasma protein

    • initiate clot formation

      • halting further blood loss.

Blood functoin of Maintenance of Homeostasis (Regulation)

• Maintaining body temperature by

  • absorbing and distributing heart throughout the body

    • and to the surface of the skin to encourage heat loss.

  • In contrast, on a cold day, blood is diverted away from the skin to maintain a warmer body core.

    • In extreme cases, this may result in frostbite.

• Maintain the chemical balance of the body.

  • Proteins and other compounds in blood act as buffers,

    • help to regulate the pH of body tissues.

  • regulate the water content of body cells and the circulatory system.

Hematopoiesis

• formation of blood cells from

  • stem cells

  • both red and white

Location of Hematopoiesis in fetal development (Early Life stages)

• Blood cells made in the

  • yolk sac

  • liver

  • spleen.

Location of Hematopoiesis in After birth (Later Life stages)

• blood cells are produced in

  • red bone marrow by stem cells

    • called hemocytoblasts.

average life span of an RBC

120 days, so red bone marrow is constantly making new cells.

hormone erythropoietin

• responsible for regulating erythropoiesis or the production of RBCs.

• is produced by the kidneys

  • released by the kidneys when oxygen concentrations in the blood get low.

• stimulates the red bone marrow to produce new RBCs.

dietary factors that affect RBC production.

• Vitamin B12 (major dietary factor)

  • requires intrinsic factor to be absorbed

  • absorbed from small intestine

  • Function for DNA synthesis

• folic acid (major dietary factor)

  • absorbed from small intestine

• Iron

  • required to make hemoglobin

  • Absorbed from small intestine

  • conserved during RBC destruction to be reused

some causes of anemia

• Too few RBCs

• too little iron

• too little hemoglobin

• insufficient vitamin B12 

Plasma

• straw colour liquid portion of blood

• 90% water

• contain many different dissolve solutes, including

  • nutrients

  • gases

  • hormones

  • protein

  • electrolytes

  • waste and products of cells activity.

three major types of proteins found in plasma:

• Albumins

• Globulins

• Fibrinogen

Albumins (major plasma protein)

• smallest of the plasma proteins,

• most abundant plasma proteins

  • account for about 60% of plasma protein.

• produced by the liver

• are responsible for the osmotic pressure in blood vessels

  • along with hydrostatic pressure

• control movement of water between blood vessels and the tissues.

• transport

  • hormones

  • some drugs

  • free fatty acids

  • bilirubin.

• Function

  • Helps maintain colloid osmotic pressure

Globulins (major plasma protein)

• 36 % of plasma proteins

• proteins produced by

  • liver plasma cells

    • specialized blood cells

    • (lymphatic tissue)

• Some types of globulins are involved in

  • lipid transport

  • those produced by plasma cells are antibodies

    • work as part of the immune system

Alpha globulins

• Origin: Liver

• Function

  • Transport lipids and fat-soluble vitamins

Beta globulins

• Origin: liver

• Function

  • Transport lipids and fat-soluble vitamins

Gamma globulins

• Origins: Lymphatic tissues

• Function

  • Antibodies (immunoglobulins)

Fibrinogen (major plasma protein)

• Origin: liver

• 4 % of total protein plasma 

• Is a protein important in blood clotting.

• The term serum is used for the fluid that is left when all clotting factors are removed from plasma.

• Function 

  • Plays a key role in blood

    coagulation

serum

• the fluid that is left when all clotting factors are removed from plasma

  • free of Fibrinogen 

Nutrients in plasma

• amino acids

• glucose

• nucleotides

• lipids that have all been absorbed from the digestive tract.

lipoproteins

• Lipids transported throught the blood (specifically blood plasma)

• lipids are not water soluble and because plasma is mostly water, lipids must combine with molecules called lipoproteins to be transported by plasma.

• different types of lipoproteins are chylomicron,

  • 3 Types

    • very low-density lipoproteins (VLDL)

    • low-density lipoproteins (LDL)

    • high-density lipoproteins (HDL).

Gases dissolved in plasma

• oxygen

• carbon dioxide

• nitrogen

Electrolytes dissolved in plasma

• sodium

• potassium

• calcium

• magnesium

• chloride

• bicarbonate

• phosphate

• sulfate

Nonprotein nitrogenous substances in plasma

• amino acids

• urea

• uric acid

The formed elements of blood are (Cellular Components)

• erythrocytes

• leukocytes

• platelets

Erythrocytes (RBCs; cellular component of blood)

• are small cells that have a biconcave shape.

• Mature RBCs do not have a nucleus and consequently cannot reproduce themselves.

• contain a pigment called hemoglobin

  • function is to bind to oxygen and transport it to the tissues.

hematocrit

• percentage of red blood cells in relationship to the total blood volume

• normal hematocrit in males

  • 43 to 49 L/L in males

• normal hematocrit female

  • is about 37 to 43 L/L

Centrigufation of blood

• the heavier red blood cells settle to the bottom and can thus be measured.

• The percentage of red blood cells in relationship to the total blood volume is called the hematocrit or packed cell volume.

  • A normal hematocrit is about 37 to 43 L/L in females and 43 to 49 L/L in males.

• On top of the RBCs is the plasma

  • the lighter component, approximately 55 percent of the total blood volume

• Between the RBCs and the plasma is a thin layer that is whitish in color and is called the “buffy coat.”

  • made up of white blood cells and platelets

  • make up roughly 1 percent of the total blood volume.

Hemoglobin

• is made of red pigment

• heme bound to protein globulin

• bind to oxygen and transport it to the tissues.

• In the lungs, hemoglobin picks up oxygen, which binds to the iron ions

  • bright red 

  • forming oxyhemoglobin

• In the body tissue the process is reversed, where it releases some of the oxygen molecules, becoming darker red

  • deoxyhemoglobin, sometimes referred to as reduced hemoglobin.

• Carboxyhemoglobin refers to hemoglobin that is carrying carbon dioxide.

Normal RBC count 

Adults male 

• 5.5 x10¹²/L of blood

Adult female 

• 4.5 x10¹²/L of blood.

oxyhemoglobin

• In the lungs, hemoglobin picks up oxygen, which binds to the iron ions

• bright red color

deoxyhemoglobin

• sometimes referred to as reduced hemoglobin

• blood that released some of the oxygen molecules

• darker red color

Carboxyhemoglobin

refers to hemoglobin that is carrying carbon dioxide.

Anemia (RBC disordeR)

• occurs when the blood has less than its normal oxygen-carrying capacity.

• occur when the following is less than normal 

  • the red blood cell count

  • hemoglobin concentration, is less than normal.

    • Normal in Men:

      • 13.8 to 17.2 grams/L

    • Women

      • 2.1 to 15.1 grams/L.

  • A normal hemoglobin level in men is 13.8 to 17.2 grams/L and in women is 12.1 to 15.1 grams/L.

• Signs and symptoms of all forms of anemia

  • tiredness

  • weakness

  • pallor

  • tachycardia

  • numbness or coldness of the hands and feet,

  • dizziness

  • headache

  • jaundice.

Iron deficiency anemia:

• Iron is needed to make hemoglobin, so people with low iron levels often have correspondingly low hemoglobin levels.

• The RBC’s are small (microcytes) and pale because they cannot synthesize their normal amount of hemoglobin.

• Pregnant women and women with heavy menstrual cycles are most susceptible to this type of anemia.

• Others with chronic bleeding conditions are also at risk of developing this type of anemia.

  • such as

    • ulcers

    • colon cancer

Aplastic anemia

• When the bone marrow is destroyed

  • the result is aplastic anemia.

• The following can desotry all bone marrow

  • Chemotherapy and radiation therapy

  • some cancers and toxins,

• Because the bone marrow is destroyed

  • the number of all formed elements produced by the body is also affected.

Hemolytic anemia:

• Red blood cells are destroyed faster than they can be produced.

  • Example sickle cell disease

Sickle cell disease (a type of hemolytic anemia)

• a genetic disorder

  • autosomal recessive condition.

• Under certain conditions, RBCs that are normal in shape will sickle and this will cause them to get stuck in capillaries.

• Symptoms/episodes that occur

  • joint and chest pain

  • numbness in the hands and feet

  • jaundice

  • frequent infections

  • sores on the skin

  • delayed growth

  • stroke

  • seizures

  • breathing difficulties

  • Retina damage

    • causes vision problems,

  • damage to

    • spleen

    • liver

    • kidney

    • lung damage

• no cure for sickle cell disease

• it can be treated or managed with

  • antibiotics

  • blood transfusions

  • pain medications

  • bone marrow transplants

  • supplemental oxygen

  • medications to promote the development of normal hemoglobin.

Megaloblastic anemia:

• Megaloblastic refers to the large red blood cells that are seen in this condition.

• caused by deficency of

  • Vitamin B12 and folic acid

  • required for the synthesis of erythrocytes

• Intrinsic factor is required for absorption of vitamin B12 by the body.

  • A deficiency of intrinsic factor

    • a chemical secreted by the parietal cells of the stomach

  • is responsible for the lack of absorption of vitamin B12 by the gastrointestinal tract.

Thalassemia (a type of anemia)

• is an inherited form of anemia

• defective hemoglobin molecule

• causing

  • microcytic

    • red blood cells that are smaller than normal

  • hypochromic

    • red blood cells that are paler than normal

  • short-lived RBCs.

Etiology

• hereditary.

  • Patients of Mediterranean descent are most likely to carry

  • the defective autosomal recessive gene that causes this disease.

• Comes in two forms:

  • thalassemia major,

    • severe form of the disease

  • thalassemia minor,

    • only minimal symptoms,

    • considered to be the “carrier” form of the disease.

Signs and Symptoms:

• Thalassemia major

  • is evident in infancy with

    • anemia

    • fever

    • failure to thrive

    • splenomegaly.

  • It is confirmed by characteristic changes in RBCs noted on microscopic examination.

  • As the child matures, splenomegaly may interfere with breathing.

  • skin becomes freckled or bronzed from the iron deposits created by the rapidly destroyed RBCs.

  • Headache

  • nausea

  • anorexia

Treatment:

• There is no cure for thalassemia.

• Frequent transfusions are necessary to treat the anemia caused by the destruction of the defective RBCs.

• A splenectomy may be recommended to slow the destruction of erythrocytes.

Leukocytes (WBC)

• are critical to our defense of disease

• Unlike RBCs, all white blood cells contain a nucleus.

• Two groups

  • whether or not they have granules in their cytoplasm

    • granulocytes

      • have granules in their cytoplasm

      • include

        • neutrophils,

        • eosinophils

        • basophils.

    • agranulocytes

      • do not have granules in their cytoplasm

      • include

        • monocytes

        • lymphocytes.

Neutrophils (granulocytes)

• account for about 60 percent of the WBC count.

• They have a nucleus with three to five lobes

• have phagocytic qualities.

• They are important in

  • the destruction of bacteria

  • their numbers increase in the early stage of acute inflammation.

Eosinophils (granulocytes)

• account for about 3 percent of all WBCs.

• They have reddish-orange cytoplasmic granules

• are involved in fighting parasitic infections

• increased in number in people with acute or active allergies.

Basophils (granulocytes)

• account for less than 1 percent of all WBCs

• They have purplish-black cytoplasmic granules

• release substances such as

  • histamine,

    • promotes inflammation,

  • heparin

    • is an anticoagulant.

Lymphocytes (agranulocytes)

• account for about 30 percent of all WBCs

• participate in immunity

• are white blood cells with large nucleus and small rim of cytoplasm

• they play an important role in the

  • lymphatic system

  • immune system.

A WBC count

• is the number of WBCs found in one cubic millimeter of blood

• this count is normally between 5.0 and 11.0 X10⁹/L cells.

Leukocytosis

A WBC count that is significantly elevated.

• can be caused by

  • infection

  • cancer

  • by some drugs.

• It can also occur after eating a large meal or experiencing stress.

Leukopenia

A WBC count below normal

• can be caused by

  • viral infections

  • congenital bone marrow disorders

  • cancer

  • immune disorders

  • some drugs.

Leukemia (Leukocytes Disorder)

• A neoplastic condition in which the bone marrow produces a large number of WBCs that are not normal.

• These abnormal cells prevent normal WBCs from carrying out their defensive functions.

• Several different kinds of leukemia exist:

  • acute lymphocytic leukemia

    • related to lymphs

  • acute myelogenous leukemia

    • related to bone marrow

  • chronic lymphocytic leukemia

  • chronic myelogenous leukemia.

Etiology:

• Causes of leukemia include

  • mutations in WBCs

    • via exposure to environmental and chemical agents

  • chemotherapy for the treatment of other cancers

  • genetic factors.

Signs and Symptoms:

• fatigue

• dyspnea on exertio

  • shortness of breath

• hepatomegaly or splenomegaly or both

• swollen lymph nodes

• abnormal bruising

• wounds that heal slowly

• frequent infections

• nosebleeds

• bleeding gums

• chronic fever

• unexplained weight loss,

• excessive sweating.

Treatment:

• chemotherapy

• radiation therapy,

• medications to strengthen the immune system

• antibodies to destroy mutated WBCs

• bone marrow transplant

• stem cell transplant.

Platelet (Thrombocytes)

• is not a cell but rather a fragment of the cytoplasm of a cell in the bone marrow called a megakaryocyte.

• Megakaryocytes are descended from myeloid stem cells and are large, typically 50–100 µm in diameter, and contain an enlarged, lobed nucleus.

• do not have a nucleus and are essential to blood clotting.

• When blood vessels are ruptured or their lining is injured, platelets form a temporary plug by sticking to the damaged site.

healthy individuals there are between

• 130.0 and 360.0 platelets X10⁹/L of blood.

Thrombocytopenia (Disorders of Platelets)

• A condition in which there are too few platelets

• blood may not clot properly causing excessive bleeding

• The bleeding may be mild or life threatening.

• can be caused by

  • leukemia

  • medications, or even idiopathic reasons.

Thrombocythemia/ Thrombocytosis(Disorders of Platelets)

• An increase in the platelet count.

• Although in most cases the situation is benign

  • can cause

    • serious thrombus

    • embolus formation

      • unwanted blood clots both of which can life threatening.

• The cause may be

  • idiopathic

  • secondary to cancer

  • hemorrhage

  • infection

  • possibly more

Blood Test

• Complete blood count (CBC)

• Differential Cell Count

• Platelet count

• Prothrombin time (PT/INR)

• Partial Thromboplastin time (PTT)

• Special Coagulation Studies e.g. Factor Assay

• Iron and Total iron binding capacity studies

• Vit B12 and Folic Acid

• ABO (blood group) and Rh factor

• Blood group antibody test

• Reticulocyte count

• RBC Electrophoresis

• Blood test for various cancer

• Various Chemistries and Microbiology tests

Blood Vessels

transport channels through which the blood travels

• form a close delivery system that begins and ends at the heart.

• The three major types of blood vessels are

  • arteries

    • carry blood away from the heart and the blood in them is oxygenated

    • (an exception is the pulmonary arteries that carry deoxygenated blood to the lungs for oxygenation).

  • veins

    • carry blood toward the heart and carry deoxygenated blood

    • (the exception is the pulmonary veins that carry oxygenated blood from the lungs back to the heart).

  • capillaries

Arteries and arterioles

• deliver oxygen and nutrients to the tissues.

• are high-pressure vessels.

• Arteries have three layers, or tunics. Listed in order from the most interior layer adjacent to the lumen to the outermost layer

  • tunica intima

  • tunica media

  • tunica externa.

tunica intima (layer of the arteries)

• most interior layer

• is made up of a single layer of squamous epithelium called endothelium.

tunica media (layer of the arteries)

• medial layer 

• is made up of smooth muscle

  • is thicker in some arteries than others.

• The smooth muscle can cause vasoconstriction or vasodilation.

tunica externa (layer of the arteries)

• outermost later

• is made up of connective tissue.

Veins and venules

• Blood is under much lower pressure in the veins than in the arteries.

• Veins also have a

  • tunica intima

  • tunica media

    • is thinner, with less smooth muscle to move the blood along its way. Than arteries

  • tunica externa.

• depend on two mechanisms to return blood to the heart.

  • One is the pumping action of skeletal muscle such as in the legs.

  • The other is pressure changes in the thoracic cavity that “draw” blood toward the heart.

• Also, veins have valves that work to prevent blood from “falling down” due to gravity as it moves toward the heart.

Capillaries

• are the smallest of the blood vessels

  • RBC pass through them in single file

• high preassure, cause blood plasma to leak

  • called interstitial fluid (exchange site of blood and tissue) 

    • contains

    • water

    • nutrients

    • hormones

    • gasses

    • waste

    • small proteins of blood

• They connect arterioles to venules

• they are abundant/numerous 

• have very thin walls

  • only about one cell layer thick.

  • The allow substances to easily pass into and out of capillaries.

• they are referred to as exchange vessels.

  • exchanging between tissues

    • waste

    • nutrients

    • gasses

      • O2 and CO2 readily diffuse in and out

    • hormones
      

• Have precapillary sphincters that control

  • the amount of blood that flows into them.

• The substances that move through the capillary walls do so through

  • diffusion

  • filtration

  • osmosis.

• Because blood is under pressure as it enters the capillary,

  • water is forced through the capillary wall via filtration.

  • This allows water to enter a tissue fluid of the body.

  • By the time blood leaves a capillary, it has a high solid concentration and a low water concentration;

    • water therefore moves back into the capillary through osmosis.

    • Water always moves toward the greater concentration of solids, if possible.

Aneurysm (circulation disorders)

• results from a ballooned, weakened arterial wall.

• An aortic aneurysm is a bulge in the wall of the aorta.

• Most aortic aneurysms occur in the abdominal aorta but some occur in the thoracic aorta.

• Most aortic aneurysms do not rupture

  • However, when they do, the resulting hemorrhage is a serious life-threatening emergency.

Etiology:

• Most causes of aneurysms are unknown.

• One identified risk to developing an aneurysm is atherosclerosis,

  • hardening of the fatty plaque deposits within the arteries

  • sometimes associated with a diet high in fat and cholesterol.

• Smoking and obesity also increase the risk of atherosclerosis.

• Congenital conditions (present from birth) may cause an aneurysm

  • some individuals are born with weak aortic walls.

• A traumatic injury to the chest may also be a risk factor.

Signs and Symptoms:

• There are often no signs and symptoms of an aneurysm

Treatment:

• surgery to repair the aneurysm. 

Thrombophlebitis (circulation disorders)

is a condition in which a thrombus and inflammation develop in a vein. 

Etiology: 

• The causes and risk factors include

  • prolonged inactivity

  • oral contraceptives

  • postmenopausal hormone replacement therapy

  • some cancers

  • paralysis in the arms or legs

  • the presence of a venous catheter

  • family history of this condition

  • varicose veins

    • enlarged, twisted veins

  • trauma to veins

Signs and Symptoms: 

• The most common symptoms are

  • tenderness and pain in the affected area

  • redness

  • swelling

  • tenseness of the affected areas

  • fever;

  • a positive Homan’s sign. 

    • A positive sign is present when there is pain in the calf or popliteal region when the foot is dorsiflexed with the knee flexed to 90 degrees.

Treatment: 

• This disorder is treated by

  • the application of heat to the affected area

  • elevation of the legs

  • anti-inflammatory drugs

  • anticoagulant medications

  • the wearing of support stockings

  • removal of varicose veins

  • Surgery to remove the clot may be needed in some cases.

Varicose veins (circulation disorders)

are tortuous or twisted, dilated veins that are usually seen in the legs.

when they occur in the rectum, they are called hemorrhoids.

Etiology: 

• may be caused by

  • prolonged sitting or standing

  • damage to valves in the veins

  • a loss of elasticity in the veins

  • obesity

  • pregnancy

  • use of oral contraceptives

  • hormone replacement therapy.

  • Family history also seems to play a part in the development of varicose veins. 

Signs and Symptoms: 

• discomfort in the legs

• discoloration around the ankles

• clusters of veins

• enlarged dark veins that are seen through the skin.

Treatment: 

• sclerotherapy

  • a medical procedure that treats varicose and spider veins by injecting a solution that scars and closes the vein.

• laser surgery

• vein stripping

• endoscopic vein surgery to close off affected veins.

Veins Used for Blood Collection

The three veins in the anti-cubital area are the first choice for blood collection

1. The median cubital vein

   • is the first choice for blood collection

   • usually large, visible, well anchored and does not bruise easily.

   • It’s a superficial vein, most commonly used for venipuncture

   • it lies over the cubital fossa and serves as an anastomosis between the cephalic and basilic veins.

2. The cephalic vein

   • is the second choice for blood collection.

   • This vein is not as well anchored and is usually more difficult to find.

   • It can be followed proximally where it empties into the axillary vein.

3. The basilic vein

   • is the third choice for blood collection

   • should only be considered if the median cubital and cephalic veins in both arms have been ruled out.

   • It is a high-risk area due to the proximity of nerves.

   • In addition, this vein tends to roll away and bruise more easily.

   • It divides to join the brachial vein.

Arteries Used for Blood Collection (see diagram)

• Doctors and respiratory technologist draw Blood Gas Samples from arteries.

• MLA/T’s do not do the procedure as it is outside their legal scope of practice in Canada.

• The sample can be obtained either through a catheter placed in an artery, or by using a needle and syringe to puncture an artery.

  • These syringes are pre-heparinized and handled to minimize air exposure that will alter the blood gas values.

• The first choice is the radial artery, which is located on the thumb side of the wrist

  • because of its small size

  • use of this artery requires extensive skill in arterial blood sampling.

  • Alternative sites for access are

    • brachial arteries

    • femoral arteries

The Heart

• size of a fist

• hollow cone shaped heart

• weights about 250-350 grams

• pumps several thousand gallons of blood in a day and several millions of gallons each year

The cardiovascular system consists

• consists of the

  • heart (a pump)

  • the vascular system

    • (a collection of pipes making up a plumbing system).

• The main function of this system is to

  • supply oxygen and nutrients to the tissues of the body

  • to remove carbon dioxide and waste products.

Location of the heart

• Lies behind the sternum

  • just slightly to the left of midline of the body

  • occupies a space called the thoracic mediastinum (middle septum) that is

    • located between the right and left lungs.

• The heart extends from the level of the second rib to about the level of the sixth rib.

• Inferiorly, the heart rests on the diaphragm.

• The heart has

  • four borders

    • superior

    • inferior

    • medial, lateral

• three surfaces

  • sternocostal

  • diaphragmatic

  • pulmonary

• The superior border is called the base and is wider than the inferior surface which is called the apex.

Chambers of the heart

• There are two atria that sit on two ventricles.

  • Right and left atrium (receiving chambers)

  • Right and left ventricle (pumping chamber)

• Atria are separated by a septum or wall called the interatrial septum

• the ventricles are separated by a wall called the interventricular septum.

• There is also a septum that separates the atria from the ventricles, the atrioventricular septum.

• The right atrium receives blood that is returning from the body to the heart and blood from the coronary sinus.

  • The right ventricle receives blood from the right atrium.

• The left atrium forms most of the base of the heart.

  • Four pulmonary veins carrying oxygenated blood enter the left atrium.

  • The left ventricle receives blood from the left atrium.

    • works harder than any other chamber because it pumps oxygenated blood out of the heart via the aorta into the systemic circulation.

    • Its myocardium is twice as thick as that of the right ventricle.

Valves of the heart

make blood flow in one direction

Tricuspid valve

• (also called the right AV or atrioventricular valve)

• located between the right atrium and right ventricle.

• named because

  • the valve consists of three cusps or leaflets

• These three cusps together prevent blood from flowing back into the right atrium

  • when the right ventricle contracts.

• The cusps of this valve are anchored by cordlike structures called chordae tendinae

  • to specialized cardiac muscle called papillary muscles.

    • These muscles contract when the ventricles contract.

Pulmonary semilunar valve:

• It is situated between the right ventricle and the trunk of the pulmonary arteries.

The bicuspid valve

• This valve is also known as the mitral valve or the left AV valve.

• has two cusps

• is located between the left atrium and the left ventricle.

• Like the tricuspid valve

  • the bicuspid valve also has chordae tendinae attached to papillary muscles.

The aortic semilunar valve

is positioned between the left ventricle and the aorta.

Layers of the heart

• endocardium

  • The innermost layer

  • It is very thin and lined with endothelium.

• muscular myocardium

  • The middle layer

  • makes up over 90 percent of the heart.

  • It is the myocardium that is responsible for the pumping action of the heart.

• epicardium

  • The outermost layer

  • also known as the visceral pericardium

  • it contains fat,

    • helps cushion the heart if the chest experiences blunt trauma.

Pericardium

• The entire membrane around the heart

• covers the heart and the large blood vessels attached to it.

2 layers

• consists of an outer fibrous layer

  • called the parietal pericardium

• an innermost layer

  • called the visceral pericardium

    • which lies directly on top of the heart.

Together, the visceral and parietal pericardia (plural) form the pericardial sac.

• A very small amount of serous (watery) fluid is found with the sac and acts to reduce friction between the two membranes.

Pulmonary circulation (memorize the flow)

• is referred to as the low-pressure circuit

  • because the blood pressure here is normally only one-eighth of that in the systemic circuit.

• The purpose of this circuit is to take deoxygenated blood to the lungs and exchange carbon dioxide for oxygen.

  • The blood returning to the heart is oxygenated blood.

• The route of the pulmonary circuit can be summarized as follows:

  1. right atrium

  2. through the tricuspid valve into the right ventricle

  3. through the pulmonary semilunar valve into the pulmonary trunk

  4. into the pulmonary arteries

  5. into the lungs

  6. into pulmonary veins

  7. finally into the left atrium.

Systemic circulation (memorize the flow)

• is referred to as the high-pressure circuit

  • because the pressure is much greater than that seen in the lungs.

• The function of this circuit is to deliver oxygen and nutrients to body cells.

  • It also picks up carbon dioxide and waste products from body cells.

• The systemic circuit can be summarized as follows:

  1. left atrium through the bicuspid valve

  2. into the left ventricle

  3. through the aortic semilunar valve

  4. into the aorta

  5. to the systemic arteries

  6. to arterioles

  7. to capillaries

  8. to venules

  9. to veins

  10. to the superior and inferior venae cavae

  11. into the right atrium of the heart.

Cardiac Cycle

• Number of cardiac cycles per minute is the same as the heart rate (pulse rate).

  • One heartbeat = one cardiac cycle

    • two heart sounds (lubb and dubb) when valves in the heart shut.

      • Lubb

        • First sound - When the ventricles contract, the tricuspid and bicuspid valves snap shut

      • Dubb

        • Second sound - When the atria contract and the pulmonary and aortic valves snap shut

• is influenced by

  • exercise

  • parasympathetic nerves

  • sympathetic nerves

  • cardiac control center

  • body temperature

  • potassium ions and calcium ions.

In One heart beat

• Atria contract and relax

• Ventricles contract and relax

• Right ventricle contracts

• Tricuspid valve closes

• Pulmonary semilunar valve opens

• Blood flows into pulmonary artery

• Left atrium contracts

• Bicuspid valve opens

• Blood fills left ventricle

• Left ventricle contracts

• Bicuspid valve closes

• Aortic semilunar valve opens

• Blood pushed into aorta

Blood Pressure

Force blood exerts on the inner walls of blood vessels

• Highest in arteries

• Lowest in veins

Systolic pressure

• Ventricles contract

• Blood pressure is at its greatest in the arteries

• Reported as the systolic number over the diastolic number.

• Control based mainly on the amount of blood pumped out of the heart.

• The amount of blood entering should equal the amount pumped from the heart.

Diastolic pressure

• Ventricles relax

• Blood pressure in arteries is at its lowest

Myocardial infarction (MI) (common heart disorders)

Commonly called a heart attack

• caused by blockage of coronary arteries

• often causes death of the individual.

• The pain associated with a heart attack is often described as pressure or fullness in the chest.

• An “infarction” is death of tissue due to deprivation of oxygen and it can occur in various organs. 

• the cardiac muscle sustains damage because of the resulting ischemia.

• Heart tissue that dies in an MI does not regenerate. 

  • It is a permanent situation that can affect the efficiency of the heart for the rest of the patient’s life.

Etiology:

• caused by obstruction of the coronary arteries as a result of

  • atherosclerosis

  • a thrombus

    • blot clot in heart

  • an embolus. 

    • blod clot in blood stream

Signs and Symptoms: 

• recurring squeezing chest pain

• pain in the

  • shoulder

  • arm

  • back

  • teeth

  • jaw

• chronic pain in the upper abdomen

• shortness of breath, especially on exertion;

• diaphoresis

  • excessive, abnormal sweating

• dizziness or fainting

• and nausea or vomiting. 

Treatment: 

• The first treatment, if possible, is chewing an aspirin at the onset of symptoms. 

  • Aspirin can help begin to break up blood clots which will allow essential oxygen to get to the myocardium. 

• In an unconscious patient without a pulse or respiration, CPR should be administered.

• Other treatment options include the use of an AED and thrombolytic drugs

  • to destroy the blood clots that block a coronary artery.

• Anticoagulant medications, such as heparin and warfarin (Coumadin)

  • should be administered to thin the blood

• medications that slow the heart rate

  • such as atenolol. 

• Angioplasty or coronary artery bypass graft

  • to open up the coronary arteries are also treatment options.

infarction

is death of tissue due to deprivation of oxygen and it can occur in various organs. 

Arrhythmias: (common heart disorders)

Also known as dysrrhythmias are abnormal heart rhythms or rates. 

Etiology: 

• These abnormal rhythms usually result when the electrical impulses of the cardiac conduction system do not travel correctly through the heart.

• The list of risk factors and causes is long.

Signs and Symptoms: 

• dyspnea

  • Shortness of breath

• dizziness or fainting

• an uncharacteristically rapid or slow heart rate

• a fluttering feeling in the chest, and chest pain. 

Treatment: 

• The first management of arrhythmias should be to treat the underlying cause. 

• Other treatment options include

  • pacemakers

  • medications

  • cardiopulmonary resuscitation

  • vagal maneuvers

  • electrical shock

  • radiofrequency catheter ablation

  • implantable cardioverter defibrillator

  • Maze procedure

  • surgery to correct heart defects.

Congestive heart failure: (CHF) (common heart disorders)

failure of the heart to pump effectively. 

The heart weakens and eventually loses its ability to supply blood to the body. 

Etiology: 

• Many risk factors exist for this condition, including

  • smoking

  • overweight

  • a diet high in fats and cholesterol

  • a lack of exercise

  • atherosclerosis

  • a history of MI

  • hypertension

  • a damaged heart valve

  • excessive alcohol consumption

  • diabetes mellitus. 

  • Congenital heart defects

  • drugs that weaken the heart

Signs and Symptoms: 

• left-sided heart failure include

  • lightheadedness

  • kidney failure

  • shortness of breath

  • pulmonary hypertension

  • cough. 

• right-sided heart failure include

  • fluid accumulation

  • edema of the

    • feet

    • ankles

    • liver

    • abdomen. 

  • The patient may experience nausea and loss of appetite which can lead to cachexia. 

    • muscle mass loss with or without fat mass loss

Treatment: 

• medications to slow a rapid heartbeat

• diuretics to decrease edema and fluid accumulation in the lungs

• medications to reduce blood pressure

• If the heart failure has progressed significantly, procedures such as surgery

  • to repair defective heart valves or other heart defects

  • implantation of a cardiac pacemaker

  • a heart transplant may be warranted.

ECG (tests to diagnose heartfailure)

This test can help determine if someone is experiencing or has experienced a heart attack in the past.

Stress tests (tests to diagnose heartfailure)

are ECGs performed while a patient is exercising or has been given drugs to increase the heart rate.

Chest x-ray:(tests to diagnose heartfailure)

show the size and shape of the lungs and heart

• can therefore indicate conditions such as congestive heart failure in which the heart may be enlarged.

Nuclear scan: (tests to diagnose heartfailure)

These scans follow radioactive substances through the blood vessels of the heart and lungs and can reveal narrow or obstructed arteries.

Electron beam computerized tomography (EBCT) (tests to diagnose heartfailure)

This procedure is much like a CT scan of the arteries and is useful for finding narrowed arteries.

Coronary catheterization: (tests to diagnose heartfailure)

This procedure uses a contrast medium that is followed through coronary arteries.

Echocardiogram (tests to diagnose heartfailure)

This procedure uses sound waves to visualize the shape or defects of the heart.

Endoscopy (tests to diagnose heartfailure)

This procedure involves inserting a tube with a tiny camera down the throat and into the stomach.

Holter Monitor (tests to diagnose heartfailure)

A device that is worn to measure your heart’s activity throughout your normal day.