CARDIOVASCULAR SYS

CARDIOVASCULAR SYSTEM

  • Closed system of the  heart and blood vessels

  • heart pumps blood

  • Blood vessels allow blood to circulate to all parts of the body

Function: deliver oxygen and nutrients and to remove carbon dioxide and other waste products

HEART

LOCATION

  • Thorax between the lungs

  • Apex: 5th Left ICS (Intercostal space) 3.5cm from the sternum

  • About the size of your fist

  • SURFACES OF THE HEART

    • Anterior (Sternocostal) Surface

      • Right Atrium, Right ventricle (most anterior part of the heart)

    • Inferior (Diaphragmatic)

      • Left ventricle, Apex of the heart, and right ventricle

    • Posterior (Base) Surface

      • Right atrium, left atrium (most posterior part of the heart)

COVERINGS

  • Pericardium

    • Visceral pericardium— next to heart

    • Parietal pericardium—outside layer

  • Serous fluid fills the space b/w the layers of pericardium

  • Pericardiocentesis: procedure that removes the excess pericardial fluid

LAYERS

  1. Epicardium

  • Outside layer

  • Parietal pericardium

  • Connective tissue layer

  1. Myocardium

  • Middle layer

  • Mostly cardiac muscle

  1. Endocardium

  • Inner layer

  • endothelium

CHAMBERS

ATRIA

  • Receiving chambers

    • Receive from Superior and inferior vena cava

  • R & L

    • Separated by atrioventricular valves (tricuspid & mitral/bicuspid valve)

VENTRICLES

  • Discharging Chambers

  • R & L

VALVES

  • Allow blood to flow in one direction

  • Four valves

    • Atrioventricular valves—between atria and ventricles

      • Bicuspid valve (left)

      • Tricuspid (right)

    • Semilunar valves— between ventricle & artery

      • Pulmonary 

      • Aortic valve

  • Valves open as blood is pumped through

  • Held in place by chordae tendineae (heart strings)

  • Close to prevent backflow

  • What happens if the valves do not close properly —> insufficiency, when ventricles contract there will be regurgitation of blood in the ventricles

    • Blood cannot pass through

    • Atria fills up

    • Atria will increase course of contraction (senotic something) 

    • Atrial enlargement


GREAT VESSELS

  • Aorta: Leaves L. Ventricle

  • Pulmonary arteries: Leaves R. Ventricle

  • Vena cava: enters. R. Atrium

  • Pulmonary veins (4): Enter left atrium

PERICARDIUM

  • Location:

    • middle mediastinum

    • posterior to the body of the sternum and the 2nd to the 6th costal cartilages

    •  anterior to the T5-T8 

  • Fibrous Pericardium

  • Serous Pericardium

    • Parietal Layer

    • Visceral Layer/ Epicardium

  • Pericardial Cavity:  slit like space between the parietal and visceral layers

    • contains 50 ml of tissue fluid

    • Pericardial fluid:  acts as a lubricant to facilitate movements of the heart

  • Pericardial Sinuses

    • Oblique Sinus: a recess that forms from the large veins of the serous pericardium

    • Transverse Sinus: s a short passage that lies between the reflection of serous pericardium around the aorta and pulmonary trunk and the reflection around the large veins

    • Nerve supply: sympathetic trunks and vagus nerves

CORONARY CIRCULATION

  • Blood in the heart chambers does not nourish the myocardium

    • The blood that goes through does not supply the heart

  • The heart has its own nourishing circulatory system

    • Coronary arteries 

    • cardiac veins

    • Blood empties in R. Atrium via the coronary sinus

  • Arterial Supply of the Heart: 

    • Right Coronary Artery

    • Left Coronary Artery: supplies major part of the heart

  • Venous Drainage of the Heart: Coronary sinus

    • continuation of the great cardiac vein

CONDUCTION SYSTEM

  • Intrinsic conduction system (nodal system)

    • SA node

      • Internodal pathways (between the two nodes)

    • AV node

    • Bundle of his/AV bundle

    • L. & R branches

    • Purkinje Fibers

  • Heart muscle cells contract, without nerve impulses, in a regular continuous way

  • Contraction is initiated by the sinoatrial node

  • Sequential simulation occurs at other autorhythmic cells

  • Special tissue sets the pace

    • Sinoatrial node

      • Pacemaker

    • AV Node

    • Bundle of His

    • Purkinje fibers

CARDIAC CYCLE

  • Atria contract simultaneously

  • Atria relax, then ventricles contract

  • Systole=contraction

  • Diastole=relaxation

FILLING OF HEART CHAMBERS

  • Cardiac Cycle: events of one completes 1 heart beat

  1. Mid to late diastole

  • blood flows into ventricles

  • ventricular filling

  • Atrial contraction

  1. Ventricular systole

  • blood pressure builds before ventricle contracts, pushing out blood

  • isovolumetric contraction phase

  • Ventricular ejection phase

  • Atria in diastole

    • Ventricles are filled up and they need to contract to eject the blood

  1. Early diastole

  • atria finish refilling, ventricular pressure is low

  • isovolumetric relaxation

chambers cannot contract all together


CARDIAC OUTPUT

CARDIAC OUTPUT (CO)

  • Amount of blood pumped by each side  of the heart in one minute

  • CO= HR (Heart Rate) X SV (Stroke Volume)

    • Stroke volume: volume of blood pumped by each ventricle in one contraction

      • Related to blood pressure


Cardiac Output Regulation

REGULATION OF HEART RATE

  • Stroke volume usually remains relatively constant

STARLING’S LAW

  • the more that the cardiac muscle is stretched, the stronger the contraction

  • Changing heart rate is the most common way to change CO


INCREASED HEART RATE

  • Sympathetic NS

    • Crisis 

    • Low blood pressure

  • Hormones

    • Epinephrine

    • Thyroxine 

      • Beta Blockers are given—beta receptors respond to it

      • Increased thyroid hormones

  • Exercise

    • More demand from the heart

    • Muscles are being used

  • Decreased blood volume

    • Less circulating blood volume=less blood Going back to heart

    • Heart thinks it needs to go fast for the peripheral organ

    • There is a reason why there is low blood volume

      • Could be blood loss

      • Losses through vomiting or LBM (losses were not replaced

      • Other body systems will work to compensate for the loss (example: kidneys regulating ot conserve water because of water loss)

DECREASED HEART RATE

  • Parasympathetic NS

  • High blood pressure or blood volume

  • Decreased venous return

BLOOD VESSELS: THE VASCULAR SYSTEM

  • Arteries

  • Arterioles

  • Capillaries

  • Venules

  • Veins

ANATOMY

  • 3 Layers (Tunics)

  1. Tunic Intima (Interna)

  • Endothelium

  1. Tunic Media 

  • Smooth muscle

  • Controlled by sympathetic nervous system

  1. Tunica Externa 

  • Mostly fibrous connective tissue

DIFFERENCES BETWEEN BLOOD VESSEL TYPES

  • Walls of arteries are thickest

  • Lumens of veins are larger

    • Lumen: cavity within tubular structure

  • Skeletal muscle milks blood in veins toward the heart

  • Capillary beds

  • Walls of capillaries are only one cell layer thick to allow for changes between blood and tissue

    • Capillary beds: vascular shunt; true capillaries (exchange vessels)

MOVEMENT OF BLOOD THROUGH VESSELS

  • Most arterial blood is pumped by the heart

  • Veins use the milking action of muscles to help move blood

  • Capillary beds

  • Walls of capillaries are only one cell layer thick to allow for changes between blood and tissue

    • Capillary beds: vascular shunt; true capillaries (exchange vessels)

PULSE

  • Pressure of blood

  • Monitored at “pressure points” where pulse is easily palpated

PULSE POINTS

  • Temporal A.

  • Facial A.

  • Carotid A.

  • Brachial A.

  • Radial A.

  • Femoral A.

  • Popliteal A.

  • Posterior tibial A. 

  • Dorsalis pedis A.

BLOOD PRESSURE

  • Measurements by health professionals are made on the pressure in large arteries

    • Systolic—pressure at the peak of ventricular contraction

    • Diastolic—pressure when ventricles relax

  • Pressure in blood vessels decreases as the distance away from the heart increases

    • Lower ex BP is different from upper ex BP

EFFECTS OF FACTORS

  • Neural factors

    • autonomic NS adjustments (sympathetic division)

  • Renal factors

    • Regulation by altering blood volume

    • Renin—hormonal control

  • Temperature

    • Heat—> vasodilation

      • Dako. ang lumen

      • Increased blood to the area

      • Promotes healing

      • Lactic acid accumulates

      • Blood washes away

      • Lactic is a by-product of lactic acid

    • Cold—> vasoconstriction

  • Chemicals

    • Various substances can cause increases or decreases

    • Example: propranolol

  • Diet

VARIATIONS IN BLOOD PRESSURE

  • Human normal range is variable

  • Normal BP

    • 140-110 mm Hg systole

    • 80-75 mm Hg systole

    • 120/80

  • Hypotension

    • Low systolic (below 110 mm HG)

    • often associated w/ illness

  • Hypertension

    • High systolic (above 140 mm HG)

    • Can be dangerous if it is chronic

CAPILLARY EXCHANGE

  • Substances exchanged due to concentration gradients

    • Energy is not used

    • Passive because of the concentration gradient

  • Oxygen and nutrients leave the blood

  • Carbon dioxide and other wastes leave the cells

    • Diffuses through the capillaries

MECHANISMS

  • Direct diffusion across plasma membranes

  • Endocytosis or exocytosis

  • Some Capillaries have gaps (intercellular clefts)

    • Plasma membrane not joined by tight junctions

  • Fenestrations of some capillaries

    • Fenestrations=pores

DEVELOPMENTAL ASPECTS OF CARDIOVASCULAR SYSTEM

  • Simple tube heart develops in the embryo and pumps by the 4th week

  • Heart becomes 4 chambered organ by end of 7 weeks

  • Few structural changes occur afterward 7th week

BLOOD 

  • only fluid tissue

  • Classified as a connective tissue

    • Living cells=formed elements

    • Non-living matrix=plasma membrane

PHYSICAL CHARACTERISTICS OF BLOOD

  • Oxygen rich–scarlet red

  • Oxygen poor--dull red

  • PH must remain b/w 7.35-7.45

  • Blood temp is slightly higher than body temp

  • Blood plasma—90% water

    • Nutrients

    • Salts (metal ions)

    • Respiratory gasses

    • Hormones 

    • Proteins 

BLOOD PLASMA

  • Plasma=55%

    • Water 

    • Electrolytes

    • Salts

    • Plasma proteins

      • Albumin

    • IMMUNOGLOBULINS: ANTIBODIES

      • IGG

        • Increase if you had infection before

      • IGA

      • IGE

      • Immunoglobulin m 

        • Increase circulating blood pag acute or recent infection

      • Immunoglobulin D

        • Denge: low WBC; platelet normal

        • Flu infection while recovering

PLASMA PROTEINS

  • Albumin: regulates osmotic pressure (protein that attracts water, water goes into the vessel)

    • Osmotic pressure: the blood that passes through the vessel it produces hydrostatic pressure; 

    • Interstitial fluid: hydrostatic pressure pushes toward the vessel (SEE GEN PHYSIO NOTES)

    • NET FILTRATION PRESSURE

  • Clotting proteins: help to stem blood loss when a blood vessel is injured

  • Antibodies: help protect the body from antigens


FORMED ELEMENTS

  • Erythrocytes = RBC

  • Leukocytes= WBC

  • Platelets=cell fragments

ERYTHROCYTES (RED BLOOD CELLS)

  • Main function: carry oxygen

  • Anatomy of circulating erythrocytes

    • Biconcave disks

    • Essentially bags of hemoglobin

    • Anucleate (no nucleus)

    • Contains very few organelles 

  • Outnumber white blood cells–1000:1 

  • 4-6 mil

  • Sacks of hemoglobin

  • Most organelles have been ejected

  • 100-120 days

    • Checking 3 month compliance 

    • More accurate than fasting blood sugar

  • Test: fasting blood sugar

HEMOGLOBIN

  • Iron-containing protein

  • Binds strongly, but reversibly, to oxygen

  • Each hemoglobin molecule has four oxygen binding sites

  • Each erythrocyte has 250 million hemoglobin molecules

  • Function: Transport oxygen bound to hemoglobin molecules; also transport small amount of carbon dioxide

LEUKOCYTES (WHITE BLOOD CELLS)

  • Crucial in the body’s defense against disease

  • These are complete cells, with a nucleus and organelles

  • Diapedesis: Able to move into and out of blood vessels 

  • Can move by ameboid motion

  • Can respond to chemicals released by damaged tissues

LEUKOCYTE LEVELS IN THE BLOOD

  • Normal levels are between 4,000 and 11,000 cells per millimeter

  • Abnormal leukocyte levels

    • Leukocytosis

    • Leukopenia

  • Leukocytosis

    • Above 11,000 leukocytes/ml

    • Generally indicates an infection

    • Causes/ effects: leukemia 

  • Leukopenia

    • Commonly caused by certain drugs

    • Complications: low immune system; dali makuha ng sakit

TYPES OF LEUKOCYTES

  • Granulocytes 

    • Granules that can be seen in their cytoplasm

    • neutrophils, eosinophils, basophils

    • Neutrophils

      • Multilobed nucleus with fine granules

      • Act as phagocytes at active sites of infection

      • 3000-7000

    • Eosinophils

      • Large brick-red cytoplasmic granules

      • Found in response to allergies and parasitic worms

      • 100-400

      • Kill parasitic worms

      • Increase during allergy attacks

      • Might phagocytize antigen-antibody complexes and inactivate some inflammatory chemicals

    • Basophils

      • Have histamine-containing granules

      • Initiate inflammation

  • Agranulocytes 

    • Lack visible cytoplasmic granules

    • Lymphocytes

      • Nucleus fills most of the cell

      • plays an important role in immune response

      • produces antibodies 

      • T cells, b cells, NK cells

    • Monocytes

      • largest of WBC

      • function as macrophages–become macrophages in the tissues

      • important in fighting chronic infection


PLATELETS (THROMBOCYTES)

  • Derived from ruptured multinucleate cells  (megakaryocytes)

  • Needed for clotting processes

  • Normal platelet count=300,000 mm^3

  • Hematopoiesis: Blood cell formation

    • occurs in red bone marrow

    • all blood cells are derived from a common stem cell (hemocytoblast)

  • Hemocytoblast differentiation

    • lymphoid stem cell produces lymphocytes

    • myeloid stem cell produces other formed elements

FATE OF ERYTHROCYTES

  • Unable to divide, grow, or synthesize proteins

  • Wear out in 100 to 120 days

  • When worn out, are eliminated by phagocytes in the spleen or liver

CONTROL OF ERYTHROCYTE PRODUCTION

  • Erythropoietin: hormone that controls the rate of erythrocyte production

  • Kidneys produce most erythropoietin as a response to reduced oxygen levels in the blood

  • Homeostasis is maintained by negative feedback from blood oxygen levels

  • What happens if there is renal failure or is undergoing dialysis?

    • Reduced erythropoietin production—> decreased oxygen carrying capacity of the blood (pale symptoms, connected to anemia)



HEMOSTASIS

  • Stoppage of blood flow result of a break in a blood vessel

  • Hemostasis involves three phases

    • Platelet plug formation

      • Collagen fibers are exposed by a break in a blood vessel

      • Platelets become “sticky” and cling to fibers

      • Anchored platelets release chemicals to attract more platelets

      • Platelets pile up to form a platelet plug 

      • Stops the bleeding

    • Vascular spasms

      • Anchored platelets release serotonin

      • Serotonin causes blood vessel muscles to spasm

      • Spasms narrow the blood vessel, decreasing blood loss

    • Coagulation

      • Injured tissues release thromboplastin

      • PF3 (a phospholipid)  interacts with thromboplastin, blood protein. clotting factors, and calcium ions to trigger a clotting cascade

      • Prothrombin activator converts prothrombin to thrombin (an enzyme)

      • Thrombin joins fibrinogen proteins into hair-like fibrin

      • Fibrin forms a meshwork 

        • Meshwork: basis for a clot

BLOOD CLOTTING

  • Blood usually clots within 3 to 6 minutes

  • clot remains as endothelium regenerates

  • clot is broken down after tissue repair

FIBRIN CLOT

UNDESIRABLE CLOTTING

  • Thrombus: a clot in an unbroken blood vessel

    • Can be deadly in areas like the heart

  • Embolus: A thrombus that breaks away and floats freely in the bloodstream

    • Clot can be dislodged and become an embolus

    • Can later clog vessels in critical areas such as the brain

    • Can be deadly in  areas  like the heart

    • Fatty foods 

    • Effect of thrombi: blood flow is decreased; heart rate is increased

BLEEDING DISORDERS

  • Thrombocytopenia: Platelet deficiency

    • Even normal movements can cause bleeding from small blood vessels that require platelets for clotting

  • Hemophilia: Hereditary bleeding disorder

    • Normal clotting factors are missing

    • 3rd phase is abnormal

BLOOD GROUPS AND TRANSFUSIONS

  • Large losses of blood have serious consequences  

    • Weakness: Caused by a loss of blood of 15-30%  

    • Shock: caused by a loss of over 30% of blood (fatal) 

      • sepsis can lead to shock

      • Toxic shock syndrome

      • Hypovolemic shock:  severe blood or other fluid loss makes the heart unable to pump enough blood to the body.

  • Transfusions: the only way to replace blood quickly  

    • Transfused blood must be of the same blood group

    • Why do they have to be the same Blood group? 

      • causes hypersensitivity

HUMAN BLOOD GROUPS

  • Blood contains genetically determined proteins  

  • Antigen: a foreign protein that may be attacked by the immune system  

  • Blood is “typed” by using antibodies that will cause blood with certain proteins to clump 

    • agglutination: when proteins start to clump

  • There are over 30 common red blood cell antigens  

  • ABO and Rh blood group antigens: cause the most vigorous transfusion reactions


ABO BLOOD GROUPS

  • Based on the presence or absence of 2 antigens

    • Type A: presence of A antigens

    • Type B: presence of B antigens

    • Type O: lack of these antigens

    • Type AB: presence of A & B antigens

Rh BLOOD GROUPS

  • Named because of the presence or absence of one of eight Rh antigens (agglutinogen D)  

  • Most Americans are Rh+  

  • Problems can occur in mixing Rh+ blood into a body with Rh– blood 



Rh DANGERS DURING PREGNANCY

  • Danger is only when the mother is Rh– and the father is Rh+, and the child inherits the Rh+ factor

  • Mismatch of an Rh- mother, carrying an Rh+ baby→ can cause problems for the unborn child

    • The first pregnancy usually proceeds without problems  

    • The immune system is sensitized after the first pregnancy  

    • Hemolytic Disease of the Newborn: In a second pregnancy, the mother’s immune system produces antibodies to attack the Rh+ blood

UNDESIRABLE CLOTTING

  • Blood samples are mixed with anti-A and anti-B serum  

  • Coagulation or no coagulation: leads to determining blood type  

  • Typing for ABO and Rh factors is done in the same manner  

  • Cross matching:  testing for agglutination of donor RBCs by the recipient’s serum, and vice versa

BLOOD GROUPS AND TRANSFUSIONS

  • Sites of blood cell formation  

    • The fetal liver and spleen are early sites of blood cell formation  

    • Bone marrow takes over hematopoiesis by the seventh month  

  • Fetal hemoglobin differs from hemoglobin produced after birth

    • Jaundice: hemolisis