Cardiovascular System/Hematologic & Lymphatic System

The heart

• the heart is in the mediastinum (area inside the thoracic cavity)

• made up of 3 layers: endocardium (innermost), myocardium (middle) & epicardium (outermost)

• the myocardium is made up of cardiac muscle

• pericardium

pericardium

protective sac surrounding the heart

function of the heart

• receives deoxygenated blood from body and pumps it into lungs

• receives oxygenated blood from lungs and pumps it into the body

• influences blood pressure, which affects overall circulation

• total circulation of blood from heart to body and back to the heart takes approximately 1 minute

left coronary artery (LCA)

supplies blood to the left side of the heart myocardium, divides into 2 branches-the left anterior descending (LAD) artery and the left circumflex (LCX) artery

right coronary artery (RCA)

supplies blood to the right side of the heart myocardium

ischemia

inadequate blood supply to muscle body part

myocardial infarction (MI) or heart attack

obstruction of the blood supply to heart = tissue death

the heart chamber

4 chambers: 2 atria & 2 ventricles (R & L)

atria receive blood

• the R atrium receives unoxygenated blood from the body

• the L atrium receives oxygenated blood from the lungs

ventricles pump blood out

• the R ventricle pumps unoxygenated blood into the lungs to become oxygenated

• the L ventricle pumps oxygenated blood out of the heart into the body

The 4 heart valves

tricuspid; mitral; pulmonary; aortic

valves

flaps of tissue that open and close in response to pressure changes, preventing backflow

tricuspid

right AV valve (Lub)

mitral

left AV valve (Dub)

Pulmonary

semilunar valve that separates R ventricle from pulmonary arteries (Dub)

aortic

semilunar valve that separates L ventricle from aorta (Dub)

deoxygenated blood

from the body: superior & inferior vena cava to the → R atrium → through tricuspid valve→ R ventricle→ pulmonary valve→ pulmonary artery→ lungs

oxygenated blood

from the lungs: → pulmonary vein → L atrium → through the mitral valve → L ventricle→ through the aortic valve → Aorta → systemic circulation

systole

ventricular contraction, resulting in ejection of blood; first sound heard when taking blood pressure (lub)

diastole

ventricular relaxation, followed by ventricular filling; initial point of no sound when taking BP (dub)

Cardiac output is an indicator of what?

heart health

stroke volume x heart rate =

cardiac output; measured as per minute, normal 4-8 L/min

stroke volume

amount of blood ejected from the L ventricle with each heartbeat (avg.~ 70 mL)

heart rate

number of times the heart beats per min (normal range 60-100 beats/min)

cardiac output

amount of blood pumped out by the systolic contraction of the ventricles in 1 minute

preload~ filling phase

• amount of blood in ventricles at end of diastole (think “volume”)- ventricles stretch

• increased in: hypervolemia; regurgitation of cardiac valves; heart failure

afterload~ pumping phase

• pressure against which the heart must work to eject blood during systole; the left ventricle

• think “pressure”: increased afterload, due to increased systemic vascular resistance, increases blood pressure

• increased in: hypertension, vasoconstriction; ↑ afterload = ↑ cardiac workload

properties of cardiac muscle

automaticity; conductivity; excitability

automaticity

striated & involuntary muscle cells

• auto= self/same/occurring within

conductivity

specialized cells (cardiac pacemaker cells in sinoatrial node) pass along electrical impulses

excitability

reacts to changes in the body and accelerates or decreases rate as needed (ex: low O2, infection, medications, electrolyte imbalance- maintain homeostasis)

action potential

rapid change of voltage, caused by electrolyte (N+ & Ca++) movement across myocardial cells-causes heart to contract

depolarization

Na+ rapidly enters muscle cells and Ca++ enters cell slow and steady, causing contraction

repolarization

K+ leaves cell to normalize negative charge inside the cell, relation

refractoriness

time it takes for cardiac cells to recover after an electrical impulse (pause between beats); if the HR is too fast, the heart cannot recover to fill adequately

cardiac conduction parts

sinoatrial node → atrioventricular node → bundle of his → Purkinje fibers

sinoatrial node (SA node)

“pacemaker” of the heart located at R atrium & superior vena cava

atrioventricular node (AV node)

receives and slows impulse from SA node, allowing for atrial contraction and ventricular filling

bundle of His (AV bundle)

receives impulse from AV node

Purkinje fibers

receives impulse from R & L bundle branches and performs final conduction of impulse to ventricles, causing contraction “conduction pathways”)

cardiac conduction

SA node fires → excitation spreads through atrial myocardium → AV node fires → excitation spreads down AV bundle → Purkinje fibers distribute excitation ventricular myocardium

cardiac conduction~ depolarization/repolarization

1. atrial depolarization, initiated by the SA node, causes the P wave

2. with atrial depolarization complete, the impulse is delayed at the AV node

3. ventricular depolarization begins at apex, causing the QRS complex, atrial repolarization occurs

4. ventricular depolarization is complete

5. ventricular repolarization begins at apex, causing the T wave

6. ventricular repolarization is complete

blood vessel functions

transport; waste removal; defense; temperature region; clotting; hormone transport; homeostasis

transport

blood carries oxygen from the lungs to the body’s cells and tissues, where it is needed for energy production. it also carries nutrients, such as amino acids, fatty acids, and glucose, to cells

waste removal

blood transports waste products, like carbon dioxide, urea, and lactic acid, from cells back to organs like the lungs, kidneys, and intestines for removal

defense

blood contains white blood cells and antibodies that help fight infections and protect the body from foreign invaders

temperature regulation

blood helps regulate body temperature by distributing heat throughout the body and allowing for heat loss through blood vessels in the skin

clotting

blood contains platelets and proteins that work together to form clots, preventing excessive blood loss when a blood vessel is damaged

hormone transport

blood carries hormones throughout the body, enabling them to reach target cells and tissues

homeostasis

blood helps maintain a stable internal environment by regulating pH, electrolyte levels, and other factors

arteries

deliver oxygenated blood away from the heart (exception: the pulmonary artery carries deoxygenated blood blood away from the heart to the lungs; the aorta is the largest artery; no valves; pressure from heart contraction

arterioles

thinnest, smallest arteries that regulate BP and blood supply through constriction and dilation

arteries vs veins?

• arteries: away from the heart; no valves

• veins: towards the heart; valves

veins

deliver deoxygenated blood to the heart (exception: the pulmonary vein carries oxygenated blood to the heart from the lungs); contains 60-70% of total blood volume at rest

venules

smallest veins that take deoxygenated, waste-filled blood from capillaries and distribute to veins

capillaries

• smallest vessels: so small that RBCs pass through them single file

• low resistance & slow blood flow allow maximum time for transport of oxygen & nutrients into body tissues

• fluids and wastes are pulled into the capillaries and taken to the kidneys for excretion

pulmonary circulation

blood travels from heart to lungs and back to heart during the oxygenation process

systemic circulation

oxygenated blood enters the body and distributes O2 to tissues while retrieving CO2 and other waste

cerebral~ circulation

circulation to brain requires 10-15% of total cardiac output

hepatic portal~ circulation

blood from GI system is detoxified in the liver and sent directly to the heart via the hepatic veins and inferior vena cava

Major blood vessels

internal jugular vein; external jugular vein; common carotid artery; subclavian artery; superior vena cava; subclavian vein; inferior vena cava; aorta; renal artery; renal vein; common iliac vein; common iliac artery; femoral artery; femoral vein

blood pressure

the force that blood exerts against blood vessel walls (measured in mmHg)

systemic vascular resistance (SVR)

force opposing the movement of blood through vessels (aka Peripheral Vascular Resistance)

systolic BP

pressure exerted against vessel walls during ventricular systole

diastolic BP

relaxation during ventricular diastole

pulse pressure

difference between systolic and diastolic pressure

factors affecting BP

diet, smoking, heredity, infection, disease, medications, Baroreceptors

diet~ BP

high fat and cholesterol may lead to atherosclerosis, which elevates blood pressure

smoking~ BP

causes vasoconstriction, leading to elevated BP

heredity~ BP

family history of heart disease can predispose a client to HTN and various cardiac conditions

infection~ BP

body increases blood supply to stimulate biologic treatment of infection and symptoms, which elevates BP

disease~ BP

impaired renal function increased fluid volume, elevating BP

medications~ BP

may elevate or lower BP

Baroreceptors~ BP

work by sensing blood pressure changes and responding to increased or decreased need for blood via the autonomic nervous system- constrict or dilate vessels (think decreased stretch with standing→ need to constrict to increase BP in orthostatic hypotension)

what does bone marrow do?

bone marrow makes nearly all the components of your blood. it is responsible for creating billions of red blood cells daily, along with white blood cells and platelets

what is bone marrow made up?

bone marrow is made of stem cells. these stem cells make red bone marrow, which creates blood cells and platelets for your blood. yellow bone marrow consists mostly of fat and stem cells that produce bone and cartilage in your body

blood/blood components

RBCs, WBC, platelets, plasma, hematopoiesis

RBCs

erythrocytes

WBCs

leukocytes (Basophils, Neutrophils~ first line of defense, Eosinophils, Monocytes, Lymphocytes)

platelets

thrombocytes

plasma

fluid portion of circulating blood

hematopoiesis

production of blood cells, it occurs in the bone marrow, primarily in long bones

WBC~ CBC lab values

4,500-11,000 per microliter (μL) of blood

• low WBC: Leukopenia, high WBC: infection

RBC- HCT/hematocrit~ CBC lab values

male: 41-50%; female: 36-47%

RBC- Hgb/hemoglobin~ CBC lab values

male: 14-18 g/dL; female: 12-16 g/dL

• low RBCs, HCT, & Hgb: anemia

platelets~ CBC lab values

normal 150,000-400,000 per microliter (μL) of blood

• low platelets-risk bleeding

CBC can help diagnose and monitor many conditions such as

anemia, infection, leukemia, iron deficiency, kidney disease and bone marrow disorders

Red blood cells (erythrocytes)

• most common blood cells 40-45% total blood volume

• flat, biconcave, no nucleus; live 120 days; A1C

• initiate vasodilation when tissues are poorly oxygenated

• responsible for initial immune response to pathogens

• consists of mainly hemoglobin (Hbg); the iron in hemoglobin binds to oxygen and allows the RBCs to carry O2 to tissues

• normal Hbg levels; male: 14-18g/dL; female: 12-16g/dL (Hbg too low? anemia s/sx?)

white blood cells (leukocytes)

• low wbc: leukopenia; high wbc: infection

• formed in bone marrow

• larger than RBCs, have a nucleus

• defend the body against pathogens, toxins, irritants, and foreign materials

• assist in tissue repair; WBCs die, forming pus

• abnormal numbers of leukocytes indicates disease or possible s/e of medication

• normal wbc count: 4,500-11,000 per microliter (μL)

types of leukocytes~ have granules in cytoplasm

neutrophils; eosinophils; basophils; lymphocytes; B-lymphocyte cells; T-lymphocyte cells; natural killer lymphocytes; monocytes; macrophage

neutrophils

phagocytic, most numerous WBCs; first line of defense against bacteria; elevated in bacterial infections, burns, or inflammation; first responders

eosinophils

release antigens & antibodies; elevated during allergic reactions and parasitic infections

basophils

release heparin and histamine; involved in allergic and inflammatory reactions (vasodilation, edema, and itching)

lymphocytes

most common, agranular; increase during viral infections and immune disorders

B-lymphocyte cells

create antibodies, mark pathogens (antigen) for destruction

T-lymphocyte cells

destroy viruses, infected cells and tumors

Natural killer lymphocyte cells

do not require antigen to target a pathogen

monocytes

largest WBCs; active during inflammation, infection & chronic disease; phagocytic; ingest cellular debris, dead tissue and pathogens; present pathogen fragments to T-cells for antibody formation

macrophage

type of monocyte, part of the innate immune response that defends against pathogens, they engulf foreign material and eliminate debris

platelets (thrombocytes)

• produced in bone marrow

• smallest elements in blood (fragments)

• essential in blood clotting

• platelets stimulate contraction of injured blood vessels and form a hemostatic plug to slow or stop bleeding

• combine with plasma to speed blood coagulation

• normal 150,000-400,000 per microliter (μL)