BioL Exam 3: Cardiovascular

mediastinum of thoracic cavity

where is the heart located?

pericardium

what is the serous membrane that covers and protects the heart? (has 2 layers)

outer fibrous, inner serous pericardium

what are the two layers of the pericardium?

parietal, visceral

what are the two layers of the inner serous pericardium?

outer fibrous pericardium

• outer most layer of pericardium

• dense irregular connective tissue that encloses and protects the heart

• attached to the diaphragm inferiorly and the pulmonary trunk and aorta superiorly

parietal layer of serous pericardium

• middle layer pericardium

• inner serous pericardium

• composed of simple squamous epithelium and areolar connective tissue that fuses to the fibrous pericardium

• The visceral and parietal layers are separated by the serous cavity, a fluid-filled space

visceral layer of serous pericardium, parietal layer of serous pericardium, outer fibrous pericardium

list the layers of the pericardium from innermost to outermost

endocardium, myocardium, epicardium

list the three layers of the heart from innermost to outer most

epicardium

innermost layer of the serous pericardium and the outermost layer of the heart wall

myocardium

• middle layer of the heart

• thickest & contains cardiac muscle

• pumps blood through heart to major arteries

endocardium

• innermost layer of the heart, lining the heart chambers and heart valves

• composed of endothelium reinforced with a thin layer of connective tissue that binds to the myocardium

myocardium

which layer of the heart is the thickest?

• specialized cardiac muscle tissue

• responsible for contraction/ relaxation cycle throughout the body

right atrium, right ventricle, left atrium, left ventricle

list the four chambers of the heart

interatrial septum

what divides the right and left atrial chambers?

interventricular septum

what divides the right and left ventricles?

atrium

• upper or receiving chamber of the heart that pumps blood into the lower chambers just prior to their contraction

• contains pectinate muscles

  • muscular ridges

• smaller chamber

right atrium

receives blood from the superior and inferior vena cava and the coronary sinus (systemic circuit) that flows into the right ventricle

left atrium

receives blood from the pulmonary veins that flows into the left ventricle

ventricles

• contains trabeculae carneae

  • ridges of muscle covered by endocardium

• one of the primary pumping chambers of the heart located in the lower portion of the heart

left ventricle

• the major pumping chamber on the lower left side of the heart that ejects blood all over the body (systemic circuit) via the aorta and receives blood from the left atrium

• much thicker

right ventricle

• the major pumping chamber on the lower right side of the heart that ejects deoxygenated blood into the lungs (pulmonary circuit) via the pulmonary trunk and receives blood from the right atrium

• contains chordae tendineae

  • string-like extensions of tough connective tissue that extend from the flaps of the atrioventricular valves to the papillary muscles

chordae tendinae

string-like extensions of tough connective tissue that extend from the flaps of the atrioventricular valves to the papillary muscles

left

which side of the heart

• receives blood rich in oxygen and poor in carbon dioxide from the lungs

• pumps it to rest of the body

right

which side of the heart

• receives blood poor in oxygen and rich in carbon dioxide from the body

• pumps it to lungs

right atrioventricular, left atrioventricular, pulmonary semilunar, aortic semilunar valves

list the 4 valves of the heart

tricuspid valve

what is another name for the right atrioventricular valve

bicuspid/ mitral valve

what is another name(s) for the left atrioventricular valve

tricuspid valve

what valve is between the right atrium and the right ventricle

bicuspid/ mitral valve

what valve is between the left atrium and the left ventricle

pulmonary semilunar valve

localized in between the right ventricle and the pulmonary trunk

aortic semilunar valve

between the left ventricle and the aorta

valves

keeps the blood moving in only one direction and then they close to prevent the back flow of blood

atrioventricular valves

valves that prevent back flow from the ventricles into the atria

semilunar valves

valves that prevent back flow from the arteries into the ventricles

pulmonary circulation

movement of blood from the right side of the heart to the lungs, and back to the left side of the heart

systemic circulation

movement of blood from the left side of the heart to the systemic cells (make up bodily tissue) of the body and then back to the right side of the heart

deoxygenated blood

what type of blood enters the heart through the right inferior and superior vena cava into the right atrium

tricuspid valve

opens allowing deoxygenated blood flow from right atrium into right ventricle

right ventricle

contracts to send deoxygenated blood through pulmonary valve & artery to lungs for oxygenation

oxygenation of blood

• Air enters the lungs, traveling down to the tiniest air sacs, the alveoli, which are surrounded by a network of tiny capillaries

• Oxygen molecules move from the alveoli (high concentration) across the thin respiratory membrane into the blood capillaries (low concentration)

lungs

where does oxygenated blood come from to re-enter the heart

pulmonary veins

what structures does oxygenated blood go through to re-enter the left atrium

arteries, arterioles, capillaries

what three blood vessels does the aorta branch into from largest to smallest/ highest to lowest pressure

to carry oxygenated blood away from the heart

coronary arteries

transport blood rich in oxygen to the muscle of the heart (myocardium)

coronary veins

transport blood poor in oxygen away from the muscle of the heart (myocardium)

cardiac veins

• carries deoxygenated blood to the coronary sinus

  • Great cardiac vein – drains areas supplied by the left coronary artery

  • Middle cardiac vein – drains areas supplied by the posterior interventricular branch

  • Small cardiac vein – drains right atrium and right ventricle

  • Anterior cardiac vein – drains right ventricle and opens directly into the right atrium 

anastomosis

• the area where two or more arteries supplying blood to the same region connect

• area where vessels unite to allow blood to circulate even if there may be partial blockage in another branch

collateral anastomosis

alternative routes provided by anastomosis

blood vessels

• these structures ensures that the heart receives the needed nutrients and oxygen to keep pumping blood through its chambers

• the heart wall is too thick and does not allow the diffusion of oxygen and nutrients to the heart

conduction system

• a specialized network of cells in the heart that generates and transmits electrical impulses, controlling the timing, rate, and rhythm of the heartbeat

  • Cardiac muscle cells repeatedly generate spontaneous action potentials that then trigger heart contractions

autorhythmicity

• ability of cardiac muscle to initiate its own electrical impulse that triggers the mechanical contraction that pumps blood at a fixed pace without nervous or endocrine control

sinoatrial node

• 1st set of nodal cells

• known as the pacemaker, a specialized clump of myocardial conducting cells located in the superior portion of the right atrium that has the highest inherent rate of depolarization that then spreads throughout the heart

• Initiates sinus rhythm (normal heart rate)

• initiates action potential

atrioventricular node

• 2nd set of specialized nodal cells 

• clump of myocardial cells located in the inferior portion of the right atrium within the atrioventricular septum; receives the impulse from the SA node, pauses, and then transmits it into specialized conducting cells within the interventricular septum

• The septum prevents the impulse from spreading directly to the ventricles without passing through the AV node

atrioventricular bundle

• group of specialized myocardial conductile cells that transmit the impulse from the AV node through the interventricular septum; form the left and right atrioventricular bundle branches

• “Bundle of His”

atrioventricular bundle branches

• specialized myocardial conductile cells that arise from the branches of the atrioventricular bundle and pass through the interventricular septum

• lead to the Purkinje fibers and also to the right papillary muscle via the moderator band

purkinje cells

• final component of conduction system

• are specialized cardiac muscle cells located in the inner ventricular walls (subendocardium) that conduct electrical impulses rapidly, ensuring synchronized contraction of the ventricles

• high glycogen

nodal/ conducting cells

where do cardiac action potentials originate

nodal/ conducting cells

• cells that initiate and propagate the action potential (the electrical impulse) that travels throughout the heart

  • sinoatrial node

  • atrioventricular node

  • bundle of his

  • atrioventricular bundle branches

  • Purkinje cells

contractile cells

• conduct impulses and undergo contractions that pump blood through the body

• they are striated, involuntary, and branched cells that use a long-lasting calcium-driven action potential and sarcomere sliding filaments to produce coordinated, forceful contractions, relying on high oxygen consumption

• 99% of cardiac muscle cells

• cardiomyocytes

ECG

• surface recording of the electrical activity of the heart that can be used for diagnosis of irregular heart function

• the overall electrical signal from the action potentials that initiate the cardiac contraction

• aka: EKG

p wave, qrs complex, t wave

list the three ECG peaks

p wave

• what ekg wave indicates atrial systole (depolarization)

• atria begin contracting and wave represents the depolarization of the atria where Na+ (sodium) is entering the cell

• AV close

• larger wave could indicate an enlargement of the atria

qrs complex

• what ekg wave indicates ventricular systole (depolarization)

• represents the depolarization of the ventricles and includes, as a component, the repolarization of the atria

• contraction of ventricles follows

t wave

• ventricular diastole (repolarization)

• represents the repolarization of the ventricles

• semilunar valves close

cardiac cycle

consists of the contraction and relaxation of both atria, rapidly followed by contraction and relaxation of both ventricles

systole

period of contraction that pumps blood into circulation

diastole

period of time when the heart muscle is relaxed and the chambers fill with blood

depolarization

• the electrical activation process where cardiac cells transition from a resting (polarized) negative state to a positive state

• causes ion exchange (sodium ions Na+ flowing in, potassium ions K+ flowing out) across the cell membrane, triggering muscle contraction and propelling blood.

  • p wave & qrs complex

sodium ions, potassium ions

what ions exchange during depolarization (flowing in, flowing out)

repolarization

• the biological process where a cell, particularly muscle or nerve cells, returns to its negative resting state after depolarization (contraction or excitation)

• sodium channels close while potassium channels open, allowing positive potassium ions to leave the cell, restoring the negative charge inside

• T wave

sodium, potassium

what channels close, open (allowing positive ions out) during repolarization

lub

• S1

• the sound created by the closing of the atrioventricular valves during ventricular contraction (systole)

dub

• S2

• the sound of the closing of the semilunar valves during ventricular diastole (relaxation)

cardiac output

• the amount of blood pumped out by each ventricle in one minute

• a measure of how effective the cardiovascular system is in performing its function of moving blood throughout the body to deliver nutrients and remove wastes

• cardiac output (CO) = stroke volume (SV) x heart rate (HR)

stroke volume

• the volume of blood pumped out by one ventricle with each beat (ml/beat)

• at rest: 70 ml/beat

• = end diastolic volume - end systolic volume

heart rate

• the number of times your heart beats per minute (beats/min)

• at rest: 75 beats/minute

end diastolic volume, end systolic volume

what two things control stroke volume

end diastolic volume

the amount of blood that collects in a ventricle during diastole (relaxation)

end systolic volume

the volume of blood that remains in a ventricle after it has contracted

preload, contractility, afterload

stroke volume and cardiac output depend on what three factors?

preload

• the degree to which cardiac muscle cells are stretched before they contract

• higher = higher the stroke volume

contractility

• the contractile strength achieved at a given muscle length or the ability to produce a contraction (generate force) 

afterload

• the pressure that the ventricles must overcome to eject blood or the back pressure that the arterial blood exerts on the aortic and pulmonary valves

• Hypertension (high blood pressure) will reduce the ability of the ventricles to eject blood and result in a lowered SV

chronotropic agents

what are factors that can change heart rate called

• The sympathetic division of the autonomic nervous system

• The parasympathetic division of the autonomic nervous system

• Hormones

• Drugs

tunica intima, tunica media, tunica externa

what are the three layers in most blood vessels from innermost to outermost

tunica intima

• innermost layer of a blood vessel

• single layer of squamous endothelium surrounded by subendothelial layer of areolar connective tissue

tunia media

• middle layer of a blood cell

• circular arrangement of smooth muscle cells with elastic fibers

  • vasoconstriction: narrows lumen to increase blood pressure

tunica externa

• outer most layer of a blood vessel

• areolar connective tissue with collagen and elastic fibers

  • fibers anchor to surrounding organs

  • vasa vasorum: smaller arteries that feed wall of larger blood vessels

arteries, veins, capillaries

list the three different blood vessel types

elastic/ conducting, muscular/ distributing, arterioles

list the three types of arteries

arteries

• moves blood from heart to capillaries

• thicker tunica media

• narrower lumen

• more resilient and resistant to blood pressure changes

• (elastic, muscular, arterioles)

elastic arteries

• Nearest to the heart

• Conduct blood from heart to smaller branches

• Largest arteries (1-3cm)

• Contains lots of elastic fibers

• Stretch to receive blood

• Recoil to deliver blood to muscular arteries

• E.g. aorta, pulmonary trunk, common carotid, common iliac

muscular arteries

• 3mm-1cm in size

• More elastic fibers than other arteries

• Internal lamina between tunica intima and media

• External lamina between tunica media and externa

• E.g. brachial, coronary

arterioles

• Smallest arteries (10 μm-3 mm)

• Larger arterioles have all 3 tunics

• Smaller arterioles have thin endothelium  and single layer of smooth muscle cells

• Resistance vessels

veins

• Conducts blood toward the heart

• Thicker tunica externa

• Larger lumen vs arteries

• Fewer elastic and collagen fibers

• Collapse when no blood

• May contain valves

• venules/ veins as blood reservoir

venules, veins as blood resevoir

list the two types of veins

venules

• Smallest veins (8 to 100 μm)

• Receive blood from thoroughfare channels and capillary beds

• Larger have 3 tunics

• Merge to form veins

veins as blood reservoir

• At rest, 30% of blood volume is in pulmonary circulation and heart chambers

• 70% in systemic circulation

• 55% of total blood volume in veins, 15% in arteries/capillaries

capillaries

• Connect arterioles to venules

• Tunica intima does not have subendothelial layer

• Thin walls allow for perfusion (rapid exchange of gas/nutrients)

• Smallest vessels

• continuous, fenestrated, sinusoidal

continuous capillaries

• Most common type of capillary

• No breaks or spaces between cells

• Tight junctions connect adjacent cells

• Intercellular clefts between cells are large enough for small molecules to cross blood to interstitial fluid