Chapter 19 - Cardiovascular System

heart location

- In the thoracic cavity - posterior to sternum left of the body midline between the lungs within the mediastinum - right ventricle lies on diaphragm

anterior interventricular artery supplies the

- anterior wall of the left ventricle - most of the interventricular septum

atrial contraction causes the following:

- compresses the opening of the great veins - pushes blood into ventricles

cardiac muscles use the following as fuel sources

- fatty acids - glucose - lactic acid - amino acids - ketone bodies

inotropic agents increase stroke volume by

- increasing contractility - increasing Ca2+ levels

fibrous skeleton of the heart functions

- maintain the shape of the heart - provide electrical insulation between the atria and ventricles - provide an anchor for the heart valves - isolate atria from ventricles

sinoatrial node (SA node)

- pacemaker of the heart that controls the heart beat - sets the rate of the heart's contractions by sending action potentials through the specialized conduction fibers to the atria and ventricles

The following valves are closed during the isovolumetric phase of the cardiac cycle:

- pulmonary semilunar - mitral - tricuspid - bicuspid

Cardiac muscle tissue contains

- sarcolemma - myofibrils - T tubules

Sequence of action potential for cardiac muscle cells

1) Na+ ions enter causing depolarization 2) Depolarization causes opening of voltage-gated K+ channels 3) slow voltage gated-Ca+ channels open causing a Ca+ -induced Ca2+ release 4) plateau occurs 5) voltage-gated Ca2+ channels close 6) Replorization occurs, returning the cell to the resting membrane potential

Sequence of initiation and conduction of an action potential in the heart

1) SA node fires action potential 2) action potential reaches AV node via gap junctions 3) action potential is delayed at the AV node 4) action potential travels down the bundle branches 5) action potential travels up the purkinje fibers

The following are great vessels

1) aorta 2) inferior vena cava 3) superior vena cava

pericardium (physical characteristics)

1) fibrous pericardium - dense irregular connective tissue encompasses the heart, but is not attached to heart (attached to diaphragm) 2) parietal layer of the serous pericardium - simple squamous epithelium and underlying layer of areolar connective tissue. adheres to the inner fibrous surface of the fibrous pericardium pericardial cavity in-between layers and is filled with serous fluid (lubricates serous membranes to prevent friction) 3) visceral layer of the serous pericardium (epicardium) - simple squamous epithelium and underlying layer of areolar connective tissue

The cardiovascular system consists of these two circulations

1) pulmonary 2) systemic

Ion channels in a cardiac nodal cell from resting membrane potential through an action potential in the following order

1) slow voltage-gated Na+ channels 2) fast voltage-gated Ca2+ channels 3) voltage-gated K+ channels

semilunar valves open

As ventricles contract and the blood forces its way into the arterial trunks

The ____ are smaller than the ______

Atria, ventricles

vein

Blood vessel carrying blood towards the heart

fossa ovalis (foramen ovale)

Closed fetal remnant that is located in wall (interatrial septum) between right and left atrium

The atria are separated from the ventricles externally by a relatively deep _______ sulcus (or ______ sulcus) that extends around the circumference of the heart.

Coronary (atrioventricular)

CO equation

HR x SV = CO

Prominent when viewing the heart from the posterior view

Left atrium and ventricle

Capillaries

Microscopic blood vessels that exchange gases with systemic cells or Alveoli in the lungs

The systemic circulation includes the movement of ______ blood through the left side of the heart

Oxygenated

The ___ ____ and primitive atrium form parts of the left and right atria

Sinus venosus

atrioventricular bundle

a bundle of modified heart muscle that transmits the cardiac impulse from the atrioventricular node to the ventricles causing them to contract (extend from AV node into and through the interventricular septum)

cardiac muscle rely heavily on

aerobic cellular respiration, approximately 25% of the cell is composed of mitochondria

End-systolic volume is defined as the

amount of blood remaining in a ventricle after contraction

heart murmur

an abnormal sound from the heart produced by defects in the chambers or valves (turbulent blood)

The left coronary artery typically branches into the ____ interventricular artery and the ___ artery

anterior, circumflex

D

areolar connective tissue

B

areolar connective tissue and fat

left atrioventricular valve (mitral/bicuspid) prevents

backflow of blood into left atrium

Aortic Semilunar Valve prevents

backflow of blood into left ventricle

right atrioventricular valve (tricuspid valve) prevents

backflow of blood into right atrium

pulmonary semilunar valve prevents

backflow of blood into right ventricle

left atrioventricular valve (mitral) name sake

bishops hat

During the refractory period, cardiac muscle

cannot be restimulated

medulla oblongata

cardiac center is located here

artery

carries blood away from the heart

cardiovascular system function

circulates nutrients, water, waste, oxygen, CO2, distributes heat to maintain homeostatis

coronary circulation

circulation of blood through the coronary blood vessels to deliver oxygen and nutrients to the heart muscle tissue

The left AV valve is forced ____ when the left ventricle begins to contract, ____ blood backflow into the left atrium

closed/preventing

Atherosclerosis

condition in which fatty deposits called plaque build up on the inner walls of the arteries

A1

coronary sinus

A large loss of blood would result in a _____ in the venous return to the heart

decrease

parasympathetic innervation ____ the heart rate, but generally tends to have no effect on the force of the contractions

decrease

Perfusion

delivery of blood per time per gram of tissue

ventricular relaxation

diastole, t-wave

cardiac cells

do not contract, they initiate and conduct electrical signals

coronary sinus

drains deoxygenated blood from the heart wall

E

endothelium

The epithelial layer of the endocardium is continuous with the epithelial layer called the ____, which lines the blood vessels

endothelium

cardiomegaly

enlargement of the heart resulting from congenital defects and coronary artery abnormalities

The outermost heart layer of the heart wall is the _____ and is also known as the _____ layer of the serous pericardium

epicardium/visceral

Desmosomes (anchoring junctions)

feature that prevents cardiac muscle cells from pulling apart

AV node (atrioventricular node) location

floor of the right atrium between the right AV valve and the opening for the coronary sinus

pulmonary circulation

flow of blood from the heart to the lungs and back to the heart

within the intercalated discs, ___ junctions increase the flow of ions between the cells as the muscle impulse moves along the _____

gap, sarcolemma

A trained athlete would be expected to have ____ compared to a non-athlete

greater ability to increase the cardiac output

pulmonary semilunar valve

heart valve located between right ventricle and pulmonary trunk

The innervation by autonomic centers in the brainstem does not initiate a heartbeat, but it can ____ or _____ the rate of the heartbeat

increase/decrease

The beginning of the ventricular contraction is the

isovolumetric contraction

E1

left atrium

B1

left ventricle

endocardium composition

membrane of epithelium (simple squamous) and underlying areolar connective tissue, including blood vessels and specialized muscle fibers (endothelium)

arterial anastomosis

more than one artery provides blood to a tissue

pecinate muscles

muscular ridges located on the anterior of the atrium and auricle

C

myocardium (cardiac muscle)

Heart Rate (HR)

number of heart beats per minute (bpm)

foramen ovale

opening in the septal wall (septum secundum) between the atria; normally present only in the fetus

cardioinhibitory center

parasympathetic innervation of the heart via the left and right vagus nerves (CN X)

isovolumetric relaxation

period when all four valves are closed and ventricular blood volume does not change

chordae tendineae function

prevent the atrioventricular valve from flipping into the atrium when the ventricle is contracting

atrial reflex (bainbridge reflex)

protects the heart from overfilling

D1

pulmonary veins

Begin within the apex of the heart and extend through the walls of the ventricles

purkinje cells

Afterload definition

resistance in the arteries to the ejection of blood by the ventricles; workload pressure exerted to eject blood from the chamber pressure that the heart must work to pump blood into the systemic circulation

papillary muscles

responsible for pulling the atrioventricular valves closed by means of the chordae tendineae (located in ventricles) consisting of

C1

right atrium

The second heart sound is produced when the ______ valves close, producing a "dubb" sound

semilunar

interventircular septum

separates the left ventricle from the right ventricle

interatrial septum

separates the right atrium from the left atrium

A

simple squamous epithelium tissue

positive inotropic agents

substances that increase contractility; an agent that causes an increase in stroke volume

The long refractory period observed in cardiac muscle prevents ____ contraction from occurring in the heart and causing pump malfunction

tetanic

cardiac reserve

the difference between a person's maximum cardiac output and cardiac output at rest

ventricular ejection

the period of time when both semilunar valves are open and blood begins to leave the heart

right atrioventricular valve (tricuspid valve) is forced closed when

the right ventricle begins to contract, preventing blood from flowing back into the right atrium

chordae tendineae (heart strings)

thin bands of fibrous tissue that attach from the papillary to the atrioventricular valves in the heart

semilunar valves physical description

three half-moon shaped cusps of dense connective tissue

right atrioventricular valve (tricuspid valve) physical description

three triangular-shaped cusps of dense connective tissue

semilunar and atrioventricular valves

two categories of heart valves

left atrioventricular (bicuspid, mitral) valve physical description

two triangular-shaped cusps of dense connective tissue

superior and inferior vena cava

veins that carry deoxygenated blood to the right atrium from the systemic circuit

epicardium composition

visceral layer of serous pericardium consisting of simple squamous and an underlying layer of areolar connective tissue

pulmonary veins location

visible in the left atrium

Stroke Volume (SV)

volume (mL) of blood pumped with each beat

cardiac output (CO)

volume of blood pumped by each ventricle in one minute

auricles of the heart

wrinkly, flat-like appendages that connect with the respective atria on the anterior of the heart. Made of pectinate muscle (that originates from smooth ridge - separation between atrium and auricle) -> ridges