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