a and p 2 chapter 20
Terms
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- how much does the heart pump per year?
- over 1 million gallons
- how many miles of blood vessels are there?
- over 60,000
- where is the heart located?
- mediastinum
- mediastinum
- area from the sternum to the vertebral column and between the lungs
- apex
- directed anteriorly, inferiorly and to the left
- base
- directed posteriorly, superiorly and to the right
- anterior surface
- deep to the sternum and ribs
- inferior surface
- rests on the diaphragm
- right border
- faces right lung
- left border
-
(pulmonary border)
faces left lung - what is located under the diagphragm?
- stomach and esophagus
- what are the hearts surfaces and borders?
-
surfaces anterior/inferior
borders right/left - fibrous pericardium
-
dense irregular ct
protects and anchors the heart prevents overstretching - serous pericardium
- thin delicate membrane
- what does the serous pericardium contain?
-
parietal layer-outer layer
pericardial cavity with pericardial fluid
visceral layer (epicardium) - epicardium
- visceral layer of serous pericardium
- myocardium
- cardiac muscle layer is the bulk of the heart
- endocardium
- chamber lining and valves
- muscle bundels of the myocardium
- cardiac muscle fibers swirl diagonally around the heart in interlacing bundles
- what are the chambers of the heart?
-
2 upper atria
2 lower ventricles - sulci of the heart
-
grooves on the surface of the heart containing coronary blood vessels and fat
coronary sulcus
anterior interventricular sulcus
posterior interventricular sulcus - coronary sulcus (sinus)
-
most important
encircles heart and marks the boundary between the atria and ventricles - anterior interventricular sulcus
- marks the boundary between the ventricules anteriorly
- posterior interventricular sulcus
-
(artery)
marks the boundary between the ventricles posteriorly - pulminary arteries have what type of blood?
- deoxygenated
- pulminary arteries are the only artery that is
- deoxygenated
- right atrium
-
receives blood from 3 sources
interatrial septum partitions the atria
fossa ovalis
tricuspid valve - fossa ovalis
- a reminant of the fetal foramen ovale
- right atrium tricuspid valve
-
blood flows through into right ventricle
has 3 cusps composed of dense ct covered by endocardium (epithelial tissue) - the right ventricle forms most of
- anterior surface of the heart
- right ventricle
-
papillary muscles
chordae tendineae
interventricular septum
pulmonary semilunar valve - papilary muscles
- are coned shaped trabeculae carneae ( raised bundles of cardiac muscles)
- chordae tendineae
- chords between valve cusps and papillary muscles
- interventricular septum
- partitions ventricles ( stops tricuspid valve from opening up)
- pulmonary semilunar valve
- blood flows into pulmonary trunk
- left atrium forms most of
- the base of the heart
- left atrium
-
receive blood from lungs
bicuspid (mitrol) valve - left atrium receives blood from lungs
- 4 pulmonary veins (2 right and 2 left)
- bicuspid valve
-
(mitral valve)
blood passes through into left ventricle
has 2 cusps
left atrioventricular, mitral, or bicuspid valve (lamb) - left ventricle forms
- the apex of the heart
- left ventricle
-
chordae tendinae anchor bicuspid valve to papillary muscles (also has trabeculae carneae like right ventricle)
-aortic semilunar valve - aortic semilunar valve
-
-blood passes through valve into the ascending aorta
-just above the valve are the openings to the coronary arteries - myocardial thickness and function
- thickness of myocardium varies according to the function of the chamber
- atria are
- thin walled, deliver blood to adjacent ventricles
- ventricle walls
-
are much thicker and stronger than the atria walls
-right ventricle supplies blood to the lungs (little flow resistance)
-left ventricle wall is the thickest to supply systemic circulation - what wall is the thickess of the cardiac walls?
- myocardium of left ventricle is much thicker than the right
- fibrous skeleton of heart
-
dense ct rings surround the valves of the heart, fuse and merge with the interventricular septum
-support structure for heart valves
-insertion point for cardiac muscle bundles
-electrical insulator between atria and ventricles - electrical insulator between atria and ventricles
- prevents direct propagation of ap's (action potentials) to ventricles
- atrioventricular valves open
-
a-v valves open and allow blood to flow from atria into ventricles when ventricular pressure is lower than atrial pressure
-occurs when ventricles are relaxed, chordae tendineae are slack and papillary muscles are relaxed - atrioventricular valves close
-
a-v valves close preventing backflow of blood ino atria
-occurs when ventricles contract, pushing valve cusps closed, chordae tendinae are pulled taunt and papillary muscles contract to pull cords and prevent cusps from everting - semilunar valves
-
-sl valves open with ventricular contraction
-sl valves close with ventricular relaxation - sl valves open with ventricular contraction
- allow blood to flow into pulmonary trunk and aorta
- sl valves close with ventricular relaxation
- prevents blood from returning to ventricles, blood fills valve cusps, tightly closing the sl valves
- function of atria
- atria contract, blood fills ventricles through a-v valves
- function of ventricles
- ventricles contract, blood pumped into aorta and pulmonary trunk through sl valves
- blood circulation
- 2 closed circuits, the systemic and pulmonic(systemic circulation and pulmonary circulation)
- systemic circulation
-
-left side of heart pumps blood through body
-left ventricle pumps oxygenated blood into aorta
-aorta branches into many arteries that travel to organs
-arteries branch into many arterioles in tissue
-arterioles branch into thin walled capillaries for exchange of gases and nutrients
-deoxygenated blood begins its return in venules
-venules merge into veins and return to right atrium - pulmonary circulation
-
-right side of heart pumps deoxygenated blood to lungs
-right ventricle pumps blood to pulmonary trunk
-pulmonary trunk branches into pulmonary arteries
-pulmonary arteries carry blood to lungs for exchange of gases
-oxygenated blood returns to heart in pulmonary veins - blood flow colors
-
blue-deoxygenated
red-oxygenated - coronary circulation
-
blood supply to the heart
-heart as a very active muscle needs lots of o2
-when the heart relaxes high pressure of blood in aorta pushes blood into coronary vessels
-many anastomoses - anastomoses
- connections between arteries supplying blood to the same region, provide alternate routes if one artery becomes occluded
- coronary arteries
-
branches off aorta above aortic semilunar valve
-left coronary artery
-right coronary artery - coronary veins
-
-collect wastes from cardiac muscle
-drains into a large sinus on posterior surface of heart (coronary sinus)
-coronary sinus empties into right atrium - where does the coronary sinus empty into?
- right atrium
- cardiac muscle histology
- branching intercalated discs with gap junctions, involuntary, striated, single central nucleus per cell
- conduction system of heart
-
coordinates contraction of heart muscle
-autorhythmic cells
-sa node
-av node
-av bundle of His - autorythmic cells
- cells fire spontaneously, act as a pacemaker and form conduction system for the heart
- sa node
-
-cluster of cells in wall of rt. atria
-begins heart activity that spreads to both atria
-exicitation spreads to av node - av node
- in atrial septum, transmits signal to bundle of His
- av bundle of His
-
the conection between atria and ventricles
divides into bundles branches and purkinje fibers, large diameter fibers that conduct signals quickly - rythm of conduction system
-
-sa node fires spontaneously 90-100 times per minute
-av node fires at 40-50 times per minute
-if both nodes are suppresed fibers in ventricles by themselves fire 20-40 times per minute - rythm of cs
-
-artificial pacemaker is needed if pace is to slow
-extra beats are forming at other sites are called ectopic pacemakers(increased by cafeine and nicotine) - depolarization
-
-cardiac cell resting membrane potential is-90mv
-excitation spreads through gap junctions
-fast na channels open for rapid depolarization - plateau phase
-
-250 msec (only 1msec in neuron)
-slow ca2 channels open, let ca2 enter from outside cell and from storage in sarcoplasmic reticulum, while k channels close
-ca2 binds to troponin to allow for actin-myosin cross-bridge formation and tension development - repolorization
- -ca2 channels close and k channels open and -90mv is restored as potassium leaves the cell
- refratory period
- very long so heart can fill
- systole
- contraction
- diastole
- relaxation
- one cardiac cycle
-
what happens to the heart in one beat at 75 beats/min, one cycle requires 0.8 sec.
-end diastolic volume (edv)
-end systolic volume (esv)
-stroke volume (sv) - at 75 beats/min, one cycle requires 0.8 sec.
- systole and diastole of both atria, plus the systole and diastole of both ventricles
- edv
- volume in ventricle at end of diastole, about 130ml
- esv
- volume in ventricle at end of systole, about 60ml
- sv
-
-the volume ejected per beat from each ventricle, about 70ml
-sv=edv-esv - isovolumetric relaxation
-
all relaxing at the same time(closed)
atriums filing up(coronary sinus) - ventricular filing
-
- rapid ventricular filing as blood flows from full atria
-diastasis:as blood flows from atria in smaller volume
-atrial systole pushes final 20-25 ml blood into ventricle
atrial ventricular valves open - ventricular systole
-
-isovolumetric contraction: brief period, av valves close before sl valves open
-ventricular ejection:as sl valves open and blood is ejected to ventricule - bp in aorta
- 120mm hg
- bp in pulmonary trunk
- 30mm hg
- differences in ventricle wall thickness allows
- heart to push the same amount of blood with more force from the left ventricle
- the volume of blood ejected from each ventricle is
- 70ml (stroke volume)
- sound of the heart beat are from
- turbulence in blood flow caused by valve closure
- what are the 2 sounds of the heart?
- lubb/dupp
- lubb
- is created with the closing of the atrioventricular valves
- dupp
- is created with the closing of semilunar valves
- cardiac output
-
amount of blood pushed into aorta or pulmonary trunk by ventricle
determined by stroke volume and heart rate - cardiac reserve
- maximum output/output at rest
- influences on stroke volume
-
preload (affect of stretching)
contractility
afterload - preload
-
frank-starling law of heart
-more muscle is stretched, greater force of contraction
-more blood more force of contraction results - contractility
- autonomic nerves, hormones, ca+2 or k+ levels
- afterload
-
-amount of pressure the heart has to overcome
-high blood pressure creates high afterload - regulation of heart rate
-
-nervous control from the cardiovascular center in the medulla
-heart rate is also affected by hormones - nervous control from the cardiovascular center in the medulla
-
-sympathetic impulses increase heart rate and force of contraction
-parasympathetic impulses decrease heart rate
baroceptors (pressure receptors) detect change in bp and send info to the cardiovascular center(located in the arch of the aorta and carotid arteries) - what hormones affect heart rate?
-
-epinephrine, norepinephrine, thyroid hormones
-ions (na+, k+, ca2+)
-age, gender, phsical fitness, and temp. - factors in heart disease
-
diabetes mellitus
genetic predisposition
male gender
high blood levels of fibrinogen
left ventricular hypertrophy - what should the total cholesterol be for an adult?
- under 200 mg/dl