-
The heart is the size of a fist and weighs
250-300 grams
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The heart is found in _________ and two thirds lies left of the _______ line
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The base of the heart is directed toward the _________ and the apex points toward the ________
-
The heart is enclosed in a double walled sac called the
pericardium
-
Deep to the pericardium is the
serious pericardium
-
THe ____________ lines the inside of the pericardium
parietal pericardium
-
THe ___________, or epicardium, covers the surface of the heart
visceral pericardium
-
THe ___________ is composed mainly of cardiac muscle and forms the bulk of the heart
myocardium
-
THe ____________ lines the chambers of the heart
endocardium
-
THe ______________ are the receiving chambers of the heart
right and left atria
-
The _____________ pumps blood into the pulmonary trunk; the _____________ pumps blood into the aorta
- right ventricle
- left ventricle
-
THe right side of the heart pumps blood into the __________ circuit; the left side pumps blood into the _________ circuit
-
Does the heart receive nourishment from the blood as it pass through the chamber?
No
-
The ______________ provides the blood supply for the heart cells
coronary circulation
-
IN a ___________ there is prolonged coronary blockage that leads to cell death
myocardial infarction
-
The __________ and ________ prevent back flow into the atria when the ventricles contract
tricuspid and bicuspid valves
-
WHen the heart is relaxed the __________ are closed, and when the heart contracts the __________ are open
- semilunar valves
- semilunar valves
-
Cardiac muscle is ________ and contraction occurs via the
- striated
- sliding filament mechanism
-
The cells of cardiac muscle fiber are
- short
- fat
- branched
- interconnected by intercalated discs
-
THe heart contracts as _____ or not at all
unit
-
THe heart's absolute refractory period is longer than a _____________, preventing
- skeletal muscle's
- tetanic contractions
-
The heart relies exclusively on _________ for its energy demands
aerobic respiration
-
Cardiac muscle is capable of switching _________ to use whatever nutrient supply is available
nutrient pathways
-
______________ is made up of specialized cardiac cells that initiate and distribute impulses, ensuring that the heart depolarizes in an orderly fashion
Intrinsic conduction system
-
THe ___________ cells have an unstable resting potential, called pacemaker potentials, tat continuously depolarizes
autorhythymic
-
Impulses pass through the auto rhythmic cardiac cells in the following order:
- 1. Sinoatrial node
- 2. Atrioventricular node
- 3.Atrioventricular bundle
- 4.Right and left bundle branches
- 5. Purkinje fibers
-
The autonomic nervous system modifies the heartbeat: the ____________ increases rate and depth of the heartbeat, and the ____________ slows the heartbeat
- sympathetic center
- parasympathetic center
-
An _____________ monitors and amplifies the electrical signals of the heart and records it as an electrocardiogram (ECG)
electrocardiograph
-
The first heart sound, lug, corresponds to the closure of the _, and occurs during _________
- AV valves
- Ventricular systole
-
THe second heart sound, dup, corresponds to the closure of the ______, and occurs during ___________
- semilunar valves
- ventricular diastole
-
___________ are extraneous heart sounds due to turbulent back flow of blood through a valve that does not close tightly
heart murmurs
-
_______ is the contractile phase of the cardiac cycle and _________ is the relaxation phase of the cardiac cycle
-
Cardiac Cycle
- a. Ventricular Filling: Mid-to-Late Diastole
- b. Ventricular Systole
- c. Isovolumetric Relaxation: Early Diastole
-
______________ is defined as the amount of blood pumped out of a ventricle per beat, and is calculated as the product of stroke volume and heart rate
cardiac output
-
Regulation of Stroke Volume:
- a. Preload: the Frank-Starling law of the heart states that the critical factor controlling stroke volume is the degree of stretch of cardiac muscle cells immediately before they contract
- b. Contractility: contractile strength increases if there is an increase in cytoplasmic calcium ion concentration
- c. Afterload: ventricular pressure that must be overcome before blood can be ejected from the heart.
-
Regulation of Heart Rate:
- a. Sympathetic stimulation of pacemaker cells increases heart rate and contractility, while parasympathetic inhibition of cardiac pacemaker cells decreases heart rate
- b. Epinephrine, thyroxine, and calcium influence heart rate
- c. Age, gender, exercise, and body temperature all influence heart rate.
-
Homeostatic Imbalance of Cardiac Output:
- a. Congestive heart failure occurs when the pumping efficiency of the heart is so low that blood circulation cannot meet tissue needs
- b. Pulmonary congestions occurs when one side of the heart fails, resulting in pulmonary edema
-
Aging aspects of the heart:
- 1. Sclerosis and thickening of the valve flaps occurs over time, in response to constant pressure of the blood against the valve flaps.
- 2. Decline in cardiac reserve occurs due to a decline in efficiency of sympathetic stimulation
- 3. Fibrosis of cardiac muscle may occur in the nodes of the intrinsic conduction system, resulting in arrhythmias.
- 4. Atherosclerosis is the gradual deposit of fatty plaques in the walls of the systemic vessels
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