Ch.18: The Cardiovascular System: THE HEART Flashcards
Location of the heart
Mediastinum> superior to the diaphragm> enclose in the pericardium cavity> posterior to the sternum> anterior to the vertebral column
Outermost layer of the heart. Protects, anchors, and prevents overfilling
Fibrous pericardium
Deep to the fibrous pericardium is the __________,a thin slippery, two layer serous membrane that forms a closed sac around the heart
Serous pericardium
_________ lines the internal surface of the fibrous pericardium
Parietal layer
________ also called EPICARDIUM, on external surface of the heart.
Visceral layer
Between the parietal and visceral layer is the slitlike ________, which contains a film of serous fluid. Decreases friction
Pericardial cavity, pericardial fluid
Blood enters the RIGHT ATRIUM via three veins
- Superior vena cava
- Inferior vena cava
- Coronary sinus
Small wrinkled protruding appendages are called
auricles
Irregular ridges of muscle called ______
trabeculae carnae
The largest artery in the body
aorta
The two ___________, located at each atrial-ventricular junction, prevents backflow into the atria when the ventricular contract
atrioventricular valve
The __________ guard the bases of the large arteries issuing from the ventricles and prevent backflow into the associated ventricles
Semilunar valves
Layers of the heart: Visceral layer of the serous pericardium, collagen and connective tissue
Epicardium
Cardiac muscle cells
Myocardium
Is continous with the endothelial lining of blood vessels, composed of simple squamous epithelium
Endocardium
Receiving chambers
Right and Left atrium
Discharging Chambers
Right and Left ventricles
The blood vessels that carry blood to and from the lungs
Pulmonary circuit
The blood vessels that carry blood to and from all the body tissues
Systemic circuit
PATHWAY OF BLOOD THROUGH THE HEART
Superior/inferior vena cava& coronary sinus>right atrium>tricuspid valve>right ventricle> Pulmonary semilunar valve>Pulmonary trunk>lungs> pulmonary veins>left atrium>bicuspid valve>left ventricle>Aorta semilunar valve>aorta> body
The functional blood supply to the heart muscle itself
Coronary Circulation
Arterial supply contains many ________ among branches for collateral routes provide additional routes for blood delivery
Anastomoses
The sinus has three large tributaries:
Great Cardiac Vein
Middle Cardiac Vein
Small Cardiac Vein
Homeostatic Imbalance:
Inflammation of the pericardium, roughens the serous membrane surfaces
Pericarditis
Homeostatic Imbalance:
Excess fluid compresses the heart and limits its ability to pump blood, heart plug
Cardiac Tamponade
Homeostatic Imbalance:
________ valve forces the heart to repump the same blood over and over because the valve does not close properly and blood backflows
Incompetent, or insufficient
Homeostatic Imbalance:
______ the valve flaps becomes stiff and constricts the opening
Stenosis
Homeostatic Imbalance:
Blockage of the coronary arterial circulation, thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium. Cells are weakened but do not die
Angina pectoris
Homeostatic Imbalance:
Commonly called a heart attack, in which cells do die. Prolonged coronary blockage
Myocardial infarction
Three fundamental differences between cardiac muscle and skeletal muscle
Means of Stimulation: automaticity, can initiate their own depolarization
Organ versus motor unit contraction: heart contract as a unit or heart doesn’t contract at all
Length of absolute refractory period: cardiac refractory period is as long as the contraction
Intercalated discs with ________ & _______
gap junctions and desmosomes
________ prevent cells from separating during contractions
desmosomes
_____ electrical synapses
gap junctions
______ cells 99% of the hear cells
contractile
______ cells 1% of the heart cells make up the conduction system
Autorhythmic
Phase occurs when Na+ channels open and Na+ diffuse into the cell. Membrane potential is reversed to 30 mV, and the Na+ channels are closed. Also opens slow Ca2
+ channels and Ca2+ ions diffuse into the cells
Depolarization phase
This is called the _______ phase when most Ca2+ channels are open, it ends as Ca channels close and K+ channels open.
Plateau Phase
__________ is due to Ca2+ channels inactivating and K+ channels opening. This allows K+ outlfow, which brings the membrane potential back to its resting voltage -90mV
Repolarization
________ is a collection of autorhythmic cells that can generate AP faster than any other part of the heart. Also called the PACEMAKER OF THE HEART
Sinoatrial (SA) node
Sequence of Excititation:
Describe first step during the Sinoatrial node
- pacemaker, originin of AP
- ap travels across from the SA node to the Av node
- Sinus rhythm
Sequence of Excititation:
Step 2: atrioventricular node
-delays the transmission of AP, allows atria to complete their contraction before the ventricles contract
Sequence of Excititation:
Step 3: Bundle of HIS
-allows atria and ventricular contractions to be synchronized
Sequence of Excititation:
Step 4: Right and Left bundle branches
-extend to the apex of the heart, then to the PURKINJE FIBERS
Homeostatic imbalances:
defects in the intrinsic conduction system can cause irregular heart rhythms
arrhythmias
Homeostatic imbalances:
A condition of rapid and irregular or out of phase contractions in which control of heart rhythm is taken away from the SA node by rapid activity in other heart regions
Fibrillation
Homeostatic imbalances:
Abnormal pacemaker may appear and take over the pacing of heart rate or the AV node may become the pacemaker
Ectopic focus
Homeostatic imbalances:
Any damage to the AV node interferes with the ability of the ventricles to receive pacing impulses causing ______
heart block
The cardiac centers are located in the
Medulla Oblongata
Cardioacceleratory center innervates the SA and AV nodes, heart muscle, and coronary arteries through _________ neurons
sympathetic
Cardioinhibitory inhibits SA and AV nodes through _________ fibers in the vagus nerve
Parasympathetic
The electrical currents generated in and transmitted through the heart spread throughout the body and can be detected with a device called an __________
Electrocardiograph EKG
Contraction of the two atria
Atrial systole
Contraction of the two ventricles
Ventricular systole
Relaxation of the two atria
Atrial Diastole
Relaxation of the two ventricles
Ventricular diastole
The first, the small ______, last about .08 s and results from movement of the depolarization wave from the SA node through the atria contract
P wave
The large ______ results from ventricular depolarization and precedes ventricular contraction
QRS complex
The _______, caused by ventricular repolarization, more spread out and has a lower amplitude than the QRS complex
T wave
The ________ is the time from the beginning of atrial excitation to the beginning of ventricular excitation
P-R interval
Marks the beginning of ventricular excitation
P-Q interval
________ plateau phases the entire ventricular myocardium is depolarized
S-T segment
The period from the beginning of ventricular depolarization through ventricular repolarization
Q-T interval
Abnormal heart sounds
heart murmurs
The ventricles are in the last part of their diastole and have the maximum volume of blood they will contain in the cycle an amount called the
end diastolic volume
The split second period when the ventricles re completely closed chambers and the blood volumes in the chambers remains constant as the ventricles contract is the
isovolumetric contraction phase
T wave, the ventricles relax, the blood remaining in their chambers referred to as the
end systolic volume
The remaining .4 is a period of total heart relaxation
quiescent period
Volume of blood pumped by each ventricle in one minute
Cardiac output
Hormone ______, increases and regulates metabolic rate
thyroxine
Hormone ______, increases heart rate
Epinephrine
Difference between maximum CO and CO when at rest
Cardiac reserve
Abnormally fast heart rate
Tachycardia
Heart rate slower than 60 beats per min
Bradycardia
