Cardiovascular System Vet. Anatomy and Physiology – Flashcards
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Heart
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Muscular hollow organ with four chambers
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Base
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wide top portion where the atria are found and the major vessels enter and exit the heart
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Apex
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pointed end of the heart that is where the left and right ventricle are found
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Auricles
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ear shaped appendages of either atrium of the heart
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Intraventricular sulci
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the borders of the ventricles; can be seen on the surface of the heart; contain fat and blood vessels
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Atria
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at the base of the heart; thin walls as they contain blood under low pressure
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Ventricles
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thick walls as they eject blood under high pressure into arteries; right ventricular wall is smaller
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Coronary arteries
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Branch off of aorta immediately after leaving the left ventricle and course around the heart
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Pericardium
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Fibrous connective tissue sac covering heart; Made of loose connective tissue covered by a layer of mesothelium
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Epicardium
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Outermost layer of the heart
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Endocardium
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Inner lining epithelium that lines the chambers and valves
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Myocardium
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The muscular middle layer of the heart
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Interventricular Septum
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Muscular structure that separates the left and right ventricles
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Moderator band
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A band of tissue in the right ventricle that originates at the interventricular septum but does not attach to the flaps of the tricuspid valve; it connects to the outside wall of the right ventricle; gives the wall of the right ventricle structural support
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Heart Valves
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Control the unidirectional blood flow in the heart as they can only open in one direction
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Atrioventricular (AV) valves
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loose, overlapping flaps of tissue attached to papillary muscles on the inner wall of the heart by cordae tendineae ("heart strings")
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Tricuspid (Right Valve)
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One-way flow from right atrium to right ventricle
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Pulmonary Valve (a semilunar valve)
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One-way flow out of right ventricle into pulmonary artery
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Mitral Valve (Left AV valve)
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One-way flow from left atrium into left ventricle
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Aortic Valve (a semilunar valve)
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One-way flow from left ventricle into aorta
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Coronary Veins
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Empty deoxygenated blood via the coronary sinus into the right atrium
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Coronary Arteries
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Supply the muscle of the heart with oxygenated blood from the aorta
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Pulmonary circulation
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Under low pressure, inside the thorax
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Systemic circulation
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Blood circulation outside the thorax; Under high pressure and includes portal and peripheral circulation
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Arteries
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Carry blood under high pressure away from the heart, has 3 layerts, inner smooth endothelium, middle smooth muscle, outter fibrous tissue
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Aorta
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largest artery in the body
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subclavian arteries
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supply the thoracic limb
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Iliac arteries
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supply the pelvic limbs
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Arterioles
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Small branches of arteries that lead to capillaries
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Capillaries
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Vessels with thin walls (no muscle in the walls); where oxygen and nutrients in the blood are exchanged for carbon dioxide and other waste products
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Venules
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Small veins that carries blood from capillaries to veins
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Veins
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carry blood under low pressure to the heart, small and medium ones have vavles
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Cranial Vena Cava
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carries blood from the left and right brachiocephalic veins to the heart
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Caudal Vena Cava
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carries blood from the left and right iliac veins to the heart
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Arterial system
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High pressure system, forcing blood to tissues
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Venous system
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Low pressure system, returning blood by gravity and muscular pressure
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Edema
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accumulation of fluid in tissues
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Diastole
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First part of the cardiac cycle when the heart is relaxed and filling with blood (lower)
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Systole
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Second part of cardiac cycle when the atria and ventricles of the heart are contracting and expelling blood into the vascular system and increasing vascular pressure (higher)
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Hypovolemic shock
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blood loss
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Anaphylactic shock and septicemic shock
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small blood vessels of the organs and tissues all dilate at the same time
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Foramen ovale
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A hole between the cardiac atria that closes at birth; allows the blood to bypass the pulmonary circulation by passing from the right atrium to the left atrium
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Ductus arteriosus
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Blood vessel that shunts blood from the pulmonary artery to the aorta in a fetus
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Auscultation
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listening to the heart by using a stethoscope
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1st heart sound
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Closure of atrioventricular valves (Tricuspid on right, Mitral on left)
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2nd heart sound
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Closure of semilunar valves
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3rd heart sound
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Rapid ventricular filling
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4th heart sound
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Contraction of the atria
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Cardiac Output
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the volume of blood that leaves the heart per minute
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Stroke Volume
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the amount of blood ejected with each cardiac contraction
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Heart Rate
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how often the heart contracts per minute
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Formula for CO
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CO (Cardiac Output) = SV (Stroke Volume) X HR (Heart Rate)
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Starling's Law
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Increased filling of the heart (increased preload) results in increased cardiac contraction
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Inotrophy
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force of contraction
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Chronotrophy
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rate of contraction
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Sinoatrial (SA) Node
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Group of automatically depolarizing cells that are the heart's pacemaker located in the wall of the right atrium
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Atrioventricular (AV) Node
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A specialized cluster of connecting cells through which, in normal animals, the depolarization wave can reach the ventricles
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The cardiac Cycle
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Impulse for depolarization travels through the SA node, the AV node, the bundle of His, and then the Purkinje Fibers, which causes ventricular contraction
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Purkinje Fibers
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Located in the left and right ventricular walls; Disseminate electrical impulses across the ventricles which cause the ventricles to contract
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Resting state
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no activity, cell membrane ion pumps constantly move sodium out of, and move potassium into the cells to maintain cell's electrical potential under readiness to discharge an impulse or depolarize
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Resting membrane potential
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the electrical charge of some cells at rest caused by differing concentrations of ions inside and outside of the cell membrane
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Depolarization
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Sodium channels open upon stimulus; Sodium rushes into cells following electrical potential or attraction; Inside of cell goes from negative charge to positive charge
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action potential
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Change in charge
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Repolarization
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Sodium channels close and potassium channels open K+ rushes out of cells following electrical potential or attraction;Inside of cell goes from positive charge to negative charge; resting potential is re-established and cell is ready to depolarize again after refractory period; Sodium-potassium pump moves ions back across membrane to re-establish Na+ concentrations outside cell and K+ inside
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Depolarization Threshold
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the required level of stimulation, or degree of change in cell's electrical potential, necessary to initiate an action potential
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All-or-None Principle
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the way in which a neuron depolarizes completely or not at all in response to stimulation
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Refractory Period
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period in the depolarization-repolarization cycle when the neuron cannot be stimulated to depolarize or can only be depolarized with a greater than normal stimulation
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Dromotropic
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electrical conduction
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P wave
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atrial depolarization (contraction)
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QRS complex
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ventricular depolarization (systole)
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T wave
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ventricular repolarization
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Normal sinus rhythm
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P waves followed by QRS waves and T waves in the normal length of time and configuration
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Arrhythmia
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abnormal pattern of electrical activity in the heart
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Premature Ventricular Contraction (PVC)
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depolarization of the ventricles out of the normal sequence, causing the ventricles to contract prematurely
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Paroxysm
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a short series of multiple PVCs
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Ventricular Flutter
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longer series of PVCs
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Ventricular Fibrillation
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severe conduction disturbance resulting in a ventricular contraction so uncoordinated that the heart simply quivers, a rapidly fatal condition
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1st degree AV block
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prolonged PR interval
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2nd degree AV block
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a P wave without a corresponding QRS complex (an intermittent missed beat on auscultation)
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3rd degree AV block
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the ventricles beat independently of the atria
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Sympathetic nerves
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stimulate the heart to beat faster and stronger under circumstances of fright or stress
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Parasympathetic nerves
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inhibit the function of the heart beat by slowing it down and weakening the force of the beat
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Nerve Origin SNS
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arise from T1-L5 spinal nerves
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Nerve Origin PNS
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arise from brain (Cranial Nerves) and sacral vertebral spinal nerves
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norepinephrine
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key neurotransmitter in the SNS
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Adrenergic (sympathomimetic) Neurons
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release norepinephrine
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Alpha1-adrenergic receptors
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associated with the sympathetic nervous system response; these receptors, when stimulated by catecholamines (dopamine, norepinephrine, epinephrine), tend to cause vasoconstriction
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Beta1-adrenergic receptors
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Located on the heart; Associated with the sympathetic nervous system response; these receptors, when stimulated by catecholamines (dopamine, norepinephrine, epinephrine), tend to cause an increase in rate and force of contraction of the heart by increasing the permeability of the heart muscle to calcium
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Beta-2 adrenergic receptors
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associated with the sympathetic nervous system response; these receptors, when stimulated by catecholamines (dopamine, norepinephrine, epinephrine), tend to cause bronchodilation and vasodilation of some blood vessels
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Muscarinic Receptors for Acetylcholine (PNS)
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found on the target organs and tissues supplied by the postganglionic neuron of the parasympathetic nervous system
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Nicotinic Receptors for Acetylcholine (PNS)
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found primarily on the postganglionic neurons of both the sympathetic and parasympathetic nervous system, as well as between motor neurons and muscle in the somatic (voluntary) motor system
