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HistologyTest Monday

Action potentials spread from the S-A node to the A-V node causing atrial depolarization
atrial depolarization seen as the ___ wave induces atrial systole P
action potentials spread through the bundle of ___, bundle branches and purkinje fibers causing _____depolarization. His ventricular
ventricular depolarization seen as the ____ complex induces ventricular _____. QRS systole
As action potential pass out of the ventricles, ventricular ____is induced. diastole
Ventricular repolarization is shown by the___wave t wave
The period of time from the onset of the P wave to the beginning of the QRS complex is termed the P-R interval
time which the entire ventricle is depolarized & roughly corresponds to the plateau phase of the ventricular action potential.diagnosis of ventricular ischemia or hypoxia because under those conditions, the__ can become either depressed or elevated ST segment
represents the time for both ventricular depolarization and repolarization to occur, and therefore roughly estimates the duration of an average ventricular action potential. Q-T INTERVAL
____circulation conveys blood from the heart to the lungs and from the lungs to the heart. Pulmonary
____circulation conveys blood from the heart to other tissues of the body from other tissues of the body to the heart. Systemic
The smallest arteries Functionally associated with network of capillaries into which they deliver blood. Regulate the amount of blood that enters these capillary networks. Arterioles
In some parts of systemic circulation it is modified so that a vein or an arteriole is interposed between two capillary networks. These vessels constitute PORTAL SYSTEM
Venous portal systems occur in vessels carrying blood to the liver, HEPATIC PORTAL SYSTEM (portal vein)
in vessels, leading to the pituitary hypothalmic-hyposeal portal system
The ___ atrium-receives blood returning from the body (via inferior and superior ___ ___ [two largest veins]) right venae cava
The __ventricle- receives blood from the right atrium and pumps it to the lungs for oxygenation via the ___ arteries. right pulmonary
__Atrium- receives the oxygenated blood returning from the lungs via the 4 ___veins. left pulmonary
__ventricle- receives blood from the left atrium and pumps it into the ___ for distribution into the systemic circulation. left aorta
• thinner • it has a center layer of cardiac muscle except in certain localized areas that contain fibrous tissue • lining of endocardium facing each chamber Interatrial septum
• is the wall between the right and left ventricle • contains cardiac muscle except in the membranous portion • endocardium lines each surface interventricular septum
Stimulation of the parasympathetic nerves ____the heart rate Stimulation of the sympathetic nerve ___the heart rate DECREASES INCREASES
(high pressure receptors), which sense arterial BP. Located in the ___ sinus and __ arch Baroreceptors carotid sinus and aortic arch.
(low pressure receptors) which are located within the walls of the __ and __. They sense central venous pressure and provide the CNS with information about cardiac distention. Volume receptors atria and ventricles
which detect alterations in oxygen, carbon dioxide tension and in pH. These receptors are carotid and aortic bodies located at the ____ of the common carotid arteries in the ___ arch Chemoreceptor bifurcation aortic arch.
The release of the neurotransmitter ___from the terminals of these fibers slows the heart rate. (An effect known as ___) reduces the force of the heartbeat and constricts the coronary arteries of the heart. acetylcholine Bradycardia
autonomic fibers secrete ____that regulates the rate of impulses emanating from the S-A node. The sympathetic component causes the rate of contraction to increase. (an effect known as ___) and increases the force of muscle contraction. norepinephrine Tachycardia
_____stimulation produces dilation of the coronary arteries by inhibiting their constriction. Sympathetic
Epicardium consists of a layer of mesothelial cells on the __ surface of the Heart and its underlying CT. the BC and nerves that supply the heart are loctated here and are surrounded by adipose tissue. outer
myocardium consisting of __muscle, the principal component of the heart. The myocardium of the ventricles are __ than that of the atria bc of the larde amounts of __muscle in the walls of the 2 pumping chambers. cardiac thicker cardiac
endocardium consisting of an __ layer of endothelium and subendothelium CT, a middle layer of CT and smooth muscle cells and a depper layer of CT aka the __ layer, which is continuous with the CT of the myocardium. inner subendocardial
The impulse conducting system of the heart is located in the ___ layer of the endocardium subendocardial
Arteries: Vessels that deliver blood to the capillaries.
chemoreceptors stiumulate __ activity, inhibit __activity, and __ arterial pressure sympathetic parasympathetic increases
Vagus nerve Terminate at SA and AV nodes Release of Ach(acetylcholine) slows the heart rate ..aka Bradycardia Force decreases and coronary arteries constrict Parasympathetic
Sympathetic in lateral horns @T1-T6 segments of spinal cords Terminate in AV &SA nodes secretion of Norepineprine causes the rate of contraction to increase aka Tachycardia Increases force of contraction Dilation of coronary arteries by inhibiting their constriction
(heart valve) Fibrosa forms the core of the valve contains fibrous extensions from the dense irregular CT of the skeletal rings of the heart
Represents loose CT located on the atrial or BV side of each valve ( Heart valve )Spongiosa
Immediately adj to the ventricular or atrial surface of each valve (heart valve) Ventricularis
These conditions known collectively as vascular heart disease, including: • rheumatic heart disease • vegetative endocarditis • degenerative calcific aortic valve stenosis • mitral annular calcification
• The electrical impulses are generated at the ___ node sinuatrial (S-A)
the __node initiates an impulse that spreads along the cardiac muscle fibers of the atria and along intermodal tracts composed of modified cardiac muscle fibers. S-A
The impulse is then picked up at the __ node and conducted across the fibrous skeleton to the ventricles by the ____ A-V node A-V Bundle (of His).
"pacemaker of the heart" is another term for which node? S-A
• The bundle divides into smaller right and left bundle branches and then into subendothelial branches commonly known as Purkinje fibers.
The A-V bundle, the bundle branches and the Purkinje fibers are mondified cardiac muscle cells that are specialized to conduct ___. impulses
• The nodes and A-V bundle and its branches are modified cardiac muscle fibers that are ___than normal. smaller
• The purkinje fibers are modified cardiac muscle fibers that are ___than normal. larger
Changes in the force and rate of the cardiac muscle contractions are regulated by hormones secreted from the adrenal medulla. norepinephrine and epinephrine are examples
Activation of adrenergic receptors (mainly __ type) by epinephrine and less efficiently by norepinephrine results in an increase in the force of contraction (positive inotropic effct) and trachycardia. β1
Other substance have the positive inotropic and chronotropic effects on the heart include: these substances .... Ca2+ thyroid hormone, caffeine, theophylline cardiac glycoside digoxin. increase intracellular Ca2+ levels in cardiac myocytes
Substance that have negative inotropic and chronotropic actions on the heart muscle include: these substances..... Adrenergic receptor antagonist: propranolol Ca2+ channel blockers these substances decrease the heart rate and force the cardiac muscle contraction.
Tunica intima -arteries innermost “intimate” Single layer of squamous epithelial cells Basal lamina Subendothelial layer
Tunica media –atteries middle layer Smooth muscle layer Elastin No fibroblasts
Tunica adventitia – arteries outermost “adventurous” Collagen and few elastin fibers Large valves also present vasa vasorum and nervi vascularis Contain fibroblasts especially in muscular arteries
vasodilation: ___the smooth muscle cells Lumen wall ___ __blood flow __vascular resistance __systemic blood pressure Relax increases More Reduce Reduce
Vasoconstriction: ___the smooth muscle cells Lumen wall ___ __blood flow __vascular resistance __systemic blood pressure Contraction decreases less increase increase cardiac output
vasodilation occurs in response to substances produced by endothelial cells calls____ endothelial derived relaxing factors (EDRFs)
the most important of the EDRFs are ..... and its related compounds which are released by endothelial cells in arteries, blood capillaries and even lymphatic capillaries. Nitric oxide (NO)
Large Arteries (Elastic Arteries) Have __ sheets of elastic lamellae in their walls• serve primarily as __tubes they facilitate the continuous and uniform ___of blood along the tube multiple conduction movement
The largest elastic arteries ..... convey blood from the heart to the systemic and pulmonary circulations (aorta and pulmonary arteries)
The ventricles of the heart pump blood into the elastic arteries during the contraction phase ___ of the cardiac cycle. (systole)
During the relaxation phase ___ of the cardiac cycle, when no pressure is generated by the heart, the recoil of the distended elastic arteries serves to maintain Arterial BP and then the flow of blood within the vessel. (diastole)
The tunica media is the ___ of the three layers of elastic arteries and consists of: • Elastin • Smooth Muscle Cells • Collagen fibers and Ground substance. thickest
The tunica adventitia in the elastic artery is relatively ___CT layer  Collagen and elastic fibers  Fibroblast and microphages  Blood vessels (vasa vasorum) and nerves (nervi vascularis). thin
Medium Arteries (Muscular Arteries). • Muscular arteries have __ smooth muscle and amid collagen fibers and __ elastin in the tunica media than do elastic arteries more less
Small Arteries & Arterioles • Arterioles have ..... layers of Smooth muscle in their TM. only 1 or 2
Large Arteries Elastic Conduction tube Important in regulating diastole and systole
Medium Arteries Muscular Less elastin in tunica media Thinner tunica intima (age and health)
Small Arteries Arterioles are not the same as small arteries Depends on the number of smooth muscle layers Different roles Arterioles control blood flow to capillary networks by contracting smooth muscle cells or increase vascular resistance
• The slight thickening of the SM at the origin of a capillary bed from an arteriole is called precapillary sphincter.
A large decrease or increase in vascular resistance has a direct effect on blood flow and systemic arterial pressure. This regulation directs blood to where it may be most needed During strenuous physical exertion, blood flow to skeletal muscle is increased by dilation of arterioles and blood flow to the intestine is reduced by arteriolar constriction. After ingestion of a large meal the reverse is true.
Continuous capillaries found in : Occluding junction Some have pericytes (contract and are controlled by NO) Muscle, lungs, and CNS
Fenestrated capillaries Endocrine glands and sites of fluid and metabolite absorption Sometimes there are differences between the organs Gall bladder and intestinal tract where they have fewer fenestrations and thicker wall when no absorption is occurring.
Dicontinuous capillaries Called sinusoidal capillaries or sinusoids __ and ___shape Vary with organs Found in large and irregular shape liver, bone marrow, and spleen
capillaries are important for • ____ is controlled through local and systemic signals. In response to vasodilating agents such as... blood flow (EDRFs, NO, low O2 tension)
• The smooth muscle in the walls of the arterioles relaxes, resulting in vasodilation, & increased blood flow through the • Capillary System
Pressure within the capillaries increases and much fluid of the plasma fluid is driven into the tissue. This process occurs in peripheral edema.
• Systemic signals carried by the ANS & release of norepinephrine by adrenal gland cause the smooth muscle of the arterioles to contract(vasoconstriction) resulting in decreased blood flow through the capillary bed o in this condition, capillary pressure can decrease & greatly increase absorption of tissue fluid  this situation occurs during loss of blood volume and can add approx 1L of fluid into the blood, preventing hypovolemic shock.
capillaries are also important in ___• density
Density of the capillary network determines the total ____ available for exchange between the blood and tissue • It is related to the metabolic activity of the tissue. • surface area
The __,___,___ muscle, and ___ muscle have rich capillary networks. • liver, kidney, cardiac muscle, and skeletal muscle
Dense CT is less metabolically active and has ___ extensive capillary networks less
Shunts allow blood to bypass ____by providing direct routes between arteries and veins. capillaries
A-V shunts are found commonly on the: skin of fingertips, nose & lips & in the erectile tissue of the penis and clitoris
The arteriole of A-V shunts is oftened: coiled, • has thick smooth muscle layer, • enclosed in CT capsule, • richly innervated
____of the arteriole smooth muscle of AV shunts send blood to capillary bed; ____of the smooth muscle sends blood to a venule, bypassing the capillary bed. contraction relaxation
Closing an AV shunt in the skin causes blood to flow from the capillary bed, enhancing heat ___. Opening of an AV shunt in the skin reduces blood flow to skin capillaries, ___body heat. loss conserving
Atypical veins- dural venous sinuses, coronary arteries, the great saphenous vein, muscular vein, central adrenomedullary vein.
are located distal to the postcapillary venules in the retuning venous network . They have one or two layers of smooth muscle that constitutes a tunica media. These vessels also have thin tunica adventitia. • Muscular venules-
• Postcapillary venules do not have true tunica media. The endothelium is the principal site of action of vasoactive agents such as histamine and serotonin.
Response to histamine and serotonin agents results in .... extravasation of fluid and emigration of WBC from vessel during inflammation and allergic reactions.
consists of an endothelium with basal lamina, a thin subendothelial layer with occasional smooth muscle cells scattered in the CT elements and in some cases a thin internal elastic membrane. Tunica intima- of Medium veins
thinner than the same layer in medium sized arteries. Several layers of circularly arranged SMC with interspersed collagen and elastic fibers. Longitudinally arranged SMC may be present just beneath the tunica adventitia. Tunica media of Medium veins
typically licker than the tunica media, has collagen fibers and networks of elastic fibers. Tunica adventitia- of Medium veins
the ___ or the Large veins, is the ___ layer of the vessel wall. (subclavian veins and the venae cavae) thickest Along with the usual collagen and elastic fibers and fibroblast, the TA also contains Longitudinally disposed smooth muscle cells.
atherosclerosis Abnormality to blood vessels Prevents blood flow Poor oxygenation Death of tissue Foam cells, fatty streaks, plaques
Larger than ventricular cells Myofibrils are located @ the periphery of the cell Nuclei are rounded & larges than nuclei of cardiac muscle Stain w/(PAS) -glycogen Pale with H & E More resistant to hypoxia than ventricular muscle cells Purkinje Fibers
Beta adrenergic receptors Anything that increases calcium Thyroid hormones Caffeine Propranolol or calcium channel blocker Circulating hormones
Nitric oxide (NO) is produced by the ___ in endothelial cells. It is an important molecule regulating relaxation of smooth muscle. eNOS
____ ____ produced between erythrocytes and endothelial cells as well as VEGF activates eNOS, increasing production of nitric oxide (NO) shear stress
once NO is produced it diffuses to the underlying smooth muscles and activated guanylate cyclase production of cGMP, which in turn activates cGMP dependent protein kinase G (PKG) metabolic pathways causing smooth muscle ____ relaxation
The reduced rate of nitric oxide (NO) production, which is a potent ___, or inactivation of NO by the superoxide anion (O2-) has a stimulating effect on smooth muscle___ contraction
nitric oxide is a vaso____ vasodilatator
systole is the ___ phase of the cardiac cycle contraction
diastole is the ___ phase of the cardiac cycle relaxation
Regulate the amount of blood that enters these capillary networks. arterioles
Created by: katie.nelson8