Anatomy 2 - Test 1 Objectives - Set 4

Front 1

Tell me about the pericardium

Back 1

Theloosely fitting superficial part of the sac is the fibrous pericardium. It protectsthe heart, anchors it to surrounding structures, and prevents it from overfilling with blood.

Theserous pericardium is a thin, slippery two-layer serous membrane that forms aclosed sac around the heart. Thevisceral layer, aka the epicardium is an integral part of the wall of theheart.

Front 2

trace blood flow through the heart chambers, notingthe location and mechanisms of the valves encountered

Back 2

The superior and inferior vena cava-> right atrium-> tricuspid valve-> right ventricle-> pulmonarysemilunar valve -> pulmonary trunk -> lungs-> four pulmonary veins-> left atrium -> mitral valve (bicuspid) -> left ventricle ->aorta

Front 3

Compare and contrast atrioventricular valves andsemilunar valves.

Back 3

atrioventricularvalves are open until the ventricles contract. The semilunar valves are forced openwhen the ventricles contract. When the ventricles relax, the blood flowsbackward toward the heart it fills the cusps and closes the valves.

Front 4

Tell me about cardiac muscle structure

Back 4

Cardiac muscle cells are short, fat, branched and interconnected. Cardiac muscle cells do not have triads. Theplasma membranes of adjacent cardiac cells interlock like ribs of two sheets ofcorrugated cardboard at intercalated disks. Largemitochondria account for 25-35% of the volume of cardiac cells

Front 5

Tell me about the functional properties of cardiac muscle.

Back 5

Cardiacmuscles are self-excitable. In cardiac muscle either all the fibers contract orthe heart does not contract at all. Cardiac muscle fibers have a longrefractory period – 200ms – nearly as long as the contraction.

Front 6

Outline the events of cardiac muscle contraction

Back 6

Depolarization - Fast gated Na channels open --90mVto +30 mV; slow gated Calcium channels open -T tubules release Ca into sarcoplasm; excitation-contraction coupling; depolarization results from inactivation of Ca channels and opening of potassium channels; Ca is pumped back into the SR and extracellular space.

Front 7

trace the conduction pathway

Back 7

SA node -> AV node -> AV bundle(bundle of HIS)-> bundle branches -> superendocardial conducting network (purkinjefibers)

Front 8

Pwave

Back 8

results frommovement of the depolarization wave from the SA node through the atria.

Front 9

QRScomplex

Back 9

QRScomplex- results from ventricular depolarization

Front 10

Twave

Back 10

T wave-ventricular repolarization

Front 11

Describe normal heart sounds

Back 11

Lub dub – lubis atrial ventricular valve closing. Dub issemilunar valves closing

Front 12

Most often, murmursindicate

Back 12

Most often, murmurs indicate valveproblems where an insufficient or incomplete valve fails to close completely.There is a swishing sound as blood backflows or regurgitates through apartially open valve after the valve has supposedly closed.

Front 13

Explain the role of the sympathetic nervous system in regulating strokevolume and heart rate.

Back 13

NE acts on Beta 1 receptorscausing the threshold to be reached more quickly. As a result the SA node firesmore rapidly and the heart beats faster. Sympathetic stimulation also enhancescontractility and speeds relaxation. It does this by enhancing calciummovements in the contractile cells. Enhanced contractility lowers end systolicvolume, so stroke volume does not decline as it would if only the heart rateincreased.

Front 14

Explain the role of the parasympathetic nervous system in regulating stroke volume and heart rate.

Back 14

Ach hyperpolarizes the membranes of itseffector cells by opening potassium. Because vagal innervation is sparse,parasympathetic activity has little or no effect on cardiac contractility.

Front 15

Tunica intima

Back 15

Tunica intima- contains endothelium –simple squamous – forms a slick surface that minimizes friction

Front 16

Tunica media

Back 16

Tunica media- mostly circularly arrangedsmooth muscle cells and sheets of elastin

Front 17

Tunica externa

Back 17

Tunica externa- composed largely of looselywoven collagen fibers that protect and reinforce the vessel and anchor it tothe surrounding structures. The tunica externa is infiltrated with nervefibers, lymphatic vessels, in in larger veins elastin fibers and its own vascular system.

Front 18

Elastic (conducting) arteries

Back 18

Elastic (conducting) arteries – thickwalled arteries near the heart – largest diameter ranging from 2.5 cm to 1 cm.They contained the most elastin. Elastic arteries are pressure reservoirs,expanding and recoiling as blood is ejected from the heart.

Front 19

Muscular (distributing) arteries

Back 19

Muscular (distributing) arteries - deliver blood to specific body organs andaccount for most of the named arteries studied in the anatomy laboratory. 1cm to .3mm diameter – have the thickestmedia that contains mostly smooth muscle.

Front 20

Arterioles

Back 20

Arterioles – larger arterioles have allthree tunics, but their tunica media is chiefly smooth muscle with a fewscattered elastic fibers. Smaller arterioles, which lead into the capillarybeds, are little more than a single layer of smooth muscle cells spiralingaround endothelial lining. Minute-to-minute blood flow into the capillary bedsis determined by arteriole diameter which varies in response to changingneural, hormonal, and local chemical influences.

Front 21

Capillary bed consists of two types of vessels

Back 21

1. A vascular shunt - a short vessel thatdirectly connects the arteriole and venule at opposite ends of the bed, and 2.True capillaries, the actual exchange vessels

Front 22

Arterial blood pressure reflects two factors:

Back 22

1. How much the elastic arteries close to theheart can be stretched (their compliance or distensibility) and 2. the volumeof blood forced into them at any time.