Human Anatomy and Physiology of the Human Body

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Human Anatomy and Physiology 260 - Midterm 1

Cardiovascular Anatomy

Arteries:
Carry Blood from the heart to the tissues
Gradually decreasing in size of vessels
oArteries - Transportation of red blood cells away from the heart oArterioles - Smaller, lead from the arteries to the capollaries oCapillaries - Gas exchange (tissue level)
3 layers of wall:
o1. Tunica Adventitia (Tough outer layer)
o2. Turnica media (Middle smooth muscular layer, changes the diameter of the blood vessel (constriction and dialation)) o3. Turnica intima (Very smooth inner layer)
oSmooth inner lumen and elastic lamina to maintain shape
3 types of arteries:
oElastic (ex. Abdominal Aorta)
Largest in size
Allows for high degree of expansion between heart beats
oMuscular (ex. Femoral artery)
Distributing arteries
Regulate flow of blood to different parts of the body
oArterioles (ex. Tributaries)
Narrow lumina
Thick muscular walls
Blood pressure mainly regulated by the degree of muscular tone Veins:
Return deoxygenated blood to the heart
oExcept Pulmonary veins carrying blood from the lungs to heart •Gradually increasing in size of vessels
oCapillaries
oVenules
oVeins
Same layer design as the arteries
Thinner tunica media (Less ability to constrict)
Similar in structure to arteries
Walls are thinner due to lower blood pressure
Poorly developed muscular layer
Accompanying (communicating) veins for extremity arteries •Three types of veins:
o1. Large (ex. Inferior vena cava)
Wide bundles of smooth muscle
Well developed tunica adventitia
o2. Medium (ex. Great saphenous vein)
Have valves to maintain direction of flow
Musculovenous pump - squeezes the vein to propel the blood to the heart o3. Small (Venules)
Unite to form venous plexuses
Veins have valves - Which helps the blood return to the heart without falling back

arteriesveins
thick walls (due to smooth muscle in tunica media)thin walls more elastic fibres in tunica mediafewer elastic fibres
smooth muscle under control of sympathetic nervous systemno significant sympathetic innervation smallest vessels (arterioles) surrounded by smooth musclevenules have no appreciable smooth muscle do not contain valveslarge vessels contain valves

Capillaries:
Simple endothelial tubes
Point of gas exchange
Arranged in the networks (Capillary beds)
O2, Nutrients, CO2, and other materials exchanged through diffusion

Mediastinum:
Middle septum occupied by tissue between two pulmonary cavities •Covered on each side by mediastinal pleura (tissue covering the lungs) •Tissues united by loose connective tissue and infiltrated by fat oAllows for accommodation to changes in movement, volume, and pressure Heart:

Pericardium is a double-walled fibro serous sac enclosing the heart enclosing the heart, prevents the heart from dilating to big - Pulverous fluid reduces friction •Tough outer fibrous pericardium stabilizes and prevents over-dilation •Serous pericardium lies within and directly covers heart oHas visceral (closer to the heart) and parietal (further away) layers •Pericardial cavity is space filled with fluid allowing heart to beat in frictionless environment •Slightly lager than clenched fist

Double self-adjusting muscular pump
Right side receives and send de-oxygenated blood
Left side receives and sends oxygenated blood
When ventricles contract they produce a wringing motion due to spiral orientation of cardiac muscle oPropels the blood out
Muscle fibers are anchored to fibrous skeleton of dense collagen •Left wall thicker than right wall
Fibrous skeleton serves to:
oPrevent over-dilation
oProvide attachment
oForm electrical insulator
oShape

Heart (Cont.)
Three tissue layers:
o1. Endocardium - Thin Internal layer for contraction
o2. Myocardium - Thick middle layer for contraction
o3. Epicedium - Thin external layer for...
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