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14. Overview of cardiovascular system Cheat Sheet (DRAFT) by

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This is a draft cheat sheet. It is a work in progress and is not finished yet.

Arrang­ement of CVS bold

Heart valves

TWO AV VALVES
Aortic and pulmonary semilunar valves
đź“Ť:AT AV JUNCTION
3 cuspus
Prevent back flow into atria after ventricle contra­ction
Guard the bases of large arteries leaving ventricles
1.Right AV valve: tricuspid 3 cuspus
đź“Ťaorta­,pu­lmonary trunk
2. Left AV valve: mitral valve (bicuspid)
Prevent black flow of blood into the associated ventricles

Operation of semilunar valves

A)vent­ricle contract and intrav­ent­ricular pressure Rises blood is pushed against semilunar valves forcing them open
B)vent­ricle relax and intrav­ent­ricular pressure falls blood flows back from arteries filling the cusps of semilunar valves & forcing them close

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Blood vessel structure:

Walls of arteries and veins are composed of 3 layers
Tunica interna - endoth­elium underlain by a subend­oth­elial layer of loose connective tissue
Tunica media - smooth muscle cells& elastic fibers,
thick in arteries and thin in veins
Tunica externa - largely collagen fibers
Capill­aries are tiny blood vessels with thin walls
 

Structure of the heart

Four chambered pump
Right side pumps blood ->p­ulm­onary circuit
Left side pumps blood-­>sy­ste­matic circuit
Pulmonary circui­t:blood gains o2 loses co2
Systematic circuit loses o2 gains co2

Valves

Operation

Desmosomes and gap junctions

Desmosomes join cell
Gap junctions: membrane channels: mediate cell-t­o-cell movement of ions and small metabo­lites: In the heart, gap junctions: important role in impulse conduc­tion. Directly transmit depola­rizing current across the entire heart
Because of these electrical connec­tions the entire myocardium behaves as a single coordi­nated unit or functional syncytium

blood vessel

3 major types of blood vessel – arteries, capill­aries, veins
heart contracts it forces blood into succes­sively smaller arteri­es—> the arteri­ole­s(s­mallest branch­es)­â€”>c­api­llary beds of body organs and tissues
Blood draining from the capill­aries flows—> venules —>small veins that merge to form larger veins -> empty into the heart
Exchanges between blood and tissue cells occur primarily through thin walled capill­aries

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Coronary circul­ation

Operation of atriov­ent­ricular

1) blood returning to heart fills atria ->p­utting pressure on AV valves­<-f­orcing them open
2)vent­ricles fill AV flaps hang Limply into ventricles
3)atria contract forcing (+nal)bld into ventricles
1)vent­ricle contract forcing blood against atriov­ent­ricular valve close
2)atri­ove­ntr­icular valves close
3)papi­llary muscles contract & chordae tendineae tighten, preventing valve flaps from everting into atria

Cardiac muscle

Striated
Short fast branched interc­onn­ected
Each cardiac myocyte contain a single nucleus
Adjacent myocytes interlock at junctions (inter­calated discs): contain anchoring desmosomes & gap junctions
Myocytes composed of sarcom­eres: contain thick (myosin) & thin(a­cti­n)f­ila­ments
Contra­ction: sliding filament mechanism

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Distri­bution of blood

Largest portion of blood at rest is in systemic veins and venules
Blood reservoir
Venoco­nst­riction reduces volume of blood in reservoirs and allows greater blood volume to flow into arteries

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