BCMB 230 Lecture Notes - Lecture 17: Heart Valve, Gap Junction, Cardiac Skeleton
16 Dec 2016
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10/27/16
o In order to be effective heart must be at right rate and proper pattern/direction
o Intrinsic control- Pacemaker- SA node mainly. Others are backups
▪ Pacemaker- preferred pathway of conduction. Less stimulus needed to
stimulate the pacemaker cells.
▪ Movement across the gap junctions to cause a contraction
▪ Cardiac skeleton- No gap junction
▪ Signal travels down bundle of his to pyritinge fibers→ contractile cells→
contraction moves from bottom up
▪ Pacemakers do not contract
o What if I want to stimulate a pacemaker cell? Depends where you are. You may
have spontaneous depolarization. Not as much signal needed because
depolarization already occurring?
o FIGURE 12.17 CONTRACTILE CELLS
▪ Atria contracts before ventricles because of contractile cells
o Extrinsic- Modification with nerves and hormones
• EKG patterns
o Leads attached to skin
o Heart sends electrical potential all the way to the skin.
• P wave-Atrial depolarization
• QRS- The typical bump/ v on an EKG atrial repolarization (end of contraction)/
ventricular depolarization( beginning of contraction)
• T- Ventricular repolarization
• Either atria on ventricle contracted- never both- whole heart never contracted
• We do have a complete relaxation between the T and P wave (fills). If heart contracts
too fast heart beat is ineffiecient.
• Contraction is systole- Ventricular
• Relaxation is diastole- Ventricular
• Valves
o Heart
o Veins
o Cusps- Look like cups that force blood in right direction. Close if you go to wrong
direcrion. Completely mechanical. No energy
o AV valves
▪ Biscuspid
▪ Tricuspid
▪ Semilunar-Let blood into the arteries= Aorta, pulmonary trunk/artery
o Blood flow
▪ Moves from Not lungs→ to lugs= Right etrile Puloary iruit
▪ Moves from Lungs→ to Not lugs= Left etrile “ystei iruit
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Document Summary
In order to be effective heart must be at right rate and proper pattern/direction. Others are backups: pacemaker- preferred pathway of conduction. If heart contracts too fast heart beat is ineffiecient: contraction is systole- ventricular, relaxation is diastole- ventricular, valves, heart, veins, cusps- look like cups that force blood in right direction. Needed to move stuff though so low bp still bad. Units mm/hg: bowl of mercury push glass tube in bowl of mercury how much it goes up tells you pressure, r=resistance= opposition to flow. Must be calculated: r=(cid:894)8h(cid:448)(cid:895)/(cid:894) r4, h= length, v= viscosity, r= radius. Increasing only resistance decreases flow: pressure and resistance relationship if flow is constant, pressure i(cid:374) the (cid:448)ei(cid:374) (cid:373)ore (cid:448)aria(cid:271)le tha(cid:374) pressure i(cid:374) the artery. Constant: pressure and resistance increase together flow increases, viscocity- measures thickness or interactions between molecules in a fluid, proteins make blood more viscous. Increasing length increases resistance: clotting issues if you decrease viscocity.
