Circulatory System Flashcards
Human Heart
Divided into left and right side pumps, each pump has two chamber
Atrium and Ventricles
Chambers of the heart
Pulmonary circuit
Right side of the heart that pumps blood to the lungs
Systemic Circuit
Left side of the heart that pumps blood to the body
Systole
Ventricle contraction
Diastole
Period between contractions
Pressure in systemic arteries
~120/80 mm Hg
Pressure in pulmonary arteries
~20/10 mm Hg, less pressure than systemic because only going to the lungs, not the top of the head, right ventricle does less work, not as muscular
Heart
Striated, multinucleate, branched and involuntary
Heart Beat
Normally originates from spontaneous APs generated by SA node in the right atrium
Electrical Synapses
Gap junctions, carry APs throughout the heart
Firing rate of SA Node
Increased by sympathetic, decreased by parasympathetic
Generation of transmission of heart beat
SA node AP spreads through atria causing contraction, AP reaches AV node at the bottom of the atria and it fires
Bundle of His
Conducts AP to ventricles, splitting into the right and left bundle branches, become Purkinje fibers in walls of ventricles
Conduction Sequence of Heart Beat
SA->AV->bundle of His->R/L bundle branches->Purkinje’s->ventricle contraction, all or nothing
Heart Valves
1 way valves that ensure that the blood flows in one direction through the heart
Tricuspid Valve
Between right atrium and ventricle
Bicuspid or Mitral Valve
Between left atrium and ventricle
Papillary Muscles
Hi pressure of ventricle contraction is prevented from everting valves by contraction of these which are connected to valves by chorda tendinea
Similunar valves
During ventricle contraction blood is pumped out of the heart through aortic and pulmonary ______
Arteries
Transport blood to capillaries, contain 16-18% of blood, control blood flow to tissues via constriction of smooth muscle sphincters at end of their arterioles
Capillaries
Perform gas/nutrient exchange, contain 5-7% of blood, at any time only 30-50% of caps are open, only 5-10% caps are open in skeletal muscle cells
Veins
Return blood to the heart from capillaries, contain 50-70% of blood and thus serve as a reservoir
One way pocket valves
Mainly activity of blood muscles move blood in veins towards the heart because of these
ANS
Operates under a priority system to control blood pressure
What happens if blood pressure drops?
Sympathetic stimulates constriction of peripheral arterioles and stimulates heart to be faster and harder, can double blood pressure in 5-15 seconds
Local Control
Matches blood flow to local needs by opening capillary beds in active tissues
What happens in response to local control?
Arteriole sphincters open in response to products of hi tissue activity such as hi CO2 and lactic acid or low O2
Heavy exercise
Increases blood pressure and doubles blood flow to active muscles via sympathetic and local control affects
Why do athletes warm up before athletic performance?
It opens the capillary beds in exercising muscles, at rest only 5-10% of skeletal muscles capillaries are open
