Circulatory System Flashcards
Perfusion
Flow of blood through a tissue
Ischemia
Inadequate blood flow
Hypoxia
Adequate circulation but oxygen supply reduced
Arteries
Carry blood away from the heart at HIGH pressure
Veins
Carry blood to the heart at LOW pressure
Arterioles
As arteries get further from the heart, pressure decreases and the arteries branch into arterioles
Arteries branch into arterioles which then branch into
Capillaries
Arterioles have ____ which can control the amount of blood entering the capillaries
Capillaries are
Smooth muscle that can restrict or increase blood going to capillaries which are very small vessels (often only wide enough for one blood cell to pass) that allow exchange of material from the blood and tissues
After blood passes through arteries branch into arterioles which then branch into capillaries, the blood enters:
Small veins called Venules which takes the blood to the veins for return to the heart
Endothelial cells make up
Endothelial cells and the capillaries
Inner linings of all blood vessels
Capillaries are a single layer of endothelial cells
Endothelial cells role in vascular function (4)
Vasodilation and vasoconstriction
Inflammation
Angiogenesis (forming new blood vessels)
Thrombosis (blood clotting)
Angiogenesis
Forming new blood vessels
Right side of the heart pumps blood to
Lungs
Left side of the heart pumps blood to
Rest of body (other than the lungs)
Pulmonary Circulation
Flow of blood from the heart to the lungs and back to the heart (right side)
Systemic circulation
Flow of blood from the heart to the rest of the body and back again (left side)
Most blood flows through only one set of capillaries before returning through the heart
EXCEPT
Portal systems in which blood goes through multiple system’s capillaries
Direct transport systems to connect two areas without passing through the whole body
Right ventricle and left ventricle
Deoxygenated or oxygenated blood?
R: deoxy
L: oxy
Atria
“Waiting rooms” where blood can collect from the veins before getting pumps to the ventricles
Ventricles
Pump blood out of the heart at high pressures into arteries
Right atrium receives ____ from the ___ and pumps ____
Deoxygenated blood from the systemic circulation (S&I Vena Cava) and pumps to right ventricle
From the right ventricle, blood passes through the
Pulmonary arteries and through the lungs to get oxygenated
Oxygenated blood from the lungs arrives back into the heart at the ____ via the _____
Left atrium
Pulmonary arteries
When oxygenated blood arrives through the left atrium, it is
Pumped into the left ventricle before being pumped out of the heart in a single large artery, the AORTA to systemic circulation
Do all arteries carry oxygenated blood?
No the pulmonary arteries carry deoxygenated blood to the lungs
Antroventricular valve is necessary to prevent
Backflow from the ventricles to the arteries due to the high ventricular pressure and low atrial pressure
AV valve between the left atrium and left ventricle is called the ____ valve
Mitral/bicuspid
Must withstand enormous pressures
AV valve between the right atrium and ventricle is called the ____ valve
Tricuspid
Semilunar valves include which valves (2)?
Separate what?
- Pulmonary valves
- Aortic semilunar valves
Between the ventricles and the arteries they pump blood into
Function of valves throughout the circulatory system / body
To create a driving force for blood to get back to the heart
Cardiac cycle consists of two parts:
Diastole and systole
Diastole
Ventricles relax and blood flows into them from the atria
Atria actually contract during this stage to put blood into the ventricles
Systole
Begins when ventricles start to contact, pressure buildup causes AV node to shut and eventually causes the semilunar valve to open and blood to shoot into the aorta and pulmonary artery
End: ventricles nearly empty and done contracting, back flow begins to occur but the semilunar valves slam when the pressure in the ventricle is less than the pressure in the arteries
Which is shorter: systole or diastole?
Systole is shorter (occupies space between Lub and dub while Diastole occupies space between Lub-dub and another Lub-dub)
Heart rate/pulse
Number of times the S/D cycle occurs in one minute
Normal HR / pulse
Around 1beat/second (45-80 is normal range)
Stroke volume
Amount of blood pumped with each systole
Why is 45 bpm or 80 bpm normal?
Stronger heart pumps more blood in one contraction (athletes) and weaker heart pumps less blood in one contraction (elderly/babies)
Cardiac output
Amount of blood pumped per minute
Cardiac output =
CO = HR x SV
Frank-Starling mechanism to increase cardiac output
If venous return(return of blood to the heart) is increased, the heart fills more, stretching it more, contracting it more forcefully
Increases SV significantly
Functional Syncytium
In cardiac muscle cells, the gap junctions through which different cells can communicate is found in intercalated disks, connections between cardiac muscle cells
AP can be communicated directly through the cytoplasm to the neighboring cardiac muscle cells
I.E. electrical synapse, no chemical
Intercalated disks
connections between cardiac muscle cells
Cardiac conduction system
AP fired in the heart is transmitted from the atrial syncytium to the ventricles
Fast vs slow sodium channels involvement in cardiac muscle action potentials
Fast are important like in neurons but:
Slow stay open longer causing depolarization to last longer in cardiac muscles than in neurons producing a plateau phase
Contraction lasts longer, so more force expels the blood
T tubules
Maximize amount of Ca2+ entering the cell by running the length of the cell to allow depolarization and activation of the sarcoplasmic reticulum to release calcium
Makes a combo of intracellular and extracellular calcium
Combo of intracellular and extracellular calcium around the cell causes
Contraction of actin-myosin fibers
SA Node
Initiates AP in the heart (pacemaker of the heart)
SA Node AP phases
0, 3 and 4 (NO 1 and 2 LIKE OTHER CARDIAC MYOCYTES)
SA Node is unique because it has an unstable resting potential which is:
Phase 3 (automatic slow depolarization) caused by sodium leak channels which brings the cell potential to threshold for VG Ca2+ channels
When VG Ca2+ channels open, ___ begins:
Phase 0
Drives membrane potential of the SA node toward positive Ca2+ equilibrium potential GRADUALLY because the channels operate more slowly than Na+ in other AP
Phase 3 of SA Node AP
Repolarization
Caused by the closure of the Ca2+ channels and opening of K+ channels leading to K+ exiting the cell to drive membrane potential toward the negative K+
Phase 0,3,4 occurs
Once per heart beat
The SA node has the most ____ which means it _____ and therefore sets the rate of contraction for the heart
Na+ leak channels
Depolarizes first