Fluid Balance: Cardiovascular Flashcards
Reservoir for blood pressure
Large arteries
Resistance vessels to regulate blood flow into capillaries (Microsopic)
Arterioles
Exchange vessels
Capillaries
Reservoir for blood volume. 60 to 70% of blood volume
Venules/veins 
Blood is a ________ tissue 
Connective
(within the systemic circuit) 
Arteries to other arteries are parallel or series?
Parallel
Series: arteries to arterioles to capillaries to veins
Why is parallel flow to other organs important?
1) and shows that story and gets appropriate “nutrition”
2) each organ “sees” The same pressure head (allows blood pressure regulation at the systemic (city) level
3) this allows organs to independently regulate blood flow
Blood pressure is regulated at the ________ level, whereas blood flow is regulated at the ________ level.
Systemic, tissue
The heart is located in the mediastinum in the __________ cavity
Thoracic
What layers does the pericardium include?
- Viseral pericardium (closest to heart)
- Pericardial space (fluid filled)
- parietal pericardium
What is the pressure on the right and left side of the heart?
Right - 20 mmHg
Left - 90 mmHg
What is the thin epithelial layer of the heart?
Endocardium
What is the muscle part of the heart?
Myocardium
What is the connective tissue part of the heart?
Epicardium a.k.a. visceral pericardium? 
Outside part of heart, closet to heart
What are the atrioventricular valves?
- Tricuspid (right)
- bicuspid/mitral (left) 
Also known as heart strings. Connects to AV valves and hold them in place, connected to the papillary muscles on the other end
Chordae tendineae
Muscles in the ventricles, Connect to the cusps of the valves via the chordae tendineae
What are the two semilunar valves between ventricles and the main arteries?
- Aortic
2. Pulmonary
What causes the lub dub sounds of the heart?
“Lub”- sound of turbulent flow when the AV valves closes
“Dub”- sound of turbulent flow when semilunar valves close
How are cardiac myocytes organized?
Connected end-to-end
Channels that form direct coupling of scaroplasm (cytoplasm)
Gap junctions
Connects adjacent cardiac muscle cells
Intercollated discs
Types of cardiac myocytes
- Autorhythmic cells
a. Pacemaker cells*
b. Conduction cells - Contractile cells*
What determines heart rate?
Sinoatrial (SA) node (pacemaker)
Atria and ventricles are electrically ____________ except through the AV node
Uncoupled
-AV node delays signal spread into ventricle
 pacemaker cells are myogenic meaning…..
It’s a nervless process. Happens on its own without neural input
Peacemaker cell action potential is about 400 times _________ then action potential seen in a neural cell
Slower
What are the two parts of the “pacemaker potential”?
- funny channel
* T type Ca++ channel 
Voltage gate Na+ channel, opens when voltage becomes more negative than threshold
Funny channel
- opens when it goes BELOW Threshold, (opposite of usual)
Pacemaker action potential:
What happens at the depolarization and repolarization phase?
depolarization phase: opening L-type Ca++ channels

Repolarization phase: opening of K + channels and closure of L-type  Ca++ channels
Characteristics of contractile cell action potential…
- can change a membrane potential by opening or closing a channel
- threshold is activated by neighboring cells
What are the phases of contractile cell action potential?
- Phase 0: rapid depolarization phase Dash voltage gated Na+ that regulate this
- phase 1: closure of the V-gated Na+ channels (brief repolarization)
- phase 2: Plateau- dependent on open L •type Ca++ channels (going in), Open V-gated K+ channels (going out of cell)
- phase 3: Repolarization phase, closed L-type Ca++, K+ channels still open
- phase 4: resting
What is the significance of the plateau phase of contractile cell action potential?
This lengthens the refractory period and prevents tetanus of cardiac muscle
Pressure is always determined by….
Volume and concentration
Excitation-contraction coupling in cardiac contractile cells is similar to Skeletal muscle but calcium comes from what three sources?
- neighboring cells
- extra cellular fluid
- Sarcoplasmic reticulum (SR)
What are the steps in excitation-contraction coupling in cardiac contractile cells?
- Current spreads through gap junctions to contractile cell
- Action potentials travel along plasma membrane and T tubules
- Calcium channels open in plasma membrane and SR
- Calcium induces calcium release from SR***
- Calcium binds to troponin, exposing myosin binding sites
- Crossbridge cycle begins (muscle fiber contracts)
- Calcium is actively transported back into the SR and ECF***
- Tropomyosin blocks myosin-binding sites (muscle fiber relaxes) 
All events in the heart during one beat to the next
Cardiac cycle
Atrial and ventricular systole and diastole are….
Not in sync
How is stroke volume (volume ejected)calculated?
SV = EDV-ESV
Blood flow out of the heart each minute.
Cardiac output (CO)
Cardiac output ALWAYS changes in accordance with metabolic demand
How is cardiac output calculated? 
CO= HR x SV
Does parasympathetic or sympathetic nerve determine heart rate?
Both!
SA node determines heart rate, both parasympathetic and sympathetic control the SA node
What nerve controls the strength of heart contractions/contractile cells? 
Sympathetic cardiac nerve
What inhibits funny and T-type channels? What opens them?
Parasympathetic (NT—>Ach), decreases slope of pacemaker potential
Sympathetic of the ANS (NT —> NE), increases slope of pacemaker potential
What can also increase heart rate by epinephrine from adrenal and B1 receptor
Hormones
The volume pumped out in each beat
Stroke volume
SV = EDV-ESV
What measures cardiac efficiency?
Ejection fraction (EF)
EF = SV/EDV x 100
What factors control or determine SV?
- EDV (aka preload)
- Cardiac contractibility
- Aortic pressure (aka Afterload) 
What’s Frank Starling‘s law of the heart?
The heart pumps the blood it receives
- most important for making adjustments for SV
An increase in EDV causes stroke volume to ________
Increase
What determines EDV?
Venous return (VR): volume that returns to the heart, flow (ml/min) from resistance and pressure
What determines VR?
Central venous pressure (CVP): pressure that is in large veins relative to the right atrial pressure
What determines central venous pressure (CVP)?
- blood volume
- respiratory pump (inspiration —> blood is drawn into the thorax, expiration blood is pushed into the heart)
- muscle pump
- Venus contraction (decrease venous compliance) aka venomotor tone
What increases venomotor tone/ decreases compliance?
-  sympathetic (NE)
- Epinephrine from the adrenal gland
What is the effect of contractability on SV?
Increased contractibility makes the heart more efficient
What factors increase contractibility?
- NE at B1 receptors in contractile cells of myocardium
- hormone: Epi From adrenal. Same as NE
How does aortic pressure (Afterload) effect SV?
Increased aortic pressure decreases SV
Decreased aerotic pressure increases SV
A decrease in arterial pressure (Afterload) …. __________ stroke volume
Increases
