Cardiovascular System Flashcards
Functions of cardiovascular system:
- controls distribution of blood
- major transportation system via blood
- participates in homeostatic mechanisms
- defense against foreign/toxic substances
What travels in the lungs via the cardiovascular system?
O2
- needed by all cells for aerobic respiration
O2 travels on…
RBC
What moves from GI tract to all cells?
- nutrients and water
- water soluble goes to plasma
- water insoluble goes on carriers
What gets transported in the blood?
- nutrients
- gas
- water
- materials
- wastes
What are some materials that are moved from cell to cell via blood?
- by product of metabolism to live for processing
- immune cells and antibodies
- clotting proteins
- hormones
Immune cells and antibodies are…
always in blood to fight infections
Clotting proteins are…
always in blood to prevent fluid loss
Hormones:
- from endocrine glands to target cells
- stored nutrients from liver and adipose to body cells
What are some wastes to be eliminated?
- metabolic wastes
- heat
- CO2
- lactic acid
Metabolic wastes is removed by the…
kidneys
Heat is removed by the…
skin
CO2 is removed by the…
lungs
Examples of homeostatic mechanisms:
- temperature regulations
- fluid balance
- regulation of ECF, pH, and osmolarity
How is temperature regulated in the body?
brings warm blood to surface to cool body
What helps with balancing fluids?
blood vessels and osmotic balance
What helps regulate ECF, pH, and osmolarity?
- plasma buffers
- kidneys
How does the cardiovascular system play a role in defense against foreign/toxic substances?
- lymphatics
- flow through kidney
Components of cardiovascular system:
- heart
- blood vessels
- blood
Heart:
- 2 pumps
- both sides of heart are linked
- not all blood is pumped each time
- both sides of heart are pumped simultaneously
T/F: blood flows from ventricle of one side and returns to atrium of same side
F, from ventricle on one side and returns to atrium of other side
The heart is located in…
mediastinum
All vessels of the heart enter and leave through the…
base (broad portion)
Right and left sides of the heart is separated by…
septum (central wall)
Both sides of the heart have…
- atria
- ventricle
Atria:
- thin walled
- low pressure reservoirs for arriving blood
- not really important as pumps
Ventricle:
- thick walled
- develop high pressure w/ contraction
- pumps blood out of heart
Flow of the blood is…
one-way, which is ensured by valve system
Right side of heart is also known as the…
pulmonary circuit
Right side of heart is a ____ pressure system
low
Blood flow through the right side:
- blood from head and body
- right atrium
- tricuspid valve
- right ventricle
- pulmonary artery
- lungs
Right side of heart propels…
blood to lungs for exchange of O2 and CO2
Left side of heart is also known as the…
systemic circuit
Left side of heart propels…
blood to all other tissues/organs
Left side of heart is a ____ pressure system
high
Blood flow through the left side:
- blood from lungs
- left atrium
- bicuspid valve
- left ventricle
- aortic semilunar valve
- aorta
- head and body
Blood flows along…
pressure gradient
- from high to low
Blood vessels is also known as…
- conduits
- closed circulatory system
In a closed circulatory system, the blood…
stays in vessels
Blood vessels are arranged in…
series and in parallel
Distribution of blood vessels to organs is…
parallel to each other
Distribution of blood vessels to each organ is…
in series
- heart to organ to heart
Arteries and arterioles are tubes that…
distribute blood
- brings blood to capillaries for exchange
Arteries and arterioles are ____ pressure vessels
high
Arteries and arterioles make up _____ of blood vessels
11%
The flow of arteries and arterioles is…
fast and pulsatile
T/F: there is enough blood to flow to every capillary bed simultaneously
F, not enough so some arteries/arterioles are constricted to limit flow to that area or dilated to increase flow to area
Constriction of arteries and arterioles are regulated…
locally or systematically by SNS
- norepi at alpha 1 -> Gq proteins -> PLC activated -> IP3 activated
Capillaries are…
exchanging vessels
Capillaries are ____ pressure vessels
mid
Capillaries make up _____ of blood vessels
5%
Blood flow in the capillaries is…
slow
Capillaries are the only place where…
nutrients, gases, and water are exchanged between blood vessels and ECF
Materials are exchanged in the capillaries by…
- mostly diffusion
- some filtration
Venules and veins are tubes that…
collect blood
- returns blood to heart
Venules and veins are _____ pressure vessels
low, with high compliance
Venules and veins make up ____ of blood vessels
67%
Venules and veins causes a…
slight increase in flow rate
Venules and veins act as…
storage vessels
Parts of the cardiac chambers:
- 2 atria
- 2 ventricles
The atria are…
receiving chambers
The ventricles are…
pumping chambers
Cardiac valves are between…
- atria and ventricles
- ventricles and receiving vessels
Cardiac valves:
- prevent backflow of blood
- have no muscle
- made of CT covered w/ epi
Cardiac valves are regulated by…
strictly passively by pressure
- can’t open or close via neurons or endocrine system
Semilunar valves (SV) are located…
at ventricular exits (pulmonary/aortic)
Right aortic valve (AV) is known as the…
tricuspid
Left aortic valve (AV) is known as the…
bicuspid/mitral
Flaps of aortic valves are anchored by…
chordae tendinae
- prevents flaps from everting during ventricular systole
Wall of heart has…
3 layers
- endocardium
- myocardium
- pericardium
Endocardium of heart:
endothelial lining
Myocardium of heart:
muscle layer
Pericardium of heart:
Fibrous CT sac filled w/ fluid that surrounds heart
Pericardium is made up of…
- epicardium
- parietal layer
- pericardial fluid in cavity, which decreases friction during systole
Epicardium is…
CT that forms visceral pericardium
Parietal layer is…
fibrous CT
- prevents sudden over-distension of cardiac chambers
Slow myocytes:
- can generate AP
- found in SA/AV node
- act as pacemakers
- don’t contribute to contraction
Fast myocytes:
- majority of myocardium
- contractile atrial, ventricular myocytes, and Purkinje cells
- move the blood
Cardiomyocytes are…
cardiac muscle cells
- 99% are contractile
- fast myocytes
- shorter than skeletal muscle
- branched and joined at the ends at intercalated discs
Cardiomyocytes form the majority of…
myocardium
T-tubules in cardiomyocytes are…
larger than skeletal muscle and branch internally
SR in cardiomyocytes are…
smaller than skeletal muscle
- 90% of Ca2+ for contraction comes from SER
- 10% comes from ECF
Cardiomyocytes has intercalated discs between cells, which have…
- desmosomes
- gap junctions
Gap junctions in cardiomyocytes are similar to…
single unit smooth muscle
Intercalated discs at cardiomyocytes allow cells to…
function as syncytium
What happens during the effective refractory period?
- Na+ channels are inactive
- can’t be opened
- another AP can’t occur
What happens during the relative effective refractory period?
- Na+ channels transition to closed state during repolarization
- another AP can occur, but it needs larger depolarization
AP of fast myocytes:
- depolarizes fast
- has stable RMP of -90mV
- high K+ conductance
- very small Na+ conductance
Phases of AP in fast myocytes:
- phase 0: depolarization
- phase 1: brief early repolarization phase
- phase 2: plateau phase
- phase 3: repolarization develops slower than depolarization
- phase 4: resting state
Phase 0 of AP in fast myocytes:
depolarization
- occurs b/c of AP
- fast VGC Na+ open (Na+ influx)
- positive feedback opens many VGC Na+
- looks like rapid upstroke on graph
- slow VGC Ca2+ begins to open at this point
Phase 1 of AP in fast myocytes:
brief early repolarization phase
- transient outward movement of K+ through open channels
Phase 2 of AP in fast myocytes:
plateau phase
- occurs b/c of slow VGC Ca2+ (L-type)
- permeability to K+ remains, but at lower conductance
Phase 3 of AP in fast myocytes:
repolarization develops slower than depolarization
- L-type VGC Ca2+ close
- slow VGC K+ opens (K+ efflux)
- Na+ inactivation gates stay closed until 1/2 way of this phase
Phase 4 of AP in fast myocytes:
resting state
- excess Na+ and Ca2+ eliminated
- muscle relaxes
AP is almost the same length as…
contraction
Membrane of myocytes is refractory for…
most of contraction
- prevents sustained contractions of myocardium
At increased heart rates, the length of both…
AP and contractions are reduced
AP of slow myocytes don’t need…
activation via external innervation (nerve supply)
External innervation of slow myocytes would alter…
membrane polarity and alter intrinsic rate (regular rhythm)
AP of slow myocytes act as…
pacemakers
- has ability to initiate AP, which results in regular rhythm
Phases of AP in slow myocytes:
- phase 0: upstroke
- phase 1 and 2: absent
- phase 3: gradual repolarization
- phase 4: “funny” Na+ channels activated when membrane potential is -60 mV
Phase 0 of AP in slow myocytes:
upstroke
- funny If channels close
- slow VGC Ca2+ open (L-type)
- depolarization is much less steep than fast myocytes
- influx of Ca2+
Phase 3 of of AP in slow myocytes:
gradual repolarization
- Ca2+ channels close at peak of AP
- slow VGC K+ opens (K+ efflux)
Phase 4 of AP in slow myocytes:
“funny” Na+ channels activated when membrane potential is -60 mV
- cycle repeats
- long refractory period
Pacemaker potential:
- lacks steady RMP
- much less negative than regular myocytes
- slow depolarization b/c of opening of Na+ and closing of K+ channels
Heart rate:
- rate of depolarization cycle
How do you modify the interval between APs in slow myocytes?
by altering permeability of slow myocytes
Sequence of excitation of heart:
- sinoatrial (SA) node
- atrioventricular (AV) node
- atrioventricular (AV) bundle
- right and left bundle branches
- subendocardial conducting network (Purkinje fibers)
SA node is the…
primary pacemaker in right atrial wall
- has lots of slow myocytes
SA node will depolarize…
faster than rest of myocardium
SA node generates a sinus rhythm of…
75 times/min
Inherent rate of SA node:
100 times/min
- tempered by extrinsic factors
Spontaneous discharge rate results in…
AP of SA node
Signal from SA node will travel through…
gap junctions along internodal pathway
- AP travels across fast myocytes of atria, which leads to contraction of atria
The internodal pathway leads to…
AV node
- only entry route for cardiac impulse to ventricles
AV node is located on…
posterior wall of right atria in interatrial septum
AV nodal delay:
- functional delay between atrial and ventricular excitation
- occurs b/c fibers have smaller diameter and fewer gap junctions
- allows optimal ventricular filling during atrial contraction
- prevents overstimulation of ventricles
Inherent rate of AV node w/out SA node:
50 times/min
Myofibers in AV node have…
similar proportion to SA node
- slower spontaneous depolarization rate
Impulse leaves AV node and travels down septum through…
AV bundle (bundle of His) - branches off into right and left bundle branches
AV bundle is located in…
superior interventricular septum
AV bundle is the only…
electrical connection between atria and ventricles
Atria and ventricles are not…
connected via gap junctions
Bundle branches break up into…
Purkinje fibers at apex
Purkinje fibers have VGC for…
both fast and slow myocytes (2 different pathways)
Purkinje fibers:
- travel about 1/3 the way up ventricular walls
- have myofibers w/ large diameters
- higher permeable gap junctions between cells
Myofibers and gap junctions in Purkinje fibers allows for…
rapid activation of ventricular myofibers from apex toward atria
Purkinje fibers are more elaborate on the…
left side
Ectopic foci:
regions other than SA node that initiate AP
Examples of ectopic foci:
- AV node
- Purkinje fibers
Ectopic foci become pacemakers when…
- own rhythmicity is enhanced
- rhythmicity of higher order pacemaker is suppressed
- all conduction between ectopic focus and areas w/ greater rhythmicity become blocked
Ectopic foci act as…
safety mechanism when normal cycle fails
Ectopic foci can induce…
- sporadic rhythm disturbances
- continuous rhythm disturbances
- both occur if active while normal center is also active
Sporadic rhythm disturbances can lead to…
premature depolarization
Continuous rhythm disturbances can lead to…
paroxysmal tachycardia
Ectopic foci can be induced by…
- ischemia
- inflammation and/or compression of cardiac myofibers
- toxic irritation of AV node, Purkinje fibers, or myocardium induced by drugs
- bundle branch blocking re-entry
Ischemia:
reduced coronary blood flow, which leads to decrease in O2 delivery
When bundle branches block re-entry, it can cause…
arrhythmias by producing extrasystole
Defective AV node can cause…
heart block: few/no impulse can reach ventricles
During heart block at AV node, ventricles will…
beat at intrinsic rate, which is too slow for life
- will need artificial pacemaker to treat
Defects in intrinsic conduction system can cause…
- arrhythmias
- uncoordinated atrial and ventricular contractions
- fibrillation
Arrhythmias:
- irregular heart rhythms
Fibrillation:
- rapid, irregular contractions
- heart becomes useless for pumping blood, which leads to poor circulation and can cause strokes
To treat fibrillation, you would need…
drugs that prolong refractory period/defibrillation
Electrocardiogram (EKG/ECG):
records electrical potential difference across body
EKG on a graph has ____ as x-axis and ____ as y-axis
time, mV
EKG records…
overall electrical activity produced by depolarization and repolarization of all cardiac myofibers at any given time point
EKG does not…
- record AP in single cell
- directly record electrical activity of heart
- not a measure contraction
EKG is used to…
- infer electrical depolarization and repolarization of heart
- record at different surface points
Leads for EKG:
- electrical connections from patient skin to recording device
- has three electrodes: positive, negative, and ground
Lead 1 for EKG:
- left arm = positive pole
- right arm = negative pole
Lead 2 for EKG:
- left foot = positive pole
- right arm = negative pole
Lead 3 for EKG:
- left foot = positive pole
- left arm = negative pole
EKG can provide info about…
- disturbances of rhythm/conduction
- extent, location, and progression of ischemic damage to myocardium
- influence of drugs on electrical activity
- relative size of chambers
- anatomic orientation of heart
Ischemia and EKG:
- damage alters electrolyte composition
- slows conduction through area
- decreased electrolyte activity alters EKG recording
Examples of types of drugs that can influence EKG:
- digitalis
- anti-arrhythmics
- Ca2+ channel antagonists
Mean electrical axis:
vector resulting from adding two of three leads
- arranged in Einthoren’s triangle
Mean electrical axis can be altered if…
- anatomical position of heart is altered
- relative mass of right and left ventricles are abnormal
In a scalar ECG pattern, upward deflection occurs b/c of…
depolarization current moving toward positive electrode (positive)
In a scalar ECG pattern, downward deflection occurs b/c of…
depolarizing current moving toward negative electrode (negative)
In a scalar ECG pattern, no deflection occurs b/c when…
- all are either depolarized or repolarized
- no change
- known as isoelectric line
Waves in a scalar ECG pattern:
parts of EKG that go above or below baseline
P wave:
- 1st upward deflection
- represents atrial depolarization
QRS complex:
- group of three waves
- Q: downward
- R: large upward
- S: downward
QRS complex represents…
ventricular depolarization
- atrial ventricular repolarization is masked b/c it occurs during ventricular depolarization
T wave:
- 3rd upward wave
- represents ventricular depolarization
Segments of waves:
- sections of the baseline between 2 waves
Intervals of waves:
- combo of waves and segments
P-R interval:
- from onset of atrial activation to onset of ventricular activation
- associated w/ passage through AV conduction system
S-T interval:
- entire ventricular depolarizes
S-T segment:
- lies on isoelectric line
- deviation from the line may indicate myocardial ischemic damage
Q-T interval:
- beginning of QRS to end of T wave
- period of electrical systole of ventricles
- varies with heart rate
Shorter Q-T interval means…
faster heart rate
R-R interval:
from R wave of one QRS complex to R wave in next QRS complex
- represents time between sequential ventricular contractions
R-R interval is used to…
calculate heart rate
