Cardiovascular system Flashcards
Red blood cells rely on ________ metabolism
anaerobic (no
mitochondria, no nucleus (anucleate))
Old RBC’s get trapped and catabolized in the _____
spleen (in red pulp)
spleen also has white pulp rich in _______
white blood cells
the “red blood cell graveyard”
spleen
Shape of RBCs. What maintains this shape?
biconcave disc. maintained by actin-myosin interactions.
where are RBCs made?
in erythroid tissue in red bone marrow
what form do RBCs take when they’re released from erythroid tissue in bone marrow?
reticulocytes (contain some endoplasmic reticulum). within 24 hrs after that they mature into a biconcave disc.
what cavity(ies) does the heart lie in?
the mediastinum (anterior portion) in the pericardial cavity in the thoracic cavity in the ventral body cavity.
systemic circuit
carries blood out and away from the heart to the rest of the body: systemic arteries (aorta away from heart and vena cava to the heart)
cardiac circuit (coronary circulation)
supplies blood to the heart itself: cardiac arteries, cardiac veins…coronary sinus
pulmonary circuit
blood to and from the lungs: pulmonary veins and pulmonary arteries
capillaries
gas exchange vessels
layers of heart wall
epicardium (outer) (aka visceral pericardium), myocardium (middle), endocardium (inner) …parietal pericardium covers the pericardial cavity wall
epicardium
outer layer of the heart. aka visceral pericardium. (parietal pericardium covers the pericardial cavity wall)
-made of areolar tissue and mesothelium, which secretes serous fluid into the pericardial cavity/sac
myocardium
cardiac muscle layer forming the bulk of the heart
Interconnected layers of cardiac muscle tissue
Contracting layer
Forms atria and ventricles
Contains nerves and blood vessels
Endocardium
inner layer of heart wall.
endothelial layer of the inner myocardial surface, lines heart valves and continuous with endothelial lining of blood vessels.
made of endothelium and areolar tissue
-endothelium made up of simple squamous epithelium
parietal pericardium
fibrous outermost layer that lines the pericardial cavity wall.
-mesothelium on inside, secreting serous fluid into cavity
-then areolar tissue
-then dense fibrous layer
pericarditis
disease of the pericardium
myocarditis
disease of the myocardium
endocarditis
disease of the endocardium (including heart valves…like pulmonary valve and tricuspid valve)
describe how atrial and ventricular muscles contract
like skeletal muscle, but the duration of the contraction is longer (longer absolute refractory period). autorhythmic, via contractile fibers and pacemaker/autorhythmic cells.
heart muscle contractions: long or short absolute refractory period?
long. this is why the heart can’t get tenitis.
intercalated discs
function to interconnect cardiac muscle cells (muscle fibers). Allow action potential to move from cell to cell.
Contain desmosomes: hold fibers together, and convey force of contraction
Linked by gap junctions: propagate muscle action potentials
intercalated discs contain ____ and are linked by ____.
desmosomes; gap junctions
function of desmosomes in intercalated discs:
hold the muscle fibers together, and convey force of contraction from one cell to the next
function gap junctions in intercalated discs:
they link the discs to each other and propagate muscle action potentials. allow ions to move from cell to cell.
Cardiac muscle functions as a
_____; heart muscle cells are
interconnected (atrial and ventricular _____)
syncytium
Cardiac cells are ________,
______ and _________
connected = functional syncytium
mechanically, electrically and chemically
in cardiac muscle, SR lacks large _________;
cardiac muscle relies more on
__________ for muscle contraction
terminal cisternae; extracellular Ca
in cardiac muscle, the T tubule is _____ and _____ and encircles the sarcomere at the ______ not the ________
short and broad; Z-lines; zone of overlap
Cardiac cells contain more intracellular _______
and ______ inclusions as most energy is
produced by ____________
glycogen and lipid; aerobic metabolism
triads or no triads formed by t-tubules with cisternae of the SR in cardiac cells?
no triads: short, broad t-tubules and small terminal cisternae of SR
mitochondria in cardiac vs skeletal muscle cells:
much more abundant in cardiac cells (25% of the cell volume)
inclusions in heart vs skeletal muscle
heart: myoglobin, lipids, glycogen (think fatty, bloody heart)
skeletal muscle: less myoglobin and lipids, plenty of glycogen (think lean muscle)
heart is in it for the long haul, needs plenty of oxygen and energy.
active metabolism (not resting) of cardiac vs skeletal muscle:
aerobic in heart (no breath=heart stops…occlusion=not enough oxygen getting to the heart and cells dying. primarily using lipids and carbs). anaerobic in muscle, primarily using breakdown of glycogen reserves.
contraction in cardiac vs skeletal muscle:
heart: twitches w brief relaxation periods. long absolute refractory periods. prevents tetanic contractions.
skeletal: usually sustained contractions.
stimulus for contraction in cardiac vs skeletal muscle cells:
trigger for contraction:
autorhythmic cells vs motor neuron impulses that generate action potential in sarcolemma
cardiac: calcium entry from extracellular fluid, and calcium release from SR
skeletal: just calcium release from SR
coronary arteries:
Branch from base of aorta. supply blood to the heart.
coronary veins:
deoxygenated.
* Path follows coronary arteries
* Join together at coronary sinus
* Empty back into right atrium to go to pulmonary circuit again
Right atrium
Collects deoxygenated
blood from systemic
circuit and coronary
sinus
right ventricle
Pumps deoxygenated
blood to pulmonary
circuit via pulmonary
artery
left atrium
Collects oxygenated
blood from pulmonary
circuit (pulmonary veins)
left ventricle
Pumps oxygenated blood to systemic circuit
Superior vena cava:
Receives blood from
head, neck, upper limbs, and chest
Inferior vena cava:
Receives blood from
trunk, viscera, and lower limbs
Coronary sinus:
Cardiac veins return blood
to coronary sinus. enters into right atrium to be returned to pulmonary circuit.
Foramen ovale
Before birth, is an opening through interatrial septum (for-amen…prayer for the fetus. ovale: one perfect baby.)
Seals off at birth, forming fossa ovalis (even fossils have the fossa ovalis. ovale matures to gain a letter.)
foramen ovale:
opening in the interatrial septum in fetuses to circumvent the pulmonary circuit (unnecessary).
fossa ovalis:
closed off foramen ovale.
Trabeculae carneae:
muscular ridges in ventricles.
raised bundles of cardiac muscles.
Includes moderator band – in right ventricle, muscular ridge that extends horizontally from inferior interventricular septum and connects to anterior papillary muscle
Contains part of conducting system
Coordinates contractions of cardiac
muscle cells
function of trabeculae carneae:
Contains part of conducting system
Coordinates contractions of cardiac
muscle cells
moderator band:
trabeculeae carneae in right ventricle
-muscular ridge that extends horizontally from inferior interventricular septum and connects to anterior papillary muscle
mitral valve
biscuspid valve (AV valve in left side)
Chordae tendineae
(connective tissue)
* anchor flaps to walls of ventricle
* prevent valve from opening
backward. Fibers originate at the
papillary muscles
Blood Pressure
Arterial pressure of the systemic circulatory system
Systolic Pressure:
< 120 mm Hg (peak pressure in arteries)
Ventricles contract, ventricular pressure rises
Closure of AV valves / opening of semilunar valves
when ventricles contract (systole), ______ close and _______ valves open
AV valves close; semilunar valves open
Diastolic Pressure:
<80 mm Hg (lowest pressure is in arteries)
Ventricles relaxed – aortic pressure falls to ~ 80 mm Hg
Opening of AV values / closure of semilunar valves
when ventricles are relaxed (diastole), ______ close and _______ valves open
semilunar valves close, AV valves open
Normal blood pressure (normotension):
< 120/80 mm Hg
Elevated blood pressure:
120-129 / <80 mm Hg
Hypertension Stage 1:
130 – 139 / 80-89 mm Hg
Hypertension Stage 2:
≥ 140 / ≥ 90 mm Hg
tachy meaning
swift (tachycardia = fast heart rate)
Intercalated Discs: Comprised of
gap junctions, desmosomes, and fascia adherens
Gap junctions:
provide a connection between
adjacent cells that is small enough for ions to
pass. Provides for chemical communication
between the sarcoplasm of adjacent cells
Desmosomes:
play a role in intercellular
adhesion. Helps the heart resist shearing
forces that are generated when the heart
contracts
Fascia adherens:
provides an anchor for myofibrillar proteins
Types of capillaries
Continuous capillary, fenestrated capillary, sinusoid
Continuous capillary
formed by endothelial cells, surrounded by basement membrane
fenestrated capillary
endothelial layer has pores (fenestrations), found in the kidneys, choroid plexus of ventricles in the brain and in endocrine glands
sinusoid capillary
incomplete or absent basement
membrane and large fenestrations, allow proteins
to pass (such as new RBC, spleen, anterior
pituitary and PTH glands have sinusoids)
Subvalvular apparatus
- Papillary muscles
- Chordae tendineae
If papillary muscles damaged,
cusps of AV valves don’t
close properly and get “regurgitation”
If semilunar valves damaged,
How can they be damaged?
may need valve replacement
carditis or rheumatic fever or calcified
Damage to which 2 valves
is most detrimental to the
cardiac system? Why?
- Bicuspid / Left AV / Mitral
and - Aortic Valve (semilunar valve)
…both on left/systemic side
Repair valves using these procedures:
*Aortic valvuloplasty
*Pulmonary valvuloplasty
*Anterior leaflet repair
*Posterior leaflet repair
*Annuloplasty rings
Aortic Valvuloplasty
-when you have a stenotic aortic valve (doesn’t open fully or close properly)
-insert a balloon to crush it open (crushes plaque)
Pulmonary Valvuloplasty
same as aortic, but catheter inserted through vein in the neck.
Annuloplasty rings
rings inserted around valve to reshape and strengthen the natural valve annulus
Annulus:
An annulus is a ring-like structure, or any body part that is shaped like a
ring. Applied to many small ring-shaped structures. The base of a heart valve that
supports the valve’s leaflets is called the annulus.
Posterior Leaflet Repair
sews up or replaces the leaflet in a valve
types of valve replacements:
mechanical valve (long lasting), tissue valve (human or bovine or porcine), ross procedure (borrowing a healthy valve), TAVI/TAVR procedure (transcatheter aortic valve replacement)
ross procedure
“Borrowing” your healthy pulmonary valve (has
seen less stress) and moving it into the position of the damaged valve aortic valve. Replace pulmonary valve
Resistance (opposition to blood flow) is influence by:
blood viscosity (higher viscosity increases resistance), total blood vessel length (longer vessel increases resistance), blood vessel diameter (small diameter increases resistance, but effect is not linear… Resistance = 1/r4 (r=½ of the vessels diameter))
how does blood viscosity influence resistance to blood flow?
–As viscosity increases, resistance increases
and flow decreases. Viscosity affected by plasma proteins and
formed elements and temperature
how does blood vessel diameter influence resistance to blood flow?
changes according to the type of vessel.
Increased diameter means less blood touching the vessel wall so less resistance as diameter increases but the effect is not linear. Resistance = 1/r4 (r=½ of the vessels diameter)
how does blood vessel length influence resistance to blood flow?
longer the vessel greater the resistance and lower the flow. As you grow the length of the vessels increases. 1 lb of adipose tissue has 200 miles of vessels, 1 lb of muscle has > 400 miles of vessels
What structure electrically insulates atria from ventricles?
the cardiac skeleton
The cardiac skeleton
consists mainly of dense connective tissue (not
electrically excitable) and prevents transmission of electrical current between the chambers of the heart (electrically isolates the atria from the ventricles)
The 4 bands of dense connective tissue in the cardiac skeleton encircle the heart valves, located around the base of the aorta, both AV valves and the pulmonary trunk, this provides a point of attachment for valve leaflets and the myocardium – electrically insulate the atrial cells from the ventricular cells
The AV node is found at the center of the cardiac skeleton. The action potential is propagated from the AV node through the atrioventricular conducting system
This results in a delay in depolarization as the action potential is propagated through the AV bundle to the apex of the heart so the ventricles contract after the atria and contraction begins at the apex of the heart forcing blood up to the base
electrical vs mechanical cells in heart
electrical: specialized cells that conduct electrical impulses, start and transmit electrical activity in the heart
mechanical: (contractile cells) cells that make up the bulk musculature in the heart. contract in response to electrical stimuli from the electrical cells
electrical events precede mechanical events.
Autorhythmic cells are connected to contractile cells by ________
gap junctions
Autorhythmic cells continuously depolarize and drift up to AP threshold due to __________
If channels (Funny channels)
Autorhythmic cells in SA and AV node: stable/unstable resting potential?…
allows for continuous depolarization of “_______”
unstable; pacemaker potentials
Cardiac tissue has voltage gated Ca channels on ________. Excess Ca concentration in the extracellular fluid can cause heart to go into ________
T tubules; spastic contraction
Cardiac Contractile Cell Action Potential
Resting membrane potential; ______mV
Cell depolarizes to threshold ( _____ mv)
Rapid depolarization as ____channels open and ____ moves ____ the cell
At +30 mV; ____ channels close, ____ is pumped _____ of cell but slow ____ channels open and _____ moves _____ cell. Have a plateau in the action potential of ~175 msec
Repolarization: slow ____ channels begin closing, slow ____ channels begin opening: ______ moves OUT of the cell and the cell becomes more ______ (repolarizes) and resting membrane potential is restored
Slow ____ channels cause a _____ absolute refractory period: can’t stimulate the cell to contract again. _____ absolute refractory period prevents ____
Relative refractory period: voltage gated ____ channels are closed but can open in response to a larger than normal stimulus
-90 mV
- 75 mV
Na ; Na ; INTO
Na; Na; OUT; Ca; Ca; INTO
Ca; potassium; K ; negative
Ca ; long; Long; tetany
Na
funny channels belong to what kind of cell and do what
autorhythmic cells: they spontaneously depolarize the cell to threshold
Long PR interval:
can reflect damage to the conducting pathway or AV node
Large QRS complex:
may indicate heart has become enlarged
Long QT interval:
can be due to;
Electrolyte disturbances
Medications
Coronary ischemia
Conduction problems
Myocardial damage
Size of the T wave:
impacted by things that influence ventricular repolarization,
Starvation
Low cardiac energy reserves
Abnormal ion concentrations
Coronary ischemia
The heart muscle demands a constant supply of oxygen. When this is interrupted a ______ ______ or heart attack can occur.
Loss of oxygen to cardiac tissue leads to _______, cells can die; the myocardium can become _______.
myocardial infarction; ischemia; necrotic
biomarkers of a myocardial infarction in blood:
cardiac troponin (T or I), high sensitivity assay (HSTn)…still detects troponin, increased levels of myoglobin (released when there is muscle tissue damage to fix it), creatine kinase (creatine phosphokinase) (MB type specific to myocardial cells)
three layers of the arterial wall?
tunica intima, tunica media, tunica externa
Where in the artery does the lipid begin to deposit?
If starts between intima and media
this must rupture through the intima into
the lumen
*As the individual ages the fibrous cap begins to thin.
* This type of plaque is termed a
________ _________.
* _______ of the cap are most vulnerable
to rupture
vulnerable plaque; Shoulders
*A rupture of the fibrous cap can lead to the
development of a ______.
* Depending on the artery this can lead to
a ______ or ________.
thrombus; stroke; heart attack
STEMI
“ST elevation myocardial infarction”: when ST segment is elevated on an ECG this means that the person is having a heart attack with a completely blocked coronary artery: have an occlusive thrombus
ST-segment elevation indicates ____ _____ ______ _____ _____, pathological Q-wave
indicates _____ ____ and T-wave inversion indicates ____ _____
full thickness cardiac muscle injury; muscle necrosis; muscle ischemia
Can categorize ACS into the (3?) following categories:
- NSTE-ACS –Non-ST Elevation ACS; 2/3rd of cases (like acute angina)
- Non-ST segment elevation myocardial infarction
(NSTEMI); incomplete or transient obstruction of blood
flow in a coronary artery - STEMI- ST segment elevation myocardial infarction
(STEMI), have an occlusive thrombus
NSTE-ACS
Non-ST Elevation Acute Coronary Syndrome: 2/3 of cases of ACS (like acute angina)
NSTEMI
Non-ST segment elevation myocardial infarction; incomplete or transient obstruction of blood
flow in a coronary artery
what is the preferred immediate
treatment for STEMI and what does
this do?
PCI – percutaneous coronary interventions:
a non-surgical procedure used to treat the blockages in a coronary artery; it opens up narrowed or blocked sections of the artery, restoring blood flow to the heart.
-(formerly known as angioplasty with stent) is a non-surgical procedure that uses a catheter (a thin flexible tube) to place a small structure called a stent to open up blood vessels in the heart that have been narrowed by plaque buildup
….best to do this if these facilities are available in the area (can get to a center that has this capacity quickly); door to balloon time
Opens and stabilizes the artery lumen
Mortality has decreased particularly in those with ST-segment elevation MI because of improvements in the initial therapy given:
Stabilize with aspirin (blood thinner), heparin (anticoagulant) and nitroglycerin (relaxed blood vessels)
Thrombolysis (clot busters)
PCI –percutaneous coronary intervention (per=through, cutaneous = skin)
Cardiac Cycle
- The period between the start of one heartbeat and the beginning
of the next - Includes both contraction and relaxation
- Two phases within any one chamber
1. Systole = contraction
2. Diastole = relaxation (dilated)
Stroke volume (SV)
the amount of blood pumped by one ventricle during contraction (beat)
SV = EDV – ESV
(the volume of blood that actually gets pumped out by one ventricle)
End-diastolic volume (EDV):
volume of blood before contraction
End-systolic volume (ESV):
volume of blood after contraction
Ejection fraction:
The percentage of EDV represented by SV (SV/EDV)
Cardiac Output (CO)
CO is the volume of blood pumped through circulatory system in 1 minute (ml/min)
- CO = HR x SV
- CO = cardiac output (mL/min)
- HR = heart rate (beats/min)
- SV = stroke volume (mL/beat)
75 bpm X 80 mL/beat = 6000 mL/min
CO= 6 L/min
