Cardio 1 Flashcards by sophie rosen

Three principal components of the circulatory system are:

the heart (the pump)
the blood vessels (the pipes)
the blood (the fluid to be moved)

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Cardiovascular function is regulated by (2), and strongly impacted by —
function.

endocrine factors
and autonomic nerves

renal

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Number one cause of death worldwide.

CVD

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Cardiovascular Disease most common symptoms (2)

Atherosclerosis and hypertension are most common.

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Cardiovascular disease affects many

organs (brain, eyes,

kidneys…)

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Multiple risk factors for cardiovascular disease

smoking,

obesity, diabetes mellitus, genetics…

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Systemic Circulation (2)

 Supply O2 and nutrients to
tissues
 Remove waste

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Pulmonary Circulation (2)

 Add O2

 Remove CO2

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function of heart valves

Keep blood flowing in one direction

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heart valve open and close due to

change in pressure

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Atrioventricular (AV)

Valves (4)

Tricuspid (RA/RV)
Mitral/Biscuspid
(LA/LV)
PA > PV  open
PA < PV closed

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Semilunar Valves (4)

1. Pulmonary (RV/Pulmon. 
Trunk)
2. Aortic (LV/Aorta)
PV > PArt  open
PV < PArt closed

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Two “loops” in the cardiovascular

system:

 Systemic and Pulmonary.

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Pulmonary loop carries

oxygen-poor
blood to the lungs and oxygen-rich
blood back to the heart.

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Systemic loop carries

oxygen-rich
blood to systemic capillaries and
oxygen-poor blood back to the
heart.

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Considered a “— system,” i.e.,

leaks are bad.

closed

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Arteries

Types: (3)

 Elastic Arteries (Heart)
 Muscular Artery (Distribution)
 Arterioles (Capillaries)

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Arteries

Function: (2)

 Carry blood to tissue capillaries from heart

 Regulate blood pressure(Arterioles)

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Veins

Types: (3)

Large Veins (Heart)
Medium-Sized Vein (Collection)
Venules (Capillaries)

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Veins

Function: (2)

 Carry blood to heart from tissue capillaries

 Reservoir of blood (Peripheral Venous Pool; PVP)

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Capillaries

Types: (3)

Continuous
Fenestrated
Sinusoid

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Capillaries

Function: (2)

Site of exchange

10,000,000,000 capillaries

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Pressure (“Hydrostatic”) is the

force exerted by a fluid in a tube (mm Hg)

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Flow is the

volume of fluid moved in a given amount of time (ml/min.)

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Resistance is

how difficult it is for blood to flow between two points at any given pressure difference. Resistance is the measure of friction that impedes flow.

Ohm’s Law:

F = ΔP/R (ml/min)=(mmHg)/(Poiseuille) If ΔP is constant and resistance increases, flow decreases.

``` Q = ΔP/R Where:  Q =  ΔP = P1 = P2 =  R = ```

 Q = Volume of blood moved in a unit of time (L/min.)  ΔP = Driving force to move blood through blood vessels = P1- P2 P1 = pressure generated by heart beat P2 = drop in pressure as move further from heart, due to friction  R = resistance of blood vessels to blood flow  Controlled by factors defined by Poiseuille’s Law

Three factors contribute to cardiovascular resistance: (3)

Blood viscosity (n) Total blood vessel length (l) Blood vessel radius (r)

``` Blood viscosity (n) affected by ```

blood volume and # of RBC (Hematocrit)

Total blood vessel length (l)

(how much tubing is needed)

Blood vessel radius (r) (3)

Vasodilated vessels increase r and decrease R, Vasoconstricted vessels decrease r and increase R Main contributor to minute-to-minute control of resistance in the vascular system)

``` --- of Vessel is a Major Determinant of Flow ```

Diameter

``` V = Q/A Where: V = Q = A = ```

V = Velocity (cm/min) Q = Blood Flow (ml/min.) A = Total Cross Sectional Area (cm2)

AV Valves (3)

1. Tricuspid (RA/RV) 2. Mitral (Bicuspid) (LA/LV) Chordae Tendineae/Papillary muscle

Seminlunar Valves (2)

1. Aortic SL (LV/Aorta) 2. Pulmonary SL (RV/Pulmon. Trunk)

Open/Close due to

pressure gradients

Function to

keep blood | moving in one direction

Types of Cardiac Myocytes (cardiocytes, cardiac muscle cells) (2)

Conductive Muscle Fibers (Autorhythmic (AR) cells, Pacemaker cells) Contractile Muscle Fibers

Conductive Muscle Fibers (Autorhythmic (AR) cells, Pacemaker cells) (4)

```  1% of myocytes  Spontaneously generate AP that lead to heart beat (Excitatory - stimulates contractile cells)  Contract very weakly  Located in conduction system of heart ```

Contractile Muscle Fibers (3)

```  99% of myocytes  Contract and generate heart beat  Types a. Atrial Myocytes b. Ventricular Myocytes ```

Cardiocytes are --- cells

striated

Functional unit =

sarcomere

Cardiac muscles anatomy and function similar to

skeletal muscle

Arteries supplying the myocardium are the --- ---, and the | blood flowing through them is the

coronary arteries | coronary blood flow.

Coronary arteries exit from behind the aortic valve cusps and lead to a branching network of

small arteries, arterioles, capillaries, venules, and | veins similar to those in other organs.

Most of the cardiac veins drain into a single large vein, the --- ---, which empties into the

Coronary Sinus | right atrium.

Cardiac Cycle

 Describes the events during a single heartbeat

Systole =

Contraction

Diastole =

Relaxation

Cardiac Cycle | Events (3)

1. Atrial Systole 2. Ventricular Systole/Atrial Diastole 3. Ventricular Diastole

Heart muscle must --- before systole can | occur and --- before diastole can occur.

depolarize | repolarize

Excitation (Depolarization) of the Heart/ Conduction System (6)

``` SA Node Internodal Pathways AV node (AV delay of 0.1 sec) Bundle of His (AV Bundle) Down Bundle Branches Up Purkinje Fibers ```

Purkinje fibers also supply

papillary muscles; these contract during | ventricular contraction to tighten chordae tendineae and prevent AV valves from prolapsing into the atria

Pacemaker Cells (5)

 1% Myocardium/Conduction System of Heart  Spontaneously generate AP leading to Contractile Cell contraction  The pacemaker cells with the fastest rate of discharge drives the heart  In general, have high action potential conduction velocities (Exception?)  Ectopic Focus

AV NODE CONDUCTION VELOCITY (METERS/SEC)

0.02-0.05

ECG

Recording of the Electrical Activity of Heart

THE WAVES OF AN ECG • P wave: • QRS complex: • T wave:

* P wave: atrial depolarization * QRS complex: ventricular depolarization/atrial repolarization * T wave: ventricle repolarization

Pacemaker Potential: | AR Cells do not have a steady

resting membrane potential

Channels of Pacemaker | Potential (2)

1. F type Channels = Voltage gated Na+ channel 2 Ca2+ (T) = transient voltage gated Ca++ channel

Channels of AP (2)

Ca2+ (L) = long lasting voltage gated Ca++ channel K+ channel = voltage gated K+ channel

NE/β1Adrenergic

↑ Po F and Ca++ (T) Channel open decrease Time to Threshold increase HR

Ach/Muscarinic

``` ↓ Po F Channel ↑ Po K+ channel Hyperpolarize Vm increase Time to Threshold decrease HR ```