Intro to Cardiovascular System

-transportation of O2 to tissues
-transportation of nutrients
-transportation of CO2 and metabolites to lungs and kidneys
-distribution of hormones
-thermoregulation
-urine formation

Functions of the cardiovascular system

-activation of sympathetic nervous system
-increased cardiac output
-increased skin blood flow
-decreased blood flow to kidney
-decreased visceral blood flow
-maintenance of blood flow to the brain

cardiovascular responses to exercise

1. FiO2 and air quality
2. airways
3. lungs and chest wall mechanics
4. diffusion/transit time
5. perfusion
6. myocardial function
7. peripheral circulation
8. tissue extraction and use of O2
9. return of CO2 and partially desaturated blood to lungs

steps in O2 transport pathway

O2 levels less than 300mL
(low oxygen)

when is anaerobic metabolism triggered?

-anterior surface
-right atrium and ventricle

sternocostal surface of heart

-inferior surface
-right and left ventricles

diaphragmatic surface of heart

-base
-left atrium and some right atrium

posterior surface of heart

the posterior surface (base)

which surface of the heart do the great vessels enter at?

3rd rib

rib level of base of the heart

5th rib at midclavicular line

rib level of apex of heart

Double-layered membrane surrounding the heart.

pericardium

-fibrous pericardium (outer)
-serous pericardium (inner)
---parietal pericardium
---visceral pericardium (on heart)

parts of pericardium

-epicardium
-myocardium
-endocardium

layers of cardiac tissue

outer layer of the heart
-surrounded by visceral pericardium

epicardium

muscular
-middle layer of the heart

myocardium

inner lining of the heart

endocardium

-functional syncytium
-inherent spontaneous rhythmicity
-polarized irritability
-all or none law

4 properties of cardiac muscle

-heart acts as one cell
-due to branching fibers and intercalated discs

functional syncytium

-heart can depolarize on its own without CNS input
-reason why dysrhythmia can occur

Inherent spontaneous rhythmicity

-some parts of the heart are more likely to depolarize than others
-SA is most irritable due to decreased refractory time

polarized irritability

all cardiac fibers depolarize or none do
-no recruitment

all or none law

easily depolarized
-60 to 100 bpm

polarize irritability of SA node

-takes a little longer to be ready for another depolarization
-40 to 60 bpm

polarize irritability of AV node

-takes a very long time to be ready for deploarization
-20-30 bpm

polarize irritability of ventricular muscle

less likely that SA node is in charge

a lower HR indicates ____ is in charge

-inferior and superior vena cava
-right atrium
-> tricuspid valve
-right ventricle
-> pulmonic valve
-pulmonary artery
-lungs

deoxygenated blood flow through heart

-lungs
-pulmonary vein
-mitral valve
-left ventricle
-aortic valve
-aorta

oxygenated blood flow through heart

70-80%
-no passive muscle contraction

How much of ventricular filling is passive?

we can survive without atria
-a fib is the most common arrhythmia with no active atrial output

impact of passive ventricular filling

Relaxation of the heart
-tricuspid and mitral open
-aortic and pulmonary valve closed

diastole

in response to pressure changes

Why do valves open and close?

Contraction of the heart
-mitral and tricuspid valves closed
-pulmonary and aortic valve open

systole

inversely proportional

resistance and radius

-elastic fibers
-more smooth muscles

artery structures

venous

more blood is in ____ system

_____ stimulates collateral channels (anastamoses)

tissue hypoxia

side depends on which coronary artery supplies posterior descending artery
-90% right
-10% left

R vs L dominant heart

-Right atrium
-right ventricle
-Left ventricular inferior wall
_left ventricular posterior wall (90%)
-posterior 1/3 oc interventricular septum

myocardium supplied by RIGHT coronary artery

-SA node (55%)
-AV node and Bundle of His (90%)
-posterior fascicle of L bundle branch

conducting system supplied by RIGHT coronary artery

-left ventricular anterolateral wall
-anterior 2/3 of septum

myocardium supplied by LEFT coronary artery circulation: ANTERIOR DESCENDING BRANCH

-most of right bundle branch
-anterior fascicle of L bundle branch
-part of posterior fascicle of L bundle branch

conduction system supplied by LEFT coronary artery circulation: ANTERIOR DESCENDING BRANCH

-left atrium
-left ventricular anterolateral wall
-left ventricular posterolateral wall
-left ventricular posterior wall (10%)

myocardium supplied by LEFT coronary artery circulation: CIRCUMFLEX BRANCH

-SA node (45%)
-AV node and bundle of His (10%)

conduction system supplied by LEFT coronary artery circulation: CIRCUMFLEX BRANCH

-left anterior descending
-circumflex artery

branches of LEFT coronary artery

1 cm long

how long is the left coronary artery before it divides?

branches of the circumflex artery

-obtuse marginal 1 and obtuse marginal 2

branch of left anterior descending artery

first diagonal branch

-55% right coronary artery
-45% circumflex branch of the LCA

what provides blood supply for SA node

what provides blood supply for AV node

-90% right coronary artery
-10% circumflex branch of the LCA

what is involved in cardiac metabolism

-glucose
-fatty acids (rest)
-lactate (prevents lactate accumulation) (heavy exercise)
-amino acids

components of oxygen consumption and where they occur?

-oxygen exchange-> respiratory function
-oxygen transport-> cardiovascular
-oxygen extraction-> circulation to muscle

-cardiac output (CO)
-arterial venous difference (A-VO2)

oxygen required for any activity is determined by ____

VO2= CO x A-VO2

-cardiac output
-arterial venous difference

VO2 formula (oxygen consumption)

the heart's ability to pump blood

cardiac output measures ____

CO = HR x SV (heart rate x stroke volume)

Cardiac output equation

the peripheral tissue's ability to extract O2

A-VO2 difference measures ____

decreases
-intrinsic rate of SA node
-not related to fitness

maximum HR ____ with age and why

increased

increased HR means _____ oxygen demand by the heart

decreased

increased HR leads to ____ diastolic filling time

-vagus nerve
-sympathetic nerves (Beta 1 receptors)

nervous control of the heart

-decreases HR
-decreases contractility
-slows conduction through AV node

vagus nerve effect on heart

AV node

vagus nerve slows HR through ____ (structure)

-increase HR
-increase contractility
-increase speed of conduction through AV node

sympathetic nerve (beta 1) effect on heart

coronary arteries and some peripheral vessels
-vasodilation of coronary arteries

Beta 2 receptors
-where and function

mainly in peripheral arteries
-vasoconstriction of peripheral arteries

alpha receptors
-location
-function

-resting HR increased because there is no vagus nerve control (based on SA node intrinsic rate)
-catecholamines released from adrenal gland (epinephrine) increase HR slowly with exercise

how does HR increase with a denervated heart due to transplant?

-baroreceptors (control BP)
-chemoreceptors (hypoxemia-> increase HR)
-body temperature
-concentration of potassium and calcium
-hormones (epinephrine, norepinephrine)

additional controls of HR

-heat: increase
-cold: decreases

heat and cold control of heart control

3.5-5.0 mEq/L

normal potassium range

-ECG changes
-ausea
-diarrhea
-numbness/tingling
-trouble breathing
-chest pain
-palpitations/irregular heart beats

hyperkalemia can cause

-dangerous ventricular arrhtyhmias
-prolonged QT
-cardiac irritability
-ST segment depression
-dizziness
-HYPOTENSION
-decreased contractility

hypokalemia can cause

call physician ASAP

what to do with hypokalemia

-CHF
-renal insufficiency
-hypovolemia

causes of hypernatremia (increased sodium)

-irritability
-agitation
-seizure
-coma
-hypotension
-tachycardia
-weak pulse
-decreased urine output

symptoms of hypernatremia

-diuretics
-drinking excessive water

causes of hyponatremia (low sodium)

-nausea
-vomiting
-headache
-confusion
-loss of energy
-drowsiness
-restlessness
-irritability
-muscle weakness, spasm, cramps
-seizures
-coma

signs of hyponatremia

effectiveness of the heart as a pump

stroke volume reflects the ____

preload, afterload, contractility

stroke volume is dependent on

venous return and distensibility
-how much blood is in the ventricle by end of diastole (relaxation)

what is preload

supine

what position is preload greatest?

1. vasodilation
2. diuresis (dehydration)

What can decrease preload?

strength of ventricular contraction

what is contractility?

-increase end diastolic volume increases heart contraction (force dependent on length)
-increase ejection fracture due to sympathetics (force independent of length)

what effects contractility?

aortic distensibility to accept blood from aorta

what is afterload?

-aortic distensibility
-vascular resistance
-patency of aortic valve
-blood viscosity

what impacts afterload>

decreases

increase in afterload, ___ Stroke volume

decreases

peripheral resistance ____ with exercise

EF= SV/EDV
-stroke volume
-end diastolic volume

ejection fraction forumla

-normal: 50-70%
-slightly below normal: 40-54%
-reduced:

resting Ejection fraction
-normal:
-slightly below normal:
-reduced:

-rapidly rises initially with aerobic exercise
-usually levels off at 40-50% VO2 max (HR increase leads to less diastolic filling time)

stroke volume levels with exercise

-main mechanism at low level exercise is stroke volume
-as exercise intensity increases, HR is main mechanism

what causes increased cardiac output?

-70% veins
-10% systemic arteries
-15% pulmonary circulation
5% capillaries

location of blood volume

-increased blood flow
-increased oxygen extraction

A-VO2 difference increased due to

25% at rest
-3X greater O2 extraction during exercise

A-VO2 difference in skeletal muscle

70-80% at rest
-less wiggle room for O2 extraction with exercise so coronary blood flow is critical

A-VO2 difference in cardiac muscle

nitric oxide
-vasodilation

endothelial derived relaxing factor
-what and function

-decreased pH
-increased PCO2
-increased Ca (vasoconstriction)
-increased ADP
-decreased O2
-increased Magnesium (vasoconstriction)
-increased temperature

local metabolite conditions leading to vasodilation during exercise
-___ pH
-___PCO2
-___ Ca (function)
-____ ADP
-____ O2
-_____ Mg (function)
-_____ temperature

congestive heart failure

local metabolite conditions are impaired with ____

-vasodilation
-occurs with autonomic neurons, synthesized by vascular endothelium, drugs, or when pressure builds on epithelium

role of nitric oxide

-liver: 27%
-kidney: 22%
-muscle: 20%

cardiac output distribution at rest