Unit 2: Cardiovascular System Flashcards
Cardiovascular system consists of
heart and blood vessels
The heart is a double pump, meaning …
it has 2 different circuits
What are the 2 cardiovascular circuits?
Pulmonary Circuit
Systemic Circuit
What side is the pulmonary circuit on, and what is its purpose?
Right side of the heart
Bring blood to the lungs for gas exchange
What side is the systemic circuit on, and what is its purpose?
Left side of heart
Bring oxygenated blood to all areas of the body
DYNAMIC bloodflow
Define dynamic bloodflow and give an example
Flow caters to the body’s current needs
During exercise, increased flow to lungs, myocardium, and skeletal muscle; decreased flow to intestines and kidneys
Where is the heart located?
Mediastinum
Center of sternum between lungs
Where is the base of the heart?
Broad upper part of heart
Where is the apex of the heart?
Pointed, left-tilting bottom of heart
Define pericardial sac and what are the layers?
Double layer serous membrane outside the heart which allows expansion without friction
Parietal pericardium, pericardial cavity, visceral pericardium (AKA epicardium)
Define parietal pericardium
Outer, tough fibrous membrane of pericardial sac
Define pericardial cavity
Cavity between parietal pericardium and epicardium that is filled with pericardial fluid
Define visceral pericardium (AKA epicardium)
Thin, moist serous membrane layer on the surface of the heart
What are the layers of the heart wall?
Epicardium
Myocardium
Endocardium
Describe the myocardium and its functions
Thick, muscular layer with a fibrous skeleton of collagen and elastin fibers
Support, cardiac muscle attachment sites, and electrical insulation
Describe the endocardium
Smooth inner layer
What are the 4 heart chambers?
Left and right atria
Left and right ventricles
Describe the atria
Upper and posterior positioned chambers
Have auricles which allow further expansion
Receive blood returning to the heart and send down to the ventricles
Describe the ventricles
Lower chambers
Pump blood out of the heart to arteries
What are the 4 heart valves?
2 atrioventricular valves (AV)
Tricuspid valve
Bicuspid/Mitral valve
2 semilunar valves
Aortic semilunar valve
Pulmonary semilunar valve
What connects the AV valves to the papillary muscle to stabilize them
Chordae tendineae
Where does blood pass to through the pulmonary semilunar valve?
Pulmonary trunk
Where does blood pass to through the aortic semilunar valve?
Aorta
Describe the path of blood flow, starting from the atria:
THEN describe the path of blood flow from the ventricles:
Ventricles relax and ventricular pressure drops
Semilunar valve closes and AV valve opens
Blood flows from atria to ventricle
Ventricle contracts and ventricular pressure increases
Semilunar valve opens and AV valve closes
Blood flows from the ventricles to the great vessels
What are nodal cells
Cardiac muscle cells which conduct electricity like neurons and do not contract like “normal” non-nodal cardiac muscle cells
Define myogenic
originates in the heart
Define autorhythmic
spontaneous, regular depolarization
What regulates the pace of the heart?
Sinoatrial (SA) node / Pacemaker
Define AV node
Atrioventricular node is the electrical gateway to the ventricles
Define AV bundle and its branches
Pathway for electrical signals from AV node thru interventricular septum down to the apex
Define Purkinje fibers
Fibers upward from the apex to spread electrical signals thru ventricular myocardium
Describe cardiac cells
Small sarcoplasmic reticulum which stores less Ca+
Large T-Tubules to carry Ca+ from ECM into cell
Intercalated discs connected with desmosomes and gap junctions
Cardiac cells are connected
electrically and metabolically
The AV node ______ electrical spread. Why?
Slows
To give time for atria to contract before ventricle
1 depolarization of the SA node =
1 heartbeat
SA node signal travels at ___ m/sec while the AV node signals travel at ____ m/sec
1 m/sec
0.05 m/sec
______ gets the electrical signal first. Why?
Papillary muscle
To stabilize the AV valves
Ventricular systole occurs from ____ to _____
apex to base
An electrocardiogram measures …
The combined electrical activity of the nodal and non-nodal cells
What occurs during the P wave ?
SA node fires, atrial depolarization and atrial systole
What occurs during the QRS wave?
AV node fires, ventricular depolarization and ventricular systole, atrial depolarization and atrial diastole
What occurs during the T wave?
Ventricular repolarization, ventricular diastole
The cardiac cycle is
1 complete contraction and relaxation
Name the 5 phases of a heart beat
Quiescent period
Atrial systole
Isovolumetric contraction of ventricles
Ventricular ejection
Isovolumetric relaxation of ventricles
What is the equation for cardiac output
SV x HR
(Stroke volume x heart rate)
Define stroke volume
Amount of mL of blood ejected
What is the equation for the ejection fraction
SV / EDV
(stroke volume divided by end diastolic volume)
What is the average end diastolic volume (EDV)?
130 mL
Define end diastolic volume (EDV)
Volume of blood in heart BEFORE heartbeat
Define end systolic volume
Volume of blood in heart AFTER heartbeat
Arteries carry blood ___________ the heart
Away from
Veins carry blood _______ the heart
Back to
What is the benefit of arterial branching?
Increase surface volume and amount of tissue perfused, therefore decreasing BP
“Feeds tissues”
What are the 2 types of circulatory routes in the vascular system?
Common
Portal System
Describe a common circulatory route
Heart
Artery
Arteriole
Capillary bed
Venule
Vein
Describe a portal system route
Heart
Artery
Arteriole
2 CAPILLARY BEDS
Venule
Vein
Give examples of portal systems in the body
Hypothalamus to anterior Pituitary gland
Stomach/intestines to Liver
What are the layers of the vessel wall?
Tunica externa
Tunica media
Tunica interna
Describe the tunica externa
Outside connective tissue layer of blood vessel wall
Describe the tunica media
Middle smooth muscle layer of blood vessel wall
Describe the tunica interna
Inner smooth layer lined with prostacyclin
Define prostacyclin
Anti-clotting lipid which repels bloods cells and platelets for smooth flow
Define blood pressure
The force blood exerts against vessel walls
Systolic refers to …
Diastolic refers to …
Ventricle contracted
Ventricle relaxed
What is pulse pressure and how do you find it?
Force exerted on smaller arteries
Systolic pressure - Diastolic pressure
Define mean arterial pressure
Average arterial pressure during 1 cardiac cycle
The main function of capillaries is
EXCHANGE!
Define precapillary sphincter
“gates” which control which capillaries are going to be perfused by arteriole
Define thoroughfare channel
Channel from arteriole which bypasses capillary bed directly into the venule
What are the 3 types of capillaries?
Continuous
Fenestrated
Sinusoids
Define continuous capillary
Found in most tissues
endothelial cells have tight junctions so only small SOLUTES can come through
Define fenestrated capillary
Found in kidneys, small intestine
endothelial cells have fenestrations (filter pores) which allow small MOLECULES through
Define fenestration
Filter pore in capillary
Define sinusoid capillary
Found in liver, spleen, bone marrow
Endothelial cells have XL fenestrations which allow proteins and blood cells through
What are the 3 routes of exchange between the capillary wall and tissue
Intercellular clefts
Fenestrations
Thru cytoplasm
Define diffusion (pertaining to capillary exchange)
Gradient from high to low concentration
Lipid soluble diffuse easily
Water soluble pass through membrane clefts, fenestrations, etc.
NO LARGE PARTICLES
Define transcytosis
Transport vesicles travel across cell membrane carrying fatty acids, big proteins, hormones, etc.
Define filtration and reabsorption (pertaining to capillary exchange)
Increased BP drives fluids out of capillary into tissue
Then when Albumin concentration rises, fluid is drawn back into capillary by Colloid Osmotic Pressure
Define colloid osmotic pressure (COP)
Pressure from build up of colloids (like albumin) in plasma, causing liquid to be drawn back into the capillary
How is venous return different from arteries
Much less pressure, relies on gravity, skeletal muscle, nearby arteries, and “thoracic pump” to pump blood back to the heart
Veins have thinner walls without smooth muscle because the pressure is much lower than arteries
What are the 3 methods of blood pressure regulation
Local
Neural
Hormonal
Define metabolic autoregulation
If tissue is not adequately perfused due to low blood pressure, waste will accumulate and the tissue responds to this by vasodilating
What are vasoactive chemicals
Substances that stimulate vasomotion in response to trauma, exercise, or arousal
Describe reactive hyperemia
Blood flow is completely cut off and then restarted so BP temporarily increases
Describe angiogenesis
Growth of new vessels from existing vessels to increase perfusion
Where are chemoreceptors
Aortic and carotid bodies
What is the purpose of chemoreceptors
Autonomic response to change in blood chemistry
1. adjust respiration
2. vasomotion
Work to stimulate vasoconstriction and increase BP and perfusion
Define hypoxemia
Low oxygen levels in blood
Define hypercapnia
High CO2 levels in blood
Define acidosis
Imbalanced pH in blood
Where is the vasomotor center and what does it do?
Medulla oblongata
stimulates cardiac and skeletal vessels to dilate (but most other vessels to constrict)
Integrates chemoreflex and baroreflex
What are proprioceptors?
Receptors which detect changes in activity and body position
What are baroreceptors?
Receptors which detect pressure in the aorta and internal carotid artery, sends signals to cardiac center in medulla oblongata to either vasodilate or vasoconstrict
Describe the angiotensin system
Angiotensinogen constantly released by liver
Kidney releases Renin when BP is low which converts Angiotensinogen to Angiotensin I
Lungs release ACE which converts Angiotensin I to Angiotensin II
Angiotensin II triggers vessels to vasoconstrict and adrenal gland to release Aldosterone
Aldosterone increases reabsorption of NaCl and H2O in kidneys
BP raised!
Define angiotensinogen
A pre-hormone constantly released by the liver
Define renin
A kidney enzyme which is released in response to low BP which converts angiotensinogen to angiotensin I
Define ACE
angiotensin converting enzyme
Released by lungs to concert angiotensin I to angiotensin II
Define angiotensin II
Powerful vasoconstrictor which stimulates the production of aldosterone
Define aldosterone
Hormone which causes kidneys to reabsorb sodium and water, therefore decreasing urine output and increasing the amount of liquid in the blood and in effect, raising BP
Name 5 hormones which control BP and blood flow
Aldosterone
Atrial natriuretic factor (ANP)
Antidiuretic hormone
Epinephrine and Norepinephrine
Define atrial natriuretic factor (ANP)
Hormone which promotes sodium and water excretion, increasing urine output and stimulating vasodilation, resulting in lowered BP
Define antidiuretic hormone
Hormone which promotes water retention and in high concentration, promotes vasoconstriction to increase BP (during times of fasting, sleeping)
Define epinephrine and norepinephrine
Hormones which bind to skeletal and cardiac vessels and promote vasodilation, especially in response to “fight or flight” situations
Define Coronary Artery Disease (CAD)
Cause?
Symptoms?
Risk Group?
Most common heart disease and cause of death in US
Narrowing and hardening of coronary arteries, build up of cholesterol (causing atherosclerosis), decreasing blood flow to the heart
Causes angina, shortness of breath, myocardial infarction
Risk: age, hypertension, high cholesterol, obesity, smoking, genetics
Define Peripheral Artery Disease (PAD)
Cause?
Symptoms?
Risk Group?
Similar to CAD but atherosclerosis occurs in peripheral arteries instead, causing poor blood flow in limbs
Can be asymptomatic or cause heavy feeling in legs, slow healing rate, weak pulse in legs, cyanosis (bluish skin)
Risk: age, hypertension, high cholesterol, obesity, strokes, genetics
Define Deep Vein Thrombosis (DVT)
Cause?
Symptoms?
Risk Group?
Blood clot in deep vein, typically in lower leg
Can be harmless, but risk of clot breaking off and traveling to lungs (pulmonary embolism) or brain (stroke)
Causes pain, tenderness, swelling in leg
Risk: age, inactivity, injury, pregnancy, obesity
Define Mitral Valve Prolapse
Mirtal/Bicuspid valve does not close completely so it leaks
Can be asymptomatic or cause cough, shortness of breath, angina, palpitations, and an increased risk of endocarditis
Risk: family history, congenital
Define hypertension
High blood pressure (over 140/90)
Asymptomatic but can lead to myocardial infarction, stroke, or kidney failure
Risk: age, high fat or sodium diet, obesity, alcohol abuse, medications, apnea, thyroid disorders, diabetes
