Exam 1: Cardiovascular System Flashcards
What is Resting Membrane Potential
Voltage (charge inside cell) difference across cell membrane when cell is at rest
Intracellular environment is more negative compared to extracellular environment
RMP for neurons is -70 mV
What are the different types of tissues
Epithelial
connective
muscle
nervous
what tissues are excitable (can be stimulated to produce electrical signals)
Nerve and Muscle tissues
How is action potential triggered
by movement of ions
REVIEW GRAPH OF AP FROM A&P I
what are the types of muscle tissue
skeletal
smooth
cardiac
Describe functions of and characteristics of skeletal muscle
functions; locomotion, posture, respiration
It is voluntary and striated
stimulated by motor neurons
Describe functions of and characteristics of smooth muscle
functions; contraction of hollow organs, vasoconstriction, vasodilation
It is involuntary and non-striated
Describe functions of and characteristics of Cardiac muscle
function; contraction of heart chambers
only found in heart
involuntary and striated
autorhythmic
Define autorhythmic
can contract on own without nerve stimulation
What components make cardiac muscle unique
branched and networked cardiac myocytes that are joined by intercalated discs
mitochondria-rich (1/3 of cell volume)
larger and branched t-tubules
graded contraction
What are the components of cardiac myocytes
*Desmosomes: strong links between adjacent cells
*Gap junctions: allow waves of depolarization to spread rapidly between cells
Define Graded contraction
amount of force generated is related to how many cross-bridges are active
-the more cross-bridges (active) = greater force of contraction
*Determined by how much Ca++ bound to troponin
Define pulmonary
relating to lungs
define systemic
relating to the entire body
In general where do arteries carry blood
away from the heart
In general where do veins carry blood
to the heart
What is the physical location of the heart
within the mediastinum which is located within the thoracic cavity
what is the mediastinum
region between pulmonary cavities (lungs)
what is the approximate size of the heart
the size of a closed fist
What factors influence heart size
age, height, weight, gender
*this is important for treatment of certain heart conditions and/or problems
Describe the hearts shape
base = top of heart
apex = bottom where it narrows
*looks like a tilted ice cream cone (point is on person’s bottom left side when viewing anteriorly)
Define Pericardium
peri = around
cardium = heart
surrounds the heart providing protection and roots great vessels. There are 2 layers to it.
Name and describe the superficial layer of the pericardium
fibrous pericardium:
-made of dense and loose CT, fairly non pliable
-function: anchors heart, prevents overdistension, protects against blunt force
Name and describe the deep layer of the pericardium
Serous Pericardium:
-composed of 2 layers
- Parietal layer
-outer/fused to fibrous pericardium - Visceral layer
-inner/aka epicardium covers heart
what is the function of pericardial fluid
found between layers of serous pericardium
Function: reduces friction during heart contraction
Define pericarditis
inflammation of the pericardium
*Caused by some viral infections
What are the different portions of the heart wall from superficial to deep
Epicardium (AKA visceral pericardium)
Myocardium
Endocardium
Describe the Epicardium (visceral pericardium)
superficial, thin, smooth layer of heart wall
Describe the Myocardium
Middle layer of heart wall, very thick
-composed of cardiac myocytes (heart muscle cells) that cause contractility
Describe the Endocardium
Deep, somewhat thin layer of heart wall
composed of simple squamous epithelium over CT layer
Covers the inner surfaces (chambers) of the heart
smooth texture for easy blood movement
How many chambers does the human heart have
4
Is blood oxygenated (O2 rich) or deoxygenated (O2 poor) when travelling through the Right side of the heart
Deoxygenated (O2 Poor)
Is blood oxygenated (O2 rich) or deoxygenated (O2 poor) when travelling through the Left side of the heart
Oxygenated (O2 Rich)
what are the 2 superior chambers of the heart known as
Right and Left Atriums (Atria is proper plural)
what are the 2 inferior chambers of the heart known as
Right and Left Ventricles
what separates the right and left atria of the heart
interatrial septum
what separated the right and left ventricles of the heart
interventricular septum
Why are the interatrial and interventricular septums necessary
separate O2 Rich and O2 Poor blood
what do the valves of the heart allow
one-way blood flow and prevent back flow of blood
What are the cusps/leaflets in the heart
Flaps that are a part of the valves
How many atrioventricular (AV) valves are in the heart
2
What are the names of the AV valves
tricuspid valve
bicuspid/mitral valve
Which side of the heart is the Tricuspid valve on and how many flaps does it have
right side and has 3 flaps
*tri before you bi
which side of the heart is the Bicuspid/Mitral valve on and how many flaps does it have
left side and has 2 flaps
How many semilunar (SL) valves are in the heart
2
what makes each of the SL valves unique
They each have 2 half moon shaped cusps
What are the names of the SL valves
Pulmonary semilunar valve
Aortic semilunar valve
In terms of blood flow, which side of the heart does blood come from when travelling through the Pulmonary Semilunar Valve
Right Side
(O2 poor blood comes from rest of body via SVC and IVC, travels through RA, Tricuspid valve, RV, then pulmonary semilunar valve, to pulmonary arteries, to lungs)
In terms of blood flow, which side of the heart does blood come from when travelling through the Aortic Semilunar Valve
Left Side
(O2 Rich blood comes from lungs via pulmonary veins, travels through LA, Bicuspid valve, LV, then Aortic semilunar valve, to aorta, to rest of body)
REVIEW FLOW OF BLOOD GRAPHIC
What are Chordae Tendinea and what is its function
connect Atrioventricular (AV) valves, so Tri- & Bi- cuspid, to papillary muscle within heart
Function: prevents inversion of valves during ventricular contraction
Describe the coronary arteries
Left and Right Coronary arteries both originate from/exit the aorta
Function: Supply O2 rich blood to heart tissue
What are the major branches of the left Coronary A. and what do they supply
Left Anterior Descending artery
-Supplies: anterior left Ventricle
Left Marginal artery
-Supplies: lateral wall of left ventricle
Circumflex artery
-Supplies: posterior wall of heart
What are the major branches of the Right Coronary A. and what do they supply
Right Marginal artery
-Supplies: lateral wall of Right Ventricle
Posterior Descending artery
-Supplies: posterior and inferior portions of heart
What is the function of the cardiac veins
Drain O2 poor blood from heart tissue
what are the major veins (cardiac)
Great Cardiac Vein (L side)
Middle Cardiac Vein (posterior)
Small Cardiac Vein (R side)
Where do the major cardiac veins drain to
Coronary sinus
What is the function of the Coronary Sinus
collects O2 poor blood from above and empties into right atrium
How can a coronary blockage occur
cholesterol and fatty deposits (plaques) build up in artery
What can result from coronary blockage
Infarction
Define Infarction
Necrosis (tissue death) due to insufficient blood flow
What is a Myocardial Infarction
“Heart Attack”
-Necrosis of myocardium due to one or more coronary blockage
*fixed with CABG (Coronary Artery Bypass Graft) surgery
what is a “widowmaker” and why is it dubbed this
Blockage of left anterior descending artery
-So serious bc this artery supplies the L ventricle, and if blood cannot get here, it cannot get to the aorta to be pumped to the brain and rest of the body
What makes cardiac muscle unique
-It is branched and networked
-joined by intercalated discs
-there is a high level of communication between cardiac myocytes
*this allows for coordinated contraction of cardiac muscle tissue
What is cardiac syncytium
arrangement of cardiac myocytes to form an interconnected mass
When one cell becomes excited, all cells become excited and heart can contract as one unit
“All or nothing” principle
What are the two types of Syncytia in the heart
Atrial syncytium: coordinated contraction of both Atria
Ventricular syncytium: coordinated contraction of both Ventricles
What are the types of Cardiac myocytes
Contractile Cells
Autorhythmic Cells
what is Autorhythmicity
ability to spontaneously generate action potentials without external nervous system influence
Describe the relationship between the different cardiac myocytes
Autorhythmic cells produce action potentials which causes the spread of action potentials through contractile cells
Where are autorhythmic cells located
near top of Right Atrium
Describe autorhythmic myocytes
autorhythmic cells that fire at their own intrinsic rates
what is the most important autorhythmic myocyte
Sinoatrial (SA) node
*located at top of R atrium
what are the other autorhythmic myocytes
-Atrioventricular (AV) node
-Bundle of His
*split into: Bundle Branches
-Purkinje fibers
(Run up sides of Ventricles, cause them to contract)
Why is the Sinoatrial (SA) node so important
Called the “Pacemaker”
-spontaneously generates APs at regular intervals (~70 BPM)
Medical intervention needed:
*If SA node not functioning: AV node beats at 50 BPM
*If AV node not functioning: Purkinje fibers beat at ~15-30 BPM
List the specific sequence of the spread of excitation in Autorhythmic myocytes
- SA node: signal spreads across atria (0.4s), atria contract
- AV node: signal delay (0.11s), allows atria to fully empty
- Purkinje fibers: signal reaches ventricles (0.08s), ventricles contract
Describe process of cardiac muscle excitation-contraction coupling
-Action Potential from adjacent cell opens voltage-gated Ca++ channels
-Ca++ enters cell
-Induces Ca++ release from Sarcoplasmic Reticulum
-Ca++ binds to troponin = muscle contraction!
What makes Action Potentials in Contractile myocytes unique
-Long refractory period compared to skeletal muscle
*this prevents tetanus (We want repeated contraction, NOT long periods of constant contraction in heart –this is deadly)
what is the resting membrane potential in skeletal muscle fibers and contractile cardiac myocytes
-90 mV
REVIEW GRAPH OF AP FOR A CONTRACTILE CARDIAC MYOCYTE
What are the phases of an AP for a contractile cardiac myocyte
Phase 0=depolarization
-Fast Na+ channels open
*Na+ rushes into cell
-At ~-40mV, L-type Ca++ channels open
*slow and steady Ca++ influx (into cell)
Phase 1=Early Repolarization
-some K+ channels open
*some K+ comes out of cell
Phase 2=Plateau
-More L-type Ca++ channels open
*allows Ca++ into cell
-Also at same time more K+ channels open
*K+ moves out of cell
——-creates plateau (counterbalance of Ca++ in and K+ out)
Phase 3=Repolarization
-Ca++ channels close
-K+ channels still open
*still getting K+ out
Phase 4=Resting Membrane Potential
-All channels are closed
-back to RMP of -90mV
what is “pacemaker potential”
Phase 1 of AP in autorhythmic myocytes
-slow positive increase of ‘RMP’ between APs
-Keeps autorhythmic cells READY to fire at a moment’s notice
what are the 3 causes of pacemaker potential
- Increased influx of Na+
-“funny” channels open in response to hyperpolarization
-Allow Na+ into cell, pushes up voltage - Decreased efflux of K+
-K+ channels close during hyperpolarization of AP, limiting K+ leaving the cell, pushes up voltage - Differential influx of Ca++
-some Ca++ channels open before threshold, pushes voltage to threshold
-once threshold is reached, L-type Ca++ channels open, producing AP
REVIEW GRAPH OF AP FOR AN AUTORHYTHMIC CARDIAC MYOCYTE
what are the phases of an AP for an autorhythmic cardiac myocyte
Phase 1=Pacemaker Potential
-In hyperpolarized state, “funny” channels open
*Allows Na+ into cell
-As we approach threshold, some Ca++ channels open
*Ca++ into cell
——pushes cell to threshold
Phase 2=Depolarization
-L-type Ca++ channels open
*more Ca++ into cell
Phase 3=Repolarization
-Ca++ channels close
-K+ channels open
*K+ moves out of cell
Why are autorhythmic myocytes never truly at rest
As soon as we hit -60mV, pacemaker potential occurs automatically, which triggers rest of AP
What is an electrocardiogram (EKG or ECG)
Record of *electrical activity of the heart
(Repolarization and depolarization)
-Electrical events correlate with physical activity
what are the different parts of an EKG
P wave
QRS Complex
T wave
what *electrical and =physical activity is recorded during the P wave of an EKG
*Depolarization of atria
=onset of atrial contraction
what *electrical and =physical activity is recorded during the QRS complex of an EKG
*Depolarization of ventricles
=onset of ventricular contraction
what *electrical and =physical activity is recorded during the T wave of an EKG
*Repolarization of Ventricles
=onset of ventricular relaxation
How to interpret EKG
-Are all waves present & normal
Ex. QRS for every P
If not: heart block-APs from SA node blocked from reaching ventricles (looks like P waves w/o QRS complex)
Ex. Long QT Syndrome
Lengthy QT interval, affects repolarization of heart
(Causes seizures, fainting, etc.)
What is Tachycardia
high heart rate
>100BPM
What is Bradycardia
Low heart rate
<60BPM
When is heart rate measured to obtain the most accurate value
when resting, not active
what is fibrillation sometimes called
“Quiver”
what is Atrial Fibrillation (A-fib)
irregular contractions atria
*irregular spacing of QRS complex and no P waves on EKG
-A-fib is compatible with life and full activity
How to treat A-fib
Beta blockers
(block beta-adrenergic receptors to drop heart rate and re-establish SA node)
what is ventricular fibrillation (V-fib)
EMERGENCY! Results in cardiac arrest
-ventricular twitches instead of proper contractions
-loss of consciousness within seconds
how to treat v-fib
FATAL unless intermediate intervention occurs
(CPR and defibrillation)
What is a defibrillator
applies a strong electrical current that depolarizes most/entire heart at once
-gives SA node a chance to re-establish normal sinus rhythm
Describe the Cardiac cycle
Pattern of contraction and relaxation of heart chambers
-Initiated by spontaneous AP from SA node
What role do the atria play in the cardiac cycle
Primer pumps
-push blood into ventricles
what role to the ventricles play in the cardiac cycle
power pumps
-“force” blood into pulmonary and systemic circulation
Define diastole
Relaxation
-blood fills chamber
Define systole
contraction
-blood is pushed out of chamber
REVIEW CARDIAC CYCLE GRAPHIC
what are the steps of the cardiac cycles
- Passive filling of atria and ventricles
- atrial systoles
-blood forced into ventricles - ventricular systole
-a. isovolumetric contraction: ventricles contract, blood is not pushed out yet
-b. Ejection:
semilunar valves get pushed open and blood is pushed out of ventricles - ventricular diastole
-a. isovolumetric relaxation:
No blood filling ventricles yet
Go back to 1.
Describe the heart sounds
(“lub dup”)
1st sound-“lub”=AV valves closing
2nd sound-“dup”=SL valves closing
3rd sound-faint=Turbulent blood flow into ventricles
don’t always hear this one
what is systolic blood pressure
Ventricular contraction forces blood into aorta
-highest pressure in aorta
(120 mmHg pressure)
what is diastolic blood pressure
decrease in aortic pressure
-lowest pressure in aorta
(80 mmHg pressure)
Describe intrinsic regulation of the heart
Cardiac output (CO)
-amount of blood (volume) pumped per minute
Stroke volume (SV)
-volume of blood pumped per beat
Changes in heart rate (HR) & stroke volume (SV) = changes in cardiac output (CO)
Venous return
-flow of blood back to the heart
-can influence SV and CO
what is Starling’s law of the heart
stroke volume of left ventricle increases as volume of blood in left ventricle increases
-Due to preload (stretch) of cardiac muscle
-Greater preload=greater force of contraction
REVIEW SCENARIO WHERE STARLING’S LAW CAN BE PUT INTO PRACTICE
Describe extrinsic regulation of the heart from Sympathetic NS
Sympathetic nervous system
-project to heart as cardiac nerves
-nerves synapse at SA node, AV node, & ventricular myocardium
-secretion of Norepinephrine (NE)
*binds to adrenergic receptors
*increased influx of Ca++ into cardiac myocytes
-excitatory influence (Fight or Flight response)
Describe Extrinsic regulation of the heart from Parasympathetic NS
Parasympathetic Nervous System
-Vagus nerve
-synapses at SA node & AV node
-secretion of Acetylcholine (Ach)
*binds to muscarinic receptors
*increased number of K+ in open position, makes depolarization more difficult
-inhibitory influence (rest and digest)
What is Vagal tone
represents efficacy of Vagus nerve (parasympathetic) activity
High vagal tone=good
-resilience to stress, Heart rate can be lowered when needed
Low vagal tone=bad
-inability to “relax” the heart
what is Heart Rate Variability (HRV)
beat to beat variation in heart rate
High HRV=good
-lots of variability can accommodate a variety of situations
-good adaptability
Low HRV=bad
-associated with frequent stress
-less variation between beats, regularly high HR
*leads to pathology or even fatality
Describe arteries
Elastic blood vessels that have lots of smooth muscle
-empty into arterioles, which then empty into capillaries
what are capillaries
site of gas/nutrient/etc. exchange with tissues
what are veins
blood vessels that have thinner walls, less elastic, less smooth muscle
-receive blood from venules
Describe flow of blood between vessels
Heart -> arteries -> arterioles -> capillaries -> venules -> veins -> heart
what are the layers of blood vessels from superficial to deep
Tunica externa
Tunica media
Tunica intima
What is the function of the Tunica externa and what tissue is it composed of
Tissue: collagenous CT
Function: prevents the vessel from shifting position too much
What is the function of the Tunica media and what tissue is it composed of
Tissue: smooth muscle
Function: performs vasodilation and vasoconstriction (changes BP)
What is the function of the Tunica intima and what tissue is it composed of
Tissue: endothelium (simple squamous epithelium
Function: helps to regulate capillary exchange and blood flow
what are the different capillary types
Continuous capillaries
Fenestrated capillaries
Sinusoidal capillaries
Describe Continuous Capillaries
-very common in nearly all tissues
-tight junctions between endothelial cells
*allows for exchange of small molecules like H20, glucose, gasses, and certain hormones
Describe Fenestrated Capillaries
-Found in kidneys & small intestines
-Fenestrations (pores) allow the exchange of larger molecules like nutrients, waste products, & large hormones-peptide)
Describe Sinusoidal Capillaries
-Rare: found where cells & very large molecules need to be transported (spleen, bone marrow, liver, etc.)
-Contain extensive intercellular gaps
what are capillary networks
-final destination of arterial blood from heart
-exchange of materials between blood & other tissues
what are portal venous systems
-where capillary bed pools into another capillary bed
-linked by veins
How many portal systems exist in the human body
2 portal systems
What are the portal systems in the human body and what are their functions
Hepatic Portal system
-directs blood from GI tract to liver
Hypophyseal portal system
-carries hormones from hypothalamus to anterior pituitary
what are the regions of the aorta
Ascending aorta
Aortic arch
Descending aorta
-becomes thoracic aorta within thorax & abdominal aorta within abdomen
what are the branchings of the aorta from R to L
Brachiocephalic A.
*branches into R. Common Carotid A. & R. Subclavian A.
Left Common Carotid A.
Left Subclavian A.
what are the arteries of the head and neck
R & L Common Carotid Aa.
*branch into internal & external carotid Aa.
Circle of Willis-supplies most of blood flow to brain
*internal carotid Aa. and others
Basilar A.
*supplies posterior brain
what are the arteries of upper & lower limbs
Major pulse points: upper limbs
-Brachial artery
-Radial artery
Femoral artery
Veins of head and neck
internal and external jugular veins
Veins of upper and lower limbs
Median Cubital Vein
-common site for blood draws
Saphenous Veins
-often used for coronary artery bypass grafts (CABG)
which direction does blood flow in terms of pressure
high pressure to low pressure
Describe process of pressure and resistance
Driving pressure (where pressure is lower) from ventricles forces blood into vessels
Blood exerts pressure against walls of blood vessels, but vessels resist against blood flow
Resistance influenced by: Blood viscosity, vessel length, vessel radius
Ventricles have to exert enough force to overcome resistance in blood vessels
BP measures pressure against artery walls
What is systolic pressure
pressure of blood against artery walls during ventricular systole (average: 120 mmHg)
what it tells us:
force of contraction of heart
What is diastolic pressure
pressure of blood against artery walls during ventricular diastole (average: 80 mmHg)
what it tells us:
condition of systemic blood vessels
*reflects ability to store energy in elastic walls
Ex. increase in diastolic pressure = decrease in vessel elasticity
how is arterial blood pressure measured
Auscultatory method
-non-invasive method that uses Korotkoff sounds
what are Korotkoff sounds
sounds in vessels due to changes in blood flow from BP cuff
what measurements are derived from BP
pulse pressure
mean arterial pressure (MAP)
what is pulse pressure
systolic minus diastolic pressure
-represents force that heart generates with each contraction
*Normal: 40-60 mmHg
what is mean arterial pressure (MAP)
average pressure in the arteries during one cardiac cycle
*Normal: 70-100 mmHg
what is vascular compliance
how much a vessel is able to stretch
-more stretch=greater compliance
Compliant arteries=GOOD
-The more compliant an artery, the more blood flow it can accommodate w/o increasing BP and overtaxing cardiovascular system
Compliance decreases as we age
veins have thinner walls, so more compliant than arteries
what is critical closing pressure
pressure where vessel collapses if flow/pressure too low
what is shock
occurs from rapid drop in BP
-can cease blood flow
-some blood flow/force is needed to keep vessel open (if we drop below that, vessel can collapse)
-necrosis of tissues if supply lost for too long
what is an aneurysm
bulge in vessel
-Radius of vessel and pressure applied is higher here
-can cause vessel to rupture
How do veins return blood to heart
Active mechanisms of venous return-
*skeletal muscle pumps:
skeletal muscle contracts, presses on veins, squeezing blood back to heart
*gravity:
returns blood from upper body (head, neck, shoulders)
*respiratory pump:
pressure on thoracic cavity squeeze veins
*one-way valves:
prevent back flow
*smooth muscle:
squeezes blood back to heart