Unit One Flashcards
What is the supply and demand concept of the heart
Cells demand O2 and nutrients, the CV system supply blood to cells
Blood flow occurs when what exists
Change in pressure, one pressure exceeds the other
What does every cell need for survival
Oxygen, nutrients, removal of CO2 and metabolic waste, optimal temperature
Oxygen is needed by the cell for what
Aerobic respiration
Nutrients are needed by the cell for what
Energy, building blocks, etc
Carbon dioxide retention causes
Acidosis leading to confusion, come, arrhythmia, muscle weakness, GI disturbances
Urea and other metabolic wastes left in blood causes
Anorexia, lethary, decreased mental acuity and coma, nausea, vomiting, bone pain, itch, SOB, seizures and death
Why do our cells need optimal temperature
Function at a narrow temperature range
Can demands be met by just diffusion from the outside of the body
No, diffusion is too slow over large distances
It takes how long for O2 to diffuse 100 micrometers
5 seconds
How long for O2 to diffuse 1 cm
14 hours
Main purpose of the cardiovascular system
Provide a sufficiently fast mechanism of delivery and removal of gasses, nutrients, and wastes by blood flow
Diffusion is important at what levels of the body
Capillaries, interstitial fluid and cell membranes
What is a blood conditioner organ
Any organ that changes the composition of the blood for the benefit of the rest of the body
What organs are blood conditioner organs
Lungs, kidneys, GI tract and skin
What two things do all blood conditioner organs have in common
Blood flow in excess of their basic metabolic needs, can tolerate substantial drops in blood flow for a short period of time
What are some organs that are important but not blood conditioners
Brain, muscle and heart
What are the characteristics of brain, muscle and heart not being blood conditioners
Blood flow is regulated to be at or just above metabolic need, loss of blood flow to these organs has more dramatic effect
The systemic circuit goes from where to where
Left ventricle, body, right atrium
The pulmonary circuit goes from where to where
Right ventricle, lungs to left atrium
The systemic and pulmonary circuit are parallel or series
Series
Function of systemic circuit
Supplies many organs, trunk, head and limbs in parallel circulation
Is the systemic circuit parallel or series
Parallel
What are the three places within the systemic circuit that has serial blood supply
Liver, kidney and anterior pituitary
Advantage of parallel circuit
If something is blocked then there are other ways around to have area receive blood, simultaneous blood supply
What is the basic flow equation
= change in pressure/ resistance to flow
Basic flow equation AKA
Ohm’s law
Flow (volume per unit time) represented by what
Q
What is the equation for resistance
8Ln/(pi)r^4
What is cardiac output
Blood from the heart
Flow (Q) is also called
Cardiac output
Normal cardiac output is
5 L/min
What is the source of blood flow
Heart
What must the heart do in order for flow to occur
Arterial pressure greater than venous pressure
How does resistance of blood flow occur
Frictions,
What is the main determinant of resistance
Blood vessel radius especially in arteriole
Why is the blood vessel radius in arterioles the most important
Radius is regulated the most here
The left ventricle has an average pressure of what
100 mmHg
Radius changes within vessels due to
Smooth muscle, dilation and constriction
How does the venous system work with pressure and bringing blood to heart
Pressure still builds up but not greater than arterial pressure and veins contain valves
Because blood flows along the path of least resistance, organs with ???? Resistance receives the ???? Flow.
Low, most
Constriction in vessels cause
Diversion to another place
What are the requirements for effective heart function
Synchronized contraction of heart muscle, valves open fully, no leaky valves, contractions adequately strong, ventricles fill adequately
What are the parts of the left heart
Left atrium, bicuspid/ mitral valve, left ventricle and aortic valve, pulmonary veins
Function of left heart
Receives blood from lungs and pumps blood to body
Parts of the right heart
IVC, SVC, coronary sinus, right atrium, tricuspid valve, right ventricle, pulmonary valve
Functions of the right heart
Receives blood from the body, pumps blood to the lungs
Describe cardiac cells
Single centrally located nucleus, branched fibers, striated, intercalated discs
What connects the adjacent cells in the cardiac muscle
Gap junctions
Gap junctions form what between cells
Electrical synapses
Atrial and ventricular syncytia are separated by what
Fibrous septum
The fibrous septum surrounds what
Openings of the two AV valves.
What are not propagated through the fibrous septum
Action potentials
Aka of hyperpolarization
Undershoot
Is a stimulus needed for cardiac cells to have an AP
No
Cardiac muscle cells exhibit what two properties
Automaticity and rhythmicity
What is automaticity
Cells generate their own action potentials without external stimuli from nerves or chemicals
What is rhythmicity
Action potentials repeat at regular intervals
What cardiac muscle tissue has the fastest inherent firing rate
SA node
SA node AKA
Pacemaker
SA node connects with conduction system and what to control the rate of the whole heart
Intercalated discs
SA node embedded where
Wall of RA
Conduction system is made of
Specialized cardiac muscle cells
Amount of actin and myosin in the conduction system
Very little and contracts very weakly
Conduction system coordinates what
Timing of atrial and ventricular contractions
Communication between the atria and ventricles is done through
Bundle of His
Function of internodal tract
Spread AP to AV node, spread AP into both atria, help to spread AP throughout cells
What does the signal move slowly through AV node
Allow for ventricle to fill with blood
How many phases of the heart
Phase 0 through 4
What is phase 0 aka
Depolarization
What occurs during phase 0
Opening of fast V gated Na+ channels
Aka of phase 1
Initial spike
What occurs during phase 1
V gated Na+ channels inactive
Phase 2 aka
Plateau
What occurs during phase 2
V gated slow Ca2+ channels open and decrease in K+ permeability also occurs
Phase 3 aka
Repolarization
What occurs during phase 3
V gated Ca2+ channels close and V gated K+ channels open
Aka of phase 4
Resting membrane potential
What occurs during phase 4
Active transport of Na+, K+ and Ca2+
Describe the SR of cardiac cells
Not well developed
Describe T tubules of cardiac cells
5x bigger in diameter
Cardiac cells greatly depend on what for initiation and strength of contraction
Extracellular Ca2+ for initiation and strength of contraction
Relaxation of heart requires what
Pumping Ca2+ back into SR and out of the cell
The duration of cardiac contraction is about equal to
Duration of the cardiac action potential
Why is the cardiac contraction equal to duration of AP
Want the contraction long enough to empty atrium or ventricle, helps to not spend extra energy
Definition of cardiac cycle
All events occurring in the heart from the beginning of one heart beat to the beginning of the next
Definition of pressure
The magnitude of the force F exerted by a fluid on the surface, divided by the surface area A
Fluid moves from an area of
High pressure to an area of low pressure
The chambers of the heart alternate between periods of
Systole and diastole
Systole aka
Contraction
Purpose of systole
Generate pressure to perform the work of moving blood
Diastole aka
Relaxation
Purpose of diastole
Release pressure so that the heart chamber can fill with blood
The cardiac cycle components relating to pressure changes are recorded from the
Left atrium and ventricle
The right cardiac cycle looks essentially the same, except the pressures are about what compared to the left
1/6
What are the primer pumps
Atria
How much of the blood in the atria moves to the ventricles before atrial systole
80%
How much of the blood moves to the ventricles from the atria during atrial systole
20%
What happens if the atria fail to function
Lower cardiac output, clot formation
When atria contract what relaxes
Ventricles
What are the three atrial pressure curves
A, C and V curve
What occurs during the A curve
Increase in pressure due to contraction (atrial systole)
What occurs during the C curve
Fluctuation in pressure due to AV valve closure
What occurs during the V curve
Increase in pressure as atrium fills
What happens to pressure in ventricle during diastole
Decreases
What occurs during isovolumic relaxation
Pressure in ventricle decreases, valve can now close, diastole
Ventricle diastole has how many phases
Three, early, middle and late
What occurs to ventricle during early diastole
Blood enters ventricle, rapid inflow
What occurs to ventricle during middle diastole
Diastasis, reduced inflow
What occurs to ventricle during late diastole
Last 20% of blood comes in, atrial systole
What is isovolumic contraction
Pressure in ventricle not greater than pressure on other side of valve
Ventricular systole has how many phases
2, early and late
What occurs in ventricle during early systole
Rapid ejection
What occurs to ventricle during late systole
Reduced ejection
Does end systole in ventricle completely empty all blood
No