Unit 4: Cardiovascular System (Part 1) Flashcards
What is the general problem with being multicellular?
you are very big!
What are some characteristics of multicellular organisms
- very large in size
- outer layer interacts with the environment
- requires oxygen and nutrients from the environment because we cannot generate them ourselves
- rate of diffusion of oxygen and nutrients is limited by distance
What is the solution of diffusion limitation in multicellular organisms
- cardiovascular system for substance transport in body
- transported by blood flow throughout the body
- bulk flow rather than diffusion***
What materials are transported from the external environment to tissues
nutrients, water, and gases
What materials are transported between tissues of the body
wastes, nutrients, and hormones
What materials are transported from body to the external environment
metabolic wastes, gases, and heat
What’re the components of the cardiovascular system
- heart: the pump of the system
- blood vessels: the vasculature (figure 15.3)
- blood cells and plasma: the fluid (figure 16.3)
Where are the blood vessels attached to the heart
the base of the heart
What is the apex of the heart
the pointy inferior end of the heart
What can be compared to the heart when discussing shape
an ice cream cone
- the base is where the important components are attached (like ice cream on the base of a cone)
- the apex is the pointy inferior end (like the pointy end of the cone)
What are the components of the blood?
~ 42% red blood cells (most dense)
<1% white blood cells (medium density)
~58% plasma (least dense)
What is another term for the region not containing erythrocytes
the Buffy coat
What components are found in the Buffy coat
platelets and white blood cells (neutrophils, basophils, eosinophils, lymphocytes, monocytes, etc.)
What are erythrocytes
red blood cells
What are leukocytes
white blood cells
What does the pneumonic NLMEB mean
“never let monkeys eat bananas” - the types of leukocytes
- neutrophils, lymphocytes, monocytes, eosinophils, basophils
What is the pericardium
the tough membraneous sac surrounding the heart
- made up of two layers with a small amount of fluid between them that acts as a lubricant (called pericardial fluid)
What are coronary arteries
supply oxygenated blood to the heart
- the heart has a very high oxygen demand; depends on adequate blood flow
- lack of blood supply to the heart results in a heart attack (myocardial infarction)
Describe the components of the internal anatomy of the heart and how blood travels throughout each part of the system
Left atrium: receives oxygenated blood from pulmonary veins, and sends it to the left ventricle
Left ventricle: receives blood from the left atrium, and sends blood to the body via the aorta
Right atrium: receives deoxygenated blood from the venae cavae (plural vena cava since we have 2), and sends it to the right ventricle
Right ventricle: receives blood from the right atrium, and sends it to the lungs
Valves: ensure blood flow is unidirectional (eg. atrioventricular (AV) valves, and semilunar valves)
(review figure 14.5 - note: the right pulmonary veins are not shown in this figure, but remember they are there!)
(review figure 14.1)
Draw/recall the pathway of blood through the heart!
include atrium(s), ventricle(s), valve(s), etc. and review figures 14.1 & 14.5 for clarification
What is the pulmonary circuit
blood flows from heart to the lungs for oxygen
What are the two types of AV valve
tricuspid (right side) and biscuspid (mitral) (left side)
(figure 4.3)
What are the two types of semilunar valve
aortic and pulmonary (figure 4.3)
The base of the heart is….
a. found at the bottom of the heart
b. found at the top of the heart
c. where major vessels attach
d. a and c
e. b and c
*in class review question
e. found at the top of the heart, and where the major vessels attach
Which type of valve DOES require cords for support
AV valves - chordae tendinae
(semilunar do not due to their shape)
*review figure 4.3 course notes
What are the two paths of blood flow through the body
pulmonary circuit and systemic circuit
(review figure 4.4 course notes)
When the ventricle contracts, the AV valves are ________, and the semilunar valves are __________
closed, open
What is the purpose of the chordae tendinae
prevents valves from being pushed back into atrium
When the ventricle is relaxed, the AV valves are ________, and the semilunar valves are ________
open, closed
What is the pulmonary circuit consisting of
blood vessels in the lungs and those that connect lungs to the heart
What is the path of the pulmonary circuit
- blood flows from right atrium to right ventricle; which is then pumped to pulmonary arteries in the lungs
- lungs have many small capillaries to increase oxygen transfer (increased resistance = decreased pressure of blood)
- oxygenated blood has low pressure; needs to return to heart via the pulmonary veins to left atrium
(review figure 14.1)
What is the aftermath capability of the pulmonary circuit
breathing
What does the systemic circuit involve
the remaining organs in the body (aside from lungs in pulmonary circuit)
What is the path of the systemic circuit
- blood flows from left atrium to left ventricle; which is then pumped to aorta, pumped to arteries, and pumped to capillary networks throughout the body
- oxygen diffuses from the blood into capillary networks, then flows to venues and larger veins
- oxygen-poor blood has low pressure; needs to return to heart through superior and inferior vena cavas and to the heart
(review figure 14.1)
What increases the pressure of blood in critical points of the double circuit
the heart
(review figure 15.1)
Arteries carry blood _________ the heart
away (think a-artieries = a-away)
Veins carry blood ___________ the heart
towards
How’s the heart different from other muscles in relation to the nervous system
the heart does not need signalling from the nervous system to contract
What specialized cells are found in the heart and what do they do
auto rhythmic cells (pacemaker cells)
- generate action potentials to create contraction without help from the nervous system
Where are pacemaker/autorhythmic cells found
the SA node (sinoatrial node), in the right atrium near the superior vena cava
(figure 14.15 *in purple)
Pacemaker cells have _____________ ___________ ____________
unstable membrane potential
What are unstable membrane potentials
slow potential that drifts upwards from -60mV until it reaches threshold and initiates action potential
(review figure 14.14)
Why are unstable membrane potentials different
have different membrane channels than other excitable cells - special I(f) channels (I stands for current, f stands for funny)
What are I(f) channels permeable to
Na+ and K+
What happens when membrane potential is negative in pacemaker cells
Na+ influx and K+ efflux, therefore slow depolarization of the cell with the increase in +ve charge
What happens when membrane potential is positive in pacemaker cells
I(f) channels close and Ca2+ channels open
- continued depolarization, threshold reached, many Ca2+ channels open, which creates the rapid depolarization stage of action potential
- at the end of depolarization, the Ca2+ channels close and K+ channels open, causing repolarization
What is a major difference between action potentials and pacemaker potentials in pacemaker cells
*in class knowledge testing question
Na+ and Ca2+ influx for pacemaker potential
only Ca2+ for action potential
What modulates the rate of the pacemaker potentials
autonomic division
What components of the autonomic system modulate the rate of the pacemaker potentials
norepinephrine, epinephrine, and acetylcholine
How do epinephrine and norepinephrine modulate the pacemaker potentials
*this is important
NE released from sympathetic neurons, E released from adrenal medulla: bind to B1 adrenergic receptors
- increase in cAMP which binds to I(f) channels; channels now stay open longer, which increases the permeability of Na+ and Ca2+
- increased depolarization increases rate of action potentials, increasing heart rate
(review figure 14.20)
How does acetylcholine modulate the pacemaker potentials
*this is important
released by parasympathetic neurons: bind to muscarinic receptors
- increases K+ permeability which hyper polarizes the cell, pacemaker potentials start at a more negative value therefore takes longer to reach threshold, decreasing heart rate
Depolarization spreads to neighbouring cells via _____ _________ in the ________________ _________
gap junctions, in the intercalated discs
What are intercalated discs
the membranes that separate cardiac muscle cells and allow electrical impulses to spread - type of gap junction!
Pacemaker/autorhythmic cells initiate the __________ _____________ of the heart
electrical excitation
Explain the conducting system of the heart
- this is important*
- action potential fired from SA node moves to adjacent cells
- rapid spread through cell of internal pathway (spread is slower through contractile cells of atrium)
- signal is passed through AV node ONLY at AV junction; a layer of fibrous connective tissue acts as insulator prevents electrical signals from atrium to ventricle; signal is slightly delayed to ensure atria is done contracting
- signal is carried to the bottom of heart (the apex: think pointy part of the cone) via bundle of his
- bundle of his divides into left and right branches; purkinje fibres transmit signals VERY rapidly to ensure all contractile cells at the apex contract together
(review figure 14.15)
What are the fastest cells to depolarize to threshold
the cells found in the SA node
Does the action potential fired from SA node stay refined to the SA node?
no, it spreads to neighbouring cells
Why is spread of action potential slower in contractile cells of the atrium?
contractile muscles have lots of protein (think actin and myosin contents of muscles, they are proteins) - which is harder for electrical impulses to fire through
What is the only pathway for action potential?
the AV node
Why is it important to conduct signals ONLY through the AV node and bundle of his?
*in class knowledge testing question
this is important
- want signal for contraction to start at bottom of the heart
- ensures the contraction drives the blood up since exits the heart at the top
List the general sequence of the action potential pathway in the heart
SA node; internodal pathway; AV node; bundle of his; bundle branches; purkinje fibres
Which of the following are AV valves
a. bicuspid
b. tricuspid
c. mitral
d. a and b
e. all of the above
*In class review question
e. all of the above
What is an ECG
electrocardiogram
How does an ECG work
records the electrical activity of the heart at the surface of the skin using electrodes
(key: on the skin surface, not internally)
What exactly does the ECG measure
the voltage differentials occurring during the cardiac cycle (single contraction-relaxation of the mechanical events)
ECGs originally used three leads to make up ________ _________
Einthoven’s Triangle
Nowadays, how many leads do ECGs use
12
What are the two components. of ECGs
waves and segments
What are the characteristics of waves on an ECG reading
deflections above or below the baseline representing electrical events
What are the 3 main wave types on an ECG
P wave
QRS complex
T wave
What is the P wave
depolarization of atria
(first wave above the baseline)
What is the QRS complex
ventricular depolarization
(complex in the middle of the baseline)
visually:
- Q is the slight repolarization below baseline
- R is the surge above the baseline
- S is the slight repolarization again below the baseline
(think to the drawn tracing of an ECG)
location of each wave:
Q wave: signal travels down bundle of his
R wave: signal travels through bundle branches
S wave: signal travels through purkinje fibres
What is the T wave
repolarization of ventricles
(last wave above the baseline)
What happens once T wave occurs
SA node fires again, creating another P wave and repeating the cycle
Where is atrial repolarization if there is no representative wave?
occurs after atrial depolarization, which is masked by the QRS complex
What are the characteristics of segments on an ECG reading
sections of baseline between two waves that represent the mechanical events (lag between electrical events)
What are the 2 main segment types on an ECG
P-R segment
S-T segment
What is the P-R segment
atrial contraction
(between P wave and QRS)
What is the S-T segment
ventricular contraction
(after the QRS, before T wave)
What is the physical makeup of Eithovens Triangle
2 electrodes attached to each arm, as well as on one leg, to form a triangle configuration when looking at the body
- each lead (pair of electrodes) has a positive end and a negative end
What is the purpose of Eithovens Triangle for an ECG
each lead provides an angle for the ECG, which are recorded one at a time
(think about looking at a new car, each angle you look at the car would be considered a new “lead”, you can see different aspects from different angles so it is important to have multiple perspectives - think to in class comparison*)
A vector that travels toward the positive end of an electrode causes the ECG to go _____
up
A vector that travels toward the negative end of an electrode causes the ECG to go _______
down
If you see a straight baseline, what does that mean about the vector travelling
it is travelling perpendicular to the electrode, causing no up or down in ECG tracing
What is considered the heart rate across the span of the ECG
P wave to P wave
Draw out the 3 waves and 2 segments together to form the “ideal” ECG formation
*this is an important concept to know
What is the scale for an ECG
flatline is at 0mV, waves occur between -1mV and +1mV (think back to the drawn tracing of the ECG pattern)
What are the two phases of the cardiac cycle
systole: contraction
diastole: relaxation
What are the 5 stages of the heart cycle in relation to systole and diastole
late diastole; atrial systole; isovolumic ventricular contraction; ventriclar ejection; isovolumic ventricular relaxation (then repeat)
(review figure 14.18**important*)
What occurs in late diastole
both sets of chambers are relaxed (therefore the entire heart is in relaxation state)
- semilunar valves closed, AV valves open, blood enters ventricles passively*
What occurs in atrial diastole
atria contract but the ventricles remain relaxed
- semilunar valves closed, AV valves open, small amounts of blood enter ventricles (this small amount tops up the ventricular filling as a result of the contraction of atria)
What occurs in isovolumic ventricular contraction
ventricles contract
- semilunar and AV valves all closed (has enough force to shut the AV valves but still not enough pressure to open the semilunar valves yet)
What occurs in ventricular ejection
semilunar valves open and AV valves remain closed (now that ventricular pressure is enough, and exceeds pressure in the arteries, the semilunar valves can open and release the blood)
- blood is ejected (think about the name of this stage)
What occurs in isovolumic ventricular relaxation
semilunar valves closed, and AV valves closed
(as ventricles relax, pressure in ventricles decreases, so blood is able to flow back into the cusps of the semilunar valves and force them shut)
(late diastole repeats after this step)
What are the two main sounds heard from the heart
“lub” and “dub”
What does the “lub” sound indicate
closing of AV valves (step 3 in the cardiac cycle - isovolumic ventricular contraction)
What does the “dub” sound indicate
closing of semilunar valves (step 5 in the cardiac cycle - isovolumic ventricular relaxation)
Liquid and gases flow from ________ areas of pressure to ________ areas of pressure
higher to lower
As the heart contracts, the pressure increases, therefore blood ___________ the heart to __________ the pressure
leaves to lower pressure
What is End Diastolic Volume (EDV)
*don’t memorize the short form here, know the full name
maximum volume in the ventricles (maximum pressure - end of ventricular filling)
What is End Systolic Volume (ESV)
*don’t memorize the short form here, know the full name
minimum volume in the ventricles (minimal pressure - end of ventricular contraction)
*Review figure 14.18 front to back and understand the concepts covered!
this is important conceptually
*Review the photo taken from lecture covering the pressure volume relationship graph
this is important conceptually
Between point A to A* on the pressure-volume relationship graph, what is occurring
low pressure in late diastole at point A, volume increases without a change in pressure over to A*
At point B on the pressure-volume relationship graph, what is occurring
SA node initiates atrial contraction, forcing a slight amount of extra blood; point of EDV
Between point B and C on the pressure-volume relationship graph, what is occurring
isovolumic ventricular contraction
Between point C and D on the pressure-volume relationship graph, what is occurring
ventricular ejection; ESV at point D
