Quiz 3 Flashcards
Cardiovascular Basic Principles
- in very small organisms (or very porous organisms), vital substances are exchanged through diffusion
- larger animals need circulatory systems to move fluid from its surface to its deepest parts
- two important parts:
- a space for fluid to move in
- pumping mechanism to distribute fluid
- cardiovascular systems are a subtype circulatory systems composed of:
- heart
- blood vessels *blood
bulk flow
- a pressure gradient causes a liquid or gas to move from one compartment to another, if there is a path for movement
- works for mixtures of substances in a fluid
- high hydrostatic pressure to low
- substances in the fluid usually move with it
- ex. blood, air in lungs, stomach contents, urine
flow equation
- flow (of volume)= ease of movement x driving force
- dv/dt= pir^4/8nl * (P2-P1)
- ease of movement and driving force control rate bulk flow (fluid flow)
- ease of movement- characteristic of the size of container (wider=more flow, longer= less flow)
special circulatory systems
- animals evolved a pumping mechanism to circulate fluid and vital substances within the body
- allowed animals to become much larger and less porous since diffusion wasnt limiting exchange
- circulatory fluid:
- one fluid: hemolymph (interstitial fluid)
- two fluids: blood and lymph
Porifera- no special circulatory system
- sponges
- can be large bc they have pores!
- water moves through the holes
- each of the cells are not that far away from the surface
- water in the ocean is essentially their circulatory system
mollusks: special circulatory system
- heart (pumping mechanism
- hemocoel- space for fluid to move around in
- one fluid: hemolymph
- some blood vessels that move into the space between cells
open vs. closed circulatory system
- two types of circulatory systems
- closed- fluid moves through vessels (tubes)
- open- fluid moves through vessels and through body cavities (hemocoel in mollusk)
- circulatory fluids can move faster in vessels because of higher pressure
- higher driving force= more efficient exchange of vital substances
open circulatory system
- hemolymph circulates in space called hemocoel, bathes all the cells in the body
- most invertebrates
- have blood vessels
- pressure: low
- rate of O2 exchange: low
closed circulatory system
- blood/lymph circulate in vessels; fluid is exchanged with cells only at capillaries
- vertebrates, cephalopods, annelids (5 hearts)
- pressure: high
- rate of O2 exchange: high
open and tracheal circulatory system
- 2 separate systems- closed system for gases (tracheal)
- circulatory system not used for gas exchange; a separate system of airways exchanges gasses
- insects
- pressure: low
- rate of O2 exchange: high
components of circulatory fluid
- one fluid: hemolymph (interstitial fluid (mollusks))
- two fluids: blood and lymph (us)
- most important function of circulatory systems is to circulate fluid (& vital substances)
- vital substances: oxygen, CO2, ions, glucose, water, proteins, fats
- O2 and CO2 are carried by molecules called respiratory pigments
respiratory pigments
- carry O2 and CO2
- dissolved in hemolymph in most invertebrates
- increases the saturation point of plasma to O2 and CO2 which allows you to carry more
- found in blood cells in 3 groups of animals:
- red blood cells in vertebrates- hemoglobin (iron)
- pink blood cells in some annelids- hemerythrin (iron)
- blue blood cells inmollusks and arthropods- hemocyanin (copper- Cu)
blood
-composed of: RBC WBC Platelets Plasma -Flows through blood vessels -functions include: Supply vital substances to tissues and organs Remove waste Immune functions (WBCs) Coagulation (platelets) Transport substances Maintain homeostasis
Lymph
-composed of:
WCBs
Watery fluid (similar to interstitial fluid)
-flows through lymphatic system
-functions include:
-Removes excess interstitial fluid from tissues
-Absorbs and transports fats from digestive system
-Immune functions (bc of present WBC)
-lymphnodes become swollen when ur sick bc of excessive production of WBC
-Is derived from fluid that is pushed through small openings in capillary walls by pressure that originates primarily from the contraction of the heart’s ventricles
-Absorbs and transports fats from the intestines.
-Is returned to the cardiovascular system through ducts with one-way valves.
Path of blood in closed circulatory system
- left side of heart
- aorta
- arteries
- arterioles
- capillaries
- venules
- veins
- vena cava
- right side of heart
- pulmonary artery
- pulmonary capillaries
- pulmonary veins
systemic circulation to/from body
- aorta to arteries to arterioles to capillaries to venules to veins to vena cava
- brings blood to the body
- taking blood from the left side of the heart to all the tissues of your body and then returning it back to the right side
- gets deoxygenated
- higher pressure system
pulmonary circulation to/from lungs
- pulmonary artery to pulmonary capillaries to pulmonary vein
- brings blood to the lungs
- same vessels as in systemic circulation, but lower pressure overall compared to systemic circulation
- right side of heart to lungs and to the left side of the heart
- where is gets oxygenated
capillaries
- site of oxygen exchange
- all tissues in body have capillary beds
- blood is oxygenated until this step
- exchange of vital substances in blood
- transition
- super small but abundant
- wall is single layer of cells (allows for transport)
- holes called frenestrations
pressure in circulation
- pressure decreases as blood gets farther from heart
- venules/veins- low pressure
- arteries, arterioles- high pressure
artery
- thick layer of muscles (smooth muscle fibers)
- small lumen
- vasoconstrict and dilate bc of muscle
- regulate blood pressure
veins
- thin layers of smooth muscle
- large lumen
- some ability to vasoconstrict (not much)
- stretchy -> blood can pool
- valves- prevents back flow, minimizes pooling, defies gravity
vena cava
- superior vena cava- coming from arms and head
- inferior vena cava- brings blood from bottom half
- returns blood to right side of heart
pulmonary arteries and veins
- right side of the heart pumps blood to the pulmonary arteries
- pulmonary arteries pumps deoxygenated blood to lungs
- there are left and right pulmonary arteries and veins for left and right lung
- pulmonary veins bring oxygenated blood from the lungs to the left side of the heart
- exceptions
left side of heart
- higher pressure system
- more muscle tissue
- this is because the length of the vessels in systemic circulation are longer (compared to pulmonary circulation)
- ease of movement is reduced bc of length -> increased pressure (driving force)
rate of flow
- equal in pulmonary and systemic circulation
- otherwise we would have a back clog of blood
bulk flow of blood and lymph
in the capillaries…
- fluid moves from blood to interstitial fluid through bulk flow at capillaries
- fluid moves from interstitial fluid to lymphatics through bulk flow
- lymphatics empty back into blood circulation
- net loss of fluid in the capillaries -> that fluid is picked up by lymphatics and returned back to circulation
two pressures contribute to bulk flow out of capillaries
- hydrostatic pressure (Ph)- higher pressure in blood vessels compared to interstitial space pushes fluid out into interstitial space
- colloid osmotic pressure (pi)- higher protein concentration in plasma compared ot interstitial space draws water into capillaries
- if Ph > pi then net filtration (movement out of capillaries)
- if Ph < pi then net absorption (movement into capillaries)
anatomy of bulk flow in capillary
- on the arteriole end- Ph > pi -> net filtration
- as you let fluid out the driving force decreases and eventually Ph < pi; however gradient remains
- the point where Ph=pi is closer to venule side; therefore there is more filtration -> net loss of fluid (this is why we need lymphatic system to bring it back)
- closer to the venule side Ph < pi which means net absorption
electrical impulse
-originate
in the left atrium
vessels
- aorta
- vena cava
- pulmonary artery
- pulmonary vein
chambers
- left atrium
- left ventricle
- right atrium
- right ventricle
- septum
valves
- do not contain contractile tissue (they are just connected)
- these valves need to be pushed open from pressure gradients
- aortic semilunar
- pulmonary semilunar
- right AV/tricuspid
- left AV/bicuspid
directions
- apex- bottom, tip
- base- top
cardiac conducting system- action potentials
-SA node -> internodal pathways -> AV node -> AV bundle -> bundle branches -> purkinje fibers
coronary arteries and veins
- blood vessels that provide your heart with vital nutrients
- provides heart with its own blood supply
- heart doesnt use the blood it pumps
chordae tendineae
- heart strings
- holds the valves in place
- makes sure they dont fold backward
- prevents back flow
right AV valve
- tricuspid valve
- 3 valves
- right atrium to right ventricle
Pulmonary semilunar valve
-right ventricle to pulmonary artery
left AV valve
- bicuspid
- 2 flaps
- mitral valve
- left atrium to left ventricle
aortic semilunar valves
-left ventricle to aorta
autorhythmic/conducting cells
- specialized muscle cells that conduct action potentials through the heart
- generate the action potentials
- no neuron needed
- pacemaker properties
SA node
- sinoatrial node
- on top of the right atrium
- action potentials are initiated here
- spread the action potentials through the internodal pathways
- sets the rhythm for the entire heart (strongest and fastest autorhythmic)
- made up of a bunch of cardiac muscle cells (myocytes) -> autorhythmic myocardium
- depolarizes the fastest
- depolarization rate- 100 times per minute
interodal pathways
- where the action potentials are spread and travel from the SA node
- in the right atrium
- much faster when spreading to atrial muscle so it has the chance to contract before action potential is spread down to ventricles
AV node
- where the action potentials collect/gather
- located between the atria and the ventricles
- delay here bc action potentials are also being spread to atrial muscle in order to contract before action potential arrive here and goes to ventricles
- depolarization rate-40 times per minute
AV bundle and bundle branches
- action potentials spread/travel through this after collecting at the AV node
- along the septum
- av bundle- bundle of his
purkinje fibers
- spread the action potential into the contractile ventricles
- ventricles start contracting from the apex of the heart and up
- depolarization rate-25-40 times per minute
why does the heart contract from the bottom up
- the exit pathways for the ventricles is the aorta or the pulmonary arteries
- so it needs to squeeze blood upwards
what causes heart muscle contraction
- action potentials
- cardiac cycle is started by the excitation
what is the most direct results of heart muscle contraction
- blood pressure changes
- contraction generates pressure changes in the chambers
- pressure gradient allows valves to open and close and blood flow
order of steps in heart
action potentials -> muscle contraction -> pressure changes
relaxation of the heart
- lack of action potentials
- causes the pressure to be high in ventricle and low in atrium
- the blood does not flow with the pressure gradient bc of valves preventing back flow
cardiac muscle
-there a 2 types of cardiac muscle cells: myocytes or cardiac muscle tissue (myocardium)
autorhythmic myocardium
- action potentials are initiated here
- *generates the heartbeat rhythm
- pacemaker cells + conducting cells = cardiac conducting system
- primary purpose is not to contract
contractile myocardium
- contracts
- shorten
- increase the pressure in the heart
- bulk of heart muscle is contractile myocardium
autorhythmic myocardium in the SA node
- spontaneously depolarize in a set rhythm
- generate action potentials all by themselves
- heart can beat on its own
- action potentials spread through contractile myocardium through gap junctions -> contraction
- excites every cell in the heart eventually
structure of the contractile myocardium
- intercalated disks connect cardiac cells
- gap junctions transfer depolarization between cells
- NO neuromuscular junction; action potentials start in cardiac conducting system
cross bridges
- cardiac muscles still have cross bridges and sarcomeres
- contract just like skeletal muscle
- however, no nmj, nueron, chemical synapse
autorhythmic myocardium
- SA noded
- AV node
- Left and right purkinje fibers
- SA is the strongest and set the rhythm for the whole heart
- the other just reinforce
which contracts first
atrium then ventricles
-this is account for in the delay in action potential in the AV node
heart block
- disruptions in conduction lead to uncoordinated contractions
- AV node or purkinje fiber pacemaker properties apparent
- when there is a block somewhere along the path the highest bpm in the open path wins
SA node action potential- funny channels
- funny channels- spontaneously opening Na/K channels
- when open, they generate “funny current” If: *net influx of Na
- K deflux, but influx of Na is way more
- when open, they cause a gradual graded depolarization
- monovalent cation channel
- voltage gated: open when the cell is hyperpolarized (threshold)
- Ca channels open and rapid depolarization -> close at peak
resting membrane potential
does not exist in cardiac autorhythmic cells
- never at rest
- does exist in contractile cardiac muscle (very negative)
action potential steps in autorhythmic myocardium
- Net Na entry through funny channels
- voltage gated Ca channels reinforce and are responsible for the rapid depolarization
- at peak: the Ca channels close and K channels open
- rapid K efflux causes repolarization
- K channels close
- repolarization of -60 is when Na channels open (funny channels) -> repeat
Contractile cardiac muscle: action potentials (excitation)
- Depolarization via gap junctions opens voltage gated Na channels -> Na influx
- voltage gated Na channel inactivation gates close
- long plateau phase caused by Ca influx
- repolarization caused by K efflux (voltage gated K channels open)
- resting membrane potential = equilibrium potential for K= -90 (no hyperpolarization)
- 200 ms- very long (prevents tetanus)
why is resting membrane potential for contractile cardiac muscle so negative
- these cells are extremely permeable to K at rest
- resting membrane potential is equal to K equilibrium potential
- no hyperpolarization in these cells
why are contractile cardiac muscle action potentials so long
- its important for the refractory period to last as long as the muscle contraction
- action potential = muscle contraction period
- voltage gated sodium channel inactivation gates stay closed during plateau phase -> absolute refractory period
- they stay shut until they are reset to closed position at the end of the action potential (then they can be opened again
- protects the heart from tetanus
- cannot contract constantly
- maintains steady contraction and relaxation cycle
Calcium induced calcium release
- action potential travels down cell membrane
- voltage gated DHP activated
- *DHP is not mechanically gated to ryanadine receptors -> they are coupled however
- DHP receptors open and let a little bit of Ca through ad the RYR are *ligand gated receptors -> calcium binds and RYR opens -> releasing a whole lot of Ca into cytoplasm
calcium spark
increase in Ca in cytoplasm
relaxation phase
- ATP used to pump it back in to the sarcoplasmic reticulum
- *sodium calcium antiporter- secondary active transport (relys on concentration gradient thats made by Na K ATPase)- exchanges calcium for sodium
depolarization in contractile cardiac muscle
starts in cardiac conducting system
source of calcium ions
- skeletal muscle: SR
- contractile cardiac muscle: SR and interstitial fluid
events in order
action potential in autorhythmic cells in SA node -> excitation spreads through heart -> contractile cells are excited -> excitation contractile coupling sequence -> pressure changes -> blood flow
cardiac cycle
- atria contract before ventricles
- left atria and right ventricles contract at the same time
- bulk flow drives movement of blood (primarily Ph- hydrostatic pressure)
- diastole = relaxation; systole = contraction
- four phases:
1. isovolumetric relaxation
2. ventricular filling
3. isovolumetric contraction
4. ventricular ejection
ventricular diastole
- isovolumetric relaxation
- ventricular filling
- pressure is dropping
ventricular systole
- isovolumetric contraction
- ventricular ejection
- pressure rising in ventricle
isovolumetric relaxation
- both atrial and ventricular muscles are relaxing
- semilunar and AV valves are closed
- blood moving from veins into atria
- pressure in ventricles is dropping
- ventricular volume is constant
- ventricular muscle cells repolarize right before this phase
ventricular filling
- when pressure atrium > pressure in ventricle -> AV valve opens
- blood flows from atrium to ventricle
- near end of period, atrium depolarizes and atrial systole starts
- more blood moves into ventricle
- at end of period, ventricular volume at max
- EDV= end diastolic volume
- ventricular volume increase while pressure is the same
- Na entry through the funny channels causes the pacemaker potential of SA nodal cells to gradually become less negative until it reaches threshold
isovolumetric contraction
- ventricle starts to contract, increased pressure pushed the AV valves closed
- lub
- pressure in ventricles increases rapidly
- SL valves still closed
- nowhere for blood to go
- ventricular muscles cells depolarize at the start of this phase
ventricular ejection
- when pressure in ventricles > pressure in arteries -> SL valves open
- ventricle is still contracting, pressure in ventricles keeps rising
- blood moves into arteries
- ventricular volume is at minimum
- ESV= end systolic volume
- the cytosolic concentration of calcium in the contractile cells of the ventricle is the highest during this phase
transition to ventricular diastole
- ventricle relaxes (start of isovolumetric relaxation)
- pressure in ventricle rapidly decreases
- when pressure of ventricle < pressure in arteries -> SL valve closes
- dub
- and the cycle starts again
End Diastolic Volume (EDV)
- maximum amount of blood in ventricle before contraction
- at the end of ventricular filling
End systolic volume (ESV)
- minimum amount left in ventricle after contraction
- at the end of ejection
stroke volume (SV)
- amount of blood expelled in one contraction
ex. EDV-ESV=SV
right heart volumes=
left heart volumes
cardiac output=
- volume of blood pumped in one minute
- cardiac output= heart rate x stroke volume
heart rate=
-heart rate= number of cardiac cycle/minute
ms to minute
800ms -> .8 s -> .8/60
pulse pressure
systolic (systole, high) - diastolic (diastole, low) in arteries
-normal- 120/80 therefore pulse pressure is 40
pressure in arteries
- daistolic pressure increases in the arteries -> bc arteries are tube always exerting pressure
- systolic pressure decreases
mean arterial pressure
1/3 of pulse pressure + diastolic pressure
- 1/3 because heart spends more time in diastole than systole
- cardiac output x resistance
- cardiac output = (1/R) x mean arterial pressure
systolic pressure
-pressure in arteries at the end of systole
diastolic pressure
-pressure in arteries at end of diastole
resistance
- radius of blood vessels
- total peripheral resistance
- R=8nL/pir^4
- n=viscosity of blood
- L=total length of vessels
- r=total radius of vessels
is edema more likely to result from high mean arterial pressure or low
- high
- hydrostatic pressure and mean arterial pressure are direct relationship
- this means filtration
- swelling
an increase in end diastolic volume will not cause
- an increase in end systolic volume
- just bc one increases does not mean the other
- the heart works harder to pump more out
in a heart with an intact conduction system, the rate of SA node action potentials equal the rate of AV node action potentials
- true
- SA node sets rhythm for entire heart
- happens at the same rate
- delay doesnt disrupt this
- this will only change if there is a block
the rapid depolarization phase of cardiac action potentials is caused by Na influx in both autorhymthic and contractile cells
- false
- autorhythmic is depolarized by Ca influx
equilibrium potential for k
= membrane potential practically
the pressure inside the left ventricle exceeds the pressure in the aorta. Which is correct
- this means ventricles are in systole
- left ventricular volume is decreasing
- left AV valve is closed- prevents back flow must be closed
- the pressure in the ventricle is causing the blood to want to move out to aorta
two branches of the nervous system
- peripheral
- central
central nervous system
-your brain and spinal cord
peripheral nervous system
- sensory and motor (efferent) division
- efferent- go to muscles and glands (effectors)
effectors
-muscles and glands
Sensory division of PNS
-detects a signal from sensory receptors
-sensory receptors stimulate sensory neurons (afferents)
-signal is sent to central nervous system (brain or/and spinal cord)
-response is cordinated by efferent neurons (motor neurons)
-
efferent neurons
- can be autonomic neurons (involuntary) or somatic motor neurons (voluntary)
- somatic- skeletal
autonomic neurons
- sympathetic
- parasympathetic
- cardiac, smooth muscle, glands
- can slow or speed up heart rate but is not the cause of the heart beat*
neuron
individual cell
nerve
- bundles of neuron axons (mostly) in the PNS
- sensory nerves, motor nerves, mixed nerves
- ex. sciatic nerve- longest nerve, starts in lumbar spinal cord a goes down to foot (motor and sensory motor neurons)
tract
- bundles of neuron axons entirely in the CNS
- ex. corticospinal tract- from motor cortex (head) down to lumbar spinal cord
ganglion/ganglia
- clusters of neuron cell bodies in the PNS
- acts as mini integration centers
- outside the CNS
- similar to nucleus in CNS
- exception- basal ganglia (in CNS)
nucleus/nuclei
-clusters of neuron cell bodies in the CNS
Regions of CNS
- white matter- axons (due to myelin)
- grey matter- cell bodies/synapses (lack myelin)
axon hillock
- beginning of the axon where action potentials are generated
- this is where the voltage gated sodium channels are -> graded -> action potential
direction of action potential down a neuron
dendrites to axon terminal bouton
anatomy of sensory neurons
- cell body is half way down
- still travels from dendrites to axon terminal
interneurons of CNS
- lie entirely in the CNS
- diverse shapes and directions of action potentials
schwann cells and olidogendrocytes
- schwann cells- PNS
- olidgodendrocytes- CNS
- wrap around axon and form insulating myelin sheaths
- nodes of ranvier are gaps in insulation
satellite cells
- PNS
- nonmyelinated schwan cells
- support cells in the PNS
astrocytes
- CNS
- several subtypes
- multiple roles
- examples:
- wrap around capillary walls and provide a filter
- source of neural stem cells
- take up K, water, neurotransmitters
- secrete neurotrophic factors
- *help form blood-brain barrier- filtration system between the blood in the capillaries and the brain itself
- provide substrates for ATP production
microglia
- CNS
- specialized immune cells
- scavengers
ependymal cells
- CNS
- one source of neural stem cells
- form barriers in the CNS
- ex. barrier between compartments- barrier in the ventricles of the brain
- source of neural stem cells