circulatory system Flashcards
Circulatory Systems: functions
Transporting
Thermoregulation
Communication between cells and organs
Communication between individuals
Circulatory Systems: functions
Transporting
Transporting things around the body
Nutrients
Waste
Gases
Metabolic products
Things that need to be regulated
Thermoregulation
Conserve heat or generate heat
Heat can be redistributed to different parts of an organism by constricting or dilating vessels
Smooth muscle is key to regulating this
Constricting or dilating vessels
Communication between cells and organs
Signaling Via hormones
Communication between individuals
Think of blushing
Why do we need a circulatory system
Bigger organisms need to ensure cells deep in the body get an adequate supply of oxygen, nutrient and so on, and that wastes don’t build up
Lot of calories stored through glycogen need to be distributed
Two types of circulatory systems
Open circulatory system -> arthropods and non-vertebrates
Closed circulatory system
Open circulatory system
Pulls in hemolymph and dumps it back into empty space
Interstitial fluid is being brought into heart and squished back out
Heart moves extracellular fluid through vessels
Fluid (hemolymph) leaves vessels and filters through tissues as interstitial fluid
The fluid in the circulatory system and the interstitial fluid are essentially the same
Fluid returns to the heart through the pores called ostia
Valves ensure directional flow
Closed circulatory system
Have distinct blood compartment that is distinct from interstitial fluid
Blood is separated from interstitial fluid
Exchange occurs with interstitial fluid at capillaries
Blood is pumped through vascular systems
One or more hearts
Flow of blood regulated by varying diameter of vessels
Specialized blood cells
In a single circulation, like with a fish, blood leaving the heart goes to
closed circulatory system
the gills
Blood is propelled through the artery via atrium and ventricle and bring it to the gills where there is an exchange of gasses that are dissolved in the water
CO2 is excreted and oxygen is gathered at gill capillaries
Blood goes back into the artery and to the body capillaries
Where oxygenated blood is distributed
Amphibians circulatory system -> frog
Blood leaves central ventricle and instead passing through lung and skin it re-enters the heart and gets pumped around again
Don’t have two capillaries in a row it is separated into two systems
Gills increase surface area for gas exchange
Oxygenated and deoxygenated blood kind of mix together
one ventricle where oxygenated and deoxygenated blood can interact
Human/mammalian circulatory system
have Two complete circulatory systems
what do the blue veins indicate
- deoxygenated blood
- Blood that is returning from various parts of your body that have been depleted of oxygen for oxidative phosphorylation
how does the circulatory system work for mammals
- Enter the right side of the heart in the chamber called atrium
- Goes into a ventricle
- Leaves the right ventricle and splits left and right
- Right Half goes to the left lung, gets oxygenated and returns to the left side of the heart entering another atrium into a ventricle and out the ventricle into a big artery called the aorta and back to give blood to the upper and lower body
human heart composition
Contain 4 chambers
2 atria and 2 ventricles
Atria
chambers that fill up with returning(venus) blood; hold it and contract a little bit and send blood into the ventricle
Ventricles - right and left
Right ventricle pumps blood through the pulmonary circuit → lungs
Goes to lungs and comes back
Left Ventricle pumps blood through the systemic circuit
Through the aorta
Sends blood to your entire body
what do ventricles do
pump blood
why is the left ventricle’s walls thicker
more pressure required to pump more blood through systemic circuit
What is generating the force that pushes the blood through your body?
The contraction of muscle cells in your heart
Pumping of heart muscle
what heart valves exist
Atrioventricular valves
Pulmonary valve and aortic valves (semilunar)
Atrioventricular valves
Between atria and ventricles prevent backflow when ventricles contract
Blood enters into atria through big veins then into the ventricle then out of the ventricle through the pulmonary artery and to your lungs
Valves ensure that during this process blood flows in one direction only
Close up to prevent backflow from ventricles to atrium
Right - tricuspid
Cusp is how many flaps it has
Left - bicuspid
Pulmonary valve and aortic valves (semilunar)
Between ventricles and major arteries
Prevent backflow (into the ventricles from the arterial system) when ventricles relax
Tricuspid
Valves ensure blood flows through the heart in one direction only
which direction is this
Out the heart
Flow of blood goes from high pressure to low pressure
Pressure is the Squeezing of blood that the heart creates
AV valve closes just as
pulmonary valve opens\
Want to push blood to pulmonary and out the atrium
the cardiac cycle contains what two phases
Diastole
Systole
Diastole
Period of Relaxation
Both sides of heart are doing the same thing at the same time
Neither heart chamber is contracting
Blood coming in from the veins
Because the pressure of venous blood is higher coming into atrium than in the ventricles, the blood trickles down (pressure difference)
Blood returning to the heart from the veins passively fills the heart chambers
Both AV valves open
Atria are not contracting
Aortic and pulmonary valves closed
Systole
Contraction starts
Want orderly contraction
Two atria contract and two valves contract
when, in systole, do the atria contract
they contract first during atrial systole
atrial systole
Forces blood into the ventricles
Creates pressure
preceeded by both AV valves opening
when both the av vales are open what is going on iwth the other valves
Aortic and pulmonary valves are closed
what comes after the atrial systole
ventriculat systole
ventricular systole
The the ventricles contract
This forces blood out of the heart and into aorta and pulmonary artery
Walls contracting, squeezing of the blood and AV valves close (when AV valve closes volume of blood iin left ventricle flattens(no blood in or out))
Aortic and pulmonary valves open
what happens when Aortic and pulmonary valves open
Pressure in ventricle is higher than pressure in aorta
this causes valves to open and blood to leave
Drops volume of blood in ventricle bc blood is moving to arteries
When pressure in ventricle drops below aortic pressure, aortic valve has to close
Prevents backflow of blood from aorta to ventricle
Blood leaves heart into arteries
Elastic pressure of arteries: why do you want to maintain pressure in arteries
Continuous flow
Caused by continuous pressure
T or F ; There is a period during left ventricular systole when both the left AV valve and the aortic valve are closed
True
Av valves close
Aortic valve opens when there is enough pressure in aorta
Before that period both are closed
Aortic valve doesn’t open until pressure gets higher than the pressure in the aorta
Effective pumping requires:
sequential contraction of chambers (atria contracting and then ventricles)
Coordinated contraction of muscle cells within each chamber
Cardiac muscles have action potentials just like skeletal muscles
Cardiac muscle cells are joined together by gap junctions
why is it important that Cardiac muscle cells are joined together by gap junctions
When you depolarize, the wave of action potential moves along the heart and they all contract together
The flow of current (Na+) between cardiac cells is key to the sequential and coordinated contraction of the heart
how do cardiac muscle cells compare to skeletal muscle cells
Cells are smaller than skeletal muscle cells
Cardiac muscle cells branch and interdigitate: can withstand high pressures
cardiac Muscle cells are joined together by something called ___
intercalated discs
-make up junctions
intercalated discs
These are junctions between muscle cells
Gap junctions
Gap junctions
Pores which small molecules can move through
Cardiac and smooth cells are arranged in sheets
Cells in the sheet are in electrical contact via gap junctions
An action potential in one cell can spread to all others in the sheet
Synchronize contractions
Why action potentials can spread from one cell to next(depolarizes one then next and next)
give a summary of where the wave of depolarization moves
A wave of depolarization, setting off contraction, sweeps across the heart from the SA node, then across the atria. It pauses at av node and then spreads across the ventricles
SA node(pacemaker) (sinoatrial)
Muscle cells that initiate their own action potentials (about 70 times a minute)
Initiates at pacemaker
Atrial muscle is linked by gap junctions so a spread of depolarization is observed through the atria and the muscle cells quickly contract as one
Squeeze extra blood into ventricles
Depolarization signal needs to travel through atria and get to ventricles
Place where the two chambers are connected →
AV node
Av node doesn’t conduct very fast
Delay occurs
why
Want atria to finish contracting before we get the ventricles contracting
The delay ensures that the atria are empty before the ventricles contract. This prevents the ventricles from contracting too early.
once the depolarization wave is through the av node where does it go
there are bundles of muscle cells that conduct the depolarization much faster than others
They lie at the heart apex (bottom of heart)
Set off depolarization up the heart
Squeezes blood up
Purkinje fibers
Electrocardiogram (ECG or EKG)
During the cardiac cycle there are so many cardiac muscle cells depolarizing and repolarizing in unison that you can pick up an electrical signal at the skin
Peaks of EKG correspond to specific events in the cardiac cycle
describe the peaks
first small bump = P-wave
- atria contracting
-atria depolarizing
Then the relaxing is the AV node delay
- Q
The deflecting downwards is the spreading through the heart
- Q
The big spike = ventricular depolairzation (QRS_)
- R
going even further below starting level
- S
last bump
- repolarizarion of the ventricles
- T
Abnormal ecg (partial heart block)
P wave happening at nice spaced intervals
Atral contractions
Atrial contractions should leave to ventricular contractions
Not happening →
irregular QRS that become partially de-linked
Atrial fibrillation
Atria are not contracting in coordination
Not beating together so there isn’t a distinct peak
Not clean intervals and don’t have clean p waves
Tachycardia
Abnormally fast heart rate
Ventricular fibrillation
Ventricles aren’t contracting together
Out of sync
Electrical shock
Atrial fibrillation isn’t so bad - why?
A lot of ventricular filling happens even before the atria contract
You could get by without atria not contracting
^^ leaky filling of ventricles
SA node cell composition
These cells have an additional ion channel
Slow influx prepotential
SA node ion channel opens up when it is polarized and lets sodium ions in
Brings itself to threshold
This then opens up voltage gated calcium channels
Depolarizes cell
Then action potential occurs(calcium bind with troponin and act with myosin and it repolarizes with potassium outflow
Bby itself, SA node has rhythmic depolarizations at about 70/minute
The cell essentially brings itself to threshold by
the slow influx of Na+
Does not have a stable resting potential
Na+ channels open when you polarize and close when depolarize
One of the major regulators is the autonomic nervous system
what type of nerves exits
Parasympathetic nerves and sympathetic nerves
Parasympathetic nerves characteristics
Rest and digest
Heart beat relatively low
Not breathing heavily
Digesting food
Slower depolarization
Sympathetic nerves
Fight or flight
Stressful
Intense exercises
Emotionally and physically stressful
Adrenaline rush
Increase heart rate
Ship blood to necessary areas
Faster depolarization
One of the main things we can change to change heart rate is
Depolarization potential
Sodium influx prepotential
Sodium influx prepotential
a gradual influx of sodium ions into a cell that occurs when there is no resting potential. This prepotential leads to the cell reaching threshold, which initiates a rapid depolarization and contraction
how do we change the heart rate with action potentials
change number of action potentials –> more is faster and less is slower
Beta blockers
Slow down the heart rate
Used to treat high blood pressure
Block the activity of the sympathetic branch
Caffeine
Works by
increasing the rates of depolarizations at the SA node
Nicotine
Stimulates the activity of the sympathetic neurons that deliver impulses to the heart
Vessel structure
what vesseles exist
arteries
arterioles
capillaries
venules
veins
Arteries - summary
Large vessels that carry blood away from heart
Aorta and pulmonary arteries
Capillaries- summary
Exchange between blood and interstitial fluids
Bring nutreitns and oxygen to cells
Arterioles- summary
Control distribution to capillary beds by adjusting state of constriction or dilation
Regulates where blood goes
Venules- summary
Blood from capillaries go here
Smaller vessels
Leaving capillary beds and goes to veins
Veins- summary
Return blood to heart
The structure of vessels through the circulatory system
All vessels are lined with
endothelium
endothelium
The surface that the blood touches inside the tubes
Made up of endothelial cells
Type of epithelial cells
Purpose is to make tight, sealed surface that keeps the contents of blood inside
In capillaries are where there is a slightly different property of the endothelium where it becomes
leaky
Where exchange occurs
describe composition of artery
Endothelium surrounded by elastin layer then smooth muscle - elastin again - and connective tissue
Connective tissue gives it strength
Resistive outward pressure
And smooth muscle
Elastin
Give vessel strength and elasticity
Vessel adaptations: arteries
Big vessels leaving the heart
Highest pressure in the whole system is herre
Need to be tough
Endothelial cells line the inside of the vessel
In the arteries and arterioles the endothelial cells are tightly bound together to prevent leakage
Elastin
Give vessel strength and elasticity
Support high blood pressure
Stretching to conserve energy from contraction
Recoil during diastole(heart relaxation) push blood forward
Pressure maintained in arteries because
it is elastic like a balloon
When ventricle is relaxed the artery recoils which keeps the blood flowing
Pressure reservoir
Blood flows continuously, not just while heart is contracting
Veins purpose
Return blood to heart
the pressure in veins is low
the pressure isnt enough to send blood back to heart
Blood tends to accumulate in veins (especially at lower extremities)
how does body move blood up
One-way flow in veins help
Also skeletal muscle contraction helps move the blood
blood in veins when you are at rest vs when you are exercising
When youre relaxed, the volume of blood in your veins is higher than when you are exercising
Veins pass through muscle and when you exercise you create pressure on the veins that pass through that muscle and that squeezes the veins
When you need actively flowing blood veins are squeezedd and that pushes blood towards heart
Get more actively circulating blood
Varicose veins/failed veins
Blood pools in veins because blood doesn’t go back to heart
Blood coming from heart go to arteries and into smaller vessels called
arterioles
There are lots of smooth muscles in arterials
Involuntary muscle
We can squeeze smooth muscles and narrow that vessel
the blood then branches off into
capillaries
what regulate blood flow to specific capillary beds
Smooth muscle cuffs - “precapillary sphincters”
These smooth muscles are targets of autonomic nervous system and hormones
Autoregulation of arteriole diameter depends on
local environment
Autoregulation
Where the capillary beds and arterials are flowing through the tissues that’s using the oxygen and so on
Arterials are keeping track of what is happening in the local environment
what causes local dilation
High CO2
Low O2
Byproducts of cellular metabolism
Lactic acid and low pH
Locally produced factors like histamine and NO cause local vasodilation
Tightening hand what is happening?
Not getting enough oxygen
Not removing waste
Builds up CO2 and lactic acid
Local control
In a capillary
Some substances can diffuse directly across the endothelial cells
like_____–
other moleules like _— move between cells via gaps between endothelial cells
O2 and CO2
glucose and water soluble substances
size of clefts
what can and cant get through
These clefts are small enough that the blood cells and large proteins are retained in the capillary
Some large proteins are selectively endocytosed and exocytosed by endothelial cells
for example
Peptide hormones
Pressure on circulatory system comes from the heart
explain how
explain how this pressure changes throughout the circulatory system
Heart squeezes on blood, creates kinetic energy and the blood rushes out of the heart with high pressure
Friction of blood against walls slows it down
Pressure becomes very low in circulatory system
Need skeletal muscle pump to move blood back
how is capillaries part of the reason blood slows down
Even though capillaries are the smallest vessels there are so many of them that their total cross sectional area is greater than any other vessels
The big area and slow flow encourages exchange between capillaries and the interstitial fluid
Then the pressure drops throughout the system, biggest drop being in the arterioles
The pressure drops from the start to end because the endothelial cells in the capillaries are leaky → movement of water out the capillaries
Two forces to consider concerning movement of fluid(water) between capillary lumen and interstitial fluid:
Blood pressure
Osmotic pressure
Osmotic pressure
There will be a net movement of water from an area of lower solutes to higher solutes
More solutes in capillary lumen so move water into capillary
When these two opposing forces are taken into consideration, there is a net movement of water____-
why
out of the capillaries
Pressure in capillaries is high
Pressure in interstitial fluid is low
Fluid comes out from capillaries(water) to interstitial fluid
Blood pressure drops along capillary
Lymphatic system
Series of vessels that surround capillaries
Where we get water back into circulatory system
Water moving out of the capillaries into the interstitial fluid needs to get back into the circulatory system
Water is taken up b the lymphatic system
Low pressure vascular system that moves fluid back to the circulatory system
Q: elephantiasis is a disease caused by a parasitic worm. Which of these is the likely underlying problem
q. Low blood pressure leads to too little water leaving the capillaries
b. The lymphatic capillaries are taking up too much fluid
c. The osmolarity of the blood/plasma is higher than the interstitial fluid
d. Blood pressure is too low
e. The lymph vessels are blocked
(e)The lymph vessels are blocked
Systolic vs diastolic pressure
The pressure is created by
he squeezing and ejection of the blood by the heart ventricles
Arterial pressure is most important because it is
driving blood into the arterioles and capillaries
Proper blood pressure ensures that blood continues to flow through the system (120-129/80-84)
too low causes ___
too hhigh causes +____
Too low and tissues don’t get enough blood flow (less than 90/60)
-Heart damage, blood loss, dehydration
Too high (above 140/90)
Leads to coronary artery disease, stroke, heart failure, atrial fibrillation, peripheral arterial disease, vision loss, chronic kidney disease
Causes: obesity, genetic factors, drug use
Too much fluid at once → pressure is too high
We are constantly doing things that could disrupt our blood presssure
like
Drinking (increasing blood volume)
standing/sitting down
Sweating (decreasing blood volume)
Stress (increased heart rate)
Exercising
how does exercising disrupt our blood pressure
Heart rate goes up
Blood flow to muscles go up
Mean arterial blood pressure goes up only a little bit
Diastolic pressure doesnt change (at resst so lollll)
Cardiac output increases (pumping more blood)
Systolic pressure increases
Relationship between vasoconstriction/vasodilation and blood pressure
Dilated vs constricted vessel
Smooth muscle is causing it
Same amount of blood going through both, contrsitced is gonna have higher pressure
Total peripheral resistance
Sum of all vascular resistances within systemic circulation
Whats gonna impede the flow of blood through everything -> resistance
Arteries supply tissues and organs in parallel circuits
Changes in resistance in these circuits determines relative blood flow
If all your body did in response to exercise was to increase blood flow to muscles there would be_____
a drop in blood pressure throughout the circulatory system
Vasoconstriction to counter the muscle vasodilation helps to maintain blood pressure
Increased heart beat also helps to maintain blood pressure
