Lecture 6 - Blood Circuits and the heart Flashcards
How many litres of blood does your heart pump daily?
7000 Litres
With someone who requires cpr, what is the main objective?
The faster you are to getting the heart started, the more likely they are to survive.
4min with stopped heart = death
What happens if your heart stops?
Within 10 second you will pass out (unconscious)
Due to brains reliance of O2 and glucose supplied by blood
have to restart heart within 4min, otherwise death
What is the mortality rate of cardiovascular disease in western society?
1/3 - 1/2
What pumps are involved in the cardiovascular system?
2x pumps
The heart pumps blood into 2 closed circuits with each beat
-systemic(s) circulation (Limbs-musculoskeletal), (Kidneys-renal), (Brain-neural),(Gut+Liver- digestive) (left)
-pulmonary circulation (supplied by right (drain back to left)(lungs)
pumps are stuck together
work simultaneously
What is the role of pumps in the heart?
to push blood out into arteries
(high pressure vessels)
which in turn supply the capillary beds (radiators) with blood (off load + pick up)
drained back to heart by low pressure veins
1x pump supplies
1x receives and passes on too another cicruit
What is the role of capillaries?
off-loading of nutrients and oxygen
pick up waste products and CO2 from cells
What percent of your total blood volume does your heart contain?
7% of blood total
smallest
What percent of your total blood volume does you Pulmonary circuit contain?
9% of blood total
What percent of your total blood volume does your Systemic circuit contain?
84% of blood total
largest
What proportion of the blood in the Systemic circuit is located in your veins?
3/4
What is the role of your veins?
not storage
Ability to hold a RESERVOIR of blood
Can channel blood to other parts of the body as needed
Where does most of the blood in your body sit?
In the veins of your systemic circuit
What is the average amount of blood in your body?
5Litres
What is the output of blood of each pump?
at rest = 5Litres per min
highly variable
exercise = 4x resting rate = 20L per min
athlete = 8x resting rate =40L per min
What are some of the features of the systemic circuit?
Largest circuit- has to reach and supply blood to many organs and systems
High Pressure (driving force)
High Resistance
– harder to push blood around the circuit
involves the LEFT ventricle Receiving OXygenated blood from the lungs and pumps it around the body
What are some of the features of the pulmonary circuit?
Smaller circuit - blood only needs to travel to the lungs
Medium Pressure
Medium Resistance
– effect how the heart LOOKS and FUNCTIONS
involves DE-oxygenates blood being pumped OUT the RIGHT ventricle into the lungs, where it is Oxygenated
What is the role of the lungs?
To Oxygenate blood
Blood drains into the LEFT side of the heart, then pushed (via pressure) out to arteries which supply the systemic capillary network (loses oxygen- pick up waste)
capillary network returns back to systemic veins then to Right side of the Heart
then pumped back to pulmonary circuit
LEFT –> arteries –> systemic capillary –> (drainage) –> systemic veins –> RIGHT –> pulmonary
What type of blood do artery and veins carry?
Systemic ARTERIES: Oxygenated, supplying the capillary beds
Systemic VEINS: DE-oxygenated blood
Pulmonary ARTERIES: DE-oxygenated blood, supplying the capillary beds
Pulmonary VEINS: Oxygenated
Which blood is considered to be blue?
oxygen DEPLETED blood
blue/purplish
from systemic –> pulmonary
What colour is cut blood and why?
Bright Red
When cut the blood very quickly binds with oxygen
Therefore doesn’t mean it always comes from capillaries
How do you define arteries and veins?
Arteries: arteries always take blood AWAY from the pumps
Veins: veins always bring blood BACK to the pumps
What is the exception regarding veins?
Gut absorbs nutrients and transports elsewhere
Gut has a good blood supply
Blood Leaving gut = Deoxygenated
Doesn’t go back directly to the heart, travels via the Hepatic Portal Vein to the Liver/Hepatic
Largest portal vein in the body
Liver has its own blood supply which is receives via Hepatic Arteries
What are Portal veins?
Veins that go from one system to another
neither of those systems being the heart
What is the Filling Phase?
Volume INCREASE (actively-burning energy to occur)(Expanding Chamber)
Venous IN-let on LEFT, FILLING ventricle
Arterial OUT-let on RIGHT, OUTLET-Valve PREVENT BACK-FLOW of arterial blood
inlet valves passively open
What is the Ejection Phase?
Volume DECREASE (Shrinking/Compressing Chamber by the THICK Muscle Walls) INLET-Valve necessary to prevent the HIGH PRESSURE blood form the Pumping chamber from returning Back into the Veins (directional flow required of the blood to eject out of the vein--> artery)
What are the requirements of a Ventricular Pump?
- a Chamber which can Change Volume
- Inlet Valve
- Outlet Valve
(valves steer the blood in the correct direction)
In-effective if it is missing one of these requirements
What is the improvement regarding Increasing the Flow of the pump?
Increase filling rate
narrow opening + inlet valve has to be open
During ejection phase, make Ejection valves closed so blood can pull directly outside the door and when inlet valve opens it can very quickly enter
Atrium, primary job allow blood to pull outside inlet door, so as inlet valve opens a lot of blood can quickly enter the chamber
What is the improvement regarding the walls of the pump?
Pumps is ineffective as only two walls work.
Make outlet the same side as inlet
Now have 3x walls able to Decrease volume and effectively reduce volume of chamber
Increasing efficency
What is the principle role of atriums?
“atriums to buildings”
Primary Role= act as a reservoir
does top up ventricle, doesn’t contribute to main pumping power of the heart
What is the shape of flow of blood in the heart?
V shaped
enters the vein
exits the artery
(makes it efficient)
What is the improvement regarding atrium size?
adding an appendage/ extension of the side of the atrium
“aurical”=(“aur-“=ear)
increases SA and Volume/Capacity of atrium
Why is “ 4x chambered heart” technically incorrect?
Left atrium+ventricle = LEFT pump
Right atrium+ventricle = RIGHT pump
4x chambers, 2x pumps
What is an auricle?
an appendage
R.auricle= an appendage or extension on the side of the atrium will increase the capacity of the atrium
Why do you only really see the anterior view of the heart and liver?
to get to it, you do NOT cut up through the spine, as you will paralyse your patient
instead saw fast through sternum - bone mends quickly and relatively easy to fix and placing retractors on either side to crank open, able to Expose Pericardium where the heart sits (shows you anterior view)
In what manner is a diagram labelled?
From Patient’s point of view
Anterior view = opposite
Posterior view = same
What does the heart consist of?
Anterior view
Superior Vena Cava (cavenous vein) Aorta Right auricle Right atrium Right Ventricle Inferior Vena Cave Anterior Inter-Ventricular Sulcus (front) Right Pulmonary artery Left Pulmonary artery Pulmonary trunk Left auricle Left atrium Left Ventricle
blood comes in superiorly, enters ventricle, exits via artery
blue = systemic -> pulmonary red= pulmonary -> systemic
What is the bulk of the heart made up by?
the Muscular Ventricles
What are some of the roles of sections of the heart?
Superior Vena Cava = drains everything superior to heart (limbs, head)
Right Auricle = an appendage or extension of side of atrium will increase capacity of atrium
Right Ventricle= blood pushed to pulmonary circuit
Inferior Vena Cave= drains everything lower than heart (trunk, legs)
Pulmonary Trunk= undivided, but divides into Right and Left pulmonary Artery
Left pulmonary Vein = drains left lung
Right pulmonary Vein = drains right lung
Left Atrium = reservoirs upstream of ventricles which allows blood to accumulate to fill pumps. Thin walls, so less efficient.
Left Ventricle = large as must pump to whole body
Aorta = systemic Artery, pumps blood off to the systemic circuit
What is the orientation of the Right atrium and why?
Right atrium is Vertically orientated
so it can receive the Input from the 2x main areas of your body (Superior and Inferior Vena Cava)
What is the orientation of the left atrium and why?
Left atrium is Horizontally orientated
as the Lungs are on Either Side
receives OXygenated blood from the Pulmonary circuit-explains look of the heart
What are ventricles designed to do?
Lift from Low pressure
Pump to High pressure
valves open and close in response to pressure changes, as the heart contracts and relaxes
What are the peak pressures in your heart?
Left ventricle:120mmHg
Right ventricle:25mmHg
(LV5:RV1)
atria receive blood on the other side of the resistance circuit.
Left atrium:5mmHg
Right atrium:2mmHg
v low pressure coming back to RA , as it is the biggest circuit that it is draining, therefore
more pressure is retained after the pulmonary circuit(smaller)
(more of the 25mmHg is retained) by the time it get back to the Left Atrium
vs
Less of the 120mmHg is retained going though the high resistance systemic circuit therefore peak pressure is only about 2mmHg in RA
What are the entry and exit steps in the Pulmonary Circuit?
blood enters the right atrium via the superior and inferior vena cavas
blood is then pumped out through the pulmonary trunk into the lungs
What are the entry and exit steps in the Systematic Circuit?
blood enters the left atrium from the pulmonary veins
blood is then pumped out to the aorta
What are special about cephalopods/ocupi/cuttle fish ?
have the 2x pumps separated
1x Gill pump
1x systemic pump
surgeons would love this as they would be able to operate on one pump without having to stop the other
What are the main Landmarks to look out for in the heart?
(Posterior and Anterior) Inter-Ventricular Sulcus
Pulmonary Trunk (artery leaving the R.Ventricle)
bulk: muscular ventricles
How do hearts of a healthy and unhealthy person compare?
Obese person will have more fat on the Outside of the heart.
However it is the fat on the INSIDE of your blood vessels that is of concern
What is the most anterior vessel to see?
Pulmonary Trunk
artery
What is our average human blood pressure?
120/70 mmHg
Blood from the carotid artery goes up how far in humans?
2metres
in a glass rod
2000 mm of blood is not a very useful measurement
sphygmomanometer, glass rod with mercury (denser liquid) instead, to see how far it rose, to measure pressure
mm of Mercury units origination
What were some of Werner Forssmann’s achievements?
catheter = 65 cm
measured from cubital fossa to approx. place of heart
cut vein and fed it up until 65cm mark (RA)
What is the Inter-Ventricular sulcus?
the Demarkation between the two ventricles
What sort of difference is there between the two areas?
textured difference
Why is the Atria NONefficent pumps?
they do not have valves (inlet esp.)
doesn’t have a strong muscular wall (therefore cannot generate a lot of pressure)
What is the role of valves?
Valves open and close in response to pressure changes, as the heart contracts and relaxes
Valves mediate the uni-directional or one way flow of blood
outlet/inlet valves on the same side , so all walls
What does the anatomy of the atria look like after dissection?
Thin and Eery
Bundles of muscle called pectinate
Light can pass through (almost translucent)
What does the anatomy of the ventricle look like after dissection?
Thickness: LeftV>RightV..»R+LAtria
What has valves?
Ventricles have Valves
Atria’s DONT have valves
LAtria and LVentricle has valve= 2x flaps=Bicuspid valve=Mitral valve
RAtria and RVentricles has valve = 3x cusps/leaflets = Tricuspid valve
What does a valve look like?
large valve flap
(atrioventricular valve)
leaflets anchored to the wall between the atrium and the ventricle
hang down
Tethered to the wall by tendonous chords calls CHORDAE TENDINAE, which are anchord to the wall by nipple looking muscles called PAPPILARY MUSCELS
What is the role of Pappilary muscles?
Relaxed during Filling (like chordae tendineae)
-flaps opan and close in response to blood flow - PASSIVE- no muscle to open/close them
Contract during ventricular Ejection. Squeeze blood inside the ventricle, Pressure Increase.
So blood will try and flow to an area of Low pressure, getting UNDER the leaflets and tries to take the valve leaflets with it passively(from when they were hanging down from ventricular filling), LIFTING that valve leaflets up, so that the FREE EDGES come in contact and close off the inlet
it is the CHORDAE TENDINEAE and PAPPILARY MUSCLES’ role to KEEP it CLOSED, RESTRAINING the valve leaflets and stopping the leaflets from getting BLOWN BACK UP into the atrium, during ventricular contraction.”heart strings”
What are some aspects of the Left ventricle?
LV forms the CORE of the heart hollow thick- with muscular walls(10mm-15mm) cone shaped cross section=donut/wheel with a cylindrical lumen/space in middle
2x Holes= big=inlet small=outlet
What are some aspects of the Right ventricle?
RV sits on the side of the left ventricle.
crescent/C shaped (like a hip pocket) lumen
thinner wall(5mm)
2X Holes= big=inlet small=outlet
What has the heart looked like during a humans lifetime?
MOTHERS STOMACH: both sides of the heart are pumping around the same circuit, complex
BORN: the two Ventricles are the same size
START BREATHING/establish adult CIRCULATION: systemic system grows larger and faster than pulmonary circuit
OVERTIME: LV has to compensate, getting bigger and with thicker walls, to form the CONE of the heart
How do you fill your heart?
From Very Low pressure from the atria
Therefore you need a bigger hole to allow the blood to fill quickly
How do you exit your heart?
exit under high pressure
(ventricles squeezing out)
therefore can have a smaller hole
What type of blood flows through the right side of the heart?
BLUE=deoxygenated=R
What type of blood flows through the left side of the heart?
RED=oxygenated=L
Describe the difference in wall thickness?
LV has a thicker wall
LV:RV (10/15mm - 5mm)
3:1
but the LV generates 5x the pressure
How do you name the semi-lunar valves?
From where the blood is being pumped too from the ventricle
Right = RV–>pulmonary trunk
“Pulmonary Valve”
Left= LV–>aorta
“Aortic Valve”
-would also see openings of coronary arteries
What could the aorta be called?
Elastic Artery
What are outlet valves called?
Semi-Lunar valves “semi moon like”
Smaller than Inlet Valves
when opened out, shape appears to look like pockets/moon
have 3x cusps
when inflated with blood, they gain strength from their 3D shape
The semilunar valves allow ejection of blood from heart–> arteries, but prevent back flow of blood into ventricles
What happens to the Outlet valve during Ventricular Ejection?
Outlet valve is in the open position
Arrow indicates flow of blood V/Heart –>arteries
Ventricles contract/push blood out
Push valve leaflets/pockets up against wall
What happens to the Outlet valve during Ventricular Filling?
Outlet valve in the closed position
Pressure of blood trying to RE-ENTER valves
fills up the pockets
this causes the outer Edges of the cusps to Close Together
forms a tight seal
Lip bulging outwards=seal
What are the requirements of Outlet muscles?
No Chordae Tendineae
No Papillary Muscles
ONLY relying on the 3D structure of the valve leaflets
Has 3x cusps but not called Tri-cuspid because that is an inlet valve
What are inlet valves made of?
Endocardium
with a CT core
What overlap happens when AV valves are open?
the rounded edges of the inlet valve cusps project into the ventricle
Why is the mitral valve called so?
is part of the inlet valve
bishop hats “mitre”= 2x stiff bits of fabric folded upon eachother at a point
upside down looks like mitral valve
mitre joint = 2x 45^ pieces of wood
What is the Chordae Tendineae like?
tough tendinous chords
What happens to the Bicuspid/Mitral Valve during Ventricular Ejection?
contraction
closes and forms Fish Mouth shape
What happens to the Tricuspid Valve during Ventricular Ejection?
contraction
closes and forms Y shape
not a perfect valve= little bit of seepage
When is the 3D shape of the outlet valve most important?
bottom=ventricle=mostly muscle= browny
top=artery=collagen(elastin)=not much muscle
=no where to anchor chordae tendineae too as there is no muscle to join the papillary muscle too
=small= do not want to clog up with papillary muscle
smaller hole=high pressure
=easier to close up
What is the difference in pressure of the outlet and inlet valves?
inlet valves=large=low pressure
Outlet valves=small=high pressure
