Studied by 106 people
Blood circulation-Overview
Right side
Deoxygenated blood enters through either the superior or inferior vena cava then will travel through the right atrium through the tricuspid valve then through the right ventricle then goes up to the pulmonary valve to release deoxygenated blood to the lungs where gas exchange occurs in the capillaries and makes deoxygenated blood into oxygenated
Left side
Then oxygenated blood comes back through the lungs into the pulmonary vein to the left atrium to the bicuspid valve and dumps into the left ventricle and then leaves through the aortic valve to the aorta
Artery and veins
Arteries=Brings blood Away
Veins: Brings deoxygenated blood towards
Thoracic Cavity
Right pulmonary cavity
Houses right lung
Mediastinum
Houses heart and great vessels
Left pulmonary cavity
Houses left lung
Superior Mediastinum
Located between pleural cavities
Superiorly terminates at the superior thoracic aperture
Inferiorly terminates at the level of the sternal angle
Inferior border of sternum
Inferiorly terminates the inferior thoracic aperture
Located between pleural cavities
Inferiorly terminates at the level of the sternal angle
Divided into three sections: Anterior, Middle, Inferior
The Thoracic Cavity
Sternal Angle (Angle of Louis)
Level between: T4-T5
Divides the mediastinum into superior and inferior mediastinum
Anterior: Contains fat, loose tissue, lymphatic vessels, and branches of the internal thoracic artery/vein
Middle: Houses heart
Posterior: Houses structures posterior to the heart i.e. Thoracic aorta, sympathetic trunk, azygous vein, thoracic duct
Superior Mediastinum
Trachea is only found in the superior part of the mediastinum because it bifurcates
The pulmonary trunk is found at the level of the sternal angle
Esophagus is found in the posterior inferior mediastinum and superior mediastinum
Superior Mediastinum
*ROLLERCOASTER METHOD
Ascending Aorta: Waiting Area
Aortic Arch: Stuck before the drop
Descending Aorta: Finally drop
Sternal Angle Significance
1- Easy locate and palpate
2-Junction between ascending aorta, aortic arch, and descending aorta
3-Bifurcation of the trachea
4-Bifurcation of the pulmonary trunk
The Pericardium
Fibrous Pericardium: Thick/outer layer
Serous Pericardium
Parietal: Second layer
Visceral: Interact with organ, within the heart, Third layer
Coronary Vessels of the Heart
Heart has four chambers
Both left/right Coronary arteries come from aorta
Auricle (elephant ears): increases the volume and allows for more blood to sit into the atriums
Anterior cardiac veins dumps deoxygenated blood from cardiac muscle into right atrium
Left coronary artery: Comes up from the ascending aorta to the pulmonary trunk and branches off and creates circumflex branch of LCA
Right coronary artery: Between right atrium and ventricle, known as atrioventricular groove
Anterior Interventricular Artery: Sits between ventricles
Coronary vessels of the heart
Sinoatrial Nodal branch of RCA
Pacemaker of the heart
Left Coronary Artery
Swings behind the left pulmonary trunk
Anastomosis, when vessel A meets up with vessel B and intertwined
Two vessels connect together which helps supply blood in one
Lots of this around the heart, protect the heart, incase of a blockage or severed artery
Coronary Vessels of the Heart
Coronary Sinus: Dumps into the right atrium, and gets blood from the great cardiac vein
Posterior interventricular groove
Posterior interventricular artery
Posterior interventricular vein
Travels down and join at the apex of the heart
Blood circulation
Four heart chambers (2 Atria and 2 Ventricles)
1 right atrioventricular valve (tricuspid valve)
3 cusps
1 left atrioventricular valve (bicuspid valve)
2 cusps
Try before you buy
2- Pulmonary and Aortic Valves (semilunar valves)
Pulmonary valve=right ventricle to the lung
Aortic valve=Left ventricle to the aorta
Semilunar valve (3 cusps): Mercedes benz logo
Right Atrium
Fossa Ovalis: Used to be an opening between the right and left side, as a fetus and seals up when you develop
Right Ventricle
Interventricular Septum: Separates the right and left ventricles of the heart
Chordae Tendinae: Ligaments of the valve-Connects the cusps to the papillary muscles which are finger like projects that help the valve do its job
Traberculae Carneae: Rough wall
Moderator Band: Conduction system and helps the heart beat, base of the anterior papillary muscle and extends to the interventricular septum
Left Atrium
Left Ventricle
Superior Mediastinum
Anterior Glands (thymus)
Veins
Arteries
Airway (Trachea)
Alimentary tract (esophagus)
Lymphatic trunks
Superior mediastinum
Superior Mediastinum
The “Dancers”
Pulmonary and systemic circuits
Right side of the heart: Recieves poor blood and sends lungs to get O2 (deoxygenated blood)
Left side of the heart: Recieves rich blood from lungs and sends out to body (oxygenated blood)
Pericardium
Fibrous Pericardium: Thickest layer on the outside, second protective layer that sits on top of the heart
Serous Pericardium: Responsible for serous fluid and allows for frictionless movement to allow your heart to beat
Visceral Pericardium: Innermost layer
Pericardial Cavity: Space between two serous pericardium
Valve incompetence
Valve does not close properly due to scar tissuem congenitals
Blood backflows
Valve Stenosis
Valve becomes stiff (Ca2+ deposits, scar tissue, common with ages, blood flow is reduced)
Constricts opening
Prevent from going out
Upper Circulatory pathway
Aorta: Gives common carotid arteries which is responsible for head and neck
Upper limb: Has the subclavian artery and so the aortic arch gives the head, neck, upper limb blood supply and once used up deoxygenated go back to the superior vena cava to the right atrium
Lower circulatory pathway
Thoracic Aorta: Blood going to the intercostal muscles around the thorax
Abdomen: Pelvis and lower lim and will travel all that blood will travel once deoxygenated and back to the heart to the inferior vena cava
Aorta
Line in middle: Diaphragm
Descending aorta: separated by sternal angle
Blood will leave the heart from the left ventricle of the heart through the ascending aorta
How do you go from the lungs to the right lower limb
Travelling from the lungs into the left atrium and then into the left ventricle through the tricuspid valve from the left ventricle to the ascending aorta through the aortic valve ascending aorta to ascending arch then thoracic aorta then through the diaphragm into abdominal aorta and bifurcate the common iliac arteries to the right common iliac artery
Recall: Branches of the Aorta
Right side
Brachiocephalic trunk which will split into the subclavian artery which is responsible for the upper limb and then the right common carotid artery which goes to head and neck
Left side
Does not have brachiocephalic trunk
Left common carotid artery and left subclavian artery directly come off the aortic arch
Arteries: Upper Limb
Right subclavian A (by the heart in the thorax)
Axillary A (armpit)
Brachial A (upper limb)
Deep A of Arm (goes to the posterior arm region responsible for triceps brachii) *Big artery*
Radial A (thumb)
Ulnar A
Arteries: Lower Limb
Right Common Iliac A (bifurcate into a right internal/external iliac artery)
Right Internal Iliac A (into/within the pelvis)
Right External Iliac A (outside the pelvis)
Femoral A (Comes from the right external artery which comes from the right common iliac)
Superior Vena Cava
Major vessels
Superior and inferior vena cava being capable of dumping blood into the right atrium
SVC (3 branches)
Right and Left
Bifurcate into a left and right brachiocephalic veins
Brings blood from the upper limb head and neck to the heart
IVC (2 branches)
Travels down the abdomen
Tributaries right and left common iliac veins
Brings blood from lower limb and abdomen into the heart
*Common Iliac Veins
Blood vessels
Delivery system of dynamic structures that begins and ends at heart
Complex delivery tunnels and their job with the arteries and to take blood away from the heart
Arteries
Carry blood away from heart, oxygenated except for pulmonary circulation and umbilical vessels of fetus
Capillaries
Contact tissue cells, directly serve cellular needs
Tissue gets oxygen, rich blood gives back the oxygen-deficient blood or the nutrition-rich blood and nutrient enriched blood
Veins
Carry blood towards the heart
Structures of blood vessel walls
Arteries
Handle much higher pressure
Have thicker walls
Contain muscle to control flow
Ex. when you get a cut the arteries will jump in and stop the bleeding from happening
Have more elasticity
Can take some of the blunt force so as the heart is pressuring each time there is an unsmooth and uneven amount of pressure coming in
Stop/preventing blood because of smooth muscle within they can constrict
Veins
Thinner wall
Pressure has been decreased
Experience a smooth low pressure amount going through
Their biggest job is to get blood back to the heart against gravity
Tunica Interna/Tunica Intima, Tunica Media, Tunica Externa
Tunica Interna/Tunica Intima
Composed on one layer which is the endothelium which forms a slick surface for the blood
Innermost layer
In a large vessel you can have an extra endothelial layer aka a basement membrane (sub-endothelial layer)
Tunica Media
Intermediate layer
has a smooth muscle layer
Controlled with the CNS allowing for vasoconstriction
Tunica Externa/Tunica Adventitia
Most external/outermost layer
Offer protection and reinforcement
Give blood vessel its structure, shape and solidity
Anchors the blood vessel to nearby structures
Composed of loose collagen fibers
Could be supplied by their own blood vessels aka VASA vasorum
Arterial System
Elastic Arteries (conducting) largest
Thick-walled, highly elastic
Near heart
Ex.Aorta
Large amount of smooth muscle
Muscular Arteries (disturbing)
Deliver to organs, more distal
Most of named arteries
Very active in vasoconstriction
Ex.Ulnar artery, radial artery, axillary artery
Have more smooth muscle allows for vasoconstriction
Arterioles
Fine control of flow to capillaries
Smallest arteries
Give fine control to flow to capillary
Nice flowing, much lower pressure
Very thin
Composed of one single smooth muscle layer and an endothelial lining
Capillaries
Smallest blood vessels
Thin walls to allow exchange
Most areas of body have rich capillary supply
Sometimes you only have one single endothelial cell
Exceptions:
Tendons and ligaments (poorly vascularized)
Cartilage, Epithelia, Cornea, Lens (no capillaries)
Cornea and lens receive their nutrients from aqueous humour
Types of Capillaries (least to most permeable)
Continuous (LEAST)
Allows smaller things to pass over their walls
Abundant in skin and muscles
Allow for oxygen and carbon dioxide to pass back and forth
The reason for why its tight is because the endothelial cells the tunica intima are joined by tight junctions (hard for things to get through in/out except for intracellular cleft such as O2 and CO2) and the tight junctions job is to hold everything tight together so there is less space for things to cross over
Intercellular Cleft: Very small openings between epithelial cells that will allow for passage of O2 and CO2
Found in skin, muscles and in the brain
Fenestrated
Have pores which are known as fenestrations
Fenestration allows capillaries to pass bigger things that require absorption such as kidneys, intestines and endocrine organs
Easier for larger stuff to cross over
@@Sinusoid @@
Super leaky
Lots of space
Larger intercellular clefts
Have fewer junctions and allows for bg things to pass across including red blood cells, bone marrow, liver, spleen
Capillary Beds
Under local control
Controlled by chemicals
Terminal arterial and blood is flowing
All diffusion happens
Ex. Blood diffusion, oxygen, CO2 exchange
Precapillary sphincters: Happens when capillary is emerging
Vascular shunt (Middle part): Cancel out the capillary beds and blood will flow back to the veins and go back to the postcapillary venule and then back to the heart
Bypass when using these sphincters could be regulated locally through chemical conditions or the central nervous system
Veins
Venules
Thin walled
Veins
Tunica externa largest layer (Collagen + elastin)
Accomodate large blood volume (up to 65% of bodys blood at one)
Venous valves
Job is to be a one way valve and prevent blood from going back so blood can go back to the heart and backflow
Cardiac Muscle Fibers
Similar to Skeletal
Striated
Sliding filament mechanism
Unlike Skeletal
Short
Fat
Branches
Interconnected
Intercalated Discs
Junction between two cardiac muscle cells
Allow all cells to behave as one unit
Desmosomes
Act like hair clips and their job is to connect one fiber to the other so that there are no separation between these two muscle fibers
Gap Junctions
Little pods and their job is allow the signal to pass from one cell to the other and is done really fast, everything will contract as one single unit
Mechanism of Contraction
Blue line=Membrane Potential
More negative=Negative ions within the cell
More positive=Positive ions outside of the cell
Ex. Sodium, potassium, calcium
Starts at negative membrane potential of -90mv
Has 3 phases
Depolarization
Plateau Phase
Repolarization
Depolarization
Due to Na+ influx through fast voltage gated Na channels. A positive feedback cycle rapidly opens many Na+ channels, reversing the membrane potential. Channel inactivation ends this phase
Sodium channels open up and starts flooding right into the muscle cell from the outside
Since sodium is positively charged there is a huge influx jump (increase) in the membrane potential because the inside of the cell is starting to receive positive ions (inside of the cell is now becoming positive) this happens because of an electrical signal
Sodium channels close known as depolarization (look at blue line at 30mv)
Plateau Phase
Stop letting sodium in
Membrane potential starts dropping right away and the reason for it happening is because inside the cell there's a lot of potassium and is positively charged and starts to leak outside of the cell
Calcium channels (Ca2+) open up which allows calcium to slowly start going in slowly and lasts longer and gives enough time for contraction
Repolarization \n
Held the action potential as high as it could be
Slow calcium gates have closed
Potassium leaking out, Potassium channels are opening, Positive ion is going out
Inside is becoming more negative and go back to the resting potential
Efflux=All potassium exiting the cell and membrane potential drop to a resting potential of -90mv
*Highest amount of force in regards to the tension contraction tension is occurring right at the end of the second stage which is the Plateau phase
Absolute refractory period
We cannot start a new contraction
Goes from when the sodium channels first open to just the end of everything
Purple line (Tension developmental contraction)
It is a force the development of the contraction happening within the heart
Starts as the sodium influx goes through and is so fast and is not going to last long
Calcium gates close
Cardiac vs. Skeletal Muscle
Skeletal Muscle
Stimulation: Each fibre stimulated by a neuron
Contraction: Each fibre works on its own
Refractory Period: 1-2 ms (full contraction is 15-100ms), contractions can build on one another (tetany)
Cardiac Muscle
Stimulation: A few self excitable cells stimulate themselves and all other cells
Contraction: All cells work as a team and contract as one
Refractory Period: 200 ms, No tetany
Tetany
Building on one force over the other and holding that contraction for a longer period of time
Self excitable cells
In the right atrium and fire at regular intervals and send an electrical signal to the heart muscle (contract) (Nervous system can step in and can regulate/upregulate or down regulate the contraction to allow your heart to pump faster/ slower etc
Contraction
Skeletal muscle
The simplest unit is one motor unit where one fiber and one muscle cell that contracts
Cardiac Muscle
We want them to all work in unison (all at the same time) in order to give us a strong enough contraction to move blood (all work together as one team)
Energy requirements of cardiac muscle
Mitochondria
Powerhouse of the cell
Make up approximately 25-35% of the whole cell volume of cardiac muscle
Lots of energy being produced
Highly dependent on aerobic metabolism in the heart which means that they rely on oxygen to metabolize the fuel
Long lasting
Fuel
Very flexible (Glucose, fatty acids, lactic acid from skeletal muscles)
Will take fat, glucose, protein in order to make energy and will continuously fuel the heart throughout
Note 
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