Cardiovasc Flashcards
Heart sits in
Mediastinum
Three layers of the heart
1) Epicardium= outer layer. attaches to the heart (it is double layered: visceral= attaches to heart + parietal= outer & fibrous)
2) Myocardium= heart muscle
3) Endocardium= inner lining- epithelial cells
Deoxygenated blood in which side of heart?
Right
Oxygenated blood in which side of heart
Left
What does pulmonary circuit do?
Oxygenates + removes carbon dioxide
What does the systemic circuit do?
provides oxygen and nutrients + removes carbon dioxide/waste products
How many chambers in the heart?
4
The Superior Vena Cava:
brings oxygen poor blood from head & arms
Inferior Vena Cava
brings oxygen poor blood to everything (except for head, arms, upper torso)
Atria function
receives blood into heart
Ventricle Function
Pumps blood into pulmonary circuit
Left Atrium receives blood from pulmonary system via which 4 veins?
2x Left pulmonary veins
2x Right Pulmonary veins
How thick is the Right Atrium ?
2-3mm
the anterior atrial wall + inner auricle surface of the right atrium have muscular ridges. What are they + what is the function?
Pectinate Muscles. They aid contraction
How thick is the left ventricle? Why is it so thick?
10-15mm. Ejects blood into systemic circuit at a high force
Where are trabeculae carnae located and what is their function?
Left and Right ventricle. purpose= pull on the chordae tendineae during contraction to stop the valves from collapsing
The fibrous skeleton are:
rings made of dense connective tissue that form around each of the 4 valves. They prevent overload stretching, insulate the atria and are insertion points for cardiac muscle cells
What is the sequence of blood flow? Start at the Right Atrium.
1) Right Atrium (blood is DEOXYGENATED).
2) Right Ventricle VIA TRICUSPID VALVE
3) Pulmonary trunk & arteries VIA PULMONARY VALVE
4) Pulmonary capillaries- O2 Increase and CO2 Decrease
5) Pulmonary Veins= OXYGENATED NOW
6) Left Atrium
7) Left Ventricle VIA BICUSPID/MITRAL/LEFT ATRIOVENTRICULAR Valve
8) Aorta and systemic arteries VIA AORTIC VALVE
9) Systemic Capillaries- Lose O2, gain CO2
10) deoxygenated blood will travel through superior vena cava, inferior vena cava and coronary sinus and return to right atrium
REPEAT!!!
How thick is the Right Ventricle?
4-5mm. much thinner than left ventricle
Similarities & difference between heart/skeletal muscle:
- Both have striations and sarcomeres
- Heart muscle= shorter than skeletal muscle (50-100um) & less circular
- heart muscle has more mitochondria
Cardiac muscle fibres are connected by what type of discs?
intercalated discs. these are made up of desmosomes and gap junctions
- desmosomes are: sticky- allow for neighbour fibres sarcolemmas to attach
- gap junctions: permit ion (Na+, K+, Ca+) passage, conduct AP
Autorhythmic Heart Fibres are the: ……………. cells.
How do they work?
PACEMAKER CELLS!
These create spontaneous AP’s that spread via gap junctions
- spontaneous= slower compared to neurons
-1) depolarisation from -60mV to -40mV (pacemaker potential) due to opening of funny channels= Na+ influx
2) At threshold: Ca+ influx= further depolarise (2nd depolarisation)
3) Repolarisation due to K+ efflux. Ca+ channels close
What is the sequence of Intrinsic conduction system?
1) SA node activates
- located at top R atrium
- AP spreads to R + L of atria via gap junctions
- myocardium contracts in L + R atria at same time
2) AV node- base of R atrium
- bottle neck affect = 100m/sec delay
- delay= allows for ventricles to fill with blood
3) AV Bundle (bundle of His)
- runs from AV node to upper section of interventricular septum
- vital for conduction of AP’s in atria to ventricles
4) R + L bundle branches
- R + L division
- purkinje fibres= run from branch and up ventricle wall. they have a large diameter which aids in conduction of AP’s= heart contractions
Arteries carry blood ………… the heart
away from
Veins carry blood ……. the heart
towards
Capillaries are the site of:
gas, nutrient and waste exchange
arteries and veins (blood vessels) have how many layers?
3, but they differ in thickness & composition
What are the layers in blood vessels?
I.M.E
1) Tunica Intima: innermost.
- endothelial cells= smooth= no friction
- arteries have layers of elastic fibres= aids distention + recoil
2) Tunia Media: middle
- elastic fibres + smooth muscle= aids vasoconstriction/dilation
- thickest in arteries
3) Tunica Externa: outer layer
- connective tissue
- fuse with adjacent tissue to anchor vessel
Do arteries or veins have higher pressure? Why?
Arteries. Due to narrow lumen
Do arteries or veins collapse when not filled with blood? why?
veins collapse due to large lumen and lack on elastic tissue. arteries do not - they have elastic tissue and narrow lumen.
Which artery is the largest in the body? Where are they found?
Elastic Artery. Found in the aorta & pulmonary trunk. They are so big that you can feel them distend on the surface of the skin.
Which artery is mainly responsible for vasoconstriction/dilation?
Muscular artery
What is the composition + size + quantity of arterioles?
- 1-2 layers of smooth muscle cells
- 15-300um
- roughly 400 million
What is the smallest blood vessel?
Capillaries.
- 5-10um
- around 20 billion of them
-common in metabolic active areas
-high surface area coverage= aids gas/nutrient/waste diffusion
- no tunica media or externa
What are the 3 types of capillaries? What are the compostition/structure and location found?
1) Continuous- most numerous, found in CNS, lungs, muscle, skin. Tube created by endothelial cells
2) Fenestrated- leaky/porous. Found in kidneys, small intesitne, choroid plexus, ciliary in eye.
3) Sinusoid- in liver, RB marrow, anterior pituitary. large diameter. very leaky. RBC and proteins travel through these.
Diastole is:
when the heart relaxes after contraction
Systole is:
when the heart contracts to pump blood out
Vasodilation is facilitated by:
- adrenaline/noradrenaline acting on Beta-2 receptors
- nitric oxide
- ions- Hydrogen or potassium
- histamine, heparin, bradykinin
- Hypoxia in systemic circuit= decrease oxygen
Vasoconstriction is facilitated by:
- adrenaline / noradrenaline acting on alpha -1 receptors
-Angiotensin II
-ADH (vasopressin) - hypoxia in pulmonary circuit
Filtration is driven by which 2 pressures? Which end- venous or arterial?
Arterial
1) Blood Hydrostatic Pressure
2) Interstitial Fluid osmotic pressure
Reabsorption is driven by which 2 pressure?
Venous
1) BCOP
2) NFP
