Flashcards in CVS Deck (72)
How much blood is there is a normal man? And how much is stored in the veins?
6L in body
3.9 in veins
Which vessels come off the arch of the aorta (right to left)?
Brachiocephalic, left common carotid, left subclavian.
Note: right and left coronary Arteries come off the ascending aorta
What are the 3 main types of arteries?
Elastic conducting - widest
Muscular distributing - most named arteries
Arterioles - narrowest
What is the tunica intima?
Inner layer of an artery containing an endothelium and subendothelium of connective tissue with internal elastic lamina.
Describe the structure of large arteries
TM - 40- 70 fenestrated elastic membranes. Smooth muscle cells (create the fibres) and collagen bundles. May contain external elastic lamina.
What is the tunic adventitia?
Outer layer of arteries.
Often contains vasa vasorum, lymphatic vessels and nerve fibres. E.g. To stimulate vasoconstriction via diffusion of noradrenaline causing depolarisation of tunica media cells.
Describe the structure of muscular arteries
TM: 40 layers of smooth muscle cells (connected via gap junctions) with a prominent external elastic lamina.
What are end arteries?
Terminal artery supplying all or most of the blood to a body part - not branching with other arteries.
E.g. Coronary, splenic and renal
Describe the structure of Arterioles
TI - sometimes just endothelial cells
TM - 1-3 layers of smooth muscle
Internal elastic lamina only present in larger.
No external elastic lamina.
TA is scant.
Describe the structure of metarterioles
Supply blood to capillary beds.
Non continuous smooth muscle layer
Each muscle cell encircles the endothelium of the capillary functioning as a sphincter controlling blood flow at every branch entering a capillary bed.
Describe the general structure and function of capillaries and list the 3 types.
Largest surface area. Up only holds 5% of blood.
Single layer of endothelium and basement membrane.
Continuous capillaries, fenestrated capillaries, sinusoid/discontinuous capillaries.
Describe continuous capillaries.
Found in nervous, muscle, connective, exocrine gland and lung tissues.
Continual layer of epithelium with cells joined by tight occlusive joints.
Pericytes are found around them and are capable of becoming fibroblasts or muscle cells in wound healing.
Describe fenestrated capillaries and the 4 routes of diffusion.
Found in gut, endocrine glands and renal glomerulosus.
Windows in endothelium bridged by a thin diaphragm.
4 routes of diffusion:
Through basement membrane
Through intercellular cleft
Describe sinusoid/ discontinuous capillaries
Found in spleen liver and none marrow.
Large diameter and slow blood flow.
Gaps exist allowing whole cells to move in and out of tissue and blood.
Describe postcapillary venules
Simple endothelium and Pericytes.
Low pressure so blood drains into them.
Compare corresponding veins and arteries.
Veins are bigger and have valves.
Arteries have bigger TM (I leg there is large TM to resist distension)
As veins get bigger TI and TA increases.
Veins contain less elastic fibres.
What are Venae comitants?
Veins wrapped around arteries.
Normally in pairs.
Pulsing of artery promotes Venus return.
What is the min and max blood flow to all tissues in the body?
5l.min-1 and 24.5
Describe the layers of the pericardium.
Serous pericardium: parietal pericardium (fused to fibrous) and visceral pericardium ( part of epicardium)
Where is the coronary sinus and great cardiac vein found?
Sinus: posterior of the heart, between left atrium and ventricle to the left of the inferior vena cava running to the left of the inferior left pulmonary vein. Great cardiac vein is the largest vein going into it on the left pulmonary vein side.
What are the rough muscular anterior walls of the atrium made of?
What is the fossa ovalis?
Ruminant of the Foramen ovale on the interatrial septum.
What muscles line the interior of the ventricles?
What do chordae tendineae do?
Attach free free edges and the ventricle surfaces of the cusps of the tricuspid valve to the papillary muscles.
What are the papillary muscles?
Muscle projections of the ventricle wall which attach to chordae tendineae. This prevents the cusps prolapsing into the atria during ventricular systole.
How is the fibrous pericardial sac connected to the diaphragm?
It is continuous via the central tendon of the diaphragm
Describe the location of the right descending coronary artery
Posterior of the heart where the right artery splits, it is the descending artery.
Describe he location of the right marginal artery.
Main branch coming off the right artery on the anterior surface.
Describe the locations of the left anterior descending artery and the left circumflex artery.
First split of the left coronary artery under left auricle. Circumflex goes round to posterior of heart. Left anterior descending splits and stays anteriorly come down between ventricle and atrium.
Describe the location of the left marginal artery.
Comes of the left circumflex artery and descends on the left side.
Where is the great cardiac vein?
Just superior to the right circumflex artery on the posterior surface but originates on the anterior surface ascending on the right side. The joins the coronary sinus on its most left, superior point,
Describe the locations of the middle and small cardiac veins
Both posterior, small is next to right coronary artery to the right. Middle is descending by the posterior descending artery.
Difference between cyanosis and asyanotic conditions?
Cyanotic there is a lower oxygen saturation due to deoxygenated blood getting into systemic circulation.
What is tetralogy of fallot?
Pulmonary valve stenosis, right ventricular hypertrophy, VSD and overriding aorta
What is tricuspid atresia and what is needed for it to be compatible with life?
Missing valve. An ASD is needed or PFO along with PDA or VSD so blood can get into the pulmonary circulation.
Describe hypoplasic left heart
Underdeveloped left ventricle and ascending aorta. VSD/ PDA needed along with a ASD or PFO
Where does a VSD normally occur?
Membranous portion of the ventral septum
What is eisenmengers syndrome?
Left to right shunt, increases blood flow to pulmonary circulation, vascular remodelling occurs and there is increased pulmonary resistance, causes increases pressure in right side of heart so blood may flow right to left.
Functional Importemce of transposition if the great vessels?
2 sererate circuits- leads to death without a shunt.
Effects of coarctation of the aorta
Narrowing at ligamentum arteriosum. Left ventricular hypertrophy. Blood supply reduced to lower body. Hypertension in limbs and head. Heart failure.
What does lateral folding achieve with regards to the primitive heart?
2 primitive cardio genie tubes together to create the heart tube
Name the regions of the developing heart.
Sinus venosus- atria - ventricle - bulbus cordis, trucus arteriosus, aortic roots.
Explain the process of folding.
5 days long occurs at day 23.
Cephalic portion grows caudally and dorsally.
Caudal portion grows cranial sand ventrally until both inflow and outflow are cranially.
Anterior in the embryo?
Thumb, posterior pinkie so cranial.
How is the transverse pericardial sinus formed?
Space between inflow and outflow at the end of looping
Describe the development of the atria
Sinus venosus is originally symmetrical but the right side grows and left side shrinks.
Right atrium forms from mostly the primitive atria and part of the sinus venous.
Left atrium forms from mostly the pulmonary veins and part of the primitive atrium.
Describe in brief the development of the great vessels
Originally a symmetric system of 6 arches.
4R becomes subclavian.
4L becomes arch of aorta
6R and L become pulmonary arteries
Describe the location of the recurrent laryngeal nerves
Both loop around level 4 (subclavian and arch of the aorta) to join the left and right vagus nerves.
Left recurrent laryngeal nerve runs just to the right of the ligamentum arteriosum.
Describe how atrial septal ion occurs.
Endocardial cushions form in the atrioventricular region which divide the heart into left and right channels.
Septum premium grows down the atria towards the Endocardial cushions, leaves a hole before it joins called ostium premium.
Ostium premium closes and ostium secundum appears.
Septum secundum and grows down, starting as a crescent shape on septum primuim.
Fossa ovale forms in the growing septum secundum.
Acts as a r->L shunt.
Describe how ventricular septation occurs
Ventricular septum grows up towards Endocardial cushions but leaving a hole called the 1degree intra ventricular foramen.
This is closed via a membranous portion of connective tissue derived from Endocardial cushions.
Describe the development of atria
Right from sinus venosus and most of primitive atrium and left from pulmonary veins and a little of primitive atrium
Symmetrical bilateral system.
4 becomes aorta Nd right subclavian.
6 becomes pulmonary arteries
What is viscosity and how does it relate to velocity?
Viscosity is how must the fluid layers resist sliding over each other.
As it decreases, velocity increases.
Link between radius and resistance
Resistance decreases with increases forth power of radius.
Origin of parasympathetic vs sympathetic
Craniosacral vs thoracolumbar
What are chromatin cells
In adrenal medulla, Innervated by pre ganglionic sympathetic. Secrete adrenaline into blood stream
Which receptors cause SM constriction/ dilate tigon
A1 = constriction
B2 = dilatation
Explain the AP in a cardiac myosotis
Transient K+ efflux.
Ca in (some K out)
Describe pacemaker action potential
Funny current (If) Na in. Done through HCN channels (hyperpolarisation activated (lower than -50mV)). And some ca?
How does contraction occur in smooth muscle and what inhibits this?
Ca in. Binds to calmodulin. This complex activates MLCK (myosin light chain kinase) this phosphorylates and activates the myosin head so the muscle can contract.
PKA inhibits MLCK
Where may a third and forth sound be heard?
Early diastole and atrial contraction respectively.
Describe the pressure changes in the internal jugular vein
Atrial contraction so pressure increases dramatically. A
Decreases due to atria relaxing. X.
Slight increase during x for ventricular contraction pushing tricuspid valve into atria. C.
Increase in pressure due to atria being full. V.
Fall in pressure as tricuspid opens at beginning of diastole. Y.
Normal range of CVP?
Pressures in heart:
Ra = 4
Main action and innervation of biceps femoris
When flexed it laterally rotates leg and extends thigh.
Long head is tibial division of sciatic and short head is fibulae division
Main action and innervation of semi membranosus and semi tendinosus
Flex knee extend thigh and medial rotation when knee is flexed.
Tibial part of sciatic nerve
Nerves that Innervated the heart?
Phrenic nerve- pericardium
Vagus nerve- parasympathetic
Sympathetic chain of ganglia.
Acute circulatory failure with inadequate or inappropriate distributed tissue perfusion so that there is a generalised lack of O2.
Describe cardio genie shock
Failure of the heart to pump enough blood e.g. Ischemia or arrhythmias.
Describe mechanical shock
Cardiac tamponade affecting filing or occlusion in pulmonary system.
Describe hypovolaemic shock
Haemorrhage and reduced blood volume.
Fluids/ blood given
Sympathetic - cold wet