Cardio Flashcards
What does the left atrium receive, and where from
Oxygenated blood from 4 pulmonary veins
What does the right atrium receive, and where from
Deoxygenated blood from superior and inferior vena cava, and coronary sinus
What does the left coronary artery branch into
Circumflex and anterior interventricular arteries
What supplies the coronary sinus
Great and small cardiac veins
What is the vagus nerve
Brake: parasympathetic nerve (rest and digest) which innervates the SA and AV nodes to decrease heart rate
What are the sympathetic cardiac nerves
Accelerator: nerve from sympathetic trunk ganglion, increases heart rate by innervating nodes and increases force of contracting by telling cardiac muscle to release more calcium
What are auricles
Folds of atria to create potential space for extra blood
What is pectinate muscle
Ridges covering the interior walls of auricle and atrium to confer strength to the atria enabling their expansion
What is the first major artery that branches off the aorta
Brachiocephalic artery
What is the second major artery that branches off the aorta
Left common carotid artery
What is the third major artery that branches off the aorta
Left subclavian artery
What are the first arteries to branch off the aorta
Left and right coronary arteries
What structure delineates the change between the thoracic and abdominal aorta?
Diaphragm
Where is the SA node located
The junction of the superior vena cava and right atrium
What is the function of the SA node
Pacemaker: cells spontaneously initiate each cardiac action potential, and hence heartbeat
What is the function of the interatrial bundle
Conducts the action potential from the right atrium to the anterior part of the left atrium
What is the function of the internodal bundles
Conduct the action potential from the SA node to the AV node
What is the function of the AV node
Slows conduction of AP from atria to ventricles, ensures atria complete their contraction before ventricles are depolarised
What is the function of the left and right branches of the AV bundle
Conduct the AP from the AV node to the left and right ventricles
What is the function of the Purkinje fibres
Conduct AP to all parts of the ventricles
What are serous membranes
Membranes which secrete fluid to lubricate internal structures
What is the name of the loose sac covering the heart
Pericardium (fibrous and serous: pericardial space filled with pericardial fluid)
What are the three layers of the heart wall
Epicardium, myocardium, endocardium
Describe the epicardium
Visceral layer of serous pericardium**, as well as adipose, blood vessels and loose irregular fibrous connective tissue
Describe the myocardium
Thick, contractile muscular layer
Describe the endocardium
Thin inner layer of heart wall made of loose irregular fibrous connective tissue and simple squamous epithelium
What valve separates the right atrium and ventricle
Right AV valve: tricuspid
What valve separates the left atrium and ventricle
Left AV valve: bicuspid
What valve separates the pulmonary artery and right ventricle
Pulmonary semilunar valve (3 cusps)
What artery leaves the right ventricle
Pulmonary artery
What artery leaves the left ventricle
Aorta
What valve separates the aorta and left ventricle
Aortic semilunar valve (3 cusps)
What supplies the right atrium
Superior and inferior vena cava
What supplies the left atrium
The four pulmonary veins (two left, two right)
What is the function of chordae tendinae
Prevent AV valves from inverting when they snap shut due to ventricular pressure
What are papillary muscles
Finger like projections of ventricular myocardium attached to chordae tendinae
What is trabeculae carnae
Muscular, beam like structures on the inner surface of the myocardium forming ridges or bridges
What does the pulmonary trunk divide into
Right and left pulmonary arteries
What are the two types of connective tissue in the cardiovascular system?
Elastin for stretch and fibrocollagen for strength
What is the main difference between the blood and lymph vascular systems
Blood: continuous loop, lymph: one way drainage system
What is the pulmonary circuit
Heart and lungs
What is the systemic circuit
Heart and rest of the body
Where do lymph projections pick up overflow
In the interstitium of capillary beds
Where are major arteries situated to avoid damage
Deep in the trunk or on flexor aspect of limbs
What are the three types of capillary
Continuous, fenestrated, sinusoidal
What are the three pathways for drainage
Deep veins, superficial veins and lymphatics
What is the only pathway for supply
Arteries
Why can veins exist more superficially than arteries
Operate at a much lower pressure so less dangerous
Where is the apex located (point of maximal impulse)
Left mid clavicular line, between ribs 5 and 6
Describe the position of the heart in the thorax
Rotated to the left, base tilted posteriorly
What separates the two ventricles
Interventricular septum
Describe pericardium
Outer wall: parietal serosa/pericardium, serous fluid, inner wall: visceral serosa/pericardium
What is diastole
Relaxation
What is systole
Contraction
Describe the four valves during diastole
AV valves open, semilunar valves closed
Describe the four valves during systole
AV valves closed, semilunar valves open
How big are capillaries
RBCs must be single file (as close as possible to walls for exchange)
Describe cardiac muscle cells
Striated, short, branched, 1 (occasionally 2) central, oval shaped nuclei per cell (compared to multinucleated, peripherally located skeletal muscle). Cytoplasmic organelles packed at poles. Interconnected with neighbouring cells via intercalated discs
Describe mitochondria in cardiac muscle cells
Make up about 20% of the cell, can never run out of ATP!
What are the three types of intercalated discs
Adhesion belts, desmosomes and gap junctions
What do adhesion belts link
Actin to actin: vertical portion
What do desmosomes link
Cytokeratin to cytokeratin: vertical and horizontal portion
What do gap junctions link
For electrochemical communication: horizontal portion
Conduction pathways are not nervous tissue, but are
Modified cardiac muscle
Describe cardiac conduction cells
Some peripheral myofibrils, central nucleus, mitochondria, glycogen, lots of gap junctions, some desmosomes, few adhesion belts (1% of all cardiac cells). Bloated compared to contractile cells.
List the vessels of the cardiac circulation
Aorta, coronary arteries, myocardial capillaries, cardiac veins, coronary sinus, right atrium
What type of nerves can alter the rate of conduction node impulse generation
Autonomic nerves
What artery branches into the right subclavian and common carotid arteries
Brachiocephalic
Where are the intercostal arteries
Along the inferior aspect of the ribs
What artery supplies the spleen, stomach and liver
Celiac trunk
What is the branching of the aorta at the pelvis called
Aortic bifurcation
What are the two paths of the aortic bifurcation
Left and right common iliac
What do the left and right common iliac arteries branch into
External and internal iliac
Describe a possible pathway for blood to the foot
Aorta, common iliac artery, external iliac artery, femoral artery, popliteal artery, posterior tibial artery, plantar arch
Describe a pathway for the return of blood from the foot
Plantar venous arch, posterior tibial vein, popliteal vein, great saphenous vein or femoral vein, external iliac vein, common iliac vein, inferior vena cava
What is the great saphenous vein
A superficial vein from in lower limbs
What are the three layers of blood vessels
Tunica intima, tunica media and tunica adventitia
Describe the tunica intima
A simple squamous epithelium which lines the lumen of all vessels, a sparse pad of loose FCT cushioning the endothelium, an internal elastic lamina: condensed sheet of elastic tissue (more developed in arteries)
Describe the tunica media
Smooth muscle, variable content of connective tissue fibres, thickness proportional to vessel diameter and blood pressure. Much thicker in arteries than veins
Describe the tunica adventitia
Loose FCT (high collagen, variable elastin), contains vasa vasorum (vessels of the vessel) in larger vessels. Lymphatics and autonomic nerves also found in this region. Thicker in veins (limit extent of capacitance)
What does IEL stand for
Internal elastic lamina
What wall of the blood vessel is the IEL a part of
Tunica intima
How is pulsatile flow dampened into vessels
Elastic walls
What is an approximate healthy blood pressure
120/80 mmHg
What are the arteriole’s function
Resistance vessels of the circulation: determine blood pressure
What is the function of the capillaries
Exchange between blood and tissues
What is the function of the venules
Start of the drainage system
What are the main features of veins
Low pressure, large volume, unidirectional flow, capacitance vessels
What is a vascular bundle
Group of veins, arteries and nerves (run along similar pathways)
How do veins ensure unidirectional flow
Valves, tone of surrounding tissue (vein “flanked” by skeletal muscle)
What are the main features of capillary beds
Very thin walls, large CSA, slow and smooth blood flow, made of endothelial cells welded to themselves to form tube
What are precapillary sphincters
Rings of smooth muscle that constrict to stop blood running into side branches of capillary beds
What is shunting
The contraction of precapillary sphincters to move blood directly from arterioles to venules
What are continuous capillaries
Tightly welded endothelial cells, continuous basement membrane
What are fenestrated capillaries
Endothelial cells with fenestrations, continuous basement membrane
What are sinusoidal capillaries
Much wider (not primarily focussed on passive exchange) capillaries with large fenestrations and incomplete basement membrane.
How do continuous capillaries exchange
Diffusion through membrane (lipid soluble substances), movement through intercellular clefts (water soluble substances), transport via vesicles (large substances)
How do fenestrated and sinusoidal capillaries exchange
Diffusion through membrane (lipid soluble substances), movement through intercellular clefts (water soluble substances), transport via vesicles (large substances), movement through fenestrations (water soluble substances)
What are the functions of the lymph vascular system
An open entry drainage system: drains excess tissue fluid and plasma proteins, filters foreign material, screens lymph for foreign antigens, and absorbs fat from intestine
Describe the structure of the lymphatic system
Lymphatic vessels: large, blind ending capillaries
What do lacteals (special group of lymphatic vessels from small intestine) do
Drain fat laden lymph into collecting vessel called cisterna chyli (milk jug) (swelling of thoracic duct)
How does exchange occur across lymph vessels
Between endothelial cells, no tight connections
Features of lymph vessels
Thinnest walls, no RBCs, valves
Lymph node structure
Many afferent lymphatics, one efferent. Bathe immune cells for immune surveillance
Metastasis meaning
Movement of primary tumour to form secondary tumour
Where are lymph vessels
Wherever there are capillary beds there will be lymphatics
What are some examples of lymph nodes (locations)
Cervical (neck), axillary (armpits), inguinal (inner hip)
What are arteries
Blood vessels with blood flowing away from the heart
What are veins
Blood vessels with blood flowing toward the heart
What are the thick and thin filaments in a myofibril
Myosin: thick, actin: thin
How can the force of contraction be increased?
Stimulate cells to release more calcium = more cross bridges
How does cardiac contraction end
Ca2+ pumped back into sarcoplasmic reticulum by SERCA
What are the phases of the cardiac cycle
Atrial systole, atrial diastole, ventricular systole (isovolumetric contraction, ventricular ejection), ventricular diastole (isovolumetric relaxation, late ventricular diastole)
Atrial and ventricular systole can be described as
Mutually exclusive
The heart spends the most time in
Diastole
What is the lubb sound
AV valves snapping shut to prevent backward movement of blood from ventricles to atria (semilunar valves closed)
What is the dupp sound
Semilunar valves snapping shut after ventricular ejection
What is the longest phase of the cardiac cycle
Passive filling of atria and ventricles
How does the systemic circuit blood pressure compare to the pulmonary circuit
Much higher
What is systolic blood pressure
Highest point on a trace (~120mmHg)
What is diastolic blood pressure
Lowest point on a trace (~80mmHg)
What is pulse pressure
The difference between the highest and lowest points on a blood pressure trace
What is mean pressure
The average blood pressure across the full cycle (below mid point as heart spends more time in diastole)
What is hypertension
High blood pressure, can be life threatening over time
What is hypotension
Low blood pressure, life threatening immediately
Why do conduction cells have actin and myosin pushed to the periphery
To make room for glycogen and mitochondria
Where does the SA node transmit signals to
RA, LA and AV node
What is the interatrial bundle
Bundle of conduction cells from SA node, along RA to LA
What is quiescence
Passive refilling of heart with blood
What is the order of de and repolarisation of parts of the heart
Atria depolarise, atria repolarise, ventricles depolarise (interventricular septum, then walls), ventricles repolarise
What does an ECG measure
Changes in voltage (directionality of trace irrelevant)
What is the P wave
Atrial depolarisation
What is the QRS complex
Ventricular depolarisation and atrial repolarisation (tall, skinny peak as happens fast)
What is the T wave
Ventricular repolarisation
How do depolarisation and repolarisation relate to contraction and relaxation
Electrical event (first!!) causes mechanical event
How does MAP relate to cardiac output and resistance
MAP = CO * TPR
How is CO determined
CO = SV * HR (strength * speed)
How is blood pressure coordinated
Within the brainstem: afferent input from CNS and periphery
Where are baroreceptors located
Aortic arch, carotid artery, embedded within walls
How do baroreceptors work
Change frequency of their signal to provide information on blood pressure
What are baroreceptors
Stretch receptors
What is the body’s reaction to the tilt test
Stroke volume falls (work against gravity) hence CO falls, HR increases to combat this. TPR increases to help combat fall in blood pressure
How is flow related to pressure and resistance
Q = ΔP / R
You don’t have control of flow unless you have a high pressure
How does cardiac output directed to the heart change during exercise?
(Divergent flow depending on metabolic needs)
Increases
How does cardiac output directed to the brain change during exercise?
(Divergent flow depending on metabolic needs)
No change
How does cardiac output directed to the kidneys change during exercise?
(Divergent flow depending on metabolic needs)
Decreases
How does cardiac output directed to the abdominal viscera change during exercise?
(Divergent flow depending on metabolic needs)
Decreases
How does cardiac output directed to the skin change during exercise?
(Divergent flow depending on metabolic needs)
Increases
How does cardiac output directed to other tissues change during exercise?
(Divergent flow depending on metabolic needs)
Decreases
How does cardiac output directed to skeletal muscle change during exercise?
(Divergent flow depending on metabolic needs)
Increases
How is peripheral resistance changed
Precapillary sphincters
How are resistance and radius of blood vessel related
R = 1/r^4 : Small change in radius = huge change in resistance (*16)
Where do we store extra blood in our body (can lose some blood and be fine)
Veins: capacitance vessels
What is compliance
The extent to which a vessel allows deformation in response to an applied force
What is the formula for compliance
ΔV / ΔP = compliance
What is venous pooling
Movement of blood down body to accumulate near feet due to gravity and low pressure of veins
What counteracts venous pooling
Valves and tone of surrounding tissue (especially skeletal muscle as it can alter its tensile state)
What is starling’s law of the heart
(Increased venous return means increased stroke volume)
The more stretched muscle fibres are before a contraction, the stronger the contraction will be: i.e the heart will contract more strongly if there’s more blood in the heart
Which blood vessel has the thickest tunica media
Artery
Which blood vessel has the thickest tunica adventitia and why
Vein, to limit capacitance capability
What is the R-R interval
Time between two R wave peaks (used to determine heart rate)
What is the Q-T interval
Time between the start of Q wave to end of T wave
What is the P-R interval
Time from start of P wave to start of Q wave
What are the three general functions of blood
Transport, immune response and coagulation
What does blood transport
Good stuff out, bad stuff in. Oxygen, water, nutrients, carbon dioxide, waste products, ions, heat, hormones, immune cells, coagulation factors
How does coagulation happen
Via platelets and coagulation factors in plasma
What is blood composed of
55% plasma, 45% formed elements
What is plasma composed of
Plasma proteins, other solutes, water
What are formed elements composed of
Platelets, white blood cells, red blood cells
What is hematopoiesis
Formation of blood cells
Where does hematopoiesis occur
In red bone marrow, which contains hemocytoblasts
Why are red blood cells biconcave
Large SA:V ratio, allow efficient diffusion of gases, flexibility for movement through narrow capillaries
What are the functions of RBCs
Contain large ammounts of hemoglobin for transporting oxygen (need iron to bind oxygen)
What is hematocrit (or packed cell volume, PCV)
The fraction of blood occupied by red cells
What is anemia
Low levels of hematocrit, often associated with iron deficiency
What is polycythemia
High levels of hematocrit resulting in very viscous blood, heart has to work very hard, vessels put under a lot of strain
What is erythropoiesis
Generation of red blood cells
What is erythropoietin (EPO)
Something which stimulates erythropoiesis
What hormone augments erythropoiesis
Testosterone
Which layer of the heart wall is vascular
Epicardium
