Extra Cardio PHYS Flashcards
What is isovolumetric contraction.
Ventricular contraction when all valves are closed. This increases ventricular pressure but as the valves are closed the volume remains unchanged.
What is the duration of systole?
Diastole?
0.3s
0.5s
What is end systolic volume?
The volume of blood remaining in the LV following systole
Define preload.
The initial stretching of the cardiac myocytes, or The volume of blood in the ventricles just before contraction (EDV).
Define afterload.
The pressure against which the heart must work to eject blood in systole.
Define contractility.
The inherent strength and vigour of the heart’s contraction during systole.
Define elasticity.
Myocardial ability to recover it’s original shape after systolic stress.
Define compliance.
How easily a chamber of the heart expands when it is filled with blood (C=ΔV/ΔP).
Define diastolic distensibility.
The pressure required to fill the ventricle to the same diastolic volume.
Give the equation for mean arterial pressure.
MAP = DP + 1/3(SP-DP).
(SP - systolic pressure, DP - diastolic pressure).
5
Give the equation for blood pressure.
BP=COxTPR.
What do arterioles respond to?
Blood pressure changes. Local, neural and hormonal factors.
Name 2 local factors that result in vasoconstriction.
Endothelin, internal BP.
Name 5 local factors that result in vasodilation.
Hypoxia, NO, K+ (accumulate from AP), CO2, H+, adenosine.
What neural factors result in vasoconstriction?
Sympathetic nerves that release noradrenaline.
What neural factors result in vasodilation?
NERUAL - Think nervous system
Parasympathetic innervation.
Name 3 hormonal factors that result in vasoconstriction.
Angiotenisn 2, ADH, Adrenaline (binds to alpha-adrenergic receptors in smooth muscle).
Name 2 hormonal factors that result in vasodilation.
Atrial natriuretic peptide, Adrenaline (binds to beta2 receptors).
Myogenic auto-regulation of blood flow: What is the response to an increase in BP?
Increased BP will result in vasoconstriction and so blood flow decreases.
Myogenic auto-regulation of blood flow: What is the response to a decrease in BP?
Decreased BP will result in vasodilation and so blood flow increases.
What is the cause of active hyperaemia?
When blood flow increases due to an increase in metabolic activity.
- Increased metabolic activity = decreased O2 and increased metabolites = arteriolar dilation = increased blood flow.
What is the cause of reactive hyperaemia?
When blood flow increases following occlusion to arterial flow.
Describe excitation-contraction coupling.
Pathway
1. Action potential causes wave of depolarisation across myocardium —> induces a Na+ sodium ion influx relative to the potassium
2. Plateau phase - Ca2+ coming into cells causes more calcium to be released from sarcoplasmic reticulum inside myocytes. -Ca2+ induced Ca2+ released.
3. The Ca2+ bonds to specific proteins Troponin C –> Troponin C changes shape, and sits on tropomyosin. This moves the tropomyosin away from myosin head, so actin myosin bridges can form
(after this, ATP needed to break bridges so myoisn can move along (muscle can relax))
==> ATP also needed to actively transport Ca2++ back to sarcoplasmic reticulum
After depolarisation, Ca2+ is returned to SR. K+ outflow = repolarisation.
What effect does myocardial contraction have on the
A) A-band of a sarcomere?
B) I band?
c) H Zone
a) stays the same
B and C - get shorter
What is the I Band ?
What is the H band?
What is the A band?
I band - region containing only Thin filaments
H band (the region containing only thick filaments)
A band - just the size of the thick myosin filaments
What is the function of troponin C?
Troponin C has a high affinity for Ca2+. TnC drives away TnI and so allows cross bridge formation.
Where are peripheral chemoreceptors found?
What do they respond to?
What connects them to to the brain
Aortic arch and carotid sinus
Monitor changes in pO2 and pCO2, and conc of H+ ions for pH of blood
(but primarily changes in pO2)
Aortic arch = vagus nerve
cartoid sinus - Glossopharyngeal
What changes can the cardiac centre make in terms of vascular control?
has Sympathetic fibres which alter the diameter of blood vessels (vasoconstriction)
And has Cardiac accelerator centre to increase heart rate and contractility (sympathetic)
and has cardiac decelerator centres to lower heart rate (parasympathetic)
To summarise, what is can the sympathetic autonomic nervous system change?
SYMPATHETIC = increasing The Heart rate, heart contractility, and diameter of blood vessels
PARASYMPATHETIC = Decreasing heart rate only
Chemorecpetors - what change would happen when chemoreceptors pick up
low pO2, high pCO2, and acidaemia?
Sympathetic nervous system REDUCES blood vessels diameter, leading to VASOCONSTRICTION and increase TPR
Also would limit blood flow to peripheral organs and give more to heart and brain, cause vasoconstriction in veins for increased EDV, more preload
Leads to increased BP and CO
What does sympathetic activity leading to increased CO and BP achieve?
pushes more blood to the lungs so more CO2 and be breathed out and more O2 can be breathed in? (to lower hypercapernia and raise hypoxia)
Where are central chemoreceptors located? what do they measure
They are in the medulla oblongate
Measure the PCO2 and pH of the CSF
===> the CO2 breakdown into H+ ions
What do central chemoreceptors do?
Arteriolar and venous constriction , which pumps more blood to the brain so BP in brain > than CSF pressure, and more blood goes to brain
What layer of the tri-laminar disc forms the cardiovascular system?
The mesoderm.
What does the TRUNCUS ARTERIOSUS - gives rise to
AORTA, AORTIC ARTERIES moves down and to the right
what does BULBUS CORDIS - gives rise
RIGHT VENTRILE , AND OUTFLOW TRACTS, moves down and to the right
What does PRIMITIVE VENTRICLE -give rise to
the left ventricle
What does PRIMITIVE ATRIUM -give rise to
gives rise to LEFT ATRIA
What does SINUS VENOSUS -give rise to
gives rise to RIGHT ATRIA, VENA CAVA AND CORONARY SINUS (pulmonary vessels
What affect does parasympathetic stimulation have on heart rate?
Decreases heart rate (-ve chronotropic). Cardiac output therefore decreases with parasympathetic stimulation. (CO=HRxSV).
What affect does sympathetic stimulation have on the heart?
○ Increase in Heart rate (positive chronotropic effect)
○ Increase in Force of contraction (positive ionotropic effect)
More Ca2+ entering myocyte,
More action potentials triggered
More contractility and cardiac output
What membrane channels are responsible for the plateau period in the cardiac AP?
Voltage gated Ca2+ ‘slow’ channels.
Briefly describe the cardiac action potential in 5 steps.
potential in 5 steps.
- Na+ channels open; influx of Na+ into cell; depolarisation.
- When the Na+ channels close, a small number of K+ leave the cell resulting in partial repolarisation.
- Ca2+ channels open and there is Ca2+ inflow. K+ channels are also open and there is K+ outflow. This results in the plateau period.
- Ca2+ channels close and K+ channels remain open. K+ leaves the cell resulting in repolarisation.
- Maintaining the resting potential (approx -90mV). Na+ inflow, K+ outflow.
Where is the SAN located?
In the RA under the crista terminalis.
Why is there rapid conduction in the bundle of his and purkinje fibres?
- The fibres have a large diameter.
- There is high permeability at gap junctions.
What is the function of the refractory period?
- It prevents excessively frequent contractions.
- It allows time for the atria to fill.
What does the P wave on an ECG represent?
What is the duration of the P wave?
Atrial depolarisation. Duration is less than 0.12s.
What does the QRS complex on an ECG represent?
What is its duration?
Ventricular depolarisation.
Duration is 0.08-0.1s. Similar to the P wave
What does the T wave on an ECG represent?
Ventricular repolarisation.
What might an elevated ST segment be associated with?
Myocardial infarction.
The ventricles are repolarising (relaxing) less, so less EDV and CO
What happens in the first step of the platelet plug, after endothelin has caused local vasoconstriction?
What receptor?
Von Willebrand factor binds to exposed collagen that from damaged vessel - using GP1b receptor
Platelets release alpha and electron dense granules.
What is in alpha?
What is in electron?
What do they both do?
Release electron granules for energy (ADP, ATP, Ca2+, Thromboxane A2)
Release alpha dense granules mediate formation of the scaffolding (Platelet dense factor, Von Willebrnad factor, Fibrinogen, Heparin antagonist)
Electron for Energy
alFA dense granules for scaFFolding
What after platelets have binded to VWF on collagen, what happens to them?
become activated and release their alpha and electron dense granules.
Change to a branches, sudapoid shape.
What is the point of the coagulation cascade? What does it do?
forms fibrin mesh to increase integrity of platelet plug formed.(extra scaffolding)
Can be activated by intrinsci or extrinsic pathway
What is the intrinsic pathway?
What is the extrinsic pathway?
Intrinsic pathway - From damage to BV that happens inside the blood vessel, uncommon - 12 > 11 > 9 > 8 >10
Extrinsic pathway - from damage outside more common 3 > 7 > 10
Both lead to common pathway, 10 > 5 > 2 > 1
What is factor 1 called- what is its inactive and active name?
Factor 1 is called fibrinogen activated becomes fibrin ,
Inactive form fibrinogen is soluble, fibrin is not soluble, - leads to FIBRIN MESH THAT SECURES CLOT
What is plasmin, and what is its purpose?
Plasmin eats fibrin, reverts back to fibrinogen back into inactive form, so no longer scaffolded the platelet plug so platelets fall away and leave tissue
degrades fibrin meshwork in the secondary platelet plug
Plasminogen —> Plasmin
what does having A blood type mean?
have A antigens, so would make/have B antibodies
what does having AB blood type mean?
have A and B antigens on your blood cells, so would make no Antibodies
What does having O blood type mean?
have no anitgens (think O) so have both A and B antibodies
What is the univseral donator?
Acceptor?
AB+ = UNIVERSAL ACCEPTOR
O - = UNIVERSAL DONAR
Outline +- blood types
Positive cannot donate to negative
Negative can donate to a positive
Why isnt ABO blood type an issue for a mother/baby?
Becuse these types of antigens CAN’T cross the placenta
What does Rhesus D postive mean ? What about Rhesus D negative?
What are its implications
Rhesus positive means the D antigen is present. Rhesus negative means the D antigen is not
present
IT is a peptide antigen, made by spleen, can cross the placenta
What are its implications
Outline the conditions for haemolytic disease of the new-born
• Mother has Rhesus NEGATIVE blood (RhD negative) and baby has Rhesus
POSITIVE blood (RhD positive). ==> Mum dd and Baby Dd
In pregnancy, mothers immune system recognises foreign Rhesus positive
blood and begins making antibodies against babies blood
FIRST baby is unaffected since it takes time for antibodies to be produced, the mother is said to
be SENSITISED to Rhesus positive blood
However, if mothers second baby also has RhD positive blood, then when mothers
blood is exposed to babies, antibodies are produced IMMEDIATELY and begin
DESTROYING BABIES RED BLOOD CELLS - resulting in HAEMOLYSIS OF
FOETUS/NEWBORN = ANAEMIA AND JAUNDICE.
define haematocrit
the ratio of the volume of red blood cells to the total volume of blood
What is found in the Anterior mediastinum?
Thymus
What is found in the Middle mediastinum?
Heart
Ascending aorta
Pulmonary trunk
What is found in the Posterior mediastinum?
Descending aorta
Oesophagus
Azygous system of veins
Thoracic duct
What is found in the Superior mediastinum?
Superior vena cava
Arch of aorta
What is the stimulating hormone for Leuckocyte production ?
granulocyte colony stimulating factor GCSF
What is the hormonal factor involved in Platelets?
Thrombopoietin is the hormonal factor
poetin =(stimulating factor) ?
(think Erythropoietin for Erythrocytes/RBC)
what is the name of the precursor to all blood cells?
What about the One after this for RBC?
Haemomatocytoblast - percussor to all blood cells
Haemomatocytoblast - Proerythroblast –> RBC
what are the two types of WBC?
Give examples of both
GRANULOCYTES - PHILS
NEUTROPHIL, EOISINOPHIL, BASOPHIL, - APPEAR GRANULATED ON HISTOLOGICAL SLIDES
AGRANULOCYTES - CYTES
MONOCYTES AND LYMPHOCYTES
Granulocytes - what is the role of neutrophils? How do they appear?
key mediators of acute inflammatory response, key in bacterial infection Mulitlobed, so many different lobed regions, faint granules
Granulocytes - what is the role of Eosinophils? How do they appear? Appearnece of Nucleus?
Fight parasites. PINK GRANULES - (THINK HAEMOTXYCIN AND EOSIN)
BI LOBED
Release antihistamines, to decrease allergic response. Bind to IgE receptors, to almost competitively inhibit histamines
Granulocytes - what is the role of Basophils? How do they appear?
Basophils contain histamine granules and cause local inflammatory responses through their interaction with IgE. Their role in the immune system is poorly understood but they potentially mediate type I hypersensitivity reactions alongside mast cells
DARK BLUE GRANULES, B FOR BLUE AND BASOPHIL
Agranulocytes - what is the role of Monocytes? How do they appear?
- Immature cells that can become macrophages, phagocytose. Kidney bean shaped nucleus. Also ivolved in bacterial infection
Resident macrophages in places
Mono = Macro
They also secrete cytokines, which modulate the immune response
Agranulocytes - what is the role of Lymphocytes? How do they appear?
Cell mediated innate immunity, adaptive response, for specific immunity - BIG NUCLUES, SMALL CYTOPLASM
They are the smallest, and respond to virus infections
What is chemotaxis?
tissues produce chemokines which recruit neutrophils allowing neutrophils to hone in to the site of infection.
The recruitment of Neutrophils through tissues producing cytokines which allow neutrophils to hone in on the site of infection
what are the 3 main types of lymphocyte? (a type of agranulocyte, with big nucleus?)
Natural killer cells -
T cells
B cells
What is the function of Natural killer cells? (Type of lymphocyte)
NK cells provide NON - SPECIFIC immunity against cells displaying foreign proteins such as cancer cells and virally- infected cells. They make up less than 5% of circulating leukocytes.
What is the function of T Cells? (Type of lymphocyte)
T cells form in the bone marrow but mature in the thymus. They are part of the adaptive immune system and are involved in cell-mediated immunity.
Once active, CYTOTOXIC T cells can directly attack infected cells. In addition, HELPER T cells have many functions including activating B cells and forming memory T cells which respond on re-infection.
What is the function of B Cells? (Type of lymphocyte)
B cells form and mature in the bone marrow. They are part of the adaptive immune system and involved in humoral immunity by secreting antibodies
What does NO do to platelets?
What does Prostacyclin do?
NO inhibits platelet adhesion
Prostacyclin inhibits platelet aggregation.
===> (both are vasodilators)
What does Ionotropic mean?
What does Chronotropic mean
Ionotropic = to do with FORCE of heart contraction
Chronotropic = to do with HEART RATE
What are the progenitors for platlets called?
Megakaryoblasts
Describe how antibodies are specific to one antigen.
Antibodies are bound to antigens via the variable region (1)
- The variable region determines the specificity of the antibody to the different
amino acids that it contains, which change the shape of the antigen binding
site (1)
What does the RCA supply?
( SA node, AV Node, Posterior IV septum)
What does the Right Marginal supply?
(Right Ventricle and APEX)
What does the Posterior Descending Artery supply?
(Right ventricle, Left Ventricle, Posterior 1/3 of IV septum)
what does the LCA supply?
(Left atrium, Left Vent. Septum and AV node and Bundles of His)
What does the LAD supply?
Goes between vents, (Anterior 2/3 of Septum, Right Ventricle and Left Ventricle)
What does the left circumflex artery supply?
flexes around to the posterior (Left Atria and Left Vent.)
What does the left marginal artery supply?
Left Marginal Goes around margin of heart (Left ventricle)
Where is the RCA found?
In the atrio-ventricular sulcus
On what aspect of the heart would you find the left atrium?
The posterior aspect. It is closely related to the oesophagus.
In 90% of hearts where does the posterior inter-ventricular artery arise from?
RCA
In 30% of hearts where does the posterior inter-ventricular artery arise from?
The circumflex artery.
In 20% of hearts where does the posterior inter-ventricular artery arise from?
The RCA and the circumflex artery
What is the ion channels that maintain action potentials in the SA and AV nodes?
L type Ca2+ channels
whereas T type are used in
initiating them in the SAN and AVN.
Which of the following is the correct order of conduction in the heart?
SA node > AV node > Bundle of His > Bundle branches > Purkinje fibres
