BLOCK 2 Flashcards
What is the effect of angiotensin II in the kidney?
Increases activtiy of Na+/H+ exchanger
effect of beta blockers?
Inhibit insulin release
What is the role of ACE enzyme during hypotension?
Breaks down bradykinin, a potent vasodilator
Effect of progesterone on respiratory centre?
Increases tidal volume and ventilation due to increased CO2 sensitivity
What causes increased cardiac output?
Increased stroke volume
What is the physiological response to hypoxia?
Vasoconstriciton of pulmonary arteries, increased tidal volume and RR
What is lung compliance?
Ability to expand- the greater the elastic recoil, the lower the lung compliance
What is pulmonary oedema?
Alvoeli fill with fluid that exert mechanical stress to reduce lung compliance
What is the effect of irritant receptors when activated?
Bronchospasm
Where are the inspiratory and expiratoryneurones found?
Medulla
What is the ventral group?
Neurons in medulla which cause forced voluntary expiration, such as cough. It sends inhibitory impulses to pontine apneustic centre.
What is the pneumotaxic centre?
Upper pons area which ihnibits inspiration and fine tunes RR.
What is the apneustic centre?
Located in lower pons which stimulates respiration. Inhibited by pneumotaxic centre to reduce respiration.
What do central cehmoreceptors respond to?
Located in medulla and respond to increased H+ in brain interstital fluid.
What depresses the respiratory medullary centre?
Opiates
Effect of lung stretch receptors?
Reduces RR rate
Where does automatic involuntary control of respiration occur?
Medulla
What is the role of type 1 pnuemocytes?
Gas exchange
Clara/club cells
Produce lysosyms and glycosaminoglycans found in the terminal bronchioles. They are columnar/cuboidal with microvilli. They are non ciliated and don’t produced mucous
Pleural pressure
Pressure surronding lung in pleural space. It is negative if it is below atmospheric pressure when doing quiet breathing.
What is the function of pulmonary surfactant?
Reduces surface tension in alevoli to prevent collapse and reduce effort of breathing
What is metabolic acidosis?
Caused by gain of acid such diabetic ketoacidosis due to severe insulin deficiency, Addison’s disease with excess cortisol or diarrhoea with loss of bicarbonates.
What increases lung compliance?
Age and emphysema which reduce elastic tissue.
What decreases lung compliance?
Pulmonary oedema, pulmonary fibrosis due to increased elastic tissue.
What is respiratory acidosis?
Caused by hypoventilation which increases CO2 due to oedema, COPD or sedatives like benzodiazeopine for anxiety or opiate overdose. There is excess H+ excretion and HCO3- retainment to compensate.
What is metabolic alkalosis?
Increase in bicarbonate levels due to activation of renin-angiotensin-aldosterone system which causes aldosterone release for reabsoprtion of Na+ for loss of H+ via exchanger. This occurs in Cushing’s syndrome, with diuretics, congenital adrenal hyperplasia which increase BP. Loss of H+ can cause metabolic aklaosis due to vomiting that loses stomach acid.
What is respiratory alkalosis?
Hyperventilation causing loss of CO2 due to hypoxia in high altitude or pulmonary embolism, CNS stimulation due to stroke or haemhorrage,
What stimulates central chemoreceptors?
Arterial CO2
How does hypercapnia affect the brain?
Causes cerebral vasodilation which may increase intracranial ressure
Trachea origin
C6 and terminates in T4/T5 for bifurcation
Functional vital capcity- normal
Obstructive conditions
Normal FEV1/FVC
Restrictive lung disease or normal lungs
Low FEV1/FVC
Obstructive lung disease
Functional vital capacity- low
Restrictive lung disease
What is an obstructive lung disease?
Airflow blockage due to emphysema, chronic bronchitis, asthma, bronchiectasis
What is a restrictive lung disease?
Reduced lung elasticity or chest eall expansio n that reduces volume that lungs can hold. Includes pulmonary fibrosis, pulmonary oedema and penumonia. These decrease lung compliance.
Where is rhythm of breathing cotrolled?
Medulla
Where does troponin I bind to?
Actin to hold troponin-tropomyosin complex in place
How do cardiac myocytes interact?
Via gap junctions.
Which muscles do not have a neuromasuclar junction?
Cardiac myocytes
Which part of the heart depolarises the fastest?
SA
What is normal ejection fraction?
55-75%
Location of baroreceptors?
Caortid sinus located in the internal carotid artery and aortic arch which detects BP
Starling’s law
Higher EDV , higher the stroke volume to a point. Venous return increases stroke volume
What phase in the ECG has slow calcium influx?
Phase 2
Effect of inhibiting Na+/K+ ATPase
Increases myocradial contractility but reduces arrythmia
Afterload
Force to overcome for contraction
What increases afterload?
Ventricular dilation which is when the ventricle dilates
Effect of stimulation of baroreceptors
Parasympathetic discharge to the SA node to decrease firing
Location of arterial barorceptors
Carotid sinus and aortic arch
PR interval
Time taken for excitation to spread from SA to the ventricles Delay at the AV node to cause atrial contraction. Then, there is conduction of AV node and AV bundle of His
What is the indication of tall T waves?
Hyperkalemia and ischaemic heart disease
What is the indication of T wave inversion?
Ischaemic heart disease
Absence of P wave
Issue with atrial depolarisation-> atrial fibrillation.
Atrial fibrillation
Chaotic signal from SAN which override pace maker cells which causes unsynchronous contraction of ventricles and atria. Associated with mitral valve disease
What is valvular heart disease?
Leaks blood back into chambers
What is S1 sound?
Lub sound caused by the atrioventricular mitral and tricuspid valves closing
What is the S2 sound?
Dub sound caused by the aortic valves closing.
What is stenosis?
Stiffening of the aortic valve which causes heart murmur
What is regurgitation?
Backflow of blood that causes heart murmur
What does troponin T bind to?
Tropomyosin
Cardaic output
Heart rate x stroke volume
ST segment
Ventricular depoalrisation- indicator for myocardial infarction
How to find stroke volume?
EDV- ESV
Action of Atrial natriuretic peptide
Antagonist of angiotensin II
B-type natriuretic peptide
Suppresses sympathetic tone and inhibits renin-angiotensin II
What is the role of renin
Angiotensionogen II to angiotensin I
What is preload?
EDV- stretch of ventircles at the end of diastole
Where is the SAN located?
Right atrium at the superior crista terminalis
Location of AV node
Atrioventricular septum
When does K+ efflux occur?
Repolarisation in eCG
Which electrolyte maintains resting potential of ventricualr electrolyte?
Potassium
Which part of the eCG is when the entire ventricle is depolarised?
ST segment
Sequence of cardiac contraction
SA node -> atria -> AV node -> Bundle of His -> right and left bundle branches -> Purkinje fibres
Which part has the highest conduction velocity?
Purkinje fibres
Which part of the heart has the slowest conduction velocity?
AV node
What is average cardiac output?
5L/min
What causes plateau of action potenital?
Slow influx of calcium
What maintains the electrical gradient?
Potassium influx in phase 4 due to Na+K+ ATPase along with sodium efflux
What contirbutes to most of total peripheral resistance and BP stability?
Arterioles
What prevents fast atrial rate from spreading to the ventricles?
AVN
When does atrial repolarisation occur?
During QRS complex
What affects PR interval?
Increases conduction velocity
What causes T wave shape?
Ventricular repolarisation due to K+ efflux
Noradrenaline
Binds to B1 receptors in SAN node
JVP a wave
Atrial contraction- absent in atrial fib
What is JVP c wave?
Closure of tricuspid valve on the right side of the heart
What is the v wave?
Passive filling of blood in atria against closed tricuspid valve
What is the x descend?
Fall in atrial pressure during ventricular systole
What is the y descent?
Opening of tricuspid valve
Which part of JVP occurs in S1?
A wave and c wave
Which part of JVP occurs in S2?
X descent, v wave and y descent
What happens after birth?
Closure of foramen ovale, ductus arteriosus and umbilical vessels.
What is the role of the ductus venosus?
IVC and umbilical vein
Precursor to aorta
Truncus arteriosus
Truncus arteriosus
Gives rise to the ascending aorta and pulmonary trunk
Precursor to SVC
Right common cardinal vein
Precursor to ligamentum arteriosum
It is an anchor of the aortic arch- precursor ids ductus arteriosus
Precursor to smooth RA?
Sinous venosus- right portion
Precursor to coronary sinous
Sinous venosus- left portion
Progenitor of primitive ventircke
Forms majority of left ventirlce- gives rise to trabeculated
Precursor to trabeculated ventricles
Bulbos cordis- smooth right ventirlce and outflow of left and right
What is the precursor for the AV and semilunar valves?
Endocardial cushion
What is the umbilical ligament give rise to?
Urachus remnant
Tetrology of the Fallot
Ventiricular hypertropy, aortic valve hypertropy, pulmonary stenosis and ventricular septal defect. It causes hypoxia and cyanosis, SOB, heart murmur.
What is important for the aorta-pulmonary spiral to form?
Migration of neural crest cells
Innervation for speech
Vagus nerve
ansa cervicalis
Anterior to the carotid sheath and innervates the strap muscles like strenohyoid, sternothyroid, omohyoid
Chordae tendinae
Attached to valve. Chordae tendinae are linked to ventricle by papillary muscles
T12
Aorta, thoracic duct, azygous vein
Where does the thesbian veins drain into?
Drain myocardium into all heart chambers, not limited to coronary sinus
What is located in superior mediastinum?
SVC, Brachiocephalic vein, thorat and supper chest
Anterior mediastinum
Lymph node, fat, thymic remnant
Middle mediastinum
Pericardium, main bronchi, arch of azygous vein, aortic root
Posterior mediastinum
Sympathetic nerve trunk, splanchnic nerve, thoracic aorta, oesophagus
Where does IVC originate?
L5
What structure is most anterior to the hila?
Phrenic nerve
What does right coronary artery supply?
AV node, SAN, right atria, most of right ventircle
Which artery bifurcates at the parotid glannd?
External carotid artery
Which lung has two fissures?
Right lung
What separates the tunica media from the other structures?
Internal elastic lamina from the tunica intima and external elasatic lamina from tunica adventitia
Tunica intima
Innermost layer of endothelila cells separated by gap junctions
Progenitor of right common carotid?
Right brachiocephlaic artery- gives rise to right subclavian artery and right common carotid
Retromandibular vein progenitor
Maxillary vein
Parathyroid veins
Thyroid plexus of veins
Effect of leukotrienes
Bronchoconstriction and implicated in asthma
Effect of prostacyclin
Vasodilation
Stroke volume
Volume of blood pumped out of the heart in one contraction
What increases blood pressure?
Length (think if someone gains weight)P), reduce diameter, viscosity
What is JVP?
Pressure of blood in the internal jugular vein and in the right atria which is directly connected without any valves. It is covered by the sternocleoidomastoid mastoid. Cannot be palpated but can be seen on the right side in a 45 degree angle
What does JVP over 3cm mean?
High pressure due to issues with heart expansion, pressure system
How to find flow?
It is cross sectional area x velocity.Volume of fluid moving in a given time period.
What increases velocity?
Reducing cross sectional area and radius.
How to find pressure?
(Q)Flow x resistance (R)
Resistance
Change in pressure/flow
What does Poisuelle’s law describe?
Factors which affect flow
Effect of polycythaemia
Increases blood viscosity to decrease flow
Where is BP highest in the heart?
Left aorta
Where is BP lowest in the heart?
Right atria
Where is resistance highest at rest?
Body > Organs > Brain > Muscles > Heart
How does resistance change during exercise?
Muscles and heart increase, organs decrease. Brain stays the same
What is the relationship between flow and pressure?
Non linear
Where is urine collected?
Bowman;s capsule of kidney
Effect of ANP and BNP
Activates cGMP for vasodilation and increase urinary excretion cGMP inhibits aldosterone and renin scretion.
How is ANP activated?
Releases CORIN protein
How is BNP activated?
Releases FURIN enzyme
Where is renin released?
Macula densa located in the DCT- epithelial cells that detect Na+. It is activated by sympathetic activity.
Effect of renin?
Conversion of angiotesinogen -> angiotensin I
Where is ACE released?
In the lungs. It acts on angiotensin I in bloodstream to form angiotesin II.
Effect of angiotensin II
It is a potent vasoconstricter of blood vessels, increases Na+ and Cl- reabsorption in the PCT and causes aldosterone release from adrenal gland. Breaks down bradykinin, a vasodilator.
How are cardiac myocytes connected?
Intercalacted discs
What is dromotropy?
Spped of impulse conducntion in AVN
Action of cardiac glycosides?
Inhibiting Na+/K+ ATPase pump
Effect of noradrenaline on SAN
Activation of low voltage T-type calcium channels and funny Na+ channels for depolarisation. Depolarisation is automatic
How long is cardiac cycle?
0.8S
Ejection fraction
Stroke volume/end diastolic volume. Measure of ventricular performance
Atrial reflex
Atrial pressure increases heart rate
What decreases ESV?
Sympathetic stimulation, shorter filling time and less venous return. These reduce EDV and stroke volume
What increases stroke volume?
Venous return, filling time, sympathetic stimulation that increases EDV
Where do veins drain in the heart?
Into coronary sinus, located in right atria
What vein is located in left atria?
Obliquevein
Which vein is in the right side down the septum?
Middle cardiac vein
Wich vein is located behind left atria, between the left and right pulmonary veins?
Pericardial sinus that separates arterial and venous flow
Epithelia of primary and secondary bronchi?
Pseudostratified cilitated columnar eptihelia with C shaped hyalien cartilage in primary brocnhi. Secondary bronchi has plates of hyaline cartilage.
Epithelia of tertiary bronchi?
Columnar epithelia, smooth muscle,
Epithelia of respiratory bronchi?
Sacs in the walls of terminal bronchi- ciliated cuboidal epithelia with clara cells and evaginations of primary alveoli
Terminal bronchi epithelia?
Last part of conducting tract. It has pseudostratified columnar epithelia, cilitated cuboidal epithelia and clara cells only, no goblet cells.
What regenerates alveolar penumocytes?
Type 2 pneumocytes. Hyperplasia is an indicator for injury
What are the stem cells of the respiratory tract?
Basal cells
What keeps olfactory mucosa moist?
Bowman’s gland
What covers most of the alveolar surface?
Type 1 pneumocytes which are simple squamous with occluding jiunctions. They have flat elongated nuclei.
Where is surfactant produced?
Type 2 pneuocytes. They have reticular fibres and elastic fibres for alveolar elasticity.
Effect of increased pulmonary pressure?
Decreased cardiac output
Haldane effect
Uptake of O2 by deoxyhaemaglobin
Bohrn Effect
Release of 02 from HbO2 due to increased levels of CO2 in the blood/lower ph
Hypxoic drive
Body uses oxygen chemoreceptors to regulate respiration
What is the first phase of ventircular contraction?
Isovolumetric contraction- ventiruclar pressure increases when the asemilunar valves are closed
What tis the final stage of the cardiac cycle?
Isovolumic ventricular relaxation
Which vein is on the septum of the left heart?
Great cardiac vein
Where are small cardiac veins found commonly?
Most are in right atria.
Location of vasa vasorum?
Tunica intima and tunica media. In the tunica
What is the vasa vasorum internae?
Directly from main artery branch
What is vasa vasorum externae?
Branch of main artery
What regulates blood flow?
Metaarterioles
What affects venous return?
Sympathetic innervation via vasoconstriction, respiratory pump and skeletal muscle pump
What maintians pressure gradient?
Elastic conducting arteries
Site of thrombogenesis?
Tunica intima
What happens to muscles during contraction?
I band and H zone shortens. A band stays the same.
Actin only area
I band
A band
Actin and myosin
