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Cardiovascular
VSCI100
| Term | Definition |
|---|---|
| How many ribs are there in a normal dog? | 13 ribs |
| What is the name of the cranial end of the ribcage? | thoracic inlet |
| What is at the caudal end of the ribcage? | diaphragm |
| What is the name of the meeting point between the dorsal (bone) ribs and the ventral (cartilage) ribs? | costochondral junction |
| In dogs, how many lobes are in the right lung and what are their names? | 4: cranial, caudal, middle, accessory |
| In dogs, how many lobes are in the left lung and what are their names? | 2: cranial, caudal |
| What is the name of the most cranial bone of the sternum? | manubrium |
| What is the name of the most caudal bone of the sternum? | xiphoid process |
| What is the pleural cavity? | The potential space between the parietal pleura and visceral pleura - has some liquid that allows the lungs to inflate |
| What is the pericardium? | double-layered membrane enclosing the heart - consists of an outer fibrous layer and an inner double layer of serous membrane and epicardium (AKA visceral pericardium) |
| What are the layers of the heart wall? | Outer epicardium, myocardium, inner endocardium |
| What is systole? | contraction - chamber empties of blood (bu-bum) |
| What is diastole? | relaxation - chamber fills with blood (-bum, bu-) |
| Which part of the heart contains all 4 valves (and also isolates electrical pathways) ? | annulus fibrosis |
| What do the chordae tendonae do? | attach to the inner heart wall and the cusps of the AV valves to prevent them from folding back in on themselves - prevents backflow into the atria |
| What is the tunica intima? | The endothelium of blood vessels - simple squamous epithelial cells |
| What is collateral circulation? | Dual artery supply to any one area of the body - prevents problems like strokes & secures blood supply (opposite of end artery) |
| Anastomoses | joining together of blood vessels that can allow a bypass of blood around something else |
| How is blood flow in the capillaries controlled? | By pre-capillary sphincter zones, thoroughfare channels, arteriovenous anastomoses (can skip the capillary bed altogether) |
| Fenestrations | small holes in capillaries to allow diffusion to happen even faster |
| What are sinusoids? | capillaries with huge diameters (still very thin walls though) |
| What is important to remember when taking radiographs? | Take 2 views - either dorsoventral or ventrodorsal AND one in right or left lateral recumbency (preferably with lungs inflated) |
| What is the cardiac silhouette? | Name given to the heart & pericardium |
| What is the unit for measuring pressure in the heart? | mmHg - millimetre of mercury |
| Hydrostatic pressure | pressure exerted by a fluid against its container - i.e blood against the vessel. Altered by vasoconstriction/dilation |
| Bulk flow | movement of fluid due to hydrostatic pressure gradient into vessel: absorption out of vessel: filtration normally net filtration |
| What is the rate of diffusion affected by? | surface area, temperature, concentration gradient, distance |
| Oncotic pressure | osmotic pressure in the blood due to large plasma proteins |
| Starling's Law | hydrostatic and oncotic pressure differences balance to determine movement of fluid |
| What causes oedema? | Failure to drain excess interstitial fluid back into vena cavae (due to high pressure in the right atrium), leads to cells being spread apart by sheer amount of fluid |
| Perfusion pressure | pressure created by pressure differences along a blood vessel |
| Cardiac output | heart rate x stroke volume |
| EDVV | end diastolic ventricular volume increases as preload increases more compliant muscle increases EDVV longer diastolic filling time increases EDVV |
| ESVV | end systolic ventricular volume increases as afterload increases decreases as contractility increases |
| Preload | pressure upstream of the chamber |
| Afterload | pressure downstream of the chamber |
| What is the danger with exposing the heart to constant high pressures? | ventricle stretches out and has to grow more muscle to produce more force - this damages its ability to contract |
| Heterometric Autoregulation | stroke volume of both sides of the heart will balance out |
| What is the benefit of the sympathetic nervous system increasing heart rate vs a pacemaker? | protects diastole, so heart has more time to fill with blood - increases cardiac output |
| Vascular resistance | perfusion pressure/flow |
| Arterial Pressure | TPR (total peripheral resistance) x cardiac output systolic pressure/diastolic pressure |
| Pulse pressure | systolic pressure - diastolic pressure |
| Which great vessels from the foetal heart persist from the aortic arches? | 3- carotid artery 4- aorta & subclavian artery 6- pulmonary arteries |
| What does the sinus venosus become? | right atrium |
| What are the 3 main veins in the foetal cardiac system? | vitelline - from the yolk sac cardinal - from the rest of the body umbilical - from the mother (oxygenated!) |
| What is the foramen ovale and what does it do? | Hole in the atrial septum - allows oxygenated blood to go from the umbilical cord through the right atrium into the left atrium so it can then be pumped out the aorta to the rest of the body |
| What is the name of the remnant of the foramen ovale? | fossa ovalis |
| What do the foetal atria become? | auricles - atrial appendages |
| What is an important difference between skeletal muscle action potentials and heart muscle action potentials? | much longer refractory period - relaxation between contractions is vital for the heart to fill with blood |
| MALTs | mucous associated lymphoid tissues |
| What are papillary muscles and where would you find them? | ventricle walls - attach the chordae tendonae to the heart wall |
| What is the trabeculae carneae? | ridged muscle in heart wall endocardium to prevent turbulence of blood during filling |
| What area(s) of the body does the brachiocephalic (arterial) trunk supply? | the head and forelimbs |
| What does lymph drain into to return liquid to the bloodstream? | the vena cavae - typically cranial |
| What is the costal arch? | United costal cartilages of ribs 10-12 (dogs) |
| How many sternebrae does a dog have? | 8 |
| What do you call the central area of the thorax? | Mediastinum |
| What does the parietal pleura include? | mediastinal, costal and diaphragmatic pleura |
| What does the visceral pleura surround? | the lungs |
| What is retia? | mesh of arteries (can be useful in cooling & slowing down blood) |
| What is effusion? | fluid collecting in the pleural cavity - creating a real space where there should only be a potential space |
| Very high heart rate for extended time leads to what? | shortened diastolic filling time, reduced EDVV, reduced stroke volume and therefore reduced cardiac output |
| Cardiac output definition | The amount of blood ejected from the heart every minute |
| Stroke volume definition | The amount of blood ejected by the heart with each beat |
| What is the ejection fraction? | stroke volume/end diastolic volume measures systolic function (how efficient the heart is) |
| What is lusitropy? | relaxation of myocardium |
| What is compliance? | ability to stretch to accommodate blood |
| What is diastisis? | small contraction of atria at the end of diastole to top up the blood in the ventricles before the AV valves close |
| Hypertension | high blood pressure |
| Hypotension | low blood pressure |
| What is the first stage of the foetal cardiovascular system? | splanchnic mesoderm cells become blood islands that become haemoblasts (primitive blood cells). simple epithelial lining develops around them |
| Which end of the embryo is the cardiogenic plate found? | cranial |
| The cardiogenic plate rolls itself up to become what? | the cardiac tube |
| What is the aortic arch? | the dorsal aortae connected to the cardiac tube |
| Cardiac tube | |
| What are the functions of the primary and secondary septa in the foetal heart? | Act as a valve in between the two atria to control direction of blood flow through the foramen ovale |
| How are the AV valves formed in the embryo? | programmed cell death of the heart wall and growth of fibrous tissue creates the valves, papillary muscles and chordae tendonae |
| Where is the very first pacemaker in the cardiac tube? | caudal part of left cardiac tube |
| Where does the precursor for the SAN arise from? | right limb of sinus venosus (later becomes right atrium) |
| What does the truncus arteriosus become? | aorta and pulmonary trunk - spiral around each other |
| What is the ductus arteriosus? | a connection between the aorta and the pulmonary arteries - closes soon after birth due to pressure differences and smooth muscle constriction |
| What does the ductus venosus do? | connects the umbilical vein to the caudal vena cava, bypassing the liver - closes soon after birth |
| In the embryo, what does the caudal vena cava develop from? | the vitelline and subcardinal (systemic) veins |
| In the embryo, what does the cranial vena cava develop from? | right cranial vein (systemic) after joining with the left |
| What happens when the umbilical artery contracts (at birth)? | flow from neonate to placenta stops |
| What happens when the umbilical vein contracts (at birth)? | venous blood delivered to the neonate (up to 30% total blood volume) |
| What happens when the umbilical cord ruptures? | umbilical arteries recoil to prevent haemorrhage umbilical artery becomes round ligament of the bladder umbilical vein become round ligament of the liver |
| What is aortic stenosis? | narrowing of the aortic valve, causing the ventricle walls to get thicker, reducing cardiac output systolic murmur |
| What is patent ductus arteriosus? | a hole between the aorta and pulmonary trunk means deoxygenated and oxygenated blood mix - lungs are over-circulated and the rest of the body is under-circulated continuous murmur |
| What is a ventricular septal defect? | hole in the interventricular septum, blood moves from left to right due to pressure differences - leads to heart failure systolic murmur louder on the right |
| How does action potential travel in the heart? | from the SAN to the AVN, then to bundle of His to Purkinje fibres. in between individual cells by intercalated discs |
| How do intercalated discs allow a functional synctium? | gap junctions that allow cations to move between cells - very rapid and instantaneous mechanism that allows all cardiac myocytes to contract at the same time |
| Ectopic pacemakers | can be heard as an extra beat, but not in the pulse since it doesn't result in useful cardiac output |
| Purkinje fibres | slower conduction allows atria to empty into the ventricles before diastole |
| How do the ion channels in myocytes work? | at rest, potassium channels are open, and close slowly as depolarisation happens during depolarisation: sodium channels open and close quickly calcium channels open and close slowly action potential generated when cell is sufficiently depolarised |
| Which myocytes are the fastest at generating action potentials? | the natural pacemaker of the heart: the SAN |
| Pacemaker potentials | the action potentials created by the SAN or AVN - automaticity and consistency |
| Which limbs do the electrodes for ECG attach to? | forelimbs and left hindlimb, neutral/earth on right hindlimb lead II is between right forelimb and left hindlimb is most used |
| In an ECG, what does the height of the wave show? | the size of the electrical potential difference |
| In an ECG, what does the width of the wave show? | time taken for potential difference to return to 0 |
| What does a vertical spike on an ECG show? | action potential travelling towards positive electrode |
| What does a vertical dip on an ECG show? | action potential travelling towards negative electrode |
| ECG waves | |
| Lymph nodes in the head | retrophyrangeal parotid mandibular (salivary glands) |
| Lymph nodes in the neck | superficial & deep cervical |
| Lymph nodes in the forelimb | axillary (armpit) |
| Lymph nodes in the thorax | dorsal & ventral thoracic mediastinal bronchial |
| Lymph nodes in the abdomen | lumbar coeliac cranial & caudal mesentric |
| Lymph nodes in the hindquarters | popliteal ischial deep & superficial inguinal iliosacral |
| Why might lymph sometimes look white instead of clear? | proteins and lipids (in chylomicrons) transported after cleaning blood from the gut |
| What intrinsic controls can alter heart rate/flow? | paracrine control using local chemicals metabolic autoregulation - can be overwhelmed by extrinsic mechanisms! |
| What does metabolic autoregulation do? | matches blood flow to the metabolic rate in tissues |
| Which chemical in paracrine control causes vasodilation, and which other chemicals does it mediate? | nitric oxide - mediates prostacyclin, histamine, bradykinin (irritated tissue) |
| When endothelium is damaged, which chemicals are released and what do they cause? | endothelin I and thromboxane A2 (released by platelets) cause vasoconstriction |
| What effect does oxygen have on blood vessels? | causes vasoconstriction |
| What effect does carbon dioxide have on blood vessels? | causes vasodilation |
| What effect does lactate have on blood vessels? | causes vasodilation |
| What effect do potassium ions have on blood vessels? | causes vasodilation |
| What is reactive hyperaemia? | mega increase in blood flow after a part of the body has experienced vascular occlusion (poor circulation - think pins and needles/foot going to sleep) |
| What is ischaemia? | Lack of blood supply |
| What is infarction? | type of necrosis: tissue death due to poor blood supply |
| What is necrosis? | tissue death |
| What are the extrinsic controls that can alter heart rate/flow? | baroreflex RAAS |
| Which part of the body coordinates the extrinsic controls? | autonomic nervous system - the cardiovascular centre in the medulla oblongata in CNS, sympathetic and parasympathetic nerves (vagus) |
| What is the baroreflex and how does it affect the cardiovascular system? | pressure (stretch) receptors in carotid arteries always sending signals to CNS - rate increases as pressure increases alerts the CNS to do something about high/low pressures |
| What is the RAAS and how does it affect the cardiovascular system? | renin-angiotensin-aldosterone system turns on when there is a long-term drop in blood pressure increases blood volume via specific pathway and therefore pressure |
| JGA | juxtaglomerular apparatus (in the kidney) |
| ACE | angiotensin-converting enzyme |
| Which part of the body governs long term regulation of blood pressure? What are some issues associated with this? | the kidney relies on normal renal function in the case of some diseases, it can re-set the normal reference range of blood pressure for the CNS - leads to more problems |
| How does the cardiovascular system respond to excercise? | metabolic autoregulation psychogenic response (getting psyched up before exercise) excercise reflex (feedback system from joints and muscles) baroreflex skeletal muscle and respiratory pumps |
| What effect does the sympathetic nervous system have on the cardiovascular system? | constricts almost all arterioles except coronary & skeletal muscle arterioles (ie non-essential in fight/flight mode) remember: graded response! |
| What effect does the parasympathetic nervous system have on the cardiovascular system? | dilates genital and coronary arterioles remember: graded response! |
| What kind of neurotransmitters does the parasympathetic nervous system use? | cholinergic - responds to acetylcholine vessels: M3 heart: M2 |
| What kind of neurotransmitters does the sympathetic nervous system use? | adrenergic - responds to adrenaline and noradrenaline vessels: alpha 1, 2, & beta 2 adrenergic , M3 cholinergic heart: beta 1 adrenergic |
| What are the different layers in the lining of most vessels? | tunica intima - endothelium tunica media tunica adventitia |
| What different adaptations can capillaries have? | continuous fenestrated discontinuous |
| What is in the hepatic triad? | hepatic artery, hepatic portal vein, bile duct |
| What is the vasa vasorum? | network of small blood vessels that supply the walls of large blood vessels |
| What is the RAAS pathway? | 1. sympathetic nervous system causes JGA to release renin 2. liver then releases angiotensinogen that then converts to angiotensin I 3. angiotensin I is converted in the lungs by ACE to form angiotensin II 4. angiotensin II causes vasoconstriction, and |
| What does aldosterone do? | causes vasoconstriction, and causes the kidneys to retain sodium ions, so water is also retained and the blood volume increases - increased blood pressure as a result |
| What is hypovolaemia? | decreased circulation blood volume - causes hydrostatic pressure to drop and reduced filtration from blood to surrounding cells |
| What is hypovolaemic shock? | acute drop in mean arterial pressure |
| How is hypovolaemia detected and dealt with? | atrial volume receptors and atrial baroreceptors detect decreased pressure/volume decreased AP frequency signal alerts the CV centre in CNS baroreflex initiated spleen contracts to release blood into circulation |
| What happens to PCV and TP after losing whole blood? (e.g haemorrhage) | at first, no change then decreases as RAAS kicks in and increases fluid in blood - so less concentrated liver replaces proteins after a few days, so TP returns to normal bone marrow replaces red blood cells over a few weeks so PCV returns to normal (th |
| What is PCV? | packed cell volume - ie concentration of red blood cells in a given sample |
| What is TP? | total protein in the blood (important! link to oncotic pressure and bulk flow) |
| What is forward heart failure? | systolic failure caused by reduced CO and arterial pressure due to thin ventricle walls meaning contractility is reduced and blood can't be pushed out of the heart |
| What are some signs of forward heart failure? | reduced perfusion leads to: cold extremities pale mucous membranes reduced capillary refill time reduced exercise tolerance (fainting/collapsing) lethargic reduced appetite |
| What is cardiac tamponade? | effusion in pericardium - means heart can't contract properly |
| What is backward heart failure? | congestive heart failure (can be right or left) - the heart can't cope with a super high preload |
| Why does backward heart failure cause effusion/oedema? | increased venous pressure leads to increased capillary pressure, so the fluid in the blood has nowhere to go but in between cells (oedema) or into the pleural cavity (effusion) |
| What disease could cause backward heart failure? | degenerative valve disease - affects AV valves and basically renders them incompetent, so blood doesn't move through the heart properly and often makes the atrium swell, which can cause the trachea and bronchi to be squished. Will cause a cough, and a mur |
| What is the difference between heart disease and heart failure? | heart disease is the early stages of heart failure, the body's compensation mechanisms are just about keeping the CO and BP high enough to allow the body to cope |
| What does long-term increased aldosterone levels cause? | myocardial remodelling - the myocardium becomes damaged, thick and scarred |
| What problems can be caused by persistent compensation mechanisms? | vasoconstriction of "non-essential organs" can cause renal failure, ulceration and sepsis in GI tract, myocardial hypoxia, oedema, effusions, fibrosis and myocardial remodelling |
| What "safety net" mechanism can try to reduce the compensatory mechanisms? | detected stretch in the myocardium stimulates the release of ANP & BNP, that cause the kidney to lose more sodium ions (and water) so blood volume and pressure drop. also causes peripheral vasodilation and can reduce renin and aldosterone doesn't work ve |
| What are ANP & BNP? | atrial natriuretic peptide and brain natriuretic peptide |
| When taking bloods, what may you want to look at that could point to heart disease? | thyroid hormones (overactive thyroid can cause high BP and heart disease) cortisol electrolytes (free ions - think calcium etc.) proBNP cardiac troponin I (signifies muscle damage - shouldn't be in the blood) |
| What is fractional shortening? | a measure of heart contractility |
| Fractional shortening equation | (LVIDd-LVIDs)/LVIDd LVID = left ventricular internal diameter d = diastole s = systole |
| What modes can be useful in echocardiography? | M-mode and B-mode, also colour doppler lets you see which direction the blood is moving |
| What are the views often used in echocardiography? | right parasternal long axis 4 chamber view --> turn 90 degrees --> right parasternal short axis view - mid ventricle turn a little and can see the base up from the apex |
| What is vertebral heart score? | a form of measuring the cardiac silhouette - starting from the 4th thoracic vertebra long axis + short axis should be around 10 ribs long useful for monitoring conditions |
Created by:
jemima123
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