Heart Flashcards
Between which ribs is the heart?
Between 3rd and 6th ribs
What are the 3 layers of the heart?
Endocardium: inner wall
Myocardium: thick muscular wall
Epicardium: visceral serous pericardium
What is also known as atria proper for the right heart?
Sinus vinarum
What are the 2 notable parts in the sinus venarum?
Intervenous tubercle
Fossa ovalis
What are the 2 notable things in the right auricle?
Pectinate muscle
Crista terminalis
What are the 5 places that the right atrium receive blood from?
Cranial vena cava
Caudal vena cava
Azygos vein
Coronary sinus
Small cardiac veins
How many papillary muscles are in the right ventricle
3
How many pulmonary veins does the left atrium receive blood from?
5-6
What structure of the foramen ovale is left in the left atrium?
The valve of the foramen ovale
Where is the cranial scapular angle?
Spinous process of T1
Where is the caudal scapular angle?
Spine bodies of T4-T5
Where is the shoulder joint?
Ventral end of 1st rib
Where is the olecranon?
Below ventral end of 5th intercostal space
What are the 2 parts of the vertebral arch?
Lamina and Pedicles
What are all 13 of the vertebral foramen put together called? A few?
Spinal cord. Vertebral canal
What are the foramen between the vertebrae called?
Intervertebral foramen
What special name does T11 have?
Anticlinal vertebra
What are the 2 layers of the vertebral disc called?
Anulus fibrosis and nucleus pulposus
What ribs are part of the costal arch and which is the floating rib?
10-12.
13
What nerves and arteries supply the thoracic wall muscles?
Intercostal arteries and intercostal nerves
Where do arteries and nerves run in the intercostal space?
Caudal medial
Which direction does muscles of expiration run?
Cranioventral
What direction do muscles of inspiration run?
Caudoventralis
What are the muscles of inspiration?
Scalenus
serrates dorsalis cranialis
external intercostal
rectus thoracis
What are the muscles of expiration?
Serrates dorsalis caudalis
Transfersus thoracis
Internal intercostal
What are the aortic cusps
Left semilunar cusp
Right semilunar cusp
Septal semilunar cusp
What are the cusps of the pulmonary valve
Right semilunar cusp
Left semilunar cusp
Intermediate semilunar cusp
What is the cardiac skeleton also known as?
Fibrous base
What are the borders to the thoracic inlet?
Bilateral: First rib
Ventrally: manubrian
Dorsally: first thoracic vertebrae
What 3 structures pass through the aortic hiatus?
Azygos vein
Aorta
Thoracic duct
What passes through the esophageal hiatus?
Esophagus
Vagal nerve trunks
What are the two components to the cardiovascular system?
Blood and lymph
What are the 3 layers of arteries and veins?
Tunica intima
Tunica media
Tunica adventitia
What is the main noteable function of the tunica intima?
It’s coagulation properties
What is the tunica media made of?
Smooth muscle
Extracellular matrix (elastin and ground substance)
What are the characteristics of elastic arteries?
Aorta
High pressure, high volume
Thick tunica media
Lots of layers of elastin fibers
What’s the major difference between muscular and elastic arteries
Elastic arteries are closer to the heart and contain a lot more elastin fibers
Muscular arteries contain mostly smooth muscle and a lot of it
What’s a continuous endothelium?
Continuous endothelium and basal lamina
What’s fenestrated endothelium?
Fenestrated endothelium but continuous basal lamina
What’s sinusoidal endothelium?
Fenestrated endothelium AND basal lamina
What are 2 major differences between veins and arteries?
Arteries have a much larger tunica media and veins have valves
What is lymph fluid plus fat droplets called?
Chyle
What layer of the heart are the valves a part of?
The endocardium
What are the differences between cardiac cells and skeletal muscle cells?
Branching
Prominent connective tissue
Central nuclei
Intercalated discs
Purkinje fibers
What are the 2 layers of the parietal pericardium
Serous: mesothelium
Fibrous: collagenous stroma
What are the 3 types of cardiac conduction cells?
Cardiomyocytes
Purkinje cells
Pacemaker cells (nodes)
What are the 2 types of action potentials?
Cardiomyocytes and Purkinje use Na for depolarization
Pacemaker cells use Ca for depolarization
What are the 5 phases of action potentials?
In Cardiomyocytes and Purkinje cells
0: depolarization Na enters
1: brief repolarization K exits
2: plateau Ca enters and balances K leaving
3: repolarization more K channels open
4: resting membrane potential
What makes pacemaker cells automatic?
Spontaneous phase 4 depolarization
What phases do pacemakers lack?
1 and 2 (brief depolarization and plateau)
What is the funny current of pacemaker cells?
What is phase 0 for pacemaker cells?
Na and K in
Slow Ca in
What is the funny current?
Occurs in pacemaker cells and it’s a slow drift of Na and K into the cell until Ca channels open at -50
What determines cell to cell conduction velocity?
How fast sodium enters the cell during depolarization (phase 0)
What are the types of calcium channels?
Voltage-gated: T-type (transient) and L-type (long-lasting)
Ligand Gated: epinephrine and norepinephrine
What channel determines the speed of repolarization?
Potassium (K) leaving
What does ERP mean?
Effective refractory period
Time before cell can be re stimulated
What slope is increased in sympathetic activity?
Slope of the funny current (the slow Na and K into the cell)
Explain excitation-contraction coupling
Stimulus causes a rush of Na to enter which allows L type Ca channel to let in a little Ca which binds Ryanodine receptor and causes a large rush of Ca from SR which binds tropomyosin and expresses actin, allowing myosin heads to swing and cause tension pulling Z band. Muscle relaxes and ATP drives Ca back into the SR through SERCa
What does hyperkalemia cause?
Sodium channels to become inactivated
What is the areolar tissue that attaches the muscles, ligaments, and bones to the underlying costal and diaphragmatic plurae?
Endothoracic fascia
What are the 2 pleural recesses?
Costodiaphragmatic recess
Costomediastinal recess
What is the cupula pleura?
Cranial part of parietal plura that extends outside of the thoracic inlet (left is larger)
What divides the dorsal and ventral mediastinum?
Divided by the roots of the lungs
What are the 3 layers of the pericardium?
Fibrous (outer layer)
Parietal serous (outer inner layer)
Visceral serous (inner inner layer also epicardium)
Mediastinal pleura on outside of this
What are the 2 ligaments that anchor apex of the heart?
Phrenicopericardial ligament
Sternopericardial ligament
Describe the relationship of the esophagus and trachea
Esophagus is left of trachea at thoracic inlet and dorsal after thoracic inlet
How many incomplete rings on the trachea are there?
35
What connects consecutive tracheal rings?
Annular ligaments of the trachea
Where is the tracheal bifurcation?
T4-T5
What is the crest inside of the trachea called?
Tracheal carina
What are the 4 surfaces of the lungs?
Costal
Diaphragmatic
Interlobar
Mediastinal
Where is the cardiac north located?
At 4th and 5th intercostal spaces (between cranial and middle lobes of right heart)
What are the borders of the triangular area of lung auscultation?
Cranial: triceps and Teres major mm @ 5th rib
Dorsal: back muscles, ribs 5-11
Basal border: caudoventral 6th rib at the costochondral junction to mid 8th rib, to dorsal 11th rib
What does the costocervical trunk branch into and what do they supply?
Deep cervical
Dorsal scapular
1-3 intercostal spaces
Muscles of base of neck
What are the 3 arteries that supply the thoracic wall?
Descending aorta
Internal thoracic
Costocervical trunk
What are the 2 veins of the heart?
Coronary sinus
Great cardiac vein (in paraconal interventricular groove and arises at apex!!)
What are the 4 lymph nodes of the thoracic cavity?
Tracheobronchial lymph nodes
Mediastinal lymph nodes
Sternal lymph nodes
Intercostal lymph nodes
Where does the thoracic duct switch to the left side?
Where does it empty?
At T5
Into left brachiocephalic vein
What is the opposite of the autonomic nervous system?
Somatic nervous system
What is the neurotransmitter of the parasympathetic and sympathetic divisions respectively?
Acetylcholine and norepinephrine
What are the 4 parasympathetic cranial nerves?
III: Oculomotor
VII: Facial
IX: glossopharyngeal
X: Vagus
Where are the intercostal nerves (thoracic spinal nerves) located?
Caudomedial to each rib
What allows for charge to spread throughout the heart simultaneously for regions?
Intercalated discs
What are the 2 phases of systole?
Isovolumetric constriction (ventricular pressure is lower than aortic)
Ejection (ventricular pressure is higher than aortic so aortic valve is open)
What two things are dependents of the strength of contraction?
Rate and extent of fiber shortening
Inotropy increases or decreases with calcium?
Increases
Inotropy increases or decreases with increases preload?
Increases
Inotropy increases or decreases with increased afterload?
Decreases
Inotropy increases or decreases with increasing heart rate?
Increases
What is the parasympathetic receptor for Cardiomyocytes?
What chemical does this receptor receive?
Muscarinic M2
Acetylcholine
What 3 things increase with increased sympathetic stimulation?
Increased rate of contraction
Increased peak force
Increased rate of relaxation
What is the definition of preload
Volume of blood in the ventricle at end of diastole
What is the definition of afterload?
Resistance left ventricle must overcome to circulate blood
What is Frank Starling Law?
Increased preload causes an increase in contractility within physiological limits
Think of that actin myosin overlap
What is the anrep effect
Chronic increase in preload causes decreased contractility vbut a very acute increase causes a short increase in contractility
What is the LaPlace Law?
(Pressure x ventricular radius)/(2 ventricular wall thickness) = afterload
What is the bowditch treppe effect?
Increased contractility with increased frequency (HR)
What is cardiac output equation?
CO=HR x stroke volume
Does systolic function = contractility?
NO!
Individual cell shortening = contractility
Chamber contraction = systolic function
What is lusitropy
Characterize rate and extent of fiber lengthening
What is the role of phosphlamben?
It inhibits SERCA which stops contraction
SNS increases SERCA and decreases phosphlambin’s effects so that the relaxation period occurs faster
Does diastolic function = lusitropy?
NO
cell lengthening = relaxation (lusitropy)
Chamber filling = diastolic function
What are the 4 phases of diastole?
Isovolumetric relaxation
Rapid filling
Slow filling
Atrial kick
What is diastolic compliance?
Compliance = stiffness = distensibility
Steeper curves = bad and less compliant
Increased compliance is better!
What happens to compliance and diastole as stiffness increases?
Decreased compliance and decreased diastolic function
What are the 2 major determinants of diastolic function and what are they influenced by?
Relaxation and stiffness (compliance)
Heart rate and preload
What is the left ventricle pressure range?
12-120
What is the right ventricle pressure range?
5-25
What is the aorta pressure range?
80-120
What is the pulmonary artery pressure range?
12-25
What is pulse pressure?
Difference in systolic and diastolic pressure
Which 2 sounds are the systolic sounds?
S1 and S2 (lub dub)
What are the diastolic sounds?
S3 and S4 (early ventricle filling and the atrial kick)
What are the ranges of pressures for the right atrium?
0-5
What are the normal pressures for the left atrium?
0-12
What is the most common disease place for dogs with a cough?
Tracheal
What is most common cause of cough with cats?
Bronchial
What is pallor and what is a cause?
Pale mucous membranes from anemia or vasoconstriction
What is a water hammer pulse?
A large difference between systolic and diastolic pressure
What is a cause of a higher heart rate than pulse palpation?
(Pulse deficit p) caused by arythmias
What is the hepatojugular reflex used for?
Test for right heart failure
What is weak arterial pulse also known as?
Pulses parvus
What is the bell of a stethoscope used well for.
To hear gallops (diastolic)
Do you use valve areas for cats?
No
What is a “click”
High pitched sound during systole associated with AV valve defernation and prolapse
What are murmurs characterized by?
Intensity, location, and timing
What are the 2 zones of the lower airways?
Conducting zone - trachea to terminal bronchial, no gas exchange
Respiratory zone - respiratory bronchial to alveolar structure - sit of gas exchange
What is the smallest tube that does not participate in gas exchange?
Terminal bronchioles
Describe bronchiole histology
Simple cuboidal
Club cells
No cartilage
What cell predominates in alveolar cells?
Club cells
What is the supporting tissue in the respiratory zone?
Elastic tissue
What are the alveoli cells and what do they do?
Alveolar type I: structural cells for gas exchange
Alveolar type II: Produce surfactant, divide to produce type I cells
Does the composition of gas matter for gas movement?
NO
What is the difference between bulk flow and diffusion
Bulk flow is the flow from high pressure to low pressure (independent of gas composition)
Diffusion is the random flow from high pressure to low pressure (dependent on gas composition)
Is gas exchange bulk flow or diffusion?
Diffusion
What is the equation for bulk flow (F)?
F=(Pb-Pa)/R
Can PAO2 be measured from PaO2?
What about PACO2 from PaCO2?
No
Yes
Describe difference between VdotA and VdotM
VdotA is volume of air entering alveolar per minute while VdotM is the amount of air entering the lungs per minute. VdotA matters more than VdotM because VdotA only takes the air reaching the respiratory zone into consideration.
What’s the best way to increase VdotA?
Deeper breaths to fill the alveolar space rather than hyperventilation which fills mostly only dead space
What are the 2 types of chemoreceptors for ventilation?
Peripheral in arteriole walls:
Central in medulla: function via CO2 and causes an increased tidal volume
What are the 2 peripheral chemoreceptors?
How are they signaled?
Carotid bodies: glossopharyngeal nerve
Aortic bodies: vagus
What plays a larger role in chemoreceptors? O2 or CO2?
CO2 because it is physiologically more beneficial
What is the purpose of the surfactants that are produced by the ATII?
Reduce the surface tension that help to reduce the CL (lung compliance)
What are the 3 determinants of lung compliance?
Elasticity
Surface tension
Ability of chest wall to inflate and deflate
What are the 3 determinants of airway resistance?
Geometry: length and branching angles
Air viscosity
Airway radius (1/r^4)
What are the 3 processes required for efficient gas exchange?
Alveolar ventilation
Perfusion of blood from systemic circulation
Perfusion of gases across the membrane
What is Henry’s law?
In equilibrium, partial pressure in gas and liquid phases are identical (allows for transfer of gases into liquid through alveolar surface)
What role does gas diffusion have on solubility?
High molecular weights cause gas to diffuse exponentially more
What is Fick’s Law?
Rate at which a gas flows across a membrane is dependent on
Surface area
Thickness of membrane
Diffusibility of gas (gamma)
Difference in partial pressure of gas
What supply the alveolar tissue with nutrients?
Bronchial arteries (pulmonary arteries bring deoxygenated blood)
What are the 3 starling forces?
Hydrostatic pressure
Oncotic pressure
Permeability of capillary endothelium
What zone is the heart at rest?
2
What is zone is the heart in during exercise?
3
What zone is an abnormal heart in?
1
What is hypoxia vasoconstriction?
Reduced airflow to alveoli results in lower blood flow to these areas
What is hypocapnic bronchoconstriction
When airways are exposed to gas with lower than normal PACO2 which redirects blood flow to better regions
Does O2 bound to Hb contribute to PaO2
NO
Only dissolved O2 in plasma does
What is the law of mass action?
Velocity of a reaction is proportional to the product of the concentration of the reactants
What are the 3 ways the body handles acids?
Respiratory - Ventilation: minutes to hours
Metabolic - Buffers
Metabolic - Renal: hours to days
What is the most important buffer?
Bicarbonate buffer
What are the 3 ways that CO2 can transport in the blood stream?
Dissolved
As bicarbonate
As carbinohemoglobin
What are the 3 measured values in blood
pH
PCO2
PO2
What are the 2 calculated measurements in blood?
HCO3 (bicarbonate)
Base excess
What are the normal values for pH, PaCO2, HCO3?
7.4, 40, 24
What is the threshold for acidemia and alkalemia?
7.35 and 7.45
What is positive base excess and what is negative base excess?
Negative: base acidosis
Positive: base alkolosis
BE DOES NOT CHANGE IN ACUTE RESPIRATORY DISTURBANCES
What are the metabolic interpretations of blood gas?
Base excess
PCO2
pH
What are the respiratory interpretations of blood gas?
PCO2
PO2
Which way does the primary disturbance go?
Goes in the direction of the pH!
BASE EXCESS DOES NOT CHANGE IN ACUTE RESPIRATORY DISTURBANCES
YES
What spinous processes make up the withers?
T2-T8
What are the 3 epaxial msucles from lateral to medial?
Longissimus, spinous system, multifidis
What is the epaxial muscle?
Longus colli
Where does trachea bifurcate in horse
4th to 6th
Where is cardiac notch of horse of left lobe
Between 3 and 6
Where is cardiac notch of right lung of horse?
Ribs 3 and 4
Where is the heart positioned in a horse?
Between intercostal spaces 2 and 6
What are the 3 branches of the costocervical trunk off the right subclavian?
Deep cervical
Dorsal scapular
Supreme intercostal
What are the 3 branches of the descending aorta?
Dorsal intercostal
Ventral intercostal
Bronchioesophageal
Should you take a radiograph on expiration or inspiration?
Inspiration
Where do you start measurement with vertebral heart scale?
At the cranial border of the 4th rib
What’s about the average vertebral heart size for dogs and cats respectively?
9.7 and 7.5
Are arrhythmias common in dogs? What about cats?
Yes
No!
