5-Cardiology Flashcards
Where is the heart located, size and apex/base location
- Midsternally
- Size of patients fist
- Base on top, apex at bottom
What is the pericardium
- Sack around the heart
- Contains a small amount of fluid
Layers of the pericardium (3)
- Fibrous (outer)
- Serous (middle)
- Visceral/Epicardium (internal)
Layers of the heart and what they do (3)
- Epicardium-Outer layer
- Myocardium-Beats
- Endocardium-Smooth inner layer
What is a myofibril
Rod-like unit that makes up a muscle cell in the heart
Intercalated discs
Connect myofibrils
Desmond
“Spot welds” between myofibrils
Gap junction
Allows signal to pass from one myofibril to the next
4 chambers of the heart and what their roles are
- RA-Reservoir for venous blood
- LA-Reservoir for oxygenated blood
- RV-Low pressure pulmonary pumping
- LV-High pressure systemic pumping
What is the role of the Atrioventricular septum (2)
- Separate atria from ventricles
- Does not allow impulse to go back to the atria
What are the heart valves controlled by and through
- Controlled by papillary muscles
- Controlled though chordae tendineae
What are the 2 main types of heart valves
- Atrioventricular
- Semilunar
What are the 2 atrioventricular valves, 2 semilunar valves and where are they
- Tricuspid-Right side
- Mitral-Left side
- Aortic-Aorta from LV
- Pulmonic-Pulmonary vein from RV
Describe semilunar valves
- Passive- control unidirectional flow
- Open during systole
- Closed during diastole
What is the RCA and where does it go
Right coronary artery, supplies right side anterior of the heart
What is the LCA, what does it split into and where do they go
-Left coronary artery
- Left circumflex artery, lateral and rear sides
- Left anterior descending artery, anterior and down
What is the coronary sinus (3)
- Meeting point of heart veins that blood deposits into
- Drains left ventricle into right atrium
- Roughly pairs arterial circulation
Steps of blood flow through the heart, start at RA (14)
- RV
- Tricuspid valve
- RV
- Pulmonic valve
- Pulmonary artery
- Lungs
- Pulmonary vein
- LA
- Mitral valve
- LV
- Aortic valve
- Aorta
- Body circulation
- Inferior/superior vena cava
What valves are open and closed during the systolic phase
Open- Aortic valve, pulmonic valve (semilunar valves)
Closed- Mitral valve, tricuspid valve (Atrioventricular valves)
What valves are open and closed during diastole
Open- Mitral valve and tricuspid valve (Atrioventricular valves)
Closed- Aortic valve and pulmonary valve (Semilunar valves)
What is preload
-The amount of blood delivered to the heart during diastole
What is Starlings Law
-The more the myocardium is stretched, the more forcefully it will contract
What is afterload
Pressure in the aorta against which the left ventricle must pump blood during systole
(Resistance a contraction must over come to eject blood)
(Decreased vessel size=increased pressure)
What is stroke volume and what effects it (3)
The amount of blood ejected by the hear in each contraction
- Preload
- Contractile force
- After load
What can change contractile force, 2 example and how they work
Catecholamines (hormones)
- Epinephrine
- Norepinephrine
-Enhance contractile fore by acting on the beta-adrenergic receptors
What is the cardiac output formula
CO=stroke volume x HR
What is the normal range for stroke volume
Normal SV 60-100ml
What is the Fick Principle (4 main point)
- Utilization of O2 is dependent upon
- Adequate O2 in the environment
- Movement of O2 across alveolar and capillary membrane, into arterial bloodstream
- Adequate RBCs to take oxygen
- Proper tissue diffusion
- Efficient off loading of oxygen at the tissue level
What is the formula for blood pressure
BP = CO (mL/min) x PVR
What is PVR
Resistance of vessels to blood flow
What regulates systolic BP number
Contractility of the heart
What regulates diastolic BP number
Vasoconstriction and vasodilation
What is pulse pressure
The difference between systolic and diastolic numbers
What is the mean arterial pressure
The average arterial pressure during a single cardiac cycle
What is the formula for mean arterial pressure (MAP)
MAP=DP + 1/3 (SP-DP)
What are the 4 components of blood
- Plasma
- Red blood cells (Erythrocytes)
- White blood cells (Leukocytes)
- Platelets (Thrombocytes)
What is the role of plasma
Fluid part of blood
What is the role of Erythrocytes
Carries O2, makes the blood red
What is the role of Leukocytes
Protect the body from infection
What is the role of Thrombocytes
Clots blood
What 4 things regulate heart function
- Brain via autonomic nervous system
- Receptors in blood vessels, kidneys, brain and heart for homeostasis
- Chemoreceptors
- Baroreceptors
Whale are Chemo and Baroreceptors located and what does each do
Aortic arch and carotid arteries
- Chemoreceptors- Regulate O2, CO2 and pH levels
- Baroreceptors- Regulate blood pressure
4 key points about the sympathetic nervous system
- Adrenergic receptors
- Fight or flight
- Alpha-beta response
- Norepinephrine
4 key points about the parasympathetic nervous system
- Cholinergic receptors
- Rest and digest
- Vagus nerve response
- Acetylcholine
The role of alpha 1 receptors
Vasoconstriction
The roles of the beta 1 receptors
- Increase HR (+ Chronotropic)
- Increase automaticity (+ Inotropic)
- Increase Contractility (+ Dromotropic)
What is the role of the beta 2 receptor
Bronchodilation
Define automaticity
Able to initiate impulses
Define excitability
Able to be stimulated to act
Define conductivity
Able to conduct impulses
List the normal electrical sequence of the heart
- SA node
- Internodal pathways
- AV node
- Bundle of His
- Bundle branches
- Perkinje fibers/network
What and where is the SA node
Dominant pacemaker site of the heart that is innervated by SNS and PNS
Top of RA
List the 4 internodal pathways
Anterior internodal tract
Middle internodal tract
Posterior internodal tract
Bachmanns bundle
What is the Bundle of His
Brings impulses from AV node in the atria through the atrioventricular septum into the bundle branches
Intrinsic firing rates of the SA, AV and ventricles
SA- 60-100
AV- 40-60
Ventricles- 20-40
Describe phases 0-4 of action potential
- Rapid depolarization
- Early rapid repolarization
- Plateau phase
- Rapid repolarization
- Period between action potentials
Describe phase 0- Rapid depolarization (2)
- Fast Na channels open, allowing NA into cell
- Inside becomes positive
Describe phase 1- Early rapid repolarization (4)
- Na channels close, Na flow stops
- K continues to leave
- Decrease in number of positive electrical charges in the cell
- Returns to resting permeability state(allowing muscles to contract)
Describe phase 2- Plateau phase (4)
- Prolonged phase of repolarization
- Ca enters, initiating contraction
- K continues to slowly leave
- Completion of muscle contraction occurs
Describe phase 3- Rapid repolarization (3)
- Cell becomes more negative
- Slow calcium channels close
- Repolarization is completed
Describe phase 4 (2)
- Period between action potentials
- Activates Na-K pumps, returning the cell to its normal state
