Cardiovascular Flashcards
What are the functions of the cv system
Transport
Maintenance - regulation, homeostasis, thermoregulation, ph,
Protection - white blood cells, clotting
What are the components
Blood
Vessels
Heart
What are the 2 divisions
Pulmonary circuit
Blood to and from lungs
Systemic
Blood to and from rest of the body
What kind of tissue is blood
Connective
What does blood carry
Dissolved gases
Nutrients
Hormones
Metabolic wastes
What does the right atria do
Receives blood from systemic circuit and passes it to right ventricle
What does the right ventricle do
Received blood from right atrium and pumps it into pulmonary circuit
What does the left atrium do
Receives blood from pulmonary circuit and passes to left ventricle
What does the left ventricle do
Receive blood from left atrium and pumps to systemic circuit
How much blood does the heart pump per minute
5L/min at rest
15-20 during exercise
= 8000L per day
What is the Q equation
Hr x sv
Why is the left side of the heart bigger
Left ventricle has to pump to whole body, rather than lungs
What are the layers of the heart wall
Myocardium
Epicardium
Pericardial fluid/space
Pericardium (outer)
What is the pericardium
Made up of fibrous connective tissue, limits expansion
Stabilises the heart
Contains pericardial fluid in pericardial cavity which lubricates
Parietal pericardium = outer serous membrane
Visceral = inner serous membrane- epicardium
What does the pericardial fluid do
Reduce friction during contraction
What is the myocardium
- a thick muscular layer between epicardium and endocardium
- forms both atria and ventricles
- contains cardiac muscle tissue, blood vessels and nerves
- interconnects with other muscle cells via intercalated disks
- large central nucleus and lots of mitochondria
What is the endocardium
Covers all inner surfaces of the heart
- internal chambers
- heart valves
Consists of epithelial tissue and is continuous with epithelium if the great vessels
What are intercalated disks
The junction between cardiac cells
Gap junctions- allowing depolarisation to pass between cells, synchronising muscle contraction
Desmosomes: bind adjacent myocytes together
Explain the ventricular differences
- both hold same amount of blood
- LV thicker muscle
- LV cylindrical
-RV thinner wall - RV pouch like shape around left ventricle
As right only delivers to lungs, mean pressure much lower
What are the cordae tendineae and papillary muscles
CT - right ventricle
PM - left ventricle
Tether valves to ventricular walls to keep them shut during systole
What are the two types of cardiac muscle cells
Contractile - produce contractions
Pacemaker - nodal/conducting, sino atrial node, atro ventricular node, purkinjie fibres (control contractile cells)
Explain the electrical system of the heart
- SA node, account for resting hr, depolarise to stimulate depolarisation (autorythmicity)
- AV node, depolarises more slowly than SA, some auto, delays so blood can finish emptying from atria
- Travels through Septum
- Bundle of his
- Purkinjie - autorythmicity, very slow
What is the fist step of the cardiac cycle and how does it relate to ECG
SA node depolarisation on its own, SA node and atrial activation begin
60-100 action potentials per min at rest
(Main pacemaker)
ECG: flat start line
What is the second step of the cardiac cycle and how does it relate to ECG
Stimulus (depolarisation) spreads atrial surfaces and reaches av node
50 msec
ECG: P wave
What is the third step of the cardiac cycle and how does it relate to ECG
100msec delay at av node, atrial contraction begins
ECG flat again P-R interval
What is the fourth step of the cardiac cycle and how does it relate to ECG
Impulse travels down septum to bundle of his branches to purkinjie fibres and by the moderator band to the papillary muscles of the right ventricle
ECG : Q wave, downwards, beginning of ventricular depolarisation
What is the fifth step of the cardiac cycle and how does it relate to ECG
Impulse distribution by purkinjie fibres and relayed trough ventricular myocardium. Atrial contractions is completed and ventricular contraction begins
ECG: QRS complex,
Big spike R, back down S
Completion of ventricular depolarisation
What happens after the fifth step
Flattening line then t wave, ventricles repolarise
What are epinephrine
A catecholamine
Epinephrine- adrenaline
Reased by adrenal medulla, upon activation of sympathetic nervous system
What is norepinephrine
A catecholamine
Initial increases in heart rate and contractility but with longer expose decreases these things
Binds to receptors in heart
Released by adrenal medulla and sypatgetic nerves interacting blood vessels
What else controls hr
Chemoreceptors
Baroreceptors - carotid sinus senses changes, aortic arch senses increases only
Low bp - low stretch of vessel, less stretch of reception, decreases afferent firing, increased syp and decreased para
