Week 3 - CV System Flashcards
What are the two circuits in the CV system?
Pulmonary circuit and systemic circuit
What are the 4 chambers of the heart?
RA - receives from systemic and passes to RV
LA - receives from pulmonary and passes to LV
RV - receives from RA and pumps to pulmonary
LV - receives from LA and pumps to systemic
What’s the hearts approximate bpm normally
70bpm (100000 a day)
What is the heart wall made up of?
Pericardium -
Fibrous tissue (collagen)
Stabilizes heart position
Lubrication (pericardial fluid)
What is myocardium?
Heart muscle, a thick muscular layer between epicardium and endocardium. LV has highest thickness.
What are some key structures and functions of the myocardium?
Short and wide
Y shaped - branched
A large central nucleus and a large number of mitochondria
Interconnections w other cardiac cells via intercalated discs
Involuntary due to auto rhytmicity
Myogenic
ANS and endocrine system
What is an Intercalated disc?
The junction between cardiac cells
2 components -
Gap junctions allowing for depolarization to pass between cells, synchronizing muscle contraction
Desmosomes bind adjacent myocytes together.
What is endocardium?
Cover all inner surfaces of the heart - internal chambers and heart valves
Consists of epithelial tissue and is continuous with the epithelium of the great vesssels.
Describe the steps of the cardiac cycle.
- SA Node activity activates atrium
- Stimulus spreads across atrial surfaces and reaches AV node
- 100msec delay at AV node. Atrial contraction begins
- Impulse carried along septum within AV bundle to the punkinje fibers and, by the moderator band to the papillary muscles of the RV
- Impulse is distributed by Purkinje fibers and relayed throughout the ventricular myocardium. Atrial contraction is completed, ventricular contraction begins.
What are the two main branches in the ANS
Sympathetic nervous system inc HR
Parasympathetic dec HR
Both control SA node
What are catecholamines?
Increase HR
Epinephrine - adrenaline
Released by adrenal medulla upon activation of sympathetic nerves inner acting this tissue
Happens during exercise, stresss, anxiety
Binds to adrenergic receptors on the heart
Norepinephrine - noradrenaline, eventually decreases hr
Released by adrenal medulla
What are the roles of chemoreceptors and baroreceptors on the heart
Chemo - monitor chemical characteristics of the blood tissues help regulate both cv and respiratory systems.
Monitors blood co2 and pH
Peripheral - carotid bodies and aortic bodies
Central - medulla
Baro - mechanoreceptors that sense changes in blood pressure on a beat to beat basis. Carotid sinus senses inc and dec
Aortic arch senses inc
