Cardiovascular System Flashcards
Components of Circulatory System
Blood
Blood Vessels
Heart
Types of Blood Vessels
Arteries/Capillaries/Veins
Arterioles/Venules
2 Circuits of Cardiovascular System
Pulmonary Circuit - Blood to and from lungs
Systemic Circuit - Blood to and from rest of body
Blood states across the body
Arteries carry oxygenated blood
Veins carry deoxygenated blood
Pulmonary Vein has oxygenated blood
Pulmonary Artery has deoxygenated blood
Location of heart
Thoracic Cavity
Near anterior chest wall
Posterior to sternum
Factors heart size
Biological sex
Age
Size of individual
Exercise
General Structure of the Heart
4 chambers acting as a double pump
2 Atria, 2 Ventricles
Atria and Ventricles (Pathway through the Heart)
Right Atrium receives blood from systemic circuit and passes it to right ventricle
Right Ventricle receives blood from right atrium and pumps it into the pulmonary circuit
Left Atrium receives blood from pulmonary circuit and passes it to the left ventricle
Left Ventricle receives blood from left atrium and passes it to the systemic circuit
Heart Wall Muscle Structure
Pericardium - Outer Wall
Epicardium - Middle Wall
Myocardium - Inner Wall
Pericardium Structure and Function
Contains fibrous tissue (collagen)
Stabilizes heart position
Provides lubrication (using pericardial fluid)
Myocardium Structure
Thick muscle layer between epicardium/endocardium
Highest thickness at Left Ventricle
Thickness changes based on what chamber needs to create more pressure
Myogenic
Interacts with ANS and endocrine system
Intercalated Disks in the Heart
Junction between cardiac cells
Contains gap junctions and desmosomes
Gap Junction Definition
Junction allowing for depolarisation to pass between cells, synchronising muscle contraction
Desmosome Definition
Bind adjacent myocytes together
Endocardium Definition
Covers all inner surfaces of the heart
Consists of epithelial tissue
Continuous with epithelium of vessels
Ventricular Wall differences
LV = thick wall, higher blood pressure needed to pump blood to rest of the body
RV = thin wall
Blood Pressures in Ventricles
LV = 80-100mmHg
RV = <15mmHg
Systemic Circuit blood pressure 4-6x higher than pulmonary circuit
Why is pulmonary circuit blood pressure low
Lungs are delicate, so low blood pressure needed. If higher, would damage blood vessels and lungs
Order of structures in cardiovascular system
Vena Cava, Right Atrium, Tricuspid Valve, Right Ventricle, Pulmonary Valve, Pulmonary Artery, Pulmonary Vein, Left Atrium, Bicuspid Valve, Left Ventricle, Aortic Valve, Aorta
Chordae Tendineae Definition
Tendinous Strings attached to valves
Tether Valves to ventricular walls
Stops valves from opening the wrong way from ventricular systole
Papillary Muscle Definition
Muscles attached to valves
Heartbeat Definition
A single contraction of the heart muscle
Contracts in series: Atria First, Ventricles Second
2 Types of Cardiac Muscle
Contractile - Produces contractions
Cardiac Pacemaker cells - conducting cells
3 Types of pacemaker cells
Sino Atrial Node
Atrio Ventricular Node
Purkinje Fibres
Replacing SAN
Artificial Pacemaker replaces SAN if it becomes dysfunctional
Cardiac Cycle
SA Node activity/atrial activation begins (t=0)
Stimulus spreads across atrial surfaces and reaches the AV Node (t=50msec) (P)
100msec delay at the AV Node, atrial contraction begins (t=150msec)
Impulse travels along interventricular septum within AV bundle, bundle branches to Purkinje fibers and to papillary muscles of RV (t=175msec) (Q)
Impulse distributed by Purkinje fibers and relayed through ventricular myocardium, Atrial contraction is completed, ventricular contraction begins (t=225msec) (QRS)
Waves on a ECG
P Wave - Atria depolarization
QRS Complex - Ventricle depolarization
T Wave - Ventricle Repolarization
When does heartrate change?
Fight/Flight System
Training/Exercise
Rest
Factors affecting Heart Rate
ANS
Catecholamines
Changes in O2/CO2 Levels
Changes in blood pressure
Changes in pH
ANS Control of Heart Rate
Sympathetic pathway increases heart rate
Parasympathetic pathway decreases heart rate
Both intervene at SAN
Types of Catecholamines
Endocrine Response from ANS
Epinephrine
Norephinephrine (Noradrenalin)
Epinephrine Features
Released by adrenal medulla from activation of sympathetic nerves innervating this tissue
Increases heart rate and contractility
Works by binding adrenergic receptors on the heart
Norephinephrine Features
Initially increases heart rate and contractility, but longer exposure results in decreased heart rate and contractility
Released by adrenal medulla, mostly from spillover from sympathetic nerves innervating the heart
Works by binding adrenergic receptors on the heart
Chemoreceptors in Cardiovascular System
Peripheral = Carotid Bodies and aortic bodies
Central = Medulla
Effects of pH on heart rate
Low pH = increased heart rate = activates sympathetic ANS
High pH = decreased heart rate = activates parasympathetic ANS
Effects of CO2 levels on heart rate
High CO2 = increased heart rate = activates sympathetic ANS
Low CO2 = decreased heart rate = activates parasympathetic ANS
Baroreceptors in Cardiovascular System
Mechanoreceptors sensing changes in blood pressure on a beat by beat basis
Carotid Sinus = Senses increases/decreases
Aortic Arch = Senses increases only
Effect of Blood Pressure on Heart Rate
Low BP = less stretch of receptor = increased sympathetic ANS activation = increased heart rate
High BP = more stretch of receptor = increased parasympathetic ANS activation = decreased heart rate
