Cardiovascular System Flashcards
Cardiovascular function
Transportation of molecules using blood
Deliver oxygen and nutrients, remove co2, ammonia and other metabolic waste
Heart location
Pericardial, in the mediastinum
Apex: points towards the left hip and rests on diaphragm (5th intercostal space) (point of maximal intensity PMI is where we put stethoscope)
Base points towards right shoulder, behind second rib
Pericardium
Serous membrane covering the heart
Serous fluid
Provides a friction free environment
Protects and anchors the heart to structures like the diaphragm
Superficial to internal:
Fibrous pericardium
Parietal layer of serous pericardium
Pericardial cavity filled with serous fluid
Visceral layer of serous pericardium
Heart anatomy wall
Heart wall composed of 3 layers
Sup to int:
Epicardium ( visceral serous layer too)
Myocardium (cardiac muscle, responsible for contraction)
Endocardium (insures blood gluides in the chamber, no friction) simple squamous epithelium (endothelium)
Ventricles
Left ventricle thicker because it pumps blood to the whole body
Blood circulation
Heart acts as two pumps:
Pulmonary circuit pump (right side of heart to lungs)
Systemic circuit pump (left side of Herat to the rest of the body)
Systemic circuit
Superior/inferior vena cava
Right atrium
Right Ventricle
pulmonary trunk
Will go either to left or right pulmonary artery (left and right lung)
Pulmonary vein
Left atrium
Left ventricle
Aorta
Blood flows simultaneously everywhere
Four chambers of the heart
Atria:
Receive blood form veins
Fill the ventricles
Blood enters passively under low pressure
Contract together
Ventricles:
Thick walled
Blood is propelled into arteries
Contact together
Blood vessels
Arteries carry blood away heart
Veins carry blood toward heart
Superior vena cava: lower body to right atrium
Inferior vena cava: lower body to right atrium
Pulmonary veins: lungs to atrium (oxygen rich blood)
Pulmonary trunk: right ventricle to lungs via pulmonary arteries (oxygen poor)
Aorta: left ventricle go body, in aorta ascending arteries are:
Brachioceohalic trunk: right arm
Left subclavian artery: left arm
Left common carotid artery: goes straight to head
Arteries pump blood, veins don’t
Cardiac circulation
Enters directly off the aorta
Cardiac arteries:bring oxygenated blood to the heart:
Right coronary artery
Marginal artery
Circumflex artery
Left coronary artery
Cardiac veins:
Great cardiac vein: “
Small cardiac vein: drain the myocardium of blood
Anterior cardiac vein: “
Coronary sinus: on posterior, receives blood from cardiac vein, then empties to right atrium
4 heart valve
Right atrioventricular vale (tricuspid) (chordate tendineae)
Left atrioventricular vale (bicuspid, mitral) (papillary muscle)
Pulmonary semilunar valve
Aortic semilunar valve
Has cusps, made of thin tough membrane
Open and close due to pressure change
Sound heard is the valves closing
AV valve
Between atria and ventricle
Open during heart relaxation, closed during ventricular contaraction
Anchored the cusp I place with the chordate rendineae tot eh papillary muscle
Operation:
Blood returning to the atria puts pressure on AV and go into ventricle passively
As ventricle fills, AV cusp hand limply into the ventricle
Atria contracts to eject blood in the into the ventricle, pressure increases in atria, AV still open
Ventricle contracts, pressur increases in ventricle, forcing blood against cusps, AV close
Tricuspid and bicuspid close at the same time, making lub sound
Majority of time spend open
Semilunar valve
Between ventricle and artery
Closed during heart relaxation, open during ventricular contraction
Operation:
Pressure in ventricules are so high that blood is pushed against valve, forcing semilunar valves open
Blood gets ejected into aorta/pulmonary trunk
Ventricles relax, pressure falls, blood falls back onto cusps of semilunar valve, forcing them to close
Semilunar valves close simultaneously, making dup sound
Majority of time closed
Congestive heart failure
Imbalance of pumping action between two sides of the heart
Eventually whole heart fails
Right heart fails, peripheral congestion, edema (swelling)
Left heart fails, pulmonary congestion, fluid accumulates in lungs and person drowns
How does the heart beat
Cardiac muscle contracts independently of nerve impulses (intrinsic conduction system)
Ensures all 4 chambers of the heart contracts in a regular continuous and unified rhythm
Atria cells beat a bit faster than ventricular cells,
through intercalated disc, the intrinsic conduction passes to the non pacemakers cells
Intrinsic conduction system
4 special nervous tissue: (not nervous system)
Sinoatrial node: in right atrium, hearts pacemaker, sends electrical signal to both atrium and to AV node
Atrioventricular node: at the junction of atria and ventricles, ensures both ventricules contract together
Atrioventricular bundle (bundle of his) and bundle branches are in interventricular septum
Purkinje fibers: spread sighing the ventricle wall muscles
Intrinsic conduction path
SA node
Atrial muscle
AV node (delay for atria to relax) atria contract
Purkinje fibers
Ventricular muscle
Ventricles contract
Heart physiology
In addition to the intrinsic conduction system, the nervous system also regulates heart activity, nerves of the autonomic nervous system act like brakes or accelerators to increase or decrease heart rate (medulla oblungata)
Cardiac cycle
One complete heartbeat
Systole (contraction, high pressure)
Diastole (relaxation, low pressure)
Atrial diastole
Atrial systole
Isovokumentric contraction
Ventricular systole
Isovokumetric relaxation
Atrial diastole
Heart is relaxed
Pressure in heart is low
AV valve open
Blood flows passively into atria and ventricles
Semilunar valves closed
Atrial systole
Just before, SA node have been activated
Ventricles stay in diastole
Atria systole
Blood forced into ventricles
Isovolumetric contraction
Atrial systole ends (high pressure in atria)
Ventricular systole begins
Intraventricular pressure rises
AV valve close (lub)
For a moment, ventricles are completely closed
Ventricular systole
Ejection phase
Ventricles systole
Intraventricular pressure now surpasses the pressure in the major arteries (pulmonary trunk and aorta)
Semilunar valve open
Atria is relaxed and filling with blood, back into diastole
Blood pressure is a measure of of pressure in this phase
Isovolumetric relaxation
Ventricular diastole begins
Pressure falls below that of major arteries
Semi,Unser valve close (dup)
For a moment, ventricules completely closed
When atrial pressure increases above Intraventricular pressure, AV valve open
