Chp 3- Cardiovascular And Lymphatic System Flashcards
Pericardium
Fibrous protective sac enclosing heart
Epicardium
Inner layer of pericardium
Myocardium
Heart muscle, the major portion of the heart
Endocardium
Smooth lining of the inner surface and cavities of the heart
Right atrium
Receives blood from systemic circulation through superior and inferior vena cava
Right ventricle
- Blood from RA
- pumps blood via pulmonary artery to lungs for oxygenation
- low pressure pulmonary pump
Left atrium
-receives oxygenated blood from lungs+ 4 pulmonary veins
Left ventricle
- blood from LA
- pumps blood to systemic circulation via aorta
- high pressure pump
- LV walls are thicker and stronger than RV
- forms most of the left side and apex of heart
Atrioventricular valves
- Prevent backflow of the blood into atria during ventricular systole
- anchored by chordae tendineae to papillary muscles
- values close when ventricular walls contract
- Tricuspid and Bicuspid valves
Tricuspid valves
Right heart valve
Bicuspid valve
Left heart valve
Semilunar Valves
- prevent backflow of blood from aorta and pulmonary arteries into ventricles during diastole
- pulmonary and aortic valves
Pulmonary valve
Prevents right back flow
Aortic valve
Prevents left backflow
Systole
Period of ventricular contraction
End systolic volume
Amount of blood in the ventricles after systole
-about 50mL
Diastole
Period of ventricular relaxation and filing of blood
End diastolic volume
Amount of blood in the ventricles after diastole
-about 120mL
Atrial contraction
Occurs during the last third of diastole and completes ventricular filling
-compromises last 20-30% of end diastolic volume
Coronary circulation
Blood circulates to myocardium during diastole
Right coronary artery
Supplies:
- right atrium
- most of right ventricle
- inferior wall of left ventricle
- AV node and bundle of His
- SA node 60% of the time
left coronary artery supplies?
- most of left ventricle
- has two divisions: left anterior descending and circumflex artery
Left anterior descending artery (LAD) supplies?
- most of left ventricle
- interventricular septum
- inferior areas of the apex
Circumflex artery supplies?
- lateral and inferior walls of the left ventricle
- portions of left atrium
- 40% of SA node
Where does coronary sinus receive blood from?
-receives venous blood from heart and empties into right atrium
Specialized conduction tissue
Allows rapid transmission electrical impulses throughout the myocardium
Where is the Sinoatrial (SA) node located?
-located at junction of superior vena cava and right atrium
What does the SA node do?
Main pacemaker of the heart, initiates the impulse rate of 60-100 bpm
What type of innervation does the SA node have?
Has sympathetic and parasympathetic innervation affecting both HR and strength of contraction
Where is the Atrioventricular (AV) node located?
At the junction of right atrium and right ventricle
What innervation does the AV node have and what is it’s intrinsic firing rate?
- Parasympathetic and sympathetic
- 40-60 bpm
What is Purkinje tissue and why is it important?
- specialized conducting tissue spread throughout the ventricles
- Right and left bundle branches of the AV node terminate here
- intrinsic firing rate of 20-40 bpm
Normal sinus rhythm originates where and what is the path it takes?
SA note–> impulse through both atria which contract together–>stimulates AV node–>transmitted down bundle of His to Purkinje fibers–>impulse spreads through both ventricles which contract together (atrial kick)
Muscle tissue
- striated muscle fibers with numerous mitochondria
- exhibits rhythmicity of contraction
- fibers contract as a functional unit
What type of muscle tissue is found in the walls of blood vessels?
Smooth muscle tissue
Define stroke volume and the normal range
- amount of blood ejected with each myocardial contraction
- 55-100 mL/beat
What is stroke volume influenced by
-LV end diastolic volume= the amount of blood left in the ventricle at the end of diastole= preload
Define Frank-Starling law
The greater the amount of preload, the greater the quantity of blood pumped
Define afterload
The force the LV must generate during systole to overcome aortic pressure to open the aortic valve
Define cardiac output
Amount of blood discharged from the left or right ventricle per minute
What is the normal range of cardiac output
4-5 L per minute
How is cardiac output determined?
HRxSV=CO
How is cardiac index calculated and what is the normal range?
Cardiac index= CO/body surface area
-2.5-3.5L/min
What is the normal range for left ventricular end diastolic pressure?
5-12 mmHg
Define ejection fraction
Percentage of blood emptied from the ventricle during systole
-clinically useful measure of LV function
How is EF calculated?
EF=SV/left ventricular end diastolic volume
What is the normal range of EF, and the consequences of low EF?
- lower EF= more impaired LV
- >55%
Define atrial filling pressure
-the difference between the venous and atrial pressures
What happens to right atrial filling pressure during strong ventricular contractions?
- decreased pressure
- enhanced atrial filling
What affects right atrial filling pressure?
- changes in intrathoracic pressure
- decreases during inspiration
- increases during coughing or forced expiration
When does venous return increase?
-when blood volume expands
When does venous return decrease?
-during hypovolemic shock
How is myocardial oxygen demand clinically measured?
HR x SBP= rate pressure produce
What is the job of arteries in peripheral circulation?
Transports oxygenated blood from areas of high pressure–>low pressure
What are arteries in peripheral circulation influenced by?
Elasticity and extensibility of vessel walls and by peripheral resistance
What are the function of arterioles?
Primary site of vascular resistance
What are capillaries?
Small blood vessels that connect the ends of arteries with the beginning of veins
What type of veins accompany arteries?
Deep veins
What is venous circulation influenced by?
- muscle contraction
- gravity
- respiration (increased return with inspiration)
- compliance of right heart
What is the job of the lymphatic system?
-drains lymph from bodily tissues and returns it to venous circulation
Lymphatic contraction occurs by:
1) parasympathetic, sympathetic, and sensory nerve stimulation
2) contraction of adjacent muscles
3) abdominal and thoracic cavity pressure changes during normal breathing
4) mechanical stimulation of dermal tissues
5) volume changes within each lymphatic vessel
Where is parasympathetic control located in the brain?
Medulla oblongata
parasympathetic stimulation occurs via which method?
Via the Vagus nerve and cardiac plexus
Where does parasympathetic innervation occur?
- innervates the SA node, AV node, and sparsely myocardium
- releases Acetylcholine
What are the effects of parasympathetic stimulation on the heart?
- slows rate and force of myocardial contraction
- decreases myocardial metabolism
- causes coronary artery vasoconstriction
Sympathetic stimulation occurs via which method?
Cord segments T1-T4, upper thoracic to superior cervical chain ganglia
What does sympathetic stimulation innervate?
- SA node, AV node, conduction pathways, myocytes
- releases epinephrine and norepinephrine
What does sympathetic stimulation cause?
- increase in rate and force of myocardial contraction and metabolism
- coronary artery vasodilation
What occurs when skin and peripheral vasculature receive sympathetic innervation?
-vasoconstriction of cutaneous arteries
What types of drugs increase sympathetic functioning?
Sympathomimetics
What types of drugs decrease sympathetic functioning?
Sympatholytics
What are baroreceptors?
Main mechanisms controlling heart rate
Where are baroreceptors located?
Walls of aortic arch and carotid sinus
Describe the process that occurs with circulatory reflex when BP increases.
Parasympathetic stimulation–> decreased rate and force of cardiac contraction–> sympathetic inhibition–> decreased peripheral resistance
Describe the process that occurs with circulatory reflex when BP decreases.
Sympathetic stimulation–> increased HR and BP and vasoconstriction of peripheral blood vessels
Where are chemoreceptors located?
Carotid body
What occurs when CO2 is increased, O2 is decreased, and pH levels are decreased?
Increased HR
What is hyperkalemia?
Increased concentration of potassium ions in the blood
What are the cardiovascular affects of hyperkalemia?
- decreases the rate and force of contraction
- produces widened PR interval and QRS
- tall T waves
Define Hypokalemia
Decreased concentrations of potassium ions
What are the effects of hypokalemia?
- flattened T waves
- prolonged PR and QT intervals
- produces arrhythmias which may progress to ventricular fibrillation
Define hypercalcemia and its affects on the cardiovascular system
Increased calcium concentration increases heart actions
Define hypocalcemia and its affects on the cardiovascular system
- decreased calcium concentrations
- depresses heart actions
What can hypermagnesemia do to the cardiovascular system?
-lead to arrhythmias or cardiac arrest
What are the effects of hypomagnesemia
- ventricular arrhythmias
- coronary vasospasms
- sudden death
What are the effects of increased peripheral resistance?
-increases arterial blood volume and pressure
What is peripheral resistance influenced by?
Arterial blood volume- viscosity of blood and diameter of arterioles and capillaries
