Circulatory System 1 Flashcards
What is cardiac output?
What is approximately the normal cardiac output at rest and during activity?
What is cardiac reserve?
it it the liters of blood pumped by the heart per min
at rest= 5L/min (volume of blood in body)
During activity= 20-25L/min
COmax - COrest= cardiac reserve volume
what is the function of the coronary sinus?
it collects cardiac deoxygenated blood and drains it into the right atrium. located between left atrium and vcentricle.
Describe the 4 Septa of the heart
- Atrial septum- behind pulmonary artery, divides the atria
- Ventricle septum - divides the ventricles
- Tendinae Chordae- anchor the tricuspid and mitral valves to the ventricles
- Annulus fibrosis- Fibrous skeleton of the heart made of 4 rings. Maintains structure/form of the heart during contractions
contributes to forming the conduction pathway for impulses (not electrically acticve)
Describe the 3 layers of the heart from inner to outermost
- Endocardium = lines the inside of the ventricles, atra, aorta,, pulmonary veins, and arteries
- Myocardium= Muscular tissue of the heart
- Pericardium= two layers:
Superficial fibrous pericardium= anchors the heart to its surroundings, prevents heart from overfilling, and protects the heart
Deep Serous pericardium= also contains two layers that line the visceral and parietal layers of the heart and contain serous fluid which provides a friction free environment for the heart to work in
the visceral layer of the serous pericardium is also called the Epicardium
When the heart contracts the ___ valves open and the ___ valves shut
when the heart relaxes the ___ valves open and the ___ valves are shut
Semilunar (aortic and pulmonary)
Atrioventricular (Mitral and tricuspid)
vice versa
Describe the two phases that occur during diastole and which valves are open and closed for each phase
- Isovolumetric relaxation= Early diastole, all valves shut, pressure decreases, ventricles relax, end systolic volume remains, , no inflow of blood yet
- Ventricular filling= mid to late diastole, pressure decreases, blood flows through open atrioventricular valves to fill ventricles, 80% of ventricular filling is complete
What is end diastolic volume? when does it occur?
maximum volume of blood in the heart, complete during the contraction of the atrium only during depolarization
Describe the two phases that occur during systole and which valves are open and closed during each phase
- Isovolumetric contraction= Volume remains the same, ventricles are starting to contract but all the valves are shut, pressure rises
- Ventricular ejection= Contraction (systole), pressure in ventricles overcomes that of the aorta and pulmonary artery and semilunar valves open to let blood out of the ventricles
What is atrial or ventricular fibrillation?
when contractions of the atrium or ventricles is out of sync resulting in less blood in ventricles and a lower cardiac output
What is mitral incompetence?
Backflow of blood into the atria due to mitral valve impairment
What is aortic valve stenosis?
rigidity of the aortic semilunar valve resulting in the heart having to work harder to pump the blood out, left ventricular hypertrophy may follow.
what is the formula for cardiac output?
=Heart rate (beats per min) x Stroke Volume (mL per beat)
Describe the steps of the intrinsic cardiac conduction system
- Depolarization of sinoatrial node in right atrium fires an impulse
- Atria depolarize and contract, electroactivity is concentrated at the atrioventricular node in right atrium
- Atrioventricular node delays the impulse to allow complete filling of the ventricles
- Impulse follows the “Bundle of His” pathway between the ventricles and splits into right and left bundle branches at the apex
- The impulse follows the “Subendocardial conducting network” also called “purkinjee fibers” throughout the ventricles
- ventricles contract
How do the sympathetic cardiac nerves affect the heart rate? Which neurotransmitter and receptors are involved?
The sympathetic trunk ganglion nerves innervate the SA and AV nodes to increase the heart rate and the force of contraction.
Norepinephrine is the neurotransmitter for the Beta-1-adrogenic receptor
What is the function of beta blocker medications?
they decrease the heart rate and force of contraction by blocking the Beta-1-adrogenic receptors from norepinephrine transmitter
How do the parasympathetic cardiac nerves affect the heart rate? which neurotransmitter is involved?
Nerve fibers from the Vagus nerve in the medulla oblongata innervate the SA and AV nodes to decrease the heart rate
the neurotransmitter is acetylcholine
How is the heart rate regulated chemically?
Hormones:
- Epinephrine- released by medulla during sympathetic NS activation, increases HR and contractility
- Thyroxine- released by thyroid, causes a sustained increase in HR and enhances the affects of epinephrine and norepinephrine
Ions:
- Calcium- Hypercalcemia increases heart activity but can disrupt function. Hypocalcemia depresses heart activity.
- Potassium- Hyperkalemia may cause heart block or cardiac arrest, Hypokalemia causes arrhythmia by weakening the force of contraction
What is Tachycardia? what is bradycardia? What is fibrillation? what is the average resting heart rate for females and males?
Tachycardia is a resting heart rate over 100beats/min
bradycardia is a resting heart rate lower than 60beats/min (can be normal with endurance training when heart hypertrophies and can pump out more blood per beat)
Fibrillation is irregular and out of sync contractions of the atria and ventricles
females= 72-80beats/min males= 64-72 beats/min
What is the formula for stroke volume?’
which volume is affected by preload?
which volume is affected by afterload?
= End diastolic volume - End systolic volume
End diastolic
End systolic
what is preload? Afterload? Contractility?
Preload= the degree to which the cardiac muscles can be stretched before they contract = End diastolic volume
Afterload= The pressure the ventricles must overcome to eject the blood= Resistance
(High afterload will increase workload for the heart which will result in a higher end systolic volume which will decrease the stroke volume)
Contractility= the ability of the heart to contract at a given muscle strength
High contractility decreases end systolic volume which increases stroke volume
What is Positive Inotropy?
stimulation of sympathetic NS to increase contractility usually via drugs
How does increasing venous return affect stroke volume?
Describe the two pumps that increase venous return
high venous input= high preload/stretch=high force of contraction= high stroke volume
- Muscular pump= muscle contractions apply pressure on veins and increase their pumping action
- Respiratory pump= On inhale abdominal pressure increases which speeds up blood flow into thoracic veins
The right and left coronary arteries arise from the base of ____ The left coronary artery splits into the ____ and _____ arteries
The ______ artery supplies blood to the interventricular septum and the _____ walls of both ventricles
the ____ artery supplies the left atrium and posterior walls of left ventricle
The right coronary artery splits into the _____ and _____ arteries
_____ artery supplies the myocardium of the lateral right side of the heart
_____ artery supplies the posterior ventricular walls and at the apex it merges with the ____ artery
Anterior interventricular
and circumflex arteries
Anterior interventricular artery
Anterior walls
Circumflex artery
right marginal artery
and posterior interventricular artery
Right marginal artery
Posterior interventricular artery
with the anterior interventricular artery
Without the influence from the autonomic nervous system, the sinoatrial node sets the resting heart rate at around _____beats/min
but at rest the _______ nervous system sets the heart rate around _____beats/min via the ______ nerve.
This is also called _____ tone
100 parasympathetic 75 Vagus Vagus tone
