Circulatory System 1

Question 1

What is cardiac output?
What is approximately the normal cardiac output at rest and during activity?
What is cardiac reserve?

Answer 1

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

Question 2

what is the function of the coronary sinus?

Answer 2

it collects cardiac deoxygenated blood and drains it into the right atrium. located between left atrium and vcentricle.

Question 3

Describe the 4 Septa of the heart

Answer 3

1. Atrial septum- behind pulmonary artery, divides the atria
2. Ventricle septum - divides the ventricles
3. Tendinae Chordae- anchor the tricuspid and mitral valves to the ventricles
4. 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)

Question 4

Describe the 3 layers of the heart from inner to outermost

Answer 4

1. Endocardium = lines the inside of the ventricles, atra, aorta,, pulmonary veins, and arteries
2. Myocardium= Muscular tissue of the heart
3. 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

Question 5

When the heart contracts the ___ valves open and the ___ valves shut
when the heart relaxes the ___ valves open and the ___ valves are shut

Answer 5

Semilunar (aortic and pulmonary)
Atrioventricular (Mitral and tricuspid)

vice versa

Question 6

Describe the two phases that occur during diastole and which valves are open and closed for each phase

Answer 6

1. Isovolumetric relaxation= Early diastole, all valves shut, pressure decreases, ventricles relax, end systolic volume remains, , no inflow of blood yet
2. Ventricular filling= mid to late diastole, pressure decreases, blood flows through open atrioventricular valves to fill ventricles, 80% of ventricular filling is complete

Question 7

What is end diastolic volume? when does it occur?

Answer 7

maximum volume of blood in the heart, complete during the contraction of the atrium only during depolarization

Question 8

Describe the two phases that occur during systole and which valves are open and closed during each phase

Answer 8

1. Isovolumetric contraction= Volume remains the same, ventricles are starting to contract but all the valves are shut, pressure rises
2. 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

Question 9

What is atrial or ventricular fibrillation?

Answer 9

when contractions of the atrium or ventricles is out of sync resulting in less blood in ventricles and a lower cardiac output

Question 10

What is mitral incompetence?

Answer 10

Backflow of blood into the atria due to mitral valve impairment

Question 11

What is aortic valve stenosis?

Answer 11

rigidity of the aortic semilunar valve resulting in the heart having to work harder to pump the blood out, left ventricular hypertrophy may follow.

Question 12

what is the formula for cardiac output?

Answer 12

=Heart rate (beats per min) x Stroke Volume (mL per beat)

Question 13

Describe the steps of the intrinsic cardiac conduction system

Answer 13

1. Depolarization of sinoatrial node in right atrium fires an impulse
2. Atria depolarize and contract, electroactivity is concentrated at the atrioventricular node in right atrium
3. Atrioventricular node delays the impulse to allow complete filling of the ventricles
4. Impulse follows the “Bundle of His” pathway between the ventricles and splits into right and left bundle branches at the apex
5. The impulse follows the “Subendocardial conducting network” also called “purkinjee fibers” throughout the ventricles
6. ventricles contract

Question 14

How do the sympathetic cardiac nerves affect the heart rate? Which neurotransmitter and receptors are involved?

Answer 14

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

Question 15

What is the function of beta blocker medications?

Answer 15

they decrease the heart rate and force of contraction by blocking the Beta-1-adrogenic receptors from norepinephrine transmitter

Question 16

How do the parasympathetic cardiac nerves affect the heart rate? which neurotransmitter is involved?

Answer 16

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

Question 17

How is the heart rate regulated chemically?

Answer 17

Hormones:

1. Epinephrine- released by medulla during sympathetic NS activation, increases HR and contractility
2. Thyroxine- released by thyroid, causes a sustained increase in HR and enhances the affects of epinephrine and norepinephrine

Ions:

1. Calcium- Hypercalcemia increases heart activity but can disrupt function. Hypocalcemia depresses heart activity.
2. Potassium- Hyperkalemia may cause heart block or cardiac arrest, Hypokalemia causes arrhythmia by weakening the force of contraction

Question 18

What is Tachycardia? what is bradycardia? What is fibrillation? what is the average resting heart rate for females and males?

Answer 18

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

Question 19

What is the formula for stroke volume?’
which volume is affected by preload?
which volume is affected by afterload?

Answer 19

= End diastolic volume - End systolic volume
End diastolic
End systolic

Question 20

what is preload? Afterload? Contractility?

Answer 20

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

Question 21

What is Positive Inotropy?

Answer 21

stimulation of sympathetic NS to increase contractility usually via drugs

Question 22

How does increasing venous return affect stroke volume?

Describe the two pumps that increase venous return

Answer 22

high venous input= high preload/stretch=high force of contraction= high stroke volume

1. Muscular pump= muscle contractions apply pressure on veins and increase their pumping action
2. Respiratory pump= On inhale abdominal pressure increases which speeds up blood flow into thoracic veins

Question 23

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

Answer 23

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

Question 24

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

Answer 24

100
parasympathetic
75
Vagus
Vagus tone

Question 25

The _____ is the only electrical connection between the atria and ventricles.
The fibrous ______ is a non-conducting pathway that insulates all other connections
How long does a contraction of the heart take?
How long is the impulse delayed at the AV node?

Answer 25

AV bundle
Annulus fibrosis (exoskeleton)
0.22sec
0.1 sec

Question 26

The various cardiac pacemaker cells have different rates of spontaneous depolarization. The SA node normally drives the heart at a rate of ____beats per minute. Without SA node input, the AV node would depolarize ______ per minute.
Without input from the AV node, the AV bundle and the subendocardial conducting network would depolarize _____ per minute

Answer 26

75
50
30