Lecture Exam 1

Heart

\*two major divisions of the circulatory system

pulmonary and systemic

\*pulmonary circuit

* right side of the heart with deoxygenated blood
* carries blood to lungs for gas exchange and then back to heart

\*systemic circuit

* left side of the heart with oxygenated blood
* supplies oxygenated blood to all tissues of the body and returns it to the heart

what type of blood does the LEFT side of the heart hold?

fully oxygenated blood from the pulmonary veins

what type of blood does the right side of the heart hold?

oxygen-poor blood from the superior and inferior vena cavae

top of the heart:

base

bottom of the heart:

apex

hearts position in the body:

directly behind the sternum

a double-walled sac that encloses the heart:

pericardium

what does the pericardium allow the heart to do?

beat without fiction and anchor into place

pericardial cavity:

* between the visceral and parietal pericardium
* its superficial fibrous layer of CT and a deep, thin serous layer

visceral pericardium:

* a serous membrane covering the heart
* AKA epicardium

term for painful inflammation of the membrane:

Pericarditis

\*3 layers of the heart wall:

Epicardium

Endocardium

Myocardium

\*epicardium

* serous membrane covering heart
* coronary blood vessels travel through this layer

\*endocardium

* smooth inner lining of heart and blood vessels
* covers the valve surfaces and it continuous with endothelium of blood vessels

\*myocardium

* layer of cardiac muscle proportional to work load
* 90%
* fibrous skeleton of the heart: framework of collagenous and elastic fibers

four chambers of the heart:

right and left atrium, right and left ventricle

\*on the surface above the atriums:

auricles

wall that separates atria:

interatrial septum

internal ridges of myocardium that are in the right atrium and both auricles:

pectinate muscles

wall that separates ventricles:

interventricular septum

internal ridges that are in both ventricles:

trabeculae carneae

\*the foramen ovale in the fetus that gets filled when it grows:

fossa ovale

separates the atria and ventricles on the outside of the heart:

antrioventricular sulcus

divides the right ventricle from the left on the outside of the heart:

interventricular sulcus

controls the blood flow between atria and ventricles

atrioventricular valves (AV)

* right AV - tricuspid
* left AV - mitral/ bicuspid

\*cord that connects AV to papillary muscles on the floor of ventricles:

chordae tendineae

* prevents AV from flipping or bulging into atria when ventricles contract

\*systole:

contraction

\*diastole:

relaxation

What controls the flow into great arteries?

semilunar valves

What are the 2 types of semilunar valves?

pulmonary and aortic

how do semilunar valves open and close?

because of blood flow and pressure

Blood flow of deoxygenated blood:

1. blood enters the right atrium from superior/inferior vena cava
2. blood in right atrium flows through right AV valve into right ventricle
3. contraction of right ventricle forces pulmonary valve open
4. blood flows through pulmonary valve into pulmonary trunk
5. blood is distributed by right/left pulmonary arteries to the lungs, unload CO2 and load O2

blood flow of oxygenated blood:

1. blood returns from lungs via pulmonary veins into left atrium
2. blood in left atrium flows through left AV valve into left ventricle
3. contraction of left ventricle forces aortic valve open
4. blood flows through aortic valve into ascending aorta
5. blood in aorta is distributed to every organ in body, unloading O2 and loading CO2
6. blood returns to right atrium via vena cava

the coronary circulation relates to:

blood vessels on heart walls

what percentage of blood pumped by the heart to the heart itself through the coronary circulation?

5% (250mL/min)

what arteries branch off the ascending aorta?

left coronary (LCA) and right coronary (RCA) arteries

what blood vessels supply blood to both ventricles and anterior 2/3 of the interventricular septum?

anterior interventricular branch (branches off of LCA)

What passes around the left side of the heart in coronary sulcus?

circumflex branch - supplies left atrium and posterior wall of left ventricle (branches off of LCA)

what branches off of the circumflex branch?

left marginal branch

what blood vessel supplies the right atrium and sinoatrial node?

right coronary artery (RCA)

what supplies lateral aspects of the right atrium and ventricle?

right marginal branch (branches off of RCA)

what supplies the posterior walls of ventricles?

posterior interventricular branch (branches off of RCA)

what disease in the constriction of the coronary arteries?

Coronary arteries disease (CAD)

* results in atherosclerosis
* starts when endothelium is damaged

medical term for a heart attack:

myocardial infarction (MI)

* interruption of blood supply to the heart from a blood clot and can cause cell death within minutes
* 27% of US deaths

what is it called when you have chest pains from partial obstruction of coronary blood flow?

angina pectoris

* pain is caused by ischemia (decrease of blood flow) or cardia muscle
* shift to anaerobic fermentation

what does the venous drainage drain?

waste

what vein drains coronary blood directly back into the heart chambers to drop off deoxygenated blood?

thebesian veins

* drop of to the right atrium by the coronary sinus

3 coronary sinus inputs:

1. great cardiac vein
2. posterior interventricular vein
3. left marginal veins

what veins travel alongside the anterior interventricular artery and collect blood for the anterior portion of the heart?

great cardiac vein

what vein is found in the posterior sulcus and collects blood from the posterior portion of the heart?

posterior interventricular

what is the large transverse vein in the coronary sulcus on the posterior side of the heart?

coronary sinus

what are the striated, short, thick, branches cells with one central nucleus surrounded by light-stained mass of glycogen and myofibrils?

cardiocytes - all beat in unison

what joins cardiocytes end to end with interdigitating folds, mechanical junctions, and electrical gap junctions?

intercalated discs

what do cardiac muscles depend almost exclusively on the make ATP?

aerobic respiration

* rich in myoglobin and glycogen

what cells make up the nerve-like conduction pathways through myocardium?

conductive and contractic cells

conductive cells

send the signals

contractic cells

receives the signal and contracts muscle

the internal pace maker:

sinoatrial node (SA)

* modifies cardiocytes by initiating heartbeat and rate
* located in right atrium near base of superior vena cava

process of the conduction system:

1. sinoatrial (SA) node fires
2. excitation (conductive cells) spreads through atrial myocardium
3. atrioventricular (AV) node fires
4. excitation spreads down AV bundle
5. Purkinje fibers distribute excitation through ventricular myocardium
6. hits cardiocyte in the ventricle and contracts

what happens during steps 3 and 4?^\`

signals starts to slow down to allow ventricles to fill up

what is the sinus rhythm?

normal heartbeat triggered by SA nodes (70-80bpm)

what is the region of spontaneous firing other than the SA node?

ectopic focus caused by caffeine or stress

if the SA node is damaged and heart rate is set by the AV node, what is the new stressed rhythm called?

nodal rhythm (40-50bpm)

what is gradual depolarization called?

pacemaker potential

what are the 3 phases to cardiocyte action potential?

depolarization, plateau, repolarization

depolarization

* brief
* stimulus opens voltage-regulated Na+ gates, membrane depolarizes rapidly
* peaks at +30MV
* Na+ gate close quickly

plateau phase

* sustains contractions for expulsion of blood from heart
* voltage-gated slow Ca2+ channels open admitting Ca2+ which triggers opening of Ca2+ channels on sarcoplasmic reticulum
* Ca2+ binds to troponin triggering contracton

repolarization

* Ca2+ channels close
* K+ channels open
* rapid diffusion of K+ out of cell returns it to resting potential

what happens during a P wave?

atrial depolarization = atrium contracts

what happens during the QRS complex?

ventricular depolarization

what happens during the ST segment?

ventricles contract

what happens during the T wave?

ventricular repolarization and relaxation

the opening and closing of valves are governed by ___

pressure changes

what is any failure of a valve to prevent reflux?

valvular insufficiency

What is it called when cusps are stiffened and the opening is constricted by scar tissue?

valvular stenosis

* result of rheumatic fever, autoimmune attack on the mitral and aortic valves and enlarged overworking heart

when there is an insufficiency in which one or both mitral valve cusps bulge into atria during ventricular contraction?

mitral valve prolapse (may cause chess pain and shortness of breath)

first heart sound is ____. What produces it?

lubb

* produced by closure of the AV valves

second heart sound is ___. What produces it?

dupp

* produced by closure of semilunar valves

ventricular filling

valves

* AV opening, semilunar closing

no sound

EDV achieved in each ventricle (130mL)

isometric contraction

valves

* AV closed, semilunar opening

first heart sound

ventricular ejection

valves

* AV closed, semilunar open

no sound

60mL of blood remaining = ESV

isovolumetric relaxation

valves

* AV and semilunar closed

second heart sound

T wave ends and ventricles begin to expand

EDV

end-disastolic volume

130mL

ESV

end-systolic volume

= EDV - SV

SV

stroke volume: amount of blood pumped per beat

SV=EDV-ESV

what are the results from the failure of either ventricle to eject blood effectively called?

congestive heart failure (CHF)

* due to chronic hypertension, valvular insufficiency

what is is called when blood backs up into the lungs causing pulmonary edema?

left ventricular failure

* symptoms: shortness of breath or sense of suffocation

what is it called when blood backs up in the vena cava causing systemic or generalized edema?

right ventricular failure

* symptoms include: enlargment of liver, ascites, distention of jugular veins, swelling of fingers
* leads to heart failure

what is the term for the amount of blood ejected by each ventricle in 1 minute?

cardiac output

= heart rate x SV

results in 4-6L/minute at rest

what is the term for the difference between a person’s maximum and minimum cardiac output?

cardiac reserve

* increases with fitness; decreases with disease

tachycardia

more than 100 beats/min

bradycardia

less than 60 beats/min

how does venous return affect SV and CO?

amount of blood coming back to the heart through veins will depends how much blood can be pumped

how does exercise affect HR, SV, and CO

increase all 3

the part of the intrinsic conduction system that initiates and sets the heart rate:

SA node

a tracing of the electrical activity of the heart is:

ECG (electrocardiograph)

atrial repolarization is hidden by ____ wave in a normal ECG

QRS

the three variables of a stroke volume:

preload, contractility, afterload