Chapter 18 The Heart Flashcards
3 Layers of The Heart Wall
- Epicardium
- Myocardium
- Endocardium
Epicardium
visceral (inner) layer of pericardium
-outermost layer of the heart
Myocardium
cardiac muscle
- middle layer
- allows heart to contract; pump blood
- thickest layer
Endocardium
endothelial cells (simple squamous epithelial); single layer thin cells -layer with direct contact with blood that is in the chambers of the heart
4 Chambers of The Heart
- 2 Atria (left and right)- receive blood from the body
- 2 Ventricles (left and right)- pumps blood out of the heart
The Right Atrium (RA) receives blood from 3 Veins
- Superior Vena Cava (drains blood from upper part)
- Inferior Vena Cava (drains blood from lower part)
- Coronary Sinus (drains blood from myocardium)
- oxygen poor blood (cause its on the right side)
- the blood will flow down into the right ventricle
Vein
blood vessels that carries blood TOWARDS the heart
The Left Atrium (LA) receives blood from?
Pulmonary Veins
- lungs: coming from the lungs to the heart
- oxygen rich blood (because its on the left side of the heart and coming from the lungs)
- blood travels down to left ventricle
The Right Ventricle (RV) pumps blood into the
Pulmonary Arteries
-lungs
The Left Ventricle (LV) pumps blood into
The Aorta
-all body tissues (except lungs)
The right side of the heart has oxygen ____ blood?
poor
- its blood returning from body tissue
- (RA, RV)
The left side of the heart has oxygen ____ blood?
rich
- containing blood from the lungs
- (LA, LV)
Arteries
blood vessels that carry blood AWAY from the heart
What Separates the 2 Atria?
The Interatrial Septum
-vertical line between the 2 Atria separating them
What Separates the 2 Ventricles?
The Interventricular Septum
-vertical line between the 2 ventricles separating them
Pathways of Blood Through The Heart
- Pulmonary Circuit
- Systemic Circuit
- Coronary Circuit
Pulmonary Circuit
blood vessels that carry blood to and from lungs (RV is the pump)
Systemic Circuit
blood vessels carry blood to and from all body tissues (LV is the pump)
Coronary Circuit
blood vessels carry blood to and from myocardium (LV is the pump)
Pathway of blood through the Pulmonary and Systemic Circuits
RA–> RV–> Pulmonary Arteries–> Lungs (where it turns to oxygen rich blood)–> Pulmonary Veins–> LA–> LV–> Aorta–> Body Tissues (goes back to oxygen poor blood) –> vena cava–> RA
Pathway of blood through the Pulmonary and Systemic Circuits
- RA
- RV
- Pulmonary Arteries
- Lungs (where it turns to oxygen rich blood)
- Pulmonary Veins
- LA
- LV
- Aorta
- Body Tissues (goes back to oxygen poor blood)
- Vena Cava
- RA
Pathway of Blood Through the Coronary Circuit
Aorta–> Coronary arteries–> myocardium (where it turns into oxygen poor blood)–> coronary veins–> coronary sinus–> RA
-shortest circuit
Pathway of blood through the Coronary Circuit
- Aorta
- Coronary Arteries
- Myocardium (turns into oxygen poor blood)
- Coronary Veins
- Coronary Sinus
- RA
Heart Valves
- allows for one-way flow through the heart (prevent backflow)
- heart valves open or close due to pressure differences
There are 4 Heart Valves
- 2 Atrioventricular valves (AV valves)- between the atria and the ventricles
- 2 Semilunar valves (SL valves)- between the ventricles and the arteries carrying blood out of the heart
The 2 AV Valves Are?
- Tricuspid Valve- between RA and RV
2. Bicuspid Valve (or Mitral Valve)- between LA and LV
The 2 SL Valves Are?
- Aortic SL Valve (Aortic Valve)- between the LV and the Aorta
- Pulmonary SL Valve (Pulmonary Valve)- between RV and pulmonary arteries
Heart Sounds are heard when___?
the valves close
- 1st heart sound (lub)- heard when both AV valves close
- 2nd heart sound (dub)- heard when both SL valves close
1st heart sound (lub) is heard when?
-both AV valves close
2nd heart sound (dub) is heard when?
-both SL valves close
When Ventricular Pressure >(is greater than) Atrial Pressure, The AV valves ____
close
-so the blood from the ventricles doesn’t go back into the atrium (prevent backflow)
When Atrial Pressure > (is greater than) ventricular pressure, the AV valves _____
Open
-to pump that blood into the ventricles
When Ventricular Pressure > (is greater than) pressure in aorta or pulmonary arteries, both SL valves____
Open
-but no lub dub sound just no sound
When pressure in Aorta or Pulmonary Arteries >(is greater than) Ventricular Pressure, both SL valves
Close
-2nd heart sound
There are no valves between ____
- there are no valves between the vena cava and RA
- there are no valves between the pulmonary veins and LA
- blood flows continuously into the 2 atria
Blood Flows continuously into ___
the 2 atria
Papillary muscles are attached to what?
chordae tendineae (heart strings)
Function of the papillary muscles and heart strings?
hold the AV valves closed during ventricular contraction (pumping blood out of heart)
Microscopic Anatomy Of Cardiac Muscle Tissue
Cardiac muscle cells are:
- Striated (stripped appearance)
- Involuntary (do not consciously control)
- Branched
- Interconnected by Intercalated Discs (connections to neighboring muscle fibers; which make it branched; holds muscle fibers together)
Intercalated Discs contain 2 kinds of Cell Junctions
- Desmosomes- anchoring junctions: hold neighboring cells together
- Gap Junctions- communicating junctions
- heart operates as a functional syncytium (coordinated unit)
- signal reaches at the same time
Intercalated Disc cell junction: Desmosomes
anchoring junctions; hold neighboring cells together
Intercalated Disc cell junction: Gap Junctions
communicating junctions
- heart operates as a functional syncytium (coordinated unit)
- signal reaches at the same time
2 Kinds of Cardiac Muscle Fiber (cardiac muscle consists of)
- Autorhythmic Fibers
2. Contractile Fibers
Cardiac Muscle Fiber: Autorhythmic Fibers
1% of all cardiac muscle tissue
- noncontractile (cannot shorten)
- unstable membrane potential
- self-depolarizes (start action potentials by itself)
- conduct electrical impulses through heart (Cardiac Conduction System)
Cardiac Muscle Fiber: Contractile Fibers
99% of all cardiac muscle tissue
- contractile (can shorten)
- have a stable membrane potential
- do not self-depolarize (need a stimulus)
- gap junction allows heart to contract as a syncytium (allows heart to contract at the same time)
Contractile Fibers cannot start action potentials (A.P) because?
it has a stable membrane potential
Autorhythmic Fibers can initiate action potentials (A.P) because?
of its unstable membrane potential
Cardiac Conduction System
- made of autorhythmic fibers
- that initiates and transmits electrical impulses (action potentials) through the heart
- that results in rhythmic contractions
5 Structures of the Cardiac Conduction System
- Sinoatrial Node
- Atrioventricular Node
- Atrioventricular Bundle
- Right + Left Bundle Branch
- Purkinje Fibers
Structure of the Cardiac Conduction System: Sinoatrial Node
pacemaker
- where action potentials begin
- self-depolarize (reach threshold) about 100x per minute
- start faster than any others; sets the pace
- starting point to start action potentials
- action potentials spread through both Atria and Contract which will flow down to ventricles
Structure of the Cardiac Conduction System: Atrioventricular Node
- slows down action potentials a little bit
- self-depolarizes about 50x per minute
- located in interatrial septum
Structure of the Cardiac Conduction System: Atrioventricular Bundle
(AV Bundle, Bundle of HIs)
- 30x per minute
- allows to go to ventricle areas
Structure of the Cardiac Conduction System: Right + Left Bundle Branch
self-depolarizes 15x per minute
-in the interventricular septum
Structure of the Cardiac Conduction System: Purkinje Fibers
- located at the apex of the heart
- release the charge, charge up both ventricles
Sinus Rhythm
the normal rhythm of the heartbeat set by the SA (sinoatrial) node
A.P of Contractile fibers: 3 phases
- Depolarization- action potential start, due to Na+ (sodium) ions entering the cell
- Plateau Phase- maintain depolarization, calcium (Ca2+) flows into the cell
- stays for a long period of time (stays contracted)= make sure contractions squeeze blood for a long time to contract more blood out of ventricles - Repolarization- action potential goes away; goes back to resting state, potassium (k+) will leave the cell (inside gets more negative)
Electrocardiogram (ECG or EKG)
recording of the flow of electrical impulses (all A.P) produced by the heat
(sum of all action potentials occurring throughout the heart)
EKG has 3 waves
- P wave- atrial depolarization
- QRS complex- ventricular depolarization
- T wave- Ventricular repolarization
EKG has 3 Segments (time spans)
- P-Q interval- time from beginning of P wave to beginning of QRS wave
- Q-T interval- time span from beginning of QRS to end of T wave; measuring how long it takes to travel to beginning to end of CCS
- S-T Segment- end of QRS wave to beginning of T wave
- steady ventricular depolarization (Contractions); Plateau phase