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A&P Chapter 17: The Heart
The Heart
65
Biology
03/14/2013

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Cards

Term
Where is the heart located?
Definition

Mediastinum (Middle Thorax)

 

Rests on the Diaphragm

Term
Where is the Apex and Base of the heart?
Definition
  • Apex: Bottom point of heart
             Points to left hip.
  • Base: Top of heart
             Points to right shoulder. 

[image]

Term
What is the sac that encloses the heart?
Definition
Pericardium
Term
What are the layers of the Pericardium?
Definition

[image]

Parietal Pericardium continues on to cover the heart itself and is then called the Visceral Pericardium.

Term
What are the layers of the heart wall?
Definition
  • Epicardium Aka Visceral pericardium (Inner layer of pericardium): Outer heart wall
  • Myocardium: heart muscle
  • Endocardium: Innermost layer
    • Simple squamous epithelium called endothelium which is continuous with blood vessel endothelium.
    • Creates a seamless path for blood
Term
Chambers of the Heart
Definition

Atria: Receiving chambers

Ventricles: Discharging chambers

[image]

Term
Seperation of the Heart Chambers
Definition
  • Interatrial septum
  • Interventricular septum
    • Externally you can see the anterior and posterior Interventricular sulci
Term
What are major landmarks that both Atria share
Definition
  • Internally they have pectinate muscles
  • Externally they have Auricles
  • In the Interatrial septum they have the fossa ovalis
  • Atrial walls are relatively thin because they don't have to pump blood far and blood is assisted by gravity.
Term
What is the Fossa Ovalis of the Atria?
Definition

The Fossa Ovalis is a depression which is a remnant of the foramen ovale.

The foramen ovale is present in the fetal heart. It directs the blood from going into the non-functional fetal lungs.

 

Immediately at birth the foramen ovale closes leaving a small depression in the interatrial septum called the Fossa Ovalis.

Term
What are the blood vessels of the Right Atria?
Definition
  • Superior Vena Cava: Blood returning to heart from above the Diaphragm
  • Inferior Vena Cava: Blood returning to heart from below the Diaphragm
  • Coronary Sinus: Blood returning to heart from the heart wall
Term
What are the blood vessels of the Left Atria?
Definition
  • 4 Pulmonary veins: 2R & 2L
  • Blood high in Obecause it's coming directly from the lungs.
Term
What are the Ventricles and their characteristics?
Definition
  • Discharge chambers
  • Thicker walls- especially the left ventricle which send blood through the body.
  • Trabeculae carnae: Muscle bundles
  • Papillary Muscles: Anchor the heart valves by collagen strings.
Term
Vessels associated with the Right Ventricle
Definition
Pulmonary trunk: Branches off to the R & L pulmonary arteries, to the lungs.
Term
Vessels associated with the Left Ventricle
Definition
Aorta: artery that sends blood to the rest of the body.
Term

What is the pathway of blood through the heart?

Pulmonary Circuit & Systemic Circuit

Definition

Pulmonary Circuit:

R atrium-->R ventricle-->pulmonary trunk-->

R & L pulmonary arteries-->lungs for oxygenation-->

Systemic Circuit:

L atrium-->L ventricle-->Aorta-->Body tissues

-->Veins-->Superior & Inferior Vena Cava

-->back to R atrium

[image]

Term

Circulation of the coronary arteries: 

 

-R & L Coronary arteries are the first 2 branches off the aorta.

-L coronary splits off into the Anterior ventricular artery and the circumflex artery

-R coronary artery continues over to the posterior side and becomes the posterior interventricular sulcus. posterior branch of the coronary is called the marginal artery

 

Definition
[image]
Term
What is anastomosis and how does it relate to coronary circulation?
Definition

Anastomosis: Joining of blood vessels

 

Anterior interventricular artery joins the posterior interventricular artery at the heart apex.

Term
The anterior interventricular artery travels in what sulcus?
Definition

Interventricular sulcus

[image]

Term
The circumflex artery and the coronary artery travel in what sulcus?
Definition

Coronary sulcus

 

[image]

Term
What is Angina Pectoris?
Definition
Pain in the heart due to insuufficient blood supply
Term
Definition
Term
What is Myocardial Infarction? (MI)
Definition

Heart Attack:

Due to lack of blood causing cell death

Term
Where do Cardiac veins return blood to?
Definition

The Coronary Sinus in the Right Atrium. (Posteriorly)

[image]

Term
What are the AV valves?
Definition

Atrioventricular Valves- passage way from atria to ventricles

Term
What type of valve is the Right AV valve?
Definition

Right AV Valve:

Tricuspid valve- has 3 cusps

 

** Remember: tri rhymes with right

Term
What type of valve is the Left AV Valve?
Definition

left AV Valve:

 

bicuspid valve: has 2 cusps

 

usually called mitral valve

 

** 2 cusps look like bishops hat: miter

Term
How do valves work?
Definition

Pressure differences cause the valves to open and close with the flow of blood.

 

Chordae tendinae, which are attached to the papillary muscles, keep valves from opening the wrong way under pressure.

Term
What are the SL valves?
Definition

SL valves: Semilunar valves

 

Guard the exit of each ventricle

Term
What is the right ventricle semilunar valve?
Definition
Pulmonary semilunar valve- goes to the lungs
Term
What is the left ventricle semilunar valve?
Definition
Aortic Semilunar Valve- goes to the body
Term
What are incompetent valves?
Definition

Valves that do not close all the way.

[image]

Term
What are stenotic valves?
Definition

Valves that do not open all the way due to calcification.

 

[image]

Term
How can a strep throat lead to valve disorders?
Definition
If strep throat goes untreated, the body will produce antibodies that develop stenotic valves.
Term
What are the characteristics of Cardiac Muscle tissue?
Definition
  • Striations
  • One nucleus
  • Intercalated discs
  • the fibers branch
  • Gap junctions
  • Desmosomes
Term
What are Gap Junctions?
Definition
  • Located in Intercalated discs
  • Have opening in the middle to allow ions to pass freely
  • Allows depolarization to spread rapidly throughout the heart so the heart contracts as one unit

[image]

 

Term
What does Functional Syncytium mean?
Definition

"one giant cell"

Means that the heart behaves as a single coordinated unit.

Term
Definition
Term
What are desmosomes?
Definition

Protein patches that anchor 2 cells together to prevent pulling apart during contraction

 

 

Term
What is unique about heart muscle contraction compared to skeletal muscle contraction?
Definition
  • AP comes from the heart itself, not a neuron.
    • called Automaticity or Autorythmicity
  • Plateau phase of the AP- extends the period of depolarization so that the heart can contract long enough to eject all the blood from the ventricles
  • The heart is a Functional Syncytium and all cells contract together as a whole unit.
Term
What are the Three phases of heart cell contraction?
Definition
  1. Depolarization: Naenters cell
  2. Plateau Phase: Ca2+ enters through slow Ca2+ gates.
    • This phase extends the period of depolarization
    • Ca2+ that entered the cell causes the SR to release more Ca2+ 
  3. Repolarization: Ca2+ channels close and K+ channels to gates to open. Kexits the cell and the cell repolarizes
Term

What is the pacemaker potential?

[image]

Definition
  • the slow, positive increase in voltage across the cell's membrane that occurs between the end of one action potential and the beginning of the next action potential
  • Takes place in the autorythmic cells to initiate contraction:
    • Opening of Nachannels by previous APs hyperpolarization
  • Membrance potential never has a flat line.
Term
Definition
Term

What is the Intrinsic Conduction System of the Heart?

(5 parts)

Definition
[image]
Term
What is the Sinoatrial Node? (SA node)
Definition
  • Pacemaker of the heart
  • Located in Right atrium near the entrance of the superior vena cava
  • Depolarizes at 75 bpm- faster than other components of intrinsic conduction system, therefore it causes them to depolarize at its rate
  • Produces sinus rythm--Normal rythm
  • Depolarization spreads rapidly through the atria and causes atrial contraction
Term
What is the Atrioventricular Node? (AV node)
Definition
  • Located in lower interatrial septum of right atrium.
  • Produces AV delay (.01 sec) to allow the atria to contract before the ventricles
    • AV delay is produced by narrowing of cells in AV node and fewer gap junctions
  • Depolarizes at 50 bpm therefore, if SA node is not functioning as pacemaker, the AV node sets the pace of the heart at 50 bpm.
Term

What is the AV Bundle?

(Bundle of His)

Definition
  • In upper interventricular septum
  • Is the only electrical pathway into the ventricles
  • Shortly divides into R & L Bundle branches that travel in the interventricular septum
Term
What are the Purkinje Fibers?
Definition
  • Start at the apex (from the AV bundle branches) and go up the walls and spread throughout the myocardium.
  • If SA node and AV node fail as pacemakers then the Purkinje fibers set pace of heart at 30 bpm
  • At this rate life is not sustainable and person will need to have artificial pacemaker put in.
Term
What is Electrocardiography? (ECG)
Definition
Measuring the electrical changes in the heart
Term
What do the waves of an ECG mean?
Definition

[image]

**Atrial repolarization is hidden in QRS complex

Term

What are the heart sounds and their meanings?

 

Definition

heart sound: LUB DUP

 

First sound (LUB): caused by the closing of the AV valves

 

Second sound (DUP): caused by the closing of the SL valves

 

** Sound is produced by the vibration of the heart wall when the valves close.**

Term
What does the heart murmur of an Incompetent valve sound like?
Definition

 

 

Incompetent valves produce a "whish" sound when the ventricle contracts and the blood regurgitates back the wrong way

Term
What does the murmur of a stenotic valve sound like?
Definition
Stenotic valves don't open well and therefore produce a high pitched whistling sound as the blood is forced through a narrow opening.
Term
What does Systole mean?
Definition
Systole: Contraction
Term
What does Diastole mean?
Definition
Diastole: Relaxation
Term
What is Cardiac Output? (CO)
Definition

Cardiac Output (CO): the amount of blood pumped by a ventricle in one minute

 

CO is determined by heart rate and stroke volume

HRxSV=CO

 

HR=beats per minute

SV=amount of blood in one beat

Term
Definition
Term
What is the typical resting CO?
Definition

resting HR(heart rate): 75 bpm

SV(stroke volume): 70mL

 

75bpm x 70mL=5250mL/min

 

every minute the heart pump ~5L of blood: the entire blood volume.

Term
What is Cardiac Reserve?
Definition
The amount the heart is able to perform beyond that which is required under ordinary circumstances of daily life
Term
What is Athlete's Bradycardia?
Definition
Slow heart rate due to strengthening the heart and increasing SV
Term
What is the bpm of bradycardia and of tachycardia?
Definition

bradycardia: <60 bpm

tachycardia: >100 bpm

Term

How is SV calculated?

(stroke volume)

Definition

Calculated as the difference between what the ventricle has before contraction and what is left after contraction.

 

SV= EDV-ESV

 

EDV:End diastolic volume- the amount of blood at end of diastole(relaxation)

ESV:End systolic volume- the amount of blood at end of systole (contraction)

Term
What is the Frank Starling law?
Definition
Frank Starling Law: The more blood to stretch a ventricle, the stronger a contraction is produced.
Term
What are the factors that influence SV?
Definition

Preload: The amount of stretch of a ventricle by blood.

**Frank Starling Law

 

Afterload: The pressure of arterial blood

High blood pressure will make it harder to pump blood into the arteries and will decrease stroke volume

 

Working against pressure can damage the heart.

Term
How does the Autonomic Nervous System influence the heart?
Definition

Sympathetic System: Increase heart rate by Norepinephrine and Epinephrine(adrenal medulla)

 

Parasympathetic System: Decrease heart rate by ACh

Term
Definition