A&P 2 - Heart Structure and Function

Cardiovascular system contains the

heart and blood vessels

Circulatory system contains the

heart, blood vessels, and the blood

What are the two major divisions of the circulatory system?

Pulmonary Circuit and Systemic Circuit

The heart pumps

blood throughout the body

Arteries ___ the heart and veins ____ to the heart

leave/return

Arteries have O₂ ___ blood on the systemic side, but O₂ ___ blood on the pulmonary side.

rich/poor

Veins have O₂ ___ blood on the systemic side, but O₂ ___ blood on the pulmonary side.

poor/rich

These are small vessels (5-10um) between arterioles and venules.

Capillaries

These vessels are where the site of O₂ & CO₂ exchange happens.

Capillaries

These vessels are where nutrient discharge and waste uptake.

Capillaries

This circuit is when the right ventricle pumps blood to the lungs.

Pulmonary Circuit

This circuit is when the left ventricle pumps blood to the rest of the body.

Systemic Circuit

Carries blood to lungs for gas exchange and back to heart.

Pulmonary Circuit

Supplies oxygenated blood to all the tissues of the body and returns it to the heart.

Systemic Circuit

The right side of the heart has what anatomical features?

- Deoxygenated blood (less oxygenated blood) arrives from inferior and superior venae cavae.

- Blood sent to lungs via pulmonary trunk.

The left side of the heart has what anatomical features?

- Fully oxygenated blood arrives from longs via pulmonary veins.

- Blood sent to all organs of the body via aorta.

Where is the heart located?

mediastinum, between lungs

The base of the heart has what features? Where is it located?

Anatomically a wide feature that is located at the superior (upper) end of the heart. Blood vessels attach here.

The apex of the heart has what features? Where is it located?

Inferior end, tilts to the left, and tapers to the tip of the heart which is pointing down toward the 5th left intercostal space.

The apex is...

___ in. wide at base

___ in. from base to apex

___ in. anterior to posterior

and weighs ___ oz.

3.5,

5,

2.5,

10

The _____ is a double-walled sac that encloses the heart (isolates heart from other organs).

Pericardium

The pericardium...

Allows the heart to beat without friction, provides room to expand yet resists excessive expansion.

The pericardium is anchored to...

the diaphragm inferiorly and sternum anteriorly.

Parietal pericardium also known as

pericardial sac

Parietal pericardium is located where?

Outer wall of sac

What type if histology (tissue) is present within the parietal pericardium?

- Superficial fibrous layer of dense irregular connective tissue.

- Deep, thin serous layer.

Visceral pericardium is also known as

epicardium

Visceral pericardium is located where?

Heart covering

What type if histology (tissue) is present within the visceral pericardium?

Serous lining of sac turns inward at base of heart to cover the heart surface.

The ____ ____ is the space inside the pericardial sac filled with 5 to 30 mL of pericardial fluid.

Pericardial Cavity

Inflammation of the pericardium

Pericarditis

What are the causes of pericarditis?

- Infection (viral/bacterial)

- Heart attack

- Trauma to chest

- Swelling/inflammation of heart muscle

- Radiation to chest

Is pericarditis acute or chronic?

Most commonly acute but sometimes it can also be chronic.

_____ most common symptom is sharp, stabbing chest pain that may travel to the left shoulder and neck. Very painful.

Pericarditis

What is the treatment for pericarditis?

- NSAIDs like aspirin Q4 hours x 2 weeks (alternatives: Ibuprofen, indomethacin) to decrease swelling.

- Antibiotics

- Pericardiocentesis

Pericardiocentesis would be utilized in which of the following pt situations?

a. cardiac tamponade

b. slow heart rhythm

c. chest pain

d. suspected damage to a heart valve

Cardiac Tamponade

A doctor inserts a needle through the chest wall and into the tissue around the heart. Once the needle is inside the pericardium, the doctor inserts a long, thin tube called a catheter. The doctor uses the catheter to drain excess fluid. The catheter may come right out after the procedure. What procedure is this?

Pericardiocentesis

Cardiac tamponade

Acute compression of the heart caused by fluid accumulation in the pericardial cavity.

Epicardium is also called

Visceral pericardium

The epicardium is the ____ layer

Outermost

The endocardium is the ____ layer

Innermost

Serous membrane covering the heart that is composed of mainly simple squamous epithelium overlying a thin layer of areolar (loose connective) tissue.

Epicardium

Coronary blood vessels travel through this layer of the heart wall.

Epicardium

Smooth inner lining of heart and blood vessels composed of simple squamous epithelium overlying a thin layer of areolar (loose connective tissue).

Endocardium

This layer of the heart wall covers the value surfaces and is continuous with endothelium of blood vessels.

Endocardium

The myocardium is the

middle layer

The myocardium contains the...

cardiac muscle and fibrous skeleton.

Fibrous skeleton of the heart is made up of...

collagenous and elastic fibers.

This structure is important for the electrical insulation between atria and ventricles; important in timing and coordination of contractile activity.

Fibrous Skeleton

What are the features of Cardiocytes?

- Striated, short, thick branches cells (Y shape)

- A lot of mitochondria

- Larger T-tubules than skeletal muscles

- Single nucleus

Intercalated discs have ___ sub structures.

3

What are features of the cardiac muscle intercalated discs?

- Interdigitating folds

- Mechanical (tight) junctions

- Electrical junctions (gap junctions)

Electrical junctions are also known as...

gap junctions.

Metabolism of cardiac muscle requires

- Aerobic respiration (ATP)

- Rich in myoglobin and glycogen

- Large mitochondria

- Organic fuels: fatty acids, glucose, ketones

- Fatigue resistant

The heart contains four chambers

The two atriums are in the (superior) upper chambers of the heart and the two ventricles are in the (inferior) bottom chambers of the heart.

The right and left atria...

return blood to the heart.

The right and left ventricles...

pump blood into arteries.

The interatrial septum separates ____ snd the interventricular septum separates ____. Both these septum(s) have what type of tissue?

atria; ventricles

- Dense Connective Tissue

The ridges in the atrium are...

the pectinate muscle.

The ridges in both ventricles are...

the trabeculae carneae

This structure connected AV valves to papillary muscles.

Chordae tendineae

What heart defect is diagnosed by echocardiogram and is the result of when a baby's duct between aorta and pulmonary trunk fails to close?

Patent ductus arteriosus

Allows blood to go around baby's lungs before birth.

Patent ductus arteriosus

1 in 4 adults have this heart defect?

Patent foramen ovale (PFO)

Patent foramen ovale (PFO) is the incomplete closure between...

right atria and left atria.

Down's syndrome can cause this heart defect?

Ventricular septal defect

Septum abnormalities can happen in ___ or ___ .

Atrial or Ventricular

Describe the blood flow through the heart

1. Blood enters 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 into pulmonary trunk.

4. Blood flows through pulmonary valve into pulmonary trunk.

5. Blood is distributed by right and left pulmonary arteries to the lungs, where it unloads CO2 and loads O2.

6. Blood returns from lungs via pulmonary veins to left atrium.

7. Blood in left atrium flows through left AV valve into left ventricle.

8. Contraction of left ventricle forces aortic valve to open.

9. Blood flows through aortic valve into ascending aorta.

10. Blood in aorta is distributed to every organ in the blood where it unloads O2 and loads CO2.

11. Blood returns to heart via venae cavae.

Blood flow through the chambers when ventricles relax?

Pressure drops inside the ventricles

Semilunar valves close as blood attempts to back up into the ventricles from the vessels

AV valves open

Blood flows from atria to ventricles

Blood flow through the chambers when ventricles contract?

- AV valves close as blood attempts to back up into the atria

- Pressure rises inside of the ventricles

- Semilunar valves open and blood flows into great vessels

Ventricles relax is known as

ventricular diastole

Ventricles contract is known as

ventricular systole

The left coronary artery (LCA) contains the

Anterior Interventricular Branch (LAD) and the Circumflex Branch.

The circumflex branch extends off to the...

left marginal branch and then ends on the posterior side of the heart.

The Right Coronary Artery (RCA) contains the...

right marginal branch and the posterior interventricular branch.

The Right Coronary Artery supplies these two structures?

Right Atrium and SA Node

Myocardial blood flow to the heart muscle during ventricular contraction is ____, unlike the rest of the body.

slowed

What two reasons explain why myocardial blood flow during ventricular contraction slowed?

1. Contraction compresses the coronary arteries and obstructs myocardium blood flow.

2. Opening of the aortic valve flap during ventricular systole covers the openings to the coronary arteries blocking blood flow into them.

Blood flow to the myocardium ____ during ventricular relaxation.

increases

True or False:

With myocardial blood supply, during ventricular diastole, blood in the aorta surges back toward the heart and into the openings of the coronary arteries.

True

This is when there is a partial obstruction of coronary blood flow that can cause chest pain that is due to ischemia, activity-dependent.

Angina pectoris

Interruption of blood supply to the heart from a blood clot or fatty deposit (atheroma) can cause death of cardiac cells within minutes. This causes severe chest pain that radiates down the left arm.

Myocardial infarction (MI) - Heart Attack

This causes 27% of all deaths in the US

Myocardial infarction (MI)

Some protection from MI is provided by ________

Arterial anastomoses

Arterial anastomoses provides

an alternative route of blood flow (collateral circulation) within the myocardium.

_____ ______ strike 1.8 million Americans each year with 40% fatality.

Heart Attacks

Anastomosis enables tissue perfusion by

multiple routes

What is the most common treatment plan for Angina pectoris?

- Statins

- Vasodilators

- Surgery (Angioplasty, stents)

Medications like statins help by...

lower cholestrol

Vasodilators MOA

Directly relax arteriolar and/or venous smooth muscle

Results in:

Decreased systemic vascular response

Decreased afterload

Peripheral vasodilation

Examples of vasodilators

Nitroglycerin, Beta Blockers

What is the most common treatment plan for Myocardial Infarction (MI)?

- Statins/ Cardiac rehab

- Vasodilators

- Anticoagulants

- Class IV Cardiac drugs

- Adenosine related compounds

Adenosine compounds medication that could be used is

dipyridamole

Ca2+ channel blockers are

class IV cardiac drugs

Give examples of anticoagulant drugs?

Heparin, clopidogrel, coumadin, aspirin

How does nitroglycerin work?

Nitroglycerin is a vasodilator, a medicine that opens blood vessels to improve blood flow. It is used to treat angina symptoms, such as chest pain or pressure, that happens when there is not enough blood flowing to the heart.

_____ works by relaxing the smooth muscle of blood vessel walls and dilating coronary arteries, which increases blood flow and oxygen supply to the heart.

Nitroglycerin

Partial obstruction of coronary blood flow causes

ischemia (chest pain)

What are the routes of administration for Nitroglycerin?

- Tablet (sublingual)

- Lotion or dermal patch

- Injection (critical/ ER)

What drug mimics nitric oxide, an endogenous nitrate releases by endothelial cells (vasodilation).

Nitroglycerin