HN220 - Midterm 3

What are the 3 components of the cardiovascular system?

1) The heart

2) Blood vessels

3) Blood

What is the purpose of blood in the cardiovascular system

acts as the fluid medium that carries nutrients and waste

Blood vessels provide a _____________ system for the cardiovascular system

closed

What is the cardiovascular systems central function?

transportation of substances

What substances does the cardiovascular system transport?

1) oxygen and nutrients to cells

2) waste from cells to liver and kidneys

3) hormones

4) immune cells

5) clotting proteins to specific target cells

Arteries branch into ___________

arterioles

Arterioles branch into ___________

capillaries

Capillaries branch into ____________

venules

Venules branch into ____________

veins

Arties carry blood ____ from the heart

away

Veins carry blood ____ the heart

toward

In pulmonary capiilary beds, O2 ____________ the blood and CO2 ________________ the blood

enters, leaves

In systematic capiilary beds, O2 ____________ the blood and CO2 ________________ the blood

leaves, enters

What are the 2 circuits of the cardiovascular circuit?

1) pulmonary circuit

2) systemic circuit

The pulmonary circuit is supplied by the _________ heart

right side

The systemic circuit is supplied by the _________ heart

left

The blood vessels in the pulmonary circuit run from heart to ____________________, and then from lungs to __________________

lungs, heart

The blood vessels in the systematic circuit run from heart to ____________________, and then from systemic tissues to __________________

systemic tissues, heart

The heart is located in the _________________________

thoracic cavity

What separates the abdominal cavity from the thoraciccavity

diaphragm

The heart is surrounded by the ________________

pericardium

What is the pericardium?

Membranous sac surrounding the heart

What is the function of the pericardium?

Lubricates the heart and decreases friction

True or false: the pericardium is another word for the heart wall

false: the heart wall is different from the pericardium

What is the outer layer of the heart?

epicardium

What is the epicardium also known as?

visceral pericardium

What is the function of the epicardium?

protects the heart

What is the myocardium?

middle layer of the heart, made of muscle

True or false: the myocardium is the thickest layer of the heart

true

The myocardium is made of ____________

cardiac muscle tissue

Great vessels are wrapped around by the _____________________

atrial myocardium

What is the innermost layer of the heart?

endocardium

What is the endocardium made of?

epithelium

What is the function of the endocardium?

Provides protection for valves and heart chambers

What ensures that blood flow is unidirectional?

valves and pressure

What drives blood flow?

pressure difference

Blood moves from ___________ pressure to _________________ pressure

higher to lower

Blood moves from ______________ to ventricles

atria

Blood moves from ventricles to _________________

arteries

What structure prevents the backflow of blood?

valves

Do valves open passively or actively?

passively

What causes valves to open?

pressure gradient

The right AV valve is also known as _____________

tricuspid valve

The left AV valve is also known as _________________

bicuspid valve or the mitral valve

What structures keep the valves from everting?

Papillary muscles and chordae tendinae

Why dont we want valves to evert?

would cause backflow of blood

What are the 2 semilunar valves?

1) pulmonary

2) aortic

The pulmonary valve leads blood to the ____________

lungs

The aortic valve leads blood to the _______________

aorta

What are the 2 types of myocardial cells?

1. Contractile Cells

2. Autorhythmic Cells

Contractile cells are found in the ____________

myocardium

Contractile cells account for ____________ % of the cardiocytes

99

What do autorhythmic cells do?

Can generate/spread AP spontaneously

What are the 2 types of autorhythmic cells?

1) pacemaker cells

2) Conduction fibers

What do pacemaker cells do?

1) Initiate APs

2) Establish heart rate (rhythm; "pace")

What do Conduction Fibers cells do?

Transmit/spread action potentials

How do cardiac muscle cells differ from skeletal cells?

cardiac muscle cells have audtorhythmicity

- the ability to generate own rhythm

Are contractile muscle cells big or small?

small

Describe the structure of contractile muscle cells?

- small

- bifurcate (divide into two branches/forks)

Contractile muscle cells have ____________________ centrally located nucleus

Single

True or false: contractile muscle cells are anaerobic

false: they are aerobic

What allows contractile muscle cells to be aerobic?

- High in myoglobin

- High in mitochondria

- Extensive blood supply

true or false: contractile muscle cell contraction is voluntary

false: involuntary

true or false: contractile muscle cells contract similarly to skeletal muscle

true

How is cardiac muscle similar to skeletal muscle?

- striated

- contains sarcomeres

How is cardiac muscle different than skeletal muscle?

- Have short and wide T tubules

- Less SR with no terminal cisternae

- Under SNS and PNS control

- Single nucleus

- Have intercalated discs to connect cells

What are intercalated discs?

junctions between cells that anchor cardiac cells

What are the 2 components of intercalated disks

1) Gap junctions

2) Desmosomes

Gap junctions connect ____________ cells _________________

adjacent, electrically

With gap junctions, the cardiac muscle cells functions as ___________

"single-unit" smooth muscle

True or false: gap junctions act as a direct connection

true

What is the purpose of desmosomes?

Provide the 'glue' that holds the cell together

Do desmosomes or tight junctions allow for chemical communication

desmosomes

What is the pacemaker of the heart?

SA node

After the SA node fires, the electrical signal travels to the __________________

AV node

What are the different groups of Conduction fibers of the myocardium

1) internodal pathways

2) Bundle of his

3) Purkinje Fibers

Are desmosomes or gap junctions used for electrical coupling?

gap junctions

Where is the action potential generated in the heart?

SA node

Where does the action potential go after it reaches atrial muscles?

The AV node

What happens after the SA node generates an action potential?

The signal spreads through atrial muscle

How does the signal spread throughout atrial muscle

via interatrial pathways

How does the signal reach the AV node?

via internodal pathways

True or False: There is a small delay once the signal reaches the AV node

true

What is the purpose of the delay at the AV node?

allows time for ventricles to fill

Where does the signal travel after the AV node?

Reaches the atrioventricular (AV) bundle (bundle of His)

What do the left and right bundle branches become?

purkinje fibers

What does the bundle of His split into?

left and right bundle branches

What do the left and right bundle branches contract?

ventricles

Describe the initiation and conduction of an impulse in the heart

1) AP initiated in SA node; signals spread through atrialmuscle via interatrial pathways

2) Signal travels to AV node via internodal pathway; AV nodaldelay

3) Atrioventricular bundle (bundle of His)

4) Splits into left and right bundle branches

5) Purkinje fibersThe Conducting System

What's the firing rate of the SA node

-70-80 AP/min

What's the firing rate of the AV node

40-60 AP/min

Cardiac cells are linked by ____ ________

GAP JUNCTIONS

True or False

Slower depolarizing cells control the pace for other cells

False

The faster depolarizing cells set the rate for the rest of the heart

Damage to the SA node causes the ___ _____ to initiate contraction

AV node

AP travel through the conduction system to the ____ of the heart

APEX of the heart

*This allows for the AP to spread upward through the ventricular muscle

What is an ECG

Composite of ALL APs generated by nodal and contractile cells

Waves in an ECG are also called __________

deflections

What are the parts of an ECG

-P wave

-QRS complex

-T wave

What is a P wave

-Atrial depolarization

-Initiated by SA node

What is the QRS complex

-Ventricular depolarization beginning at the apex

-Atrial repolarization also occurs but obscured by QRS complex