Human Phys Exam 2 — Chapter 14: Cardiovascular System

The heart contributes to homeostasis by doing what?

by pumping blood through blood vessels to the tissues of the body.

What are the 3 components of the cardiovascular system?

1. Heart (acts as a pump)

2. Blood Vessels

3. Blood

With each beat, the heart pumps blood back into 2 closed circuits. What are they?

1. Pulmonary Circulation

2. Systemic Circulation

Pulomnary Circulation

blood vessels that carry blood from RIGHT side of the heart to alveoli ( air sacs ) of lungs and then back to the Left Side of Heart

What are alveoli?

air sacs

Systemic Circulation

blood vessels that carry blood from LEFT side of heart to ALL ORGANS & tissues of body EXCEPT ALVEOLI and then BACK to RIGHT side of heart

In BOTH pulmonary circulation and systemic circulation, Blood is …

carried away from & then returned to the heart

What are arteries and what do they do?

large blood vessels that carry blood AWAY from heart

Arteries branch to from smaller vessels called?

arterioles

Arterioles branch to give rise to even smaller vessels called?

capillaries

What is the smallest blood vessel of the body?

capillaries

Blood flows from capillaries to larger vessels called?

venules

What do venules give rise to?

larger vessels called veins

What is the role of veins

to carry blood back to heart

System Circulation is…

parallel flow

Parallel blood flow allows for 2 things?

1. allows each organ to receive its own supply of feshly oxygenated blood

2. allows blood flow to be regulated independently

In parallel flow, does the same portion of blood flow from one organ to the next?

No

What is the heart

a hollow muscular organ about the size of a closed fist

The heart is located where?

thoracic cavity (mediastinum)

Where does the heart lie?

mostly to the left of the body’s midline

thoracic relates to what part of body?

chest

What is the Pericardium?

membranous sac that encloses the heart; confines the heart to its position in thoracic cavity BUT allows for movement for vigorous & rapid contraction

What is the function of the pericardium

to protect and achor the heart

The pericardium has two layers. What are they?

1. outer parietal layer

2. inner visceral layer AKA epicardium

Pericardial cavity

• between parietal and visceral layers of pericardium

• filled with thin film of lubricating fluid AKA pericardial fluid

What is the function of the pericardial fluid?

reduces friction within pericardium as the heart moves

Where is the inner visceral layer or epicardium?

on the surface of heart

The heart wall is composed of 3 layers. What are they?

1. Epicardium: has epithelium and connective tissue

2. Myocardium: forms the bulk of the heart wall; cardiac muscle

3. Endocardium: epithelial cells that line the heart

The heart has chambers. How many are there and which ones?

• 4

• 2 atria ( upper chambers )

• 2 ventricles ( lower chambers )

Do both sides of the heart each have an atrium and ventricle?

Yes; Each side has an atrium and ventricle

The right side of the heart serves which circuit?

pulmonary circuit

The left side of the heart serves what circuit?

systemic circuit

Which side of the heart has a smaller workload?

right ( left has to pump blood to all the organs)

What is the function of the septum?

• muscular partition that separates L & R side of heart

• prevents blood from mixing between 2 sides of the heart

The atria chamber receives or pumps blood?

receives blood

Does the atria have thin or thick walls?

thin walls

The atria has 2 chambers: one on the left & one on the right. On the right side there are two major veins in the atria. What are they & what distinguishes them?

1. Superior vena cava: brings blood mostly from body parts ABOVE the heart

2. Inferior vena cava: brings blood mostly from body parts BELOW the heart

The right atria is where/how the heart receives what type of blood?

deoxygenated blood

The atria has 2 chambers: one on the left & one on the right. On the left side there is ONE major vein in the atria. What is it?

Pulmonary Vein(s)

The left atria is where/how the heart receives what type of blood?

oxygenated blood; through the pulmonary veins

The ventricle receives or pumps blood?

pumps blood OUT of the heart

The ventricle has 2 chambers: one on the left & one on the right. On the right side there is one main artery that the ventricle pumps into. What is it?

Pulmonary trunk

The ventricle has 2 chambers: one on the left & one on the right. On the left side there is one main artery that the ventricle pumps into. What is it?

Aorta artery

The aorta artery branches into smaller arteries and then carries what type of blood to all parts of body except alveole?

oxygenated blood

What does the pulmonary trunk divide into?

pulmonary arteries

What do the pulmonary arteries do?

carry deoxygenated blood TO the lungs

The left ventricle is about ___ times thicker than the right ventricle

3

What is the function of a heart valve?

to prevent blood from flowing backward; ensurese one way flow of blood

What does AV stand for? and its function?

atrioventricular valves; prevents backflow into atria (makes sure blood is able to flow into the ventrile from the atria)

What are the two valves on the right side of the heart?

1. Tricuspid atroventricular valve (AV); Right AV

2. Pulmonary semilunar valve

What are the two valves on the left side of the heart?

1. Bicuspid valve atrioventricular valve (AV) AKA MITRAL VALVE

2. Aortic Semilunar valve

What do valves have that prevent them from stretching?

fibrous skeleton

Valves open and close in response to?

pressure changes as heart contracts and relaxes

What is the function of chordae tendineae

connect to AV valves and papillary muscles to prevent valve cusps from opening back up INTO the atria when vesicles contract

What are Semilunar (SL) valves

• cusps attached to walls of pulomnary trunk & aorta

• allow ejection of blood from heart INTO arteries BUT prevent blood blackflow into ventricles after trying to be pumped out ( allows blood to keep flowing to organs)

Fibrous Skeleton definition

4 dense connective tissues that surround the valves of heart, fuse with one another and merge with interventricular septum

Fibrous rings support the 4 valves of the heart and do what?

fuse to one another

Coronary arteries vs coronary veins

coronary arteries: deliver blood to heart wall ( go from heart to heart tissue)

coronary veins: deliver blood from heart wall (from the heart wall to the right atrium)

What is the coronary or cardiac circulation?

heart’s own network of blood vessels

Cardiac muscle budles appear to be arranged in spiral, _____ vortex.

myocardial

The right side of the heart receives ______ blood from the ______ circulation and pumps it into the _______ ciruclation.

deoxygenated; systemic; pulmonary

The left side of the heart receives ______ blood from the ______ circulation and pumps it into the _______ ciruclation.

oxygenated; pulmonary; systemic

Heart valves are surrounded by what type of rings?

fibrous rings

Fibrous rings fuse with one another AND the ________ _______.

interventricular septum

When the heart relaxes, the high pressure of blood in the aorta propels blood through the ______ ________.

coronary arteries

Cardiac muscle fibers connect to neighboring fibers by ______ _____.

intercalated disks

what do intercalated discs contain that help cardiac muscle fibers connect to neighboring fibers?

desmosomes and gap junctions

desmosomes function

mechanically bind cardac muscle fibers together

Are mitochondria larger and more numerous in cardiac or skeletal muscle fibers?

cardiac

The autorhythmic fibers of the heart have 2 important functions. What are they?

1. act as a pacemaker: sets rhythm of electrical excitation that causes heart’s contraction

2. form the conduction system: pathway that rapidly delivers AP throughout the heart muscle because of the gap junctions

What is the function(s) of the conduction system

• ensures that the chambers of the heart contract in a coordinated manner

• initiate/conducts APs to other heart cells via gap channels

What makes up the conduction system?

collection of modified muscle cells

• pacemaker

What does the conduction system NOT contribute significantly to?

contractile forces

The conduction system starts where?

superior wall of the right atrium

In the conduction system, the AP travels from the superior wall of the right atrium to/through ?

through the apex of the heart and and myocardium of the ventricles

What structures are involved in the conduction system (5) IN ORDER OF FLOW? And what do all these structures have?

1. Sinoatrial (SA) node

2. Atrioventricular (AV) node

3. Atrioventricular (AV) bundle … Bundle of HIS

4. Right and left bundle branches

5. Purkinje fibers in the ventricular wall

• these components of heart all have autorhythmic fibers

pacemaker potential definition

the spontaneous depolarization to threshold that occurs in an autorhythmic fiber of cardiac muscle

autorhythmic cardiac muscle fibers can initiate their own Action Potential because they have what?

unstable resting membrane potential

Pacemaker potentials relate to what type of cells?

nodal or non-contractile cells

What are the three phases to the Pacemaker potentials? And what happens in each phase?

1. Pacemaker potential

   • In the first half: Voltage-gated K+ channels close and F-type Na+ channnels open

   • In 2nd Half: T-type voltage-gated Calcium channels open & F-Type N+ channels close

2. Depolarizing Phase

   • L-type voltage-gated Calcium Channels open

3. Repolarizing Phase

   • L-type voltage-gated Calcium channels close

   • Voltage-Gated K+ channels open

What is an F-type of channel

F for funny

Once contractile cells receive the signal what steps follow?

1. Produce force

2. Do not spontaneously depolarize

3. Contract in a similar fashion to skeletal muscle

4. Produce muscle AP only in response to signals from NODAL CELLS

Unlike autorhythmic fibers, contractile cells have a resting membrane of what?

-90 mV

What are the 4 phases to the contractile cell action potential?

1. Depolarizing Phase

2. Initial repolarizing phase

3. Plateau phase

4. Final repolarizing phase

Describe what happens in the 1st phase of the contractile cell action potential: Depolarizing phase

Fast voltage-gated Na+ channels open

Describe what happens in the 2nd phase of the contractile cell action potential: Initial Repolarizing phase

• Fast voltage-gated Na+ channels close

• Fast voltage-gated K+ channels open

Describe what happens in the 3rd phase of the contractile cell action potential: Plateau phase

• L-type voltage-gated Calcium channels open

• fast voltage-gated K+ channels close

• slow voltage-gated K+ channels partially open

Describe what happens in the 4th phase of the contractile cell action potential: Final repolarizing phase

• L-type voltage gated Calciium channels close

• Slow voltage-gated K+ channels fully open

Contractile muscle cells have _____ refractory periods.

long

Sketal muscle action potential are ___ compared to cardiac muscle.

fast

Action potentials in SK muscle allow ____ contraction which does NOT happen in Cardiac muscle .

tetanic

Non-contractile cell damage can be alleviated by what?

artificial pacemaker

Cardiac muscle mainly relies on what type of respiration for ATP production?

aerobic

ECG or EKG stands for what?

Electrocardiogram

What is an electrocardiogram?

• recording of AP signals that propagate through the heart every heartbeat

• summed electrical activity of the heart recorded from the skin

What does an electrocardiogram consist of?

• waves

• intervals

• segments

What are the 5 parts of an electrocardiogram?

1. P Wave

2. P-R Interval

3. QRS complex

4. S-T segment

5. T wave

What does the P Wave represent?

depolarization of the atria

What does the P-R interval represent? ( also known as P-Q interval)

• represents the AV node delay

• represents the conduction time from the beginning of the P wave to the beginning of the QRS complex

• represents the conduction time from the beginning of atrial excitation to ventricular excitation

What does the QRS complex represent?

represents ventricular depolarization