Circulatory System

Question 1

Stroke volume

Answer 1

• The volume of blood pumped from one ventricle of the heart in a single pump (healthy individuals have the same stroke volume for both ventricles)
• SV = EDV - ESV
• EDV = volume of blood in ventricle before contraction
• ESV - volume of blood in the ventricle at the end of the contraction

Question 2

Activated thrombin converts:

Answer 2

Fibrinogen to fibrin

Question 3

What does the Q wave of electrocardiogram represent?

Answer 3

Depolarization through the interventricular septum (which initiates ventricular depolarization)

Question 4

What are known as capacitance vessels?

Answer 4

Veins because of their high capacity —> most of the body’s blood is found in veins

Question 5

Pulmonary circulation:

Answer 5

Moves deoxygenated blood to the lungs in order to become oxygenated
The pathway is as follows:
Superior/inferior vena cava —> right atrium —> tricuspid valve —> right ventricle —> pulmonary semilunar valve —> pulmonary arteries —> lungs —> pulmonary veins —> left atrium

Question 6

Which blood do cardiac veins carry?

Answer 6

Deoxygenated blood from the myocardium

Question 7

What does thromboplastin convert?

Answer 7

Prothrombin (inactive precursor) to thrombin (active form)

Question 8

Automaticity

Answer 8

A property of all cardiomyocytes, allowing cardiomyocytes to have the ability to generate action potentials without external nerves having to initiate the action potential

Question 9

Cardiac output

Answer 9

• volume of blood being pumped by the heart (ventricle) in one minute

CO = HR x SV

Question 10

What do activated platelets release?

Answer 10

Thromboplastin (also called a tissue factor)

Question 11

How to calculate mean arterial pressure

Answer 11

MAP = CO x TPR
Cardiac output from the heart multiplied by the total peripheral resistance of the vessels

Question 12

What is another name for the respiratory pump?

Answer 12

Abdominothoracic pump because it involves both the abdomen and the thoracic cavity

Question 13

Hemolymph

Answer 13

Functions as both blood and interstitial fluid in organisms that contain an open circulatory system
It contains nutrients (similar to blood) and lies between cells (similar to interstitial fluid)

Question 14

Sinuses

Answer 14

• found in organisms with open circulatory systems (arthropods)
• Small, open-ended chambers that hemolymph move into form the dorsal vessel

Question 15

Hemocoel

Answer 15

A large cavity (body cavity) that surrounds all of the internal organs of the insect where sinuses empty hemolymph into
It allows for the hemolymph to surround and nourish all of the organs

Question 16

Ostia

Answer 16

Openings in the tubular hearts in which hemolymph can re-enter the relaxed heart and go back to the dorsal blood vessels
It does so by locomotion and muscular contractions

Question 17

Spiracles

Answer 17

Tiny holes that allow air to pass into the tracheal tubes/system (act as nostrils)

Question 18

Tracheal system

Answer 18

(Act as lungs) Responsible for gas exchange between the insects cells (the hemolymph) and the environment

Question 19

Which circulation has a higher resistance to blood flow?

Answer 19

Systemic circulation

Question 20

Coronary circulation

Answer 20

Circulation in which the heart pumps blood to itself

Question 21

Which part of the heart received oxygen-rich blood from the coronary arteries?

Answer 21

Coronary arteries branch off the aorta and provide oxygen-rich blood to the hearts myocardium (beginning of coronary circulation)

Question 22

SA node

Answer 22

(Sinoatrial node)
Known as the pacemaker of the heart
Usually initiates the cardigan cycle
Has the greatest automaticity in the heart: most likely to reach the threshold and stimulate action potentials to ripple through the other heart cells (stimulating a heartbeat)
Sends signal to contract both atria to send blood to the ventricles
Sends signal to the AV nose to initiate contraction

Question 23

Which nerve of the parasympathetic nervous system sends a signal to slow down the SA node?

Answer 23

The parasympathetic vagus nerve extends from the medulla oblongata and inner gates the SA node, the vagus nerve exerts a default signal to slow down the SA to a normal rate

Question 24

Path of cardiac conduction:

Answer 24

1) SA node: reaches threshold and sends a wave of depolarization to both atria causing both of them to contract and send the blood to the ventricles
2) AV node: once the wave of depolarization reaches the bottom of the right atrium, it reaches the AV node which adds a brief delay between contraction of the atria and ventricles (this allows them to contract at different times so ventricles can completely fill)
3) Bundle of His: AV node sends an electrical signal to the bundle of His, located in the interventricular septum
4) Left and right bundles: Bundle of His sends an electrical signal to the left and right bundle branches
5) Purkinje fibers: the left and right branches pass the signal to the purkinjie fibers, located within the walls of the ventricles, allow for coordinated ventricular contraction

Question 25

Systole

Answer 25

The phase of the cardiac cycle where *blood pressure* is **highest** in the **arteries**

Question 26

When does systole occur during the cardiac cycle?

Answer 26

Right *after* the **ventricles** eject blood *into** their connecting arteries

Question 27

Diastole

Answer 27

Phase of the cardiac cycle where *blood pressure* is **lowest** in the **arteries**, the *myocardium* is completely relaxed at this point

Question 28

When does diastole occur during the cardiac cycle?

Answer 28

Right *after* the end of **ventricular contraction**

Question 29

Lub

Answer 29

When both atrioventricular valves snap shut, causing the semilunar valves to open The *left and right atria are relaxed* as the **left and right ventricles are contracting**

Question 30

Dub

Answer 30

Semilunar valves snap shut The *left and right ventricles are relaxed* as the **left and right atria are contracting**

Question 31

Between which heart sounds does systole occur?

Answer 31

Lub & dub

Question 32

Between which heart sounds does diastole occur?

Answer 32

Dub & lub

Question 33

Intercalated discs

Answer 33

Contact points between adjacent cardiomyocytes that connect heart cells to each other Allow for signal transduction Made up of desmosomes and gap junctions

Question 34

Desmosomes

Answer 34

Small proteins that adhere cardiomyocytes together Act like “stitches”, stitching cardiomyocytes together

Question 35

Gap junctions

Answer 35

Protein tunnels that connect cytoplasm of cardiomyocytes Allow molecules and ions to directly pass from cell to cell and therefore propagating *action potentials* from one tell to the rest of the heart

Question 36

Syncytium

Answer 36

Connect of many heart cells together, allowing for the coordination of heart function as a unified organ

Question 37

Umbilical vein

Answer 37

Carries **oxygenated blood** from the *placenta* to the fetus via the *umbilical cord*

Question 38

Ductus venosus

Answer 38

Connects the *umbilical vein* to the *inferior vena cava* Allows **oxygenated blood** coming from the umbilical vein to flow into the inferior vena cava and mix with *deoxygenated blood* Blood inside the inferior vena cava can then be *slightly oxygenated*

Question 39

Foramen ovale

Answer 39

A hole in the fetal heart allowing for the slightly oxygenated blood to travel directly from the **right atrium to the left atrium**

Question 40

Arterial end of the capillary

Answer 40

Forces plasma *out* of the vessel because **hydrostatic pressure** is high This is how nutrients get dropped off to the tissues

Question 41

Venous end of the capillary

Answer 41

Wastes are pulled back *into* the capillary due to **oncontic pressure** (a type of osmotic pressure)

Question 42

At the venous end of the capillary, what causes wastes to be pulled into the capillary?

Answer 42

When there is a **high protein content** within the venous end, oncontic pressure increases causing water to flow back into the capillary along with the substances dissolved in it

Question 43

Lymph nodes

Answer 43

An aggregate of lymphocytes (immune cells) that trigger immune response when they come across factors that must be eliminated and thus filters out harmful bacteria from lymph

Question 44

What do cardiac veins and coronary arteries carry?

Answer 44

Cardiac veins: deoxygenated blood from the heart Coronary arteries: oxygenated blood to the heart

Question 45

What would occur if there were a decrease in plasma protein levels?

Answer 45

Is levels of plasma protein (e.g. albumin) decreased, the **oncotic pressure** in the blood vasculature would decrease as well, leading to *less water* returning to the blood and more water remaining in the interstitial fluid —> this leads to the increase in lymph volume

Question 46

blood brain barrier

Answer 46

* blockade of cells * prevents or slows the passage of drugs, ions and pathogens into the central nervous system * it is permeable to oxygen, carbon dioxide, glucose and general anesthetics

Question 47

hemorrhage

Answer 47

* excessive bleeding * results in **decrease in arterial pressure** * the decrease in pressure is sensed by arterial baroreceptors * in order for the body to compensate for the reduced blood pressure, it increases the heart rate and system vascular resistance

Answer 48

* maintains pH of internal fluids of all cells *