Chapter 50: Circulatory System

Question 1

What makes up the circulatory system?

Answer 1

Heart, blood vessels, and the blood

Question 2

Why do animals need a circulatory system?

Answer 2

Needed to obtain nutrients and get rid of wastes

Question 3

What animals do not require a circulatory system?

Answer 3

-Single-celled organisms exchange directly with the environment
•Structures and body shapes allow for this
-Gastrovascular systems bring the external environment inside the animals (sponges)

Question 4

What are the two types of circulatory systems?

Answer 4

Open and closed

Question 5

What makes up the open circulatory system?

Answer 5

-Arteries, valve, pump, and ostium
-The blood (hemolymph) flows to the tissues and to the ostium (returns blood to the heart to be pumped again)
•No capillaries

Question 6

What makes up the closed circulatory system?

Answer 6

-Arteries, valve, and pump
-Blood never leaves the circulatory system. It is exchanged within the system via the capillaries to the tissues
-Extracellular fluid
•Fluid inside and outside the circulatory system
o In the circulatory system: Blood plasma
o Around the cells: interstitial fluid
•Blood is kept separate from the interstitial fluid

Question 7

Advantages to a closed circulatory system

Answer 7

-Faster transport through vessels
-Blood can be directed to specific tissue by varying resistance
o When you’re cold, your circulatory system constricts the blood vessels (keep the blood away from the skin) in order to keep your warmer
-Specialized carrier can travel in the vessels and transport hormones or nutrients to specific sites
o Metabolic cost to maintain the circulatory system

Question 8

What are the two circuits to the closed circulatory system? What do they do?

Answer 8

-Pulmonary circuit: blood travels from the heart to the rest of the body and back to the heart
o Right ventricle
o Get rid of CO2
-Systemic circuit: blood travels from the heart to the rest of the body and back to the heart
o Left ventricle
o Deliver blood through capillaries to provide resources

Question 9

What does the closed circulatory system contain?

Answer 9

Arteries, Capillaries, and Venules

Question 10

What do arteries do?

Answer 10

Cary blood away from the heart and branch into arterioles (smaller arteries) that feed the capillary beds

Question 11

What are capillaries? What do they do?

Answer 11

The site of exchange between blood and tissue fluid
-Thin and small
-Give oxygen and pick up wastes and nutrients
-Red blood cells have to go single file through the capillary
Oxygen and nutrients go out, and carbon dioxide and wastes go in

Question 12

What do the Venules do?

Answer 12

Drain the capillary beds and form veins, which deliver blood back to the heart

Question 13

What is a bruise?

Answer 13

Damage to the capillary beds

Question 14

What do two-chambered hearts contain?

Answer 14

• Atrium: receives blood from the body via the veins
• Ventricle: receives pumped blood from the atrium and sends it to the gills
• Blood from the gills collects in the aorta and is distributed throughout the body

Question 15

Drop of Blood through the heart (Steps)

Answer 15

Blood enters through major veins into the right atria
-Main entry ways:
• Superior Vena Cava, Inferior Vena Cava, Coronary Sinus
-The blood (deoxygenated) will open up the tricuspid value and go from the right atrium into the right ventricle via the AV valve
-The artia will contract (adding more blood to the ventricle) due to SA node
•Causes the AV valve to seal shut
-Blood goes into the pulmonary trump to the pulmonary artery (deoxygenated)
-The force of the ventricular contraction pushes the blood that way
-Blood goes to the lungs, where it’ll be oxygenated
-Oxygenated blood returns to the left atrium of the heart though the pulmonary veins
-The ventricle fills as blood enters through an AV valve
-The left atrium contracts and pushes the blood to the left ventricle
-Left ventricle contracts and pushes the blood through the left aorta

Question 16

What is the superior vena cava?

Answer 16

returns blood from the tissues in the upper body (anything above the diaphragm)

Question 17

What is the inferior vana cava?

Answer 17

returns blood from the lower body (anything below the diaphragm)

Question 18

What is the coronary sinus?

Answer 18

on the posterior part of the heart. Blood returning to the heart from the heart

Question 19

Benefits to four-chambered hearts with two atria and two ventricles

Answer 19

-With separate pulmonary and systemic circuits
 Systemic circuit always receives blood with higher O2 content
 Gas exchange is maximized (due to chambers)
 Circuits can operate at different pressures

Question 20

What are heart murmurs?

Answer 20

Heart murmur detected in leak of the tricuspid valve and mitral valve

Question 21

What are Atrioventricular valves ?

Answer 21

lie between the atria and ventricles and prevent backflow when ventricles contract

Question 22

what are pulmonary valves?

Answer 22

ie between the ventricles and the major arteries and prevent backflow when ventricles relax

Question 23

Describe the cardiac cycle

Answer 23

-Cardiac cycle: two artia contract and then the two ventricles
o Systole: when ventricles contract
o Diastole: When ventricles relax

Question 24

How are cells in electrical contact with each other?

Answer 24

Gap junctions

Question 25

What are gap junctions and what things use them?

Answer 25

Gap Junctions spread of action potential stimulates contraction in unison

• Atria are connected with gap junctions
• Ventricles are connected with gap junctions
• Heart has its own intrinsic rhythm

Question 26

What are pacemaker cells?

Answer 26

Cells that can initiate action potential without input from the nervous system

-Also called conducting cells or special cells

-Sinoatrial node (SA): primary pacemaker cells
-The resting potential of these cells is less negative and not so stable so that cells gradually reach threshold
-Action potentials are broader and slower to return to resting potential
•Due to calcium

Question 27

What is the Sinoatrial node?

Answer 27

Primary pacemaker cell

Question 28

What is difference between cardiac action potentials and neural action potentials?

Answer 28

-Cardiac action potentials are slower than neuronal action potentials
 Since there are voltage gated calcium channels instead of VGSC
-Start out negative, get to the threshold. Activate a VGPC and come back to rest

Question 29

Funny current (steps)

Answer 29

-The conducting cell fires action potential over and over again
 The funny current/channels
-Funny channel opens and allows sodium to flow in (also potassium, but mostly sodium due to its gradient)
-Trigger for funny channel: negativity voltage (-60)
 The ions flows depending on the concentration and electric gradients
 The result of the opening is positivity
 Calcium channels open
• Positive feedback
• Makes channels deactivate
• (-35) for Ca (L type channels)
• Inactivation gate closes and VGPC are triggered
• Activation gates for potassium close, and sodium gated open
-After VGPC channels, potassium flows out
 Gets negative and activate the funny channels
• Sodium flows in

Question 30

How is the heart influenced by neural activity?

Answer 30

Increase/decrease heart rate

Question 31

What is the effect of norepinephrine on the heart?

Answer 31

(increases the heart rate) from sympathetic nerves increases permeability of Na+/K+ and Ca2+ channels

Question 32

What is the effect of acetylcholine on the heart?

Answer 32

-Acetylcholine decreases heart rate
 Parasympathetic nerves increases permeability of K+ and decreases that of Ca2+ channels
 The resting potential rises more slowly and action potentials are farther apart

Question 33

How is heart muscle contraction coordinated?

Answer 33

• An action potential is generated in the sinoatrial node
• The action potential spreads through gap junctions in the atria and they contract together, but does not spread to the ventricles

Question 34

What control intrinsic rhythm?

Answer 34

The SA and AV node

Question 35

What occurs while the heart is at rest (diastole)?

Answer 35

-AV node and SA node are silent

 Connected by Bundle of His and Purkinje fibers

Question 36

what happens during ventricle contraction?

Answer 36

• The SA node will depolarize
• Keep the depolarization from spreading to the ventricles through the AV valves (made of dense regular connective tissue)