Lesson 8: Circulation and The Heart

Question 1

what is the function of a circulatory system?

Answer 1

It transports many essential materials around the body

Question 2

what essential materials does the circulatory system transport around the body?

Answer 2

• oxygen from the respiratory system
• nutrients from the digestive system
• hormones from the endocrine system
• chemicals and cells from the immune system (ex: T-cells, B-cells, macrophages)
• metabolic wastes from the cells to the lungs and kidneys
• thermal energy (keeps the body temp regulated)

Question 3

how did circulation evolve over time?

Answer 3

circulation became a “need” later in the evolutionary timeline as organisms increased in size and cells were no longer in contact with the environment
- it wasn’t always something we saw in primitive organisms that first existed; because organisms grew and got larger in size and complexibility, circulation became more necessary to have

Question 4

what does the circulatory system allow for?

Answer 4

allows for oxygen and nutrients to be delivered to every cell in the body; also allows for wastes in the cells to be removed from the body (brings nutrients to where it needs to go but gets waste products out as well)

Question 5

what are key features that a circulatory system needs to be considered one?

Answer 5

1. fluid that transports or circulates materials throughout the body (for humans it is blood)
2. a network of tubes in which the fluid circulates (blood vessels)
3. a pump that pushes the fluid through the tubes (the heart *beats and pushes fluids through different parts of the body)

Question 6

what are the different types of circulatory systems in organisms?

Answer 6

1. none!
2. open
3. closed

Question 7

types of circulatory systems: none- describe this system and how it works + who has it

Answer 7

not all living things required or even have a circulatory system!
- unicellular organisms like some bacteria, algae, and fungi can function without a circulatory system (because they directly exchange gases with the environment)
- some simple multicellular organisms do not require a circulatory system either, but instead depend on an internal body cavity lining covered in flagella to circulate fluid through the body

Question 8

what is flagella and what is it for?

Answer 8

microscopic hair like structures that help with locomotion (they move things around) –> this is essentially what simple organisms use as a circulatory system

Question 9

types of circulatory systems: open- describe what it is and how it works + who uses it

Answer 9

in an open circulatory system, the circulating fluid is pumped into a connected system of body cavities (often called sinuses)
- these openings bathe the cells directly in the hemolymph, which is a mixture of blood fluid and tissue fluid (all of their fluids are mixed together into one fluid, and this fluid gets pushed through body cavities)
- the contraction of one or more hearts forces this hemolymph around the body
*most invertebrates like snails or insects have this system

Question 10

are open circulatory systems efficient or inefficient? why?
who is this system practical for and why?

Answer 10

this is relatively inefficient as the hemolymph is under low pressure and circulates slowly
- takes a long time for nutrients and things to get to where they need to go
HOWEVER, it is practical for many animals with low metabolic rates which therefore have lower oxygen and energy demands

Question 11

types of circulatory systems: closed- what is it, how does it work, and who has it?

Answer 11

in a closed circulatory system, the fluid (often blood), is contained within a network of tubes called blood vessels
- what makes this system “closed” is that the blood in our bodies are not flowing freely- it is contained in blood vessels
- the blood and tissue fluid in our bodies are SEPERATE and do not mix (unlike in open systems)

all vertebrates and some complex invertebrates have a closed system
- there is a lot of variation in the structure of closed circulatory systems
- for instance, human circulatory systems differs from a fishes circulatory system, though we are both vertebrates

Question 12

closed circulatory systems include complex “heart” structures depending on their evolution: this can be…

Answer 12

aortic arch, two chambered heart, three chambered heart, four chambered heart

Question 13

what is the aortic arch? who is it found in?

Answer 13

type of closed circulatory system with enlarged blood vessels that work like hearts to pump blood through the system (found in earthworms)

Question 14

what is the two chambered heart? who is it found in?

Answer 14

this structure is commonly found in fish; one atrium and one ventricle

Question 15

what is the three chambered heart? who is it found in?

Answer 15

this structure is commonly found in amphibians; right and left atrium and then one ventricle

Question 16

what is the four chambered heart? who has it?

Answer 16

this structure is found in reptiles, mammals, and birds; animals that have this system can or can not have a septum
- consists of a left and right ventricle and a left and right atrium

Question 17

what is a septum? what does it do?

Answer 17

the septum divides the heart into two sides; septums seperate deoxygenated blood to oxygenated

Question 18

what is the two-circuit circulatory system?

Answer 18

in these systems, the circulation of blood to the lungs (pulmonary circuit) is seperate from the circulation of blood to the rest of the body (systemic circuit)

Question 19

what is the pulmonary circuit?

Answer 19

the part of the circulatory system that delivers blood to the lungs

Question 20

what is the systemic circuit?

Answer 20

the part of the circulatory system that delivers blood around the body

Question 21

what is the heart? where is it located? what is it made up of and what does each part do?

Answer 21

the heart is a muscular organ found in the middle of the chest, directly under the breastbone (it is the center and most important part of your circulatory system)
- the heart has two atria, which RECEIVE BLOOD FROM YOUR BODY at the TOP of the heart (both atrias are responsible for receiving from the top of the heart)
- the heart has two ventricles, which RECEIVE BLOOD FROM YOUR ATRIA at the BOTTOM of the heart (they reside at the bottom of the heart)

Question 22

feature difference(s) between ventricles and atria

Answer 22

ventricular walls are much thicker and more muscular than the atria; this is because the ventricles have to pump blood a much longer distance
- ventricles are responsible for pumping blood to the rest of the body, which is a really long distance; on the other hand, atria pumps blood to the ventricles, which is really close in comparison (thus, they have less muscle)

Question 23

what does the right side of the heart do? what does the left side do?

Answer 23

• right side: receives blood from your systemic circuit (body) and circulates blood to your pulmonary circuit (lung)
  left side: receives blood from the pulmonary circuit (lungs) and circulates blood to the systemic circuit (body)

Question 24

where does blood enter from in the heart?

Answer 24

blood enters your right atrium from one of two blood vessels
- blood from your upper body tissues enters from your superior vena cava
OR
- blood from your lower body tissues enter from your inferior vena cava

*SUPERIOR ON TOP INFERIOR ON BOTTOM

Question 25

once blood enters the right atrium, what happens? what is the process like?

Answer 25

1. once blood enters, your right atrium beats and contracts, which forces blood to enter the right ventricle THROUGH THE ATRIOVENTRICULAR VALVE (specifically the tricuspid valve)
2. then, blood leaves your right ventricle through the semilunar valves (specifically the pulmonary semilunar valve) to go towards your lungs via your left pulmonary arteries
   –> blood essentially exits the heart through the left pulmonary artery and into the lungs

Question 26

what helps the valves in the heart to prevent backflow of blood?

Answer 26

the valves are supported by tough cords called CHORDAE TENDINEAE, which prevents blood from flowing backwards

Question 27

what happens after blood exits the right ventricle and into the lungs? what is the process like?

Answer 27

1. blood is oxygenated in the lungs and returns to the heart via the right pulmonary veins
2. it then enters the left atrium, and is pushed (by contraction) towards the left ventricle through the MITRAL VALVE (the other atrioventricular valve)
3. now that blood is in the ventricle, it has to get pushed out. It is pushed through the semilunar valve (specifically the aortic semilunar valve) and enters the aorta so it can be distributed through the body

Question 28

what are the different types of valves in the heart and how do they differ?

Answer 28

in general, there are valves called the atrioventricular valves. these valves are between the atrium and ventricles
- there is the TRICUSPID valve, which is located on the right side of the heart between the right atrium and right ventricle
- there is the MITRAL valve, which is located on the left side of the heart, between the left atrium and left ventricle

there are also valves called the semilunar valves, which are located between the ventricles and arteries.
- there is the pulmonary semilunar valve (between right ventricle and left artery)
- there is the aortic semilunar valve (between left ventricle and aorta)

Question 28

what are the coronary blood vessels? what do they do?

Answer 28

supply of blood vessels which branch off the aorta; it supplies blood to the heart and allows for contraction of the heart and circulation of the blood throughout the body

Question 29

what is the pericardium? what does it do?

Answer 29

the pericardium is a double layer membrane that protects the heart
- it prevents friction from damaging the tissues in the heart, and keeps the heart lubricated (it is filled with fluid that allows for this)

Question 30

systemic circuits carries ____ blood from ___ to ___

Answer 30

systemic circuits carries oxygenated blood from heart to all body tissues (high o2 low co2)

Question 31

pulmonary circuits carries ____ blood from the ___ to the ___

Answer 31

pulmonary circuits carries deoxygenated blood from the heart to the lungs (low o2, high co2)

Question 32

difference between arteries, capillaries, and veins?

Answer 32

arteries carry blood away from the heart, capillaries are small vessels that carry blood to body cells, and veins carry blood back to the heart