Describe the function of the circulatory system in 1 word.
In one word, the circulatory system is to TRANSPORT gases & nutrients to every part of the body
What does the circulatory system prioritize and an example of this?
3 arteries leading to the top of the body versus 1 artery to the bottom because PRIORTIZE THE BRAIN!
Quantities of blood vessels & why?
- There are lots and lots of blood vessels because it needs to transport these essential nutrients to every single cell in the body
- Each body cell must be 1 cell away from blood vessels
Why do some organisms have hearts whereas others do not?
- As organisms get larger, the distance increases between recipient cells and cells involved with digestion/respiratory system; diffusion gets too slow
- That is why some organisms have a heart to pump the blood whereas others are so small, they do not require it OR their respiratory surface is right on the skin
The 4 functions of the circulatory system?
- Transportation of CO₂ and O₂
- Transportation of nutrients and waste into/from the cells
- Transporation of chemical messengers (hormones) in the body
- Maintain body temperature
- Eg. blood thickens to keep heart warm
- Eg. if cold, blood vessels shut down (frostbite occurs) and focuses on keeping your core and brain alive
Blood: def
The medium in which materials (O₂, CO₂, nutrients, wastes, nutrients) are dissolved in and transported to all parts of the body
Blood: components
55% Plasma: mostly water
Less than 1% Immune System cells:
- White Blood Cells: fight off infection, familiar to your body alone
- Platelets: clots blood
45% Red Blood Cells (thickest)
- Sole purpose is to transport oxygen to blood
- No nucleus or mitochondria because it is not necessary
- Uses anaerobic respiration for energy because it does not need oxygen
Heart: def + structure
- A pump that pushes blood through the blood vessels
- Has cardiac muscle to maximize pumping
- Septum has oxygen rich blood is kept separate from oxygen poor blood
Blood Vessels: def
Highways for blood to move through
Blood Vessels: Arteries/Arterioles (func, oxygenated or?, structure)
- Transports blood at high pressure away from heart to capillaries
- Oxygenated except for pulmonary artery
- Highly elastic walls to expand and snap back which keeps blood following in right direction and provides additional pumping motions
- Thick, muscular to withstand high pressure
Blood Vessels: Veins/Venules (func, oxygenated or?, structure + veins)
- Transports blood at low pressure from capillaries towards the heart
- Deoxygenated (with waste products) except for pulmonary veins which is why veins have a deep, purlish colour
- Thin walls
- One way valves to prevent backflow caused by gravity when skeletal muscles relax and there is no pressure (smaller contractions to move blood vs arteries who has the heart to pump)
- Varicose veins result when valves don’t close properly/lose elasticity and blood just pools
Blood Vessels: Capillaries
- Thin, 1 cell layer and small diameter
- Increased surface area for gas exchange by diffusion
- Closest distance for each cell
- Microscopic
- Low pressure; parking
Why is the aorta so big and muscular?
Aorta is the biggest & most muscular artery because left ventricle is under high pressure and must be strong and elastic to receive the blood or else it will rupture and you will die
Why is the left atrium so big?
It is is bigger (¾ of heart) with more muscle because it needs to push blood to every tip of your body cells
BLOOD FLOW?
- Deoxygenated blood flows from the rest of the body into the heart via the superior (top) and inferior (bottom) vena cavas (veins)
- The blood enters the right atrium (“meeting place”)
- The blood goes through atrioventricular (AV) valve or “tricuspid valve” and into right ventricle
- Blood leaves left ventricle and goes through semilunar valve into pulmnary artery
- Pulmonary artery leads blood into each lung where gas exchange occurs
- Oxygenated blood leaves the lungs and enters the heart via the pulmonary veins
- The blood enters the left atrium (“meeting place”)
- The blood goes through another atrioventricular (AV) valve and enters the left ventricle
- The oxygenated blood gets pumped out of the left ventricle, through another semilunar valve, into the aorta
- The oxygenated blood is now pumped out through the aorta to the rest of the body so the cells can receive what it needs
Where is the blood made?
Blood cells are made in the bone marrow (fatty tissue inside your bones)
Why do blood cells need to be made in the bone marrow?
Because they have no nucleus and cannot divide
What is the function of the heart’s septum?
Prevents mixing of deoxygenated and oxygenated blood
What are the vessels in which the pulse is felt?
Arteries
Blood flow through vessels in closed circulatory system?
Veins = Heart = Arteries = smaller arteries = arterioles = capillaries = venules = smaller veins = veins
