Circulation and The Heart (lesson eight) Flashcards
Does unicellular organisms 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
do all multicellular organisms have circulatory systems?
Some simple multicellular organisms do not either but instead depend on an internal body cavity lining covered in flagella to circulate fluid through the body (recall: flagella are microscopic hair-like structures that help with locomotion)
Open circulatory systems
- 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, a mixture of blood and tissue fluid
- The contraction of one or more hearts forces the hemolymph around the body
- Most invertebrates, like snails and insects, have this type of system
is an open circulatory system inefficient or efficient?
- This is a relatively inefficient method of circulation because the hemolymph is under low pressure and circulates slowly
- This is practical for many animals with low metabolic rates which therefore have lower oxygen and energy demands
Closed circulatory system?
- in a closed circulatory system, the fluid, often blood, is contained within a network of tubes called blood vessels
- The blood and tissue fluid (recall- the interstitial fluid) are always separate
- All vertebrates and some complex invertebrates have a closed system
- There is a lot of variation in the structure of closed circulatory systems
how many variations of a closed circulatory system are there?
Closed circulatory systems may include one of 5 versions of an increasingly complex “heart” structure depending on their evolution
Aortic Arch
- which are enlarged blood vessels that work like hearts to pump blood through the system
- found in earthworms
Two Chambered Heart
this structure is commonly found in fish
Three Chambered Heart
commonly found in amphibians
Four Chambered Heart
This structure is found in reptiles, mammals, and birds (which may or may not have a septum)
two-circuit circulatory system
- humans have an example of a complex closed circulatory system, called a two-circuit circulatory system
- In these systems, the circulation of blood to the lungs (pulmonary circuit) is separate from the circulation of blood to the rest of the body (systemic circuit)
how is a two-circuit circulatory system possible?
This is possible because of our four-chambered heart
where is the Heart found
found in the middle of your chest, directly under your breastbone, is the center of your circulatory system
what is the heart made up of?
- You have two atria, which receive blood from your body at the top of the heart
- You have two ventricles, which receive blood from your atria at the bottom of the heart
does the atrium or the ventricular have thicker walls?
- The ventricular walls are much thicker and more muscular than the atria
- This is because the ventricles have to pump blood a much longer distance
- Because the atria do not have to pump blood far there is less muscle required (blood in atria must only be pumped into ventricles)
septum
Your heart is divided into two sides by the septum
what right side of the heart receive?
The right side of your heart receives blood from your systemic (body) circuit and circulates blood to your pulmonary (lung) circuit
what does the left side of the heart receive?
The left side of your heart receives blood from your pulmonary (lung) circuit and circulates blood to your systemic (body) circuit
Circulation Through the Heart
- 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 enters from your inferior vena cava
- Your right atrium then beats and blood enters the right ventricle through your atrioventricular valve (specifically, the tricuspid valve)
- Blood then leaves your right ventricle through the semilunar valves (specifically, the pulmonary semilunar valve) to go towards your lungs via your left pulmonary arteries
- Blood is then oxygenated in the lungs and returns to your heart via the right pulmonary veins
- It enters your left atrium and then is pushed towards your left ventricle through the mitral valve (the other atrioventricular valve)
- Blood then gets pushed through the semilunar valve (specifically, the aortic semilunar valve) and enters the aorta so it can be distributed through the body
chordae tendineae
The atrioventricular valve is supported by tough cords called chordae tendineae and prevents blood from flowing backwards
coronary blood vessels
- the heart has its own supply of blood vessels called the coronary blood vessels which branch off the aorta
pericardium
- Your heart is protected by a double-layer membrane called the pericardium
- Like the pleural membrane around the lung, it is filled with fluid and prevents friction by providing lubrication
what are the circulatory system’s functions?
- It delivers oxygen from the respiratory system
- It delivers nutrients from the digestive system
- delivers hormones from the endocrine system
- delivers chemicals or cells from the immune system
- delivers metabolic wastes from the cells to the lungs and kidneys
