Biomechanics - Circulation Flashcards
What is an essential function of all organisms to allow for bodily functions to operate?
Organisms need to be able to obtain materials from and dispose of waste into the environment and do these for all cells in their body
What are the two methods of getting resources into and out of the body?
- Simple diffusion
- Circulatory system
What is simple diffusion? What kind of animals use these?
- All of the organisms cells are in direct contact with the environment allowing for substance to move in an out of the organisms by diffusion
- Small simple animals
What is a circulatory system? What kind of animal use these?
- Where the inputs and outputs of an organism and delivered to cells by an internal system and most of the cells are not directly exposed to the environment
- Larger more complex animals
What are the main components of a circulatory system?
- Central pump (e.g. heart)
- Circulating fluid (e.g. blood)
- System of vessels (e.g. blood vessels)
What are the two types of circulatory system?
- Open circulatory system
- Closed circulatory system
What is the simplest circulatory system? What kind of animal has this? How does it work? Why is it called open?
- Open circulatory system
- Invertebrates
- As the insect moves it create internal pressure difference ∴ aid the movement and diffusion of interstitial fluid
- There is no difference between blood and interstitial fluid
What is the more complicated circulatory system? What kind of animals has this? How does it work? Why is it called closed?
- Closed circulatory system
- Vertebrates
- Where a muscular pump pushes the blood around the body mechanically pumping the blood around the body
- The blood is separated from interstitial fluid as it is carried by blood vessels
What are the two kinds of closed circulatory system?
- Single circulatory system
- Double circulatory system
What is the single circulatory system? what animal is it found it?
- Where the heart consists of two chambers, a single atrium and ventricle, which then pumps blood through gill capillaries where O2 is absorbed and CO2 removed, then pumped around the rest of the body
- Fish
What is the double circulatory system? what animal is it found in?
- Where oxygen poor and oxygen rich blood are pumped by seperate sides of the heart into and out of the lungs
- Mammals
What is the main difference between single and double circulatory system?
Single pumps blood around the body using only one ventricle and atrium where O2/CO2 gets absorbed/removed from capillaries directly in contract with the enviro, Double pumps blood using two ventricles and atriums and O2/CO2 gets absorbed/removed from lungs
What is the structure of the human heart (double circulatory system) and the basic function of each part?
two upper atria (singular atrium) that receive blood and two lower ventricles that pump blood, right side receives/pumps O2 poor blood from body to lungs, left side receives/pumps O2 rich blood from lungs to body
What are atrioventricular valves?
valves that sallow blood to flow from atrium to ventricle but stop (normally) blood flowing back the other way
What operates in higher pressure, the atrium or ventricles? why?
Atrium because they only receive blood, not pump it
What is one way the valves are optimised to allow max blood flow?
Large valve size
What are the terms for the contraction and relaxation of the heart?
Contraction = systole Relaxation = diastole
What is the heart rate?
The number of beats per minute (e.g. pulse)
What is the stroke volume?
The amount of blood pumped in a a single contraction
What is the equation for stroke volume?
SV (stroke volume) = EDV (end diastolic volume, blood in ventricles at end of relaxation) – ESV (end systolic volume, blood in ventricles at end of contraction)
What is cardiac output?
The volume of blood pumped into the systemic circuit per minute
What is cardiac output a product of? what is the equation for it?
- Depends on the stroke volume and stroke rate
- Cardiac output (per min) = Heart rate * stroke volume
What are the processes of the cardiac cycle? How does volume and pressure change?
1 - AV (atrioventricular) valve opens and left ventricle starts to fill with blood, semilunar valve (aorta valve) closes: V = +, P = small +
2 - AV valve closes ventricle contracts: V = 0, P = +
3 - Semilunar value opens and blood ejects into aorta, ventricle still contracting: V = -, P = +
4 - semilunar valve closes and ventricle contracts: V = 0, P = -
When the blood is ejected into the aorta, why does the pressure still increase?
The ventricle is still systolic exerting pressure on the blood
What is the stroke work?
The work done by the heart during a cardiac cycle
How do you calculate the stroke work?
The area in the volume loop diagram, e.g. ∆V (m^3) * ∆P (Nm-2)
How do you work out the cardiac power?
Work * heart rate per second (NOT pulse as this is per min)
What does more work, the right or left ventricle? Why
The left ventricle as it undergoes a larger pressure change
What are the trees types of blood vessels? What is the function of them?
- Arteries, veins and capillaries
- connect the heart to the entire body
What do arteries do? What is their structure? What is the purpose of this?
- Carry blood AWAY from the heart
- have thick outer layer of elastic connective tissue and thick smooth muscle layer between the connective tissue and epithelium
- provides strength and elasticity require to transport high pressure blood
How do arteries change as they get closer to organs?
Branch into smaller arterioles
What do capillaries do? What is their structure? What is the purpose of this?
- transfer materials to the individual cells
- Have one cell thick wall of epithelium with microscopic pore wall
- increases SA:V ratio to maximise the rate of material transfer
What do Veins do? What is their structure? What is the purpose of this?
- Carry blood back to the heart
- have layers of smooth muscle and connective tissue but thinner walls with one way valves
- allows veins to expand and collet low pressure blood and valves prevent back flow of deoxygenated blood
How do the veins change as they get closer to the heart?
Begin as branding network of smaller venues that meets with veins
What kind of tissue do veins pass through, why and how is this important?
- Veins pass through muscle tissue
- As muscles contract it aids the pumping of blood back to the heart
- Important in the transportation of blood back from the extremities at low pressure
What is the equation to calculate blood pressure?
BP = CO * TPR
- BP = blood pressure (mm Hg)
- CO = Cardiac output
- TPR = total peripheral resistance
What affects the blood flow and pressure?
The physical laws governing movement of fluids through pipes
How does the velocity change with pipe width? Why is this?
As the pipe become narrower the resistance increases so the velocity decrases
How does the velocity of blood change in the arteries, capillaries and veins? Relate this to diameter of pipe and pressure
- Arteries = fast as very high pressure, medium width pipe
- Capillaries = very slow, low pressure and low width
- Veins = medium, low pressure but wide pipe
Why is blood flow in the capillaries needed to be so slow?
To allow for the exchange of materials between blood and cells
What is true for all veins?
All veins carry blood toward the heart
What kind of circulatory system do mammals have?
Closed double circulatory system
Why is blood pressure higher during systole than diastole?
Contraction of the heart during systole increase the blood pressure, relaxation in diastole decrease blood pressure
In animals with closed circulatory system gas exchange happens across the thin wall of ______
Capillaries
In animals with open circulatory system gas exchange happens in what kind of blood vessel?
Trick question, it doesn’t happen across blood vessels, instead the interstitial fluid is pumped into the space between cells where exchange occurs
