Topic 1 - The Heart (+Water) (1.1 to 1.4) Flashcards
What is a mass transport system
A system which transports substances (such as oxygen) from one part of an organism in one direction via vessels or tubes
Why are mass transport systems used
They overcome limits of diffusion → making transport in an organism more efficient
Larger organisms need mass transport systems as their small Sa:V is low, so the rate of diffusion is low
By having a mass transport system molecules such as glucose can diffuse into cells faster
How does having a mass transport system affect metabolic rate
It ensures a high metabolic rate as mammals have a high demand for glucose and oxygen
A mass transport system helps make the diffusion of these molecules more efficient
What type of system is the circulatory system
It is a mass transport system
What are the features of an efficient circulatory system (4 features)
- Pump
- Transport medium
- Blood vessels
- Exchange surfaces
Why are different blood pressures needed in a circulatory system
Different pressures are needed for different process / reactions in the body
Why do exchange surfaces like capillaries make the circulatiry system more efficient
They have a high SA:V ratio making diffusion more efficient
What are the features of an open circulatory system
No vessels to transport blood
Blood (Haemolymph in insects) is pumped into body cavities
Haemolymph has direct contact to cells / tissue for nutrient exchange
(Short diffusion distance between the heart and cavities)
Low blood pressure (no vessels to maintain a pressure gradient)
Why do smaller organisms have open circulatory systems
Small organisms have a low metabolic demand so efficient transport is not required
They have a large Sa : V so diffusion can be effective
What are the features of an closed circulatory systen
They have blood enclosed in vessels
This maintains a high blood pressure, so blood flows faster
This enables a higher metabolic rate (as o2 and glucose can be transported to cells faster)
Why do mamals have a high metabolic rate
Mamals have a large number of cells, so they have a greater requirement for energy
What vessels does blood pass through when going around the body (not a specific artery / veins)
Heart → arteries (first the pulmonary artery) → arterioles → capillaries → venules →veins → heart
What are the properties / blood flow in a 3-chambered heart
Oxygenated and deoxygenated blood enter into two different chambers and then mix together in the third chamber
Blood is taken to the lungs in the 3rd chamber, oxygenated and put back into the 2nd chamber.
The oxygenated blood enters the 3rd chamber and is taken to the rest of the body
What are ectotherms
Organisms that rely their environment to regulate body temperature
They have lower metabolic demands as they dont regulate their body temperature
What are the main features of a single circulatory system
Blood flows through the heart once per each full circuit of the body
2 chambered heart
Gill exchange network (deoxygenated blood going to gills) e.g fish
Systemic circuit ( blood going to body)
What are the main features of a double circulatory system
Blood flows through the heart twice for each full complete circuit of the body
4- chambered heart to ensure blood is pumped to the rest of the body at a high pressure
Pulmonary circuit - blood to lungs + back to heart
Systemic circuitb- supplies oxygenated blood to all the metabollic cells
How much of blood plasma is made of water
90%
What is a polar molecule
A molecule with unevenly distributed charges (it is dipole)
Water is a polar molecule
What is cohesion
Molecules forming bonds with similar molecules
How is water cohesive
Water forms hydrogen bonds to other water molecules
This allows water to flow (which makes it useful
Water can bond to up to 4 other water molecules
How is water a solvent
It is able to surround polar molecules and ions
It forms hydrogen bonds with the ions letting them be dissolved and transported
How is water a thermal buffer
It has a high specific hera capacity (lots of energy needed to change its temp)
It has a high latent heat of vaporisation (lots of heat needed to break bonds)
→ vaporised water carries heat away from the body
What is the heart made of
Cardiac muscle
How does the heart ‘beat’
Myogenic - It can move without instructions from the brain
Cardiac muscle can contract and relax via some input from the nervous system
What are the 4 heart chambers
Left atrium
Right atrium
Left ventricle
Right ventricle
The atria are the smallest chambers
The left ventricle has more muscle than the right ventricel
What are the 4 heart valves and where do they prevent backflow
Bicuspid valve → prevents backflow from the left ventricle to the left atrium
Tricuspid valve prevents backflow of blood between the right ventricle and right atrium
Semi lunar valves → prevents backflow between the pulmonary valve and the right ventricle
Prevents backflow between the aorta and left ventricle
What divides the oxygenated and deoxygenated blood in the heart
The septum
Why is there a thicker cardiac muscle wall in the left ventricle
It has to pump blood further through the systemic circuit (blood must maintain a higher pressure)
Having more muscle means the force of contraction will be greater
What type of valves are the tricuspid and bicuspid
They are atrioventricular valves
What vein supplies deoxygenated blood to the heart
The superior vena cava (takes deoxygenated blood from above the heart)
The inferior vena cava ( takes deoxygenated blood from bellow the heart)
What artery brings deoxygenated blood to the lungs
The pulmonary artery
What vessel brings blood into the heart from the lungs
The pulmonary vein brings oxygenated blood into the left atrium
How does oxygenated blood leave the heart
The ascending aorta → takes blood to the top of the body (systemic circuit)
The descending aorta - takes oxygenated blood to below the heart
What is the systemic circuit
Delivers oxygenated blood to respiring cells and takes carbon dioxide back from cells
What is the pulmonary circuit
Deoxygenated blood is moved to the alveoli in order to become oxygenated
Why does the right ventricle have less muscle than the left
The right ventricle only brings blood to the pulmonary circuit so not as much pressure is required
Thinner muscle ensures lower blood pressure which prevents damage to the lungs / pulmonary circuit
What are the 4 layers of the arteries called
Tunica externa (outside layer)
Tunica media (middle layer)
Tunic intima (inside layer)
Lumen
What is in the tunica externa (arteries)
A layer of collagen
→ prevents the artery from bursting / overstretching due to high blood pressure
(Prevents rupture)
→ Gives support
What is in the tunica Media (arteries)
-smooth muscle
→ thickest layer of the artery, it contracts and relaxes to change the size of the lumen
(Manages change in blood pressure)
-Elastic fibers
→ stretch and recoil to accommodate an increase in blood volume
Recoils to maintain blood pressure and to push it fowards
What is in the tunica intima (arteries)
-smooth endothelial lining
→ reduces resistance of blood flow making it faster
→ highly folded allowing it to stretch and accommodate for an increase in blood volume
Why do arteries have a narrow lumen
→ maintains a high blood pressure (blood flow is fast)
Why is a pump needed in a mass circulatory system
Facilitates mass flow (mass transport)
Generates pressure differences
Why is a transport medium needed in a circulatory system
needed to carry biological molecules such as glucose around an organism
Why are blood vessels needed in a circulatory system
Controls the direction of blood flow + helps maintain blood pressure
Why are exchange surfaces needed in a transport system
allows for more efficient transfer of molecules (e.g in the capillaries)
How is water adhesive
It can form hydrogen bonds with other O-H groups such as the ones in glucose.
What is adhesion
The bonding of two different molecules
Why does water move upwards in the xylem
Water forms stronger hydrogen bonds to the O-H groups to glucose (found in the cellulose walls)
This causes the water molecules at the edge to climb upwards, bringing other water molecules with it
Why is the endothelial lining in blood vessels folded
To allow it to contract and relax with the blood vessel
Why do arteries have elastic fibers
So that they can stretch to accommodate an increase in blood volume
and so they can recoil to maintain high blood pressure, and push the blood forward
Why do arteries have a thick wall of smooth muscle
The thick wall of smooth muscle allows the artery to contract and relax, pushing blood forwards
What do veins do
They carry deoxygenated blood back to the heart at a lower pressure
What do arteries do
They carry oxygenated blood away from the heart to cells at a high pressure (fast blood flow)
What is in the tunica externa (veins)
Layer of collagen
it prevents the vein form collapsing due to low pressure
What is in the Tunica Media (veins)
A thin layer of smooth muscle and elastic fibers
(the muscle does not contract and relax)
What is in the Tunicas Intima (veins)
Smooth (folded) endothelial lining
it reduces the resistance of the blood
Why do veins have valves
To prevent backflow of blood due to gravity
What makes up a vein
Tunica externa
Tunica Media
Tunica Intima
Lumen + Valves
How is blood moved / pushed in the veins
Skeletal muscle surrounding the veins contracts, narrowing its lumen
This causes blood to be pushed forwards / upwards
Where are capillaries found
They are the most abundant blood vessel and can be found next to every living cell in our body
What are the layers of the capillary
They have a 1 cell layer thick wall made of endothelial cells (porous walls)
They have a very narrow lumen (that can only fit 1 cell at a time)
How does blood flow through a capillary
At a low pressure and speed, giving time for exchange to occur
Only 1 blood cell at a time
Why does the speed going through a capillary have to be low
So that efficient transfer and exchange and transfer of minerals can occur (e.g oxygen)
And to prevent capillary damage
what is the cardiac cycle
The rhythmic cycle where chambers alternatively contract and relax
What does systole mean
contraction
What does diastole mean
Relaxation
What are the main stages of the cardiac cycle
Atrial systole
ventricular systole
cardiac diastole
How do valves passively open or close
They open / close due to differences in pressure
when the pressure is greater in front of the valve it closes
when the pressure is greater behind the valve it opens
What is the purpose of tendons connected to valves
They prevent valve inversion
(opening the wrong way)
What happens in atrial systole
Blood fills the atria under low pressure
As the atria fills the pressure increases
As the atria pressure is greater than the ventricular pressure the atrioventricular valve opens
the heart muscle in the atria contracts forcing blood into the ventricle
what happens in ventricular systole
Ventricles contact so the pressure increases
ventricular pressure > atrial pressure so AV valves close
ventricular pressure > arterial (blood vessel) pressure so semi lunar valves open
What happens in cardiac diastole
atria and ventricular walls relax
decrease in ventricular pressure so the semi lunar valves close
Lower pressure in the atria draws blood in from veins
Why does low pressure in the atria cause blood from the veins to move into it
As blood moves through mass movement - (high to low pressure)
What is systolic blood pressure
Pressure exerted against the arterial wall when the heart contracts
what is diastolic blood pressure
Pressure exerted against the arterial wall when the heart muscle relaxes
how many times does the heart ‘beat’ in the cardiac cycle
The entire cardiac cycle is considered as one heart beat
What is the average blood pressure on the right side of the heart
25/10 mmHg
What is the average blood pressure on the left side of the heart
120/80 mmHg
In a cardiac cycle pressure graph where does each valve open / close
The av Valve closes as the ventricular pressure increases (bottom left of the graph)
The semi lunar valve opens when the ventricular pressure is above the arterial ( labeled above the av closing)
The SL valve closes when the ventricular pressure falls
The AV valve opens when ventricular pressure is lower than atrial
