organisation(heart and lungs) Flashcards
what is the direction of blood flow in the arteries ?
arteries carry blood away from the heart
what is the direction of bloodflow in the veins?
veins carry blood towards the heart
what are capillaries?
capillaries are tiny blood vessels that have a wall which is only one cell thick and this is where the exchange of substances takes place
what is the purpose of valves in the veins?
valves prevent the backflow of blood and ensures it only travels in one direction.
explain 3 adaptation’s of the arteries
-arteries have thick walls to withstand the high pressure of the blood flow
-elastic walls so they can stretch and return to its original shape due to the high volume of blood that passes through the arterteries
-thick muscle to allow them to change their size and direct blood flow
give 3 adaptations of veins
-wall of the vein is relatively thin due to only having a low volume of blood passing through
-contain valves to prevent the backflow of blood because the blood is at a low volume and needs to be returned to the heart
-has a wider lumen to keep blood pressure low
give 3 adaptations of the capillaries
-have walls that are only one cell thick for a short diffusion distance so substances can easily diffuse in and out of them
-has permeable walls to allow substances to easily move in and out of the capillaries
-narrow lumen to slow down the blood which allows more time for diffusion
what is the direction of blood flow in the capillaries?
through the tissues and organs through diffusion
what is the role of the capillaries?
to exchange substances with the cells of the body for example oxygen,glucose,and carbon dioxide
what is the equation to calculate the rate of blood flow?
rate of blood flow=volume of blood(ml)/time(min)
state and explain 4 features that most exchange surfaces have in common?
1.good blood supply so it can maintain a strong concentration gradient as blood is constantly replaced-increases rate of diffusion
2.large surface area so lots of molecules can diffuse across at the same time
3.surfaces are very thin for a short diffusion pathway
4.surfaces are permeable so substances are able to pass through the surface
what is gas exchange?
the exchange of oxygen and carbon dioxide between the bloodstream and the atmosphere
when breathing in air moves…(6 steps)
1.into the body through the mouth and nose
2.down the trachea
3.into the bronchi
4.through the bronchioles
5.into the alveoli(air sacks)
6.oxygen then diffuses into the blood in the networks of capillaries over the surface of the alveoli
give the process of inhalation? (5 steps)
1.air is drawn into the lungs
2.ribs move upwards and outwards
3.diaphragm flattens
4.volume of chest increases
5.pressure inside chest decreases
what is the alveoli the site for?
gas exchange
explain 4 adaptations of the alveoli for gas exchange?
1.walls are very thin-made up of one layer of cells-short diffusion pathway-increases rate at which co2 and o2 can diffuse across
2.very large surface area-walls are folded and humans have many alveoli-increases rate of diffusion as more molecules can diffuse across at one time
3.walls are moist-allows the gases to dissolve-increases the rate of diffusion-easier to diffuse across membranes
4.rich blood supply-next to the capillaries-maintains a strong concentration gradient-increases rate of diffusion-stronger driving force for the molecules to move
give three adaptations of the lungs?
1.capilleries are thin-short diffusion path
2.breathing in and out-maintains concentration gradient
3.good blood supply-same as above
what is blood?
blood is a tissue made up of 4 main components
what are the 4 main components of blood?
red blood cells
white blood cells
plasma
platelets
what is the role of red blood cells?
to carry oxygen from the lungs to our bodies tissues so that are cells can use it in cellular respiration
what is haemoglobin?
haemoglobin is the red pigment in our rbc that can bind to oxygen in order to transport it around the body
give 3 adaptations of rbc?
1.do not have a nucleus-more space for oxygen and haemoglobin-increase volume of oxygen transported to cells
2.shaped like a biconcave disk-large surface area for absorbing oxygen
3.small and flexible-allowing them to squeeze through narrow capillaries for efficient oxygen delivery
what is the role of wbc?
they are part of the immune system and defend the body against pathogens and infection
how do wbc defend us against pathogens?
phagocytosis-engulf pathogen
produce antibodies-bind onto pathogens and help destroy them
produce antitoxins-neutralise any toxins making us feel ill
