B5 - The human body Flashcards
(47 cards)
What is the job of the lungs during gas exchange? explain process
the lungs transfer oxygen and remove co2 from the blood
lungs contain millions of tiny little air sacks called alveoli where gas exchange takes place
alveoli are surrounded by tiny blood vessels called capillaries, this is where gas exchange takes place.
oxygen from the alveoli diffuses into the capillaries, co2 opposite happens
how are alveoli specialised to maximise the rate of diffusion of o2 and co2? (4)
- enormous surface area
- moist lining for dissolving gases
- good blood supply
- thin walls
explain the two circuits of the double circulatory system
first circuit: heart pumps deoxygenated blood to the alveoli for oxygen. The oxy blood then returns to the heart
second circuit: heart pumps oxygenated blood all around the other organs of the body; oxy given up at the body cells. Returns!!
What are the 4 chambers?
right and left ventricles and artria
What are the valves in the heart?
makes sure the blood flows in the right direction
when the ventricles contract, the valves to the atria close and the valves to the blood vessels open, preventing backflow
What are the arteries and its adaptations? (2)
- the heart pumps the blood out at high pressure, so the artery walls are strong and elastic
- they contain thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back
What are the capillaries and its adaptations? (3)
Tiny
Carry blood really close to every cell in the body to exchange substances with them
They have permeable walls, so substances can diffuse in and out
What are the veins and its adaptations?
the blood is at low pressure so the walls aren’t as thick as the arteries
bigger lumen for blood flow
also valves to prevent backflow
What is plasma?
pale yellow liquid??
what does plasma carry?
red blood cells, white blood cells, and platelets
water
food products
urea
hormones
antibodies
red blood cells?
transport oxygen from the lungs to all the cells in the body
what are the adaptations of red blood cells? (4)
- small biconcave disc shape to give a large surface area to vol ratio, which increases the rate at which oxy can diffuse out of the cell
- packed with haemoglobin
- don’t have a nucleus for more space for haemoglobin to carry more oxygen
- small and flexible - they can pass through tiny capillaries close to the blood cells
What are sensory receptors?
sensory receptors detect changes in your external/internal environment (stimulus). Different sensory receptors detect different stimuli.
What happens when a stimulus is detected by receptors?
when a stimulus is detected by receptors, the information is sent as a nervous impulse, along sensory neurones to the CNS
What is the CNS?
It’s a processing centre
Coordinates the response of the nervous impulses
CNS then sends info to an effector (muscle / gland) along a motor neurone.
the effector then responds accordingly
explain the nerve process list it out
stimulus detected by receptors
then sent along sensory neurons to CNS
CNS sends response to an effector
along a motor neuron
effector responds accordingly (muscle/gland)
What is the gap between 2 neurones?
Synapse
electrical impulse triggers the release of chemical transmitters, which diffuse across the gap
these chemicals bind to receptor molecules in the membrane of the next neurone
Name the adaptations of neurones (3)
passed along the axon of the neurone
- branched endings (dendrites) so they can connect with lots of other neurones
- some axons are surround by a fatty sheath (an electrical insulator, which speeds up impulse)
- neurones are long which speeds up impulse
define a reflex arc (2)
- reflex actions are involuntary, and quick.
- the nerve pathway that underlies our unconscious reflexes
how do reflexes work? (2)
- sensory neurone connects to a relay neurone in the spinal cord or unconscious part of the brain
- which directly links to the right motor neurone
What are hormones?
are specific chemical messengers produced in various glands called endocrine glands
Are released directly into the blood and carried
They only produce a response to particular effectors. These effectors have receptors that the hormones bind to.
Endocrine system (2)
- Has glands the secrete hormones
- these act as chemical messengers and travel in bloodstream to effectors, which have receptors to respond to the hormone.
What is the adrenal gland? (3)
- Adrenaline is a hormone
- Which prepares the body for fight or flight
- it does this by activating processes that increase the supply of oxygen and glucose to cells.
what is thyroxine?
hormone released by the thyroid gland, and regulates metabolic rate.
