B5 - The human body Flashcards
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.
What is the pituitary gland?
master gland
tells other glands to release their hormones
E.G it releases TSH. if the pituitary gland detects low levels of thyroxine, it will release TSH, which stimulates thyroid to produce more thyroxine. This is called a negative feedback system.
What is stage 1 of the menstruation cycle?
stage 1: day 1 where the menstruation starts. the lining of the uterus breaks down
what is stage 2 of the menstruation cycle?
uterus lining is repaired, from day 4 to 14, becomes a thick spongy layer full of blood vessels ready for a fertilised egg to implant there.
what is stage 3 of the menstruation cycle?
an egg develops and is released from ovary (ovulation) at about day 14
what is stage 4 of the yk what cycle?
lining is maintained for about 14 days (day 28)
if not fertilised egg has landed on the wall by day 28, the spongy lining starts to break down again
what is oestrogen?
Released by the ovaries
Causes the lining of the uterus to thicken and grow
there is an increase in oestrogen during stage 2 and falls once the lining grows
what is progesterone?
Released by the ovaries
maintains the lining of the uterus for the implantation of a fertilised egg.
when progesterone falls, there is a low oestrogen level; the uterus lining breaks down, restarting the cycle
FSH follicle-stimulating-gland
released by the pituitary gland
causes a follicle (and egg and its surrounding cells) to mature in the ovaries
LH luteinising hormone
Released by the pituitary gland
stimulates ovulation at day 14 (the follicle ruptures and egg is released)
how can hormones promote natural preganancy?
Some women have low level of FSH to cause the follicle to develop and their eggs to mature.
So, the hormones FSH and LH can be injected to stimulate ovulation
What is IVF?
“In vitro fertilisation” involves collecting collecting eggs from a women’s ovaries and fertilising it with a mans sp3rm. Once the embryos are tiny balls, one or 2 of them are transferred to the women’s’ uterus to improve the chance of pregnancy
contraceptives with Progesterone (3)
- injection, implant, mini-pill
- stimulates the production of thick cervical mucus making it less likely for the sperm to reach the egg.
- thins the lining of the uterus to reduce chance of egg implanting
Barrier methods
a con😏
female con; worn in the pepe
diaphragm fitted over the cervix
what are the other type of methods
IUDs / natural methods / sterilisation
Cons of contraception (3)
- side effects: acne / irregular periods
- possibility of doing method wrong
- medical input: uncomfortable
pros of contraception
- Long lasting methods
- cond😏 prevents STIs
- some prevents ovulation
homeostasis
the regulation of conditions, such as body temperature, water content, and blood glucose levels
type 1 diabetes
pancreas stops producing insulin
people with this need insulin therapy (injecting insulin several times a day)
this makes sure glucose is removed from the blood quickly once food has been digested. this stops the level of glucose from getting too high
type 2 diabetes
when you become resistant to insulin or the pancreas doesn’t produce enough
can also cause ur blood sugar lvl to rise to a dangerous level.
can be controlled by:
eating healthy diet
exercising regularly
losing weight if necessary
how is the level of glucose in the body maintained?
- metabolism of cells removes glucose from the blood
- vigorous exercise removes more glucose from the blood
excess glucose can be stored as glycogen in the liver and in muscles
how does the body respond when the blood glucose level is too high
insulin secreted from the pancreas
insulin removes glucose from the blood
how does the body respond when the blood glucose level is too low?
glucagon is secreted by the pancreas
glucagon makes glycogen turn into glucose
blood glucose increased✅
why does one side of the heart have a thicker wall of cardiac muscle?
as it needs to contract at a faster pressure to pump oxygenated blood around the body
