B5 Flashcards
mwhat do cells need?
oxygen, glucose, amino acids, water, ions
what are waste products?
carbon dioxide and urea
how are alveoli specialised?
- enormous surface area
- moist lining
- thin walls with calls with partially permeable cell membranes
- a good blood supply
what is the job of the lungs?
transfers oxygen to the blood and removes carbon dioxide
what is a partially permeable membrane?
the membrane will only allow a certain type of substances to go through the membrane
what is the gaseous exchange system?
- system made up of the nose, mouth, trachea and lungs
- responsible for oxygenating the blood, and removing carbon dioxide from it
what is the digestive system?
- food is broken down
- dissolved food molecules are transferred into the bloodstream at the small intestine by diffusion and other transport processes
- once the dissolved food molecules are in the bloodstream, they can be transported to all the cells in the body.
- this is particularly important for glucose as it is needed by all cells for the process of respiration
what is the excretory system?
- system made up of the kidneys and bladder
- responsible for removing waste products that have been made by the body
what is the circulatory system?
transports substances, such as oxygen, around the body in the bloodstream. It links together all the other systems in the body
what is diffusion?
the movement of a substance from an area of high concentration to low concentration
how does the body diffuse oxygen?
in the lungs by the alveoli
what does the blood transport?
oxygen, carbon dioxide, glucose, urea
what is osmosis?
the net movement of water molecules from a high concentration to a lower concentration across a partially permeable membrane
what is active transport?
the transport of molecules against their concentration gradient from a region of low concentration to a region of high concentration
why is blood important?
it flows around the body, transporting substances to and from cells
what is in blood?
red blood cells, white blood cells, platelets and plasma
what does plasma do?
transports carbon dioxide, digested food molecules, urea and hormones; distributing heat
what do red blood cells do?
transport oxygen
what do white blood cells do?
Ingest pathogens and producing antibodies
what do platelets do?
Involved in blood clotting
why is the left side of the heart bigger?
it puumps blood to teh body
what is in cardiac heart muscles and why?
mitochondria to provide them with ATP
- this releases the energy needed for the muscle to contract
what are the 4 chambers?
right and left ventricle
right and left atria
what are valves for?
keep blood flowing in one direction and the right direction
how does blood flow into the heart?
vena cave(right)
pulmonary vein(left)
where does the right ventricle pump blood to?
lungs
what do the arteries do
carry blood away from the heart
what do capillaries do
they are involved in the exchange of materials at the tissues
what do veins do
carry blood into the heart
why are arteries thick and elastic?
blood pressure in them is high
so they can stretch and spring back
why are capillary walls one cell thick?
to increase the rate of diffusion by decreasing the distance it occurs by
why are veins thin?
the blood is at a lower pressure
why do veins have a large lumen?
to help blood flow
why do blood cells have a biconcave disc shape?
to give a large surface area to volume ratio
this increases the rate that oxygen diffuses in and out of the cell
what is the advantage of their size?
they can pass through the the capillaries close to the body cells
why do multicellular organisms need exchange surfaces?
they have small surface area to volume ratios which makes diffusion slow
how do multicellular organisms get around the problem?
they have specialised exchange surfaces
what are receptors?
- specialised groups of cells
- sense changes in the environment
- linked to sensory neurons
what are the concentration of receptors based on?
how much information that part of the body gets from the environment
what are the types of receptors?
chemical, pain, pressure, light, stretch, temperature, balance
what are chemical receptors for?
smell and taste
what are neurones?
nerve cells
what is the nervous system made of
neurones
what is a stimulus
sense organs that detect changes in the world around us
what part detects the stimulus?
receptors
what is the CNS made of
spinal crd and brain
what does the CNS do
coordinates the response
- decides what to do about the stimulus and tells something to do it
the journey of a stimulus
stimulus to receptor to sensory neurone to CNS to motor neurone to effector to response
what os the use of an axon
electrical impulses pass through it
what are dendrites
branched endings that allow the neurone to connect with other neurones
what is the myelin
fatty sheath
- acts as insulator, speding up the impulse
why are neurones long?
it speeds up the impulse
- if it has to connect to other neurones, it slowws the impuslse down
what is the connection between two neurones
synapse
what is an effector
gland or muscle
what do synapes do?
when electrical impulse hits the end of the nerve, it causes the release of some chemicals which diffuse across gap to trigger another electrical impulse
what is a synapse
connection between two neurones
what are hormones?
chemical messengers
where do hormones come from?
endocrine glands adn travel through bloodstream to target organs
how are hormones connected to their target organ?
organs are covered in receptors for the hormones to bind to
what system provides slower, longer-lasting responses
endocrine system
how are hormones slower tean nerves
they travel through the bloodstream but nerves go straight through neurones/CNS
what is the pituitary gland?
master gland
- produces hormones that control and regulate the others
what is homeostasis
the body’s way of maintaining our internal environment
how can the body counteract changes to its internal environment?
-receptors
- nerves
- hormones
- effectors
what systens aree controlled and maintained by homeostasis?
- temperature
- oxygen, CO2 conc, sugar, ph level, water levels in our blood
what does thyroid gland produce?
thyroxine
what does thyroxine do?
helps regulate metabolism, brain development and growth
what is a reflex?
involuntary response to avoid harm/protect us
what is a refel arc?
the passage of information in a reflex(from receptor to effector)
where does a reflex impulse travel to and why?
straight to the spine to speed up the process
how can the brain override a reflex response
uses a neurone that connects to the motor neurone in the reflex arc
what is the relay neurone
carries nerve impulses within the CNS
examples of reflexes
dodging, flinching, breathing
what releases adrenaline?
adrenal gland just above kidney
adrenaline: fight or flight
- prepares the body for flight or fight
- it activates processes that increases the supply of oxygen and glucose to cells
how does adrenaline work?
Adrenaline binds to specific receptors in the heart. This causes the heart muscle (the effector) fo contract more frequently and with more force, so heart rate and blood pressure increase.
• This increases blood flow to the muscles, so the cells receive more oxygen and glucose for increased respiration.
Adrenaline also binds to receptors in the liver. This causes the liver to break down its glycogen stores to release glucose.
• This increases the blood glucose level, so there’s more glucose
in the blood to be transported to the cells.
what does the negative feeedback system do?
the body’s way of controlling the levels of hormones in the blood
what does the body trigger a response for?
when the level of a substance has gone above or below the normal level
what is the metabolic rate?
the speed at which chemical reactions occur at in the body
negative feedback for thyroxine
too low: pituitary glands will release TSH. this stimulates thyroid gland to make more thyroxine so the thyroxine levels increase
too high: thyroxine inhibits pituitary gland from producing TSH. less TSH means thyroid gland wont release as much thyroxine so the levels decrease
what happens at stage 1 and stage 2?
1: menstruation starts. lining of uterus breaks down and is released
2: uterus lining is repaired until it becomes a thick spongy vessels ready for fertilised egg
what happens at stage 3 and 44?
3: egg develops and is released from ovary
4: lining = maintained but if no fertilised egg lands on uterus, spongy lining breaks down and cycle starts again
FSH
- follicle stimulating hormone
- released by pituitary gland
- causes follicle to mature in one of the ovaries
- stimulates oestrogen production
what is a follicle?
an egg and its surrounding cells
oestrogen
- released by ovaries
- causes lining of the uterus to thicken and grow
LH
- luteinising hormone
- released by pituitary gland
- LH surge stimulates ovulation where the follicle ruptures and egg gets released
- stimulates remains of follicle to develop into corpus luteum (secretes progesterone)
progesterone
- released by ovaries
- maintains lining of uterus for implantation of a fertilised egg
- inhibits release of FSH and LH (so does oestrogen)
- low progesterone level allows FSH to increase
how can hormones be used to treat infertility?
developments in modern reproductive technologies
how are hormones used in natural pregancy?
FSH and LH can be injected to stimulate ovulation
- FSH causes follicles to develop and eggs to mature
what is IVF?
- collecting eggs from ovaries and fertilising them in a lab with sprem. once the emryos are balls of cells, on eor two gets transferred to improve chance of preganacy
- FSH and LH are given to improve chances
contraceptives using progesterone
injection, implant, IUS, mini-pill
how progesterone and oestrogen contraceptives work?
- stimulates thick discharge to stop sperm getting through
- thins lining of uterus to reduce chance of fertilised egg
- prevents ovulation by inhibiting FSH and LH
barrier methods
condoms(98%), female condoms(95%), diaphragm(92-96%)
intrauterine devices
- t shaped
- contains copper
- prevents sperm from surviving
- 99% effective
natural methods
pull out or having sex at less fertile time
- least effective
sterilisation
cutting tubes and vasectomies
over 99% effective
evaluation of contraception
- side effects like heavy periods, acne, headaches
- possibility of doing it wrong- condom could split or not pull out in time
- may feel uncomfortable about getting devices inserted or having to go doctors frequently
- length of action- if on pills, you may have to go docs often over if you had a device
- STD’s- only condoms protect against stds
why do conditions in the body need to be kept in a narrow range
- so the enzyme controlled metabolic reactions in the cell can happen at an appropriate rate
- if not, the cells wont function normally
what does antagonistic mean
some effectors in homeostasis work in opps to one another - one may increase and the other increaases
what needs to be kept steady?
- blood glucose concentration
- water content
- body temperature
what removes glucose from the body
normal metabolism of cells and vigorous energy removes lots
what is stored in the liver
excess glucose as glycogen
insulin and glucagon
- must be kept steady
- hormones that work antagonistically
what happens when blood glucose level is too high?
- insulin is added
- blood has too much glucose
- insulin is secreted by pancreas
- excess glucose and insulin
- insulin removes glucose from blood and moves from blood into liver and muscle cells
what happens when blood glucose level is too low?
- blood has too little glucose
- glucagon secreted by pancreas
- lack of glucose but also glucagon
- glucagon makes liver turn glycogen into glucose
- glucose is released into blood by liver
- blood sugar is increased
what is type 1 diabetes
- where the pancreas stops producing insulin
- blood sugar can rise to a level that can kill them
- insulin therapy is needed
- this removes glucose from the blood quickly and stops level in blood getting too high
- they need to think about limiting intake of foods with simple carbs and take regular exercise
what is type 2 diabetes
- person becomes resistant to insulin or pancreas doesn’t produce enough
- can cause blood sugar level to rise to dangerous level
- being overweight or obese is a risk factor and can increase chances
can be controlled by healthy diet, regular exercise and losing weight
u can also use medication or insulin injections
