B3: Organism-level Systems Flashcards
what is a voluntary action
an action that occurs as a result of you consciencely deciding that you want to do something.
What is a reflex action
involuntary reactions that occur without thinking by missing out the brain as this means the reaction can take place faster,normally 0.2 seconds and happen when you are in danger
The reflex arc pathway
stimulus-receptor-sensory neurone-spinal cord-motor neurone-effector-response
voluntary action pathway
stimulus-receptor-sensory neurone-spinal cord-brain-spinal cord-motor-effector-response
stimulus
change in the environment
receptors
group of cells that detect the change in environment
effectors
where the response occurs from and can be muscles or glands.Muscles respond by contracting and glands responf by relseasing hormones
what do receptor cells do
change the stimulus into electrical impulses that travel along neurones to your CNS
What is the CNS
-central nervous system
-made up of the brain and spinal cord
-very delciate so are protectd by bones.Skull protects brain,backbone protects spinal cord
light’s receptor cell and sense organ
r-light
so-light
chemical’s receptor cell and sense organ
r-taste
so-tounge
pressure and heat’s receptor cell and sense organ
rc-pressure and temperature
so-skin
chemical’s receptor cell and sense organ
r-smell taste
so-nose
sensory neurone
carries electrical impulses from receptor cells to the CNS
relay neurones (reflex arc only)
-carry electrical impulse from sensory neurone to motor neurone across the spinal cord
motor neurones
carry electrical impulses from the CNS to effectors
nerves
the term to describe the bundles of the the hundreds or even thousands of neurones found together
cornea
transparent coating on the front of the eye that protects the it and also refracts incoming light
pupil
the central hole in the iris that allows light to enter the eye
iris
coloured ring of muscle tissue that altars the size of the pupil by contracting or relaxing
lens
transparent bioconvex lens that focuses light clearly onto the retina
ciliary body
ring of muscle tissue that altars the shape of the lens
suspensory ligaments
ligament tissue that connects the ciliary muscle to the lens
optic nerve
nervous tissue that carries nerve impulses to the brain.
how are images formed
cornea refracts incoming light rays that provides most of the focus to the incoming light.The light then passes through the pupil and then refracted again by the lens,which creates a sharp image on the retina.Photoreceptors in the retina produce a nervous impulse when exposed to light.This impulse travels down the optic nerve to the brain and the brain intereprets these impulses as a vidual image
what happens when the ciliary muscles contract
your lens becomes more convex(wider) and you can focus on nearby objects
what happens when the ciliary muscles relax
your lens becomes less convex(thinner).Your can focus on distant objects
short sightedness
when distant objects appear blurry and is caused by a person’s lens being too strong or by the eyeball being too long.
Long sightedness
when a person cannot focus on short distanced objects and caused by a persons lens being too weak or the eyeball being too short
what is the two types of photoreceptors in the retina
rods and cones
rods
responsive to light,not different colours, and allow you to see in low levels of light.
cones
respond to different colours and different cone cells respond to red and green light
whats the most common form of colour blindness
red-green and is genetically inherited and usually affects males
What is the function of the brain
process all info collected by receptor cells about stimuli.Also recieves and proccesses imformation from your hormonal system
what does having a brain mean for neuronal communication
much faster
what is the brain protected by
skull
cerebrum
complex behaviour-learning and memory for example
cerebellum
controls posture,balance and involunatry movements
medulla
controls heart and breathing rate
hypothalamus
regulates temperature and water balance
pituarity gland
stores and relseases hormones that regukate many body functions
what did scientists used to do in order to study brain function
placed electrons inside animal brains.These would trasmit electrical impulses,which result in movement in different parts if the aminla’s body.This enabled scientists to link an area of the brain to the region of the body it controls.
CT scans(computed tomography)
use X-rays to create 3D images of the inside of the body.the position of any abnormalities can be linked with changes in a patients behaviour.Not used regulalry as X-r-ray radiation increases the risk of cancer
MRI(magnetic resonance imaging)
use powerful magnets to identify brain abnormalites.A new technquice callled fMRI(functional MRI) produces images in real time and so scientisits can identify areas of the brain that show increased blood flow,areas that are active when a person is carrying out a specific activity
CNS
brain and spinal cord
PNS
all neurones that connect CNS to rest of body
sesnory and motor
types of nerve damage
injury
disease
genetic disease
ingesting a toxic substance like lead
what does damage to the nervous system do
prevents impulses from being passed effectively through the nervous system
what are the effects of nervous system damage
an inability to detect pain
numbness
loss of coordination
can PNS regenerate
yes,but limited.
minor will self heal and more severe can be treated through surgery
What can damage to the CNS lead to
-loss of control of body systems
-partial or complete paralysis
-memory loss or processing difficulties
-the CNS cannot regenertae so any damage is permanent unless manually corrected by surgery
why is is difficult to treat spinal cord
has 31 pairs of nerves each with many nerve fibres,making it difficult to indentify and repair damage to an individual nerve fibre.Could lead to disability or permanent loss of function
why is is difficult to treat brain
made up of delicate and fragile tissue.
how can we treat the brain
radiotherapy and chemotherapy-treating brain tumours
surgery-removing damaged brain tissue
deep brain stimulation-inserting an electrode to stimuate brain function
what are hormones
chemical messengers that are made in endocrine glands and are secretes in the blood in the plasma
-cause a response in specific cells that are found in target organs
homeostasis
when your body internally regulates and changes to fit the change in external environment
what do the hypothalamus and pituitarty glands do
produce hormones that regulate the production of other hormones
what gland produces throxine
thyroid
what do the adrenal glands produce
adrenaline
what produces insulin
pancreas
what do the ovaries produce
oestrogen and progesterone
what do the testes produce
testosterone
target cells
hormones will diffuse out of the blood and bind to specific receptors for that hormone,found on the membrane or is the cytoplasm of cells in the target organs.Once bound to their recptors,the hormones will stimulate the target cells to produce a response
what is the endocrine system
all the endocrine glands and the hormones that they produce.Controls and coordinates body processes with the nervous system.They send information about how the body should respond to a change in environment
nerves
very fast
electrical impulse along the axon of a neuron
short acting
very precise
hormones
slower
in the blood
longer acting
larger area
thyroxine
hormone produced in the thyroid gland that regulates the body’s metabloic rate(rate of energy tansfer in order to perform its functions)
what is the function of the thyroid gland
take iodine found in many foods and convert it into thyroxine by combining it with the amino acid tyrosine
what is adrenaline
secreted by adrenal glands and prepares the body for intensive action when stressed.’fight or flight response’
negative feedback
a control method the body uses to keep internal conditions constant
what does thyroxine control
how much energy is available to cells
How are thyroxine levels controlled when there is less thyroxine that needed
when body needs more energy hypothalamus cause pg to release TSH and this stimulates thyroid gland to release thyroxine.This increases the metabolic rate allowing cells to transfer additional energy
how are thyroxine levels controlled when there is more thyroxine than needed
the hypothalamus inhibits the production od TSH.The thyroid gland therefore stops releasing thyroxine
how are adrenaline levels controlled
in times of stress,the brain signals the adrenal glands to secrete adrenaline,when stress is removed the signlas stop
what does adrenaline even do
-you respire more quickly to increase the rate of ATP production
-increase the rate of breathing
-increase heart rate
-diverting blood to muscles
what is the menstrual cycle
monthly cycle which a woman’s body gets ready for pregnancy and is usually 28 days
ovulation
happens 14 days into the cycle and is where an egg starts to mature
menstruation
the matured egg is put on the uterus lining,if not fertilised the uterus lining and egg are removed from the body
