bio paper 2 homeostasis and response

what is homeostasis

an organism’s ability to regulate /control its internal conditions so crucial reactions can happen at optimal rates

what needs to be regulated with homeostasis

blood glucose concentration, internal temperature, water levels

what is a reflex arc

signals bypasses brain , much quicker

a practical for the nervous system

reaction time- ruler drops in between finger +thumb, measure distance, repeat +calculate mean, nit too many times as the nervous system will get better

how does the signal travel

receptor - stimulator - sensory neurone - motor neurone - effector

what is the pituary gland

in the brain it’s a “master gland” which secretes several hormones into the blood in response to body conditions. these hormones in turn act on other glands to stimulate other hormones to be released to bring about effects

how is blood glucose concentration monitored

its monitored and controlled by the pancreas

if the blood glucose concentration is too high then

pancreas produces the hormone insulin that causes glucose to move from the blood into the cells . in liver and the muscle cells excess glucose is converted to glycogen for storage

if the blood glucose concentration is too low then

pancreas produces the hormone glucagon that cause glycogen to be converted into glucose and released into the blood. glucagon interacts with insulin in a negative feedback cycle to control blood glucose (sugar) levels in the body

what is type 1 diabetes

disorder in which the pancreas fails to produce sufficient insulin . it is characterized by uncontrolled high blood glucose levels and is normally treated with insulin injections

what is type 2 diabetes

the body cells no longer respond to insulin produced by the pancreas . a carbohydrate controlled diet and an exercise regime and common treatments . obesity is a risk factor for type 2 diabetes

what does the central nervous system do

it uses nerves that carry electrical impulse , very quick acting , usually short effects

what does the receptor cell do

it detects stimuli (a change in the environment)- have a cell membrane, nucleus and cytoplasm just like other animal cells

what are neurones

nerves that carry electrical impulses

what is the sensory neurone

it transports the impulse from the receptor cell

what is the relay neurone

transfers the impulse from the secondary neurone to the motor neurone

what is the motor neurone

transports the impulse to the muscle

synapse

a gap between 2 neurones

effectors(muscles or glands)

bring responses which restore optimum levels

what is the endocrine system

composed of glands which secrete chemicals called hormones directly into the bloodstream

what is the hormonal system

it uses hormones to control our body

hormones

chemical messengers that travel in the blood , slow acting but longer effect

what hormones are releasd in menstrual cycle

FSH, oestrogen , LH, ovulation

what is the FSH hormone

it causes eggs to mature. made in the pituitary gland

oestrogen hormone

makes uterus lining thicker and is made in the ovaries

LH

it stimulates the eggs to be released . made in the pituary gland

ovulation (release of an egg)

happens on day 14 of menstrual cycle

Oral contraceptives

• prevent pregnancy , contain oestrogen(sometimes progesterone) . This inhibits FSH production , so no eggs mature.

• It’s usually 99% effective and can strop straight away if women wants to get pregnant

• But remember to take them daily and dont protect against STIs

Role of thyroxine in body

It’s from the thyroid gland which stimulates the basal metabolic rate . It plays an important role in the growth and development of. Thyroxine levels are controlled by negative feedback

Role of adrenaline in the body

It’s produced by the adrenal gland in times of fear or stress . It increases the rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for “fight or flight”.

What is IVF and how is it used

• technique which helps couples to have babies

• Women given FSH which helps eggs to mature and LH to help eggs be released

• Egg is taken from female and fertilised with sperm

• Develops into an embryo in test tube

• They inserted back into the uterus of the women to develop

How does the reflex arc work

• stimulus is detected by receptors

• Electrical impulses passed from sensory neurone to CNS

• They cross the synapse with chemicals into the relay neautron

• They travel down relay neuron to another synapse

• They cross this new synapse with chemicals into the motor neuron

• The electrical impulses travel down the motor neurone to effector

• The muscle contracts or The gland to release hormones