B5 Flashcards
Homeostasis- stable enteral environment
Cells need right conditions to function eg enzyme action
Response to changes in internal and external conditions
Automatic control systems- INTERNAL Environment- nervous and hormonal communication eg body temp, blood glucose, water content
3 components- receptors, coordination centres and effector
Negative feedback
Level of something is too high or low so body uses negative feedback to bring it back to normal.
Nervous system
Organisms respond to stimulating survive
A single cell can respond to its environment but multicellular need to communicate first so they’re evolved and develop nervous and hormonal communication systems
CNS
In vertebrates consists of brain spinal cord only and in mammals connected to body by sensory and motor neurones
Sensory neurone
Carry info as electrical impulses from CNS to effectors
Motor neurone
Also carry electrical impulses from CNS to effectors
Effectors
Muscles and glands responding to nervous Imulses
Complex organs
Receptors detect stimuli
Many types such as taste in the tongue and sound in the ears
Can form part of a larger complex organs retina in eyes covered in light receptors
CNS is coordination centre
Receives info from from receptors and coordinates a response
Stimulus-receptor-sensory neuron-CNS-motor neurone-effector-response
Synapse
Connection between two neurones
Nerve signal is transferred but chemicals which diffuse across the gap
Chemicals set off a new electrical signal in next neurone
Reflex prevent injury
Don’t involve a conscious part of the brain
Eg bright light in your pupils automatically get smaller so less light gets into the eye
Passage of information in a reflex is called a reflex arc
Endocrine
Hormones are released in blood and go around the body but only affect particular organs (target organs)
They control things in the organs and cells that need constant adjustment
Made in endocrine glands which make up the endocrine system
Pituitary gland
Produces many hormones that regulate body conditions
Aka MASTER GLAND
As these hormones act on other glands directing them to relapse hormones that bring change
Ovaries
Produces oestrogen
Testes
Produce testosterone which controls puppetry and sperm production
Thyroid
Produces thyroxine
Regulates rate of metabolism heart rate and temp
Adrenal gland
Produces adrenaline to prepare body for fight or flight response
Pancreas
Produces insulin which regulates blood glucose level
Nerves
Fast and act for short time on a precise area
Hormones
Slower action for a long time in a general way
Insulin and glucagon
Carbs put glucose into the blood form the gut
Normal metabolism removes glucose form blood
Lots of exercise removes much more glucose from blood
Excess will be stored as glycogen in liver and muscles
Level of glucose in blood must be steady changes are monitored by pancreas using insulin and glucagon in negative feedback
Blood glucose too HiGH
Insulin separated from blood by pancreas
Glucose moves from blood into liver and muscle cells
And insulin makes insulin change glucose into glycogen
So blood glucose reduced
Blood glucose to LOW
Glucagon separated buy pancreas from blood
Glucagon makes liver turn glycogen into glucose and it’s real eased into the blood
Type one diabetes
Pancreas produces little or no insulin meaning glucose level can rise to a level and kill them so they need insulin therapy which makes sure glucose is removed form blood quickly once food is digested.
The amount of insulin needed depends on how active and the diet of of a person.
They might also try and limit the amount of rich foods such as carbs the intake
Type 2
Person is resistant to their own insulin (bodies cell don’t respond properly). Can cause blood sugar level to rise to a dangerous level. Being over weight can increase the chance of developing this.
Can be controlled but regular exercise and carb controlled diet
Puberty and menstrual cycle
Puberty realises sex hormones
Men- testosterone produced by testes and stimulates sperm production
Women- oestrogen in ovaries brings physical change and involved in menstrual cycle
4 stages
Stage1 - menstruation starts / uterus lining breaks down for 4 days
Stage2- uterus lining builds back up / from day 4-14 into a think spongy layer full of blood vessels ready to receive a fertilised egg
Stage3-egg develops and is released / at day 14 it’s called ovulation
Stage4- wall maintained / no fertilised egg by day 28 spongy layer breaks down and cycle starts again
4 hormones
FSH.
pituitary gland caused an egg to mature in one of the overuse in structure called follicle. Stimulates overuse to produce oestrogen
Oestrogen.
Produced in ovaries causes lining of uterus to grow. Stimulates release of LH which causes release of egg and inhibits release of FSH
LH.
Produced by pituitary gland. Stimulates realise of egg at day 14
Progesterone.
Produced in ovaries by remains of the follicle after ovulation. When level of this falls the lining breaks down. Inhibits release is LH and FSH
