Homeostasis & Response Flashcards
What’s homeostasis?
The regulation of internal environment/conditions in cells and organisms.
What are the 3 conditions in humans?
- Blood & glucose concentration
- Water Levels
- Temperature
What is a stimulus?
A change in the environment
Name 2 automatic control systems
- Nervous
* Hormonal
What are automatic control systems made of?
Receptors, coordination centres and effectors.
What’s the process of negative feedback?
The receptor detects the change.
The coordination centre receives and processes the information and organise a response.
The effector produces the response that will restore the optimum level.
What are two examples of coordination systems?
Brain and Pancreas
What are two examples of effectors?
Muscles and Glands
What’s the central nervous system made of?
Brain and Spinal Cord
What’s the path of the nervous system?
The stimulus is detected by the receptor.
An electrical impulses is passed to the sensory neuron, then to the relay neuron and then to a motor neuron.
The motor neuron triggers the effector to give a response.
What are neurons?
Individual nerve cells
What are the 4 parts of the nervous system?
The CNS
Sensory Neurones - neurones that carry information as electrical impulses from receptors to the CNS.
Motor Neurones - neurones that carry information as electrical impulses from the CNS to effectors.
Effectors - muscles and glands responding to nervous muscles impulses
What are relay neurones?
Neurones in the CNS
What’s a synapse?
The connection between two neurones
How is the nerve signal transferred?
Chemicals diffuse to move across the gap.
What are reflexes?
Rapid, automatic responses that don’t require the brain.
What’s the pathway of a reflex?
The neurones in reflex arcs go through the spinal cord or the unconscious part of the brain (the CNS).
The receptor detects the stimuli and the sensory neurones sends an impulse to the CNS.
Then the impulses passes on a relay neurone and then a motor neurone on a synapse.
The motor neurone sends the impulse to the effector.
How do you investigate reaction time?
Rest your arm on a table and have someone hold a ruler with zero at your thumb and forefinger.
The person holding the ruler should drop it unexpectedly and the other person should catch it as fast as they can.
The higher the number, the slower their reaction time.
Repeat several times and find a mean.
What factors can affect reaction time?
Age, gender, drugs
What is the brain made of?
Billions of interconnected neurones
What does the brain do?
It’s in charge of all of our complex behaviour.
What’s the cerebral cortex?
The outer wrinkly part of the brain and it controls consciousness, intelligence, memory and language
What does the medulla do?
Controls unconscious activities like breathing.
What is the cerebellum responsible for?
Muscle coordination
What methods can you use to study the brain?
Studying patients with brain damage
MRI Scans
Electrically stimulating the brain
What’s the sclera?
The supporting wall of the eye
What’s the cornea?
The outer layer in the front of the eye that refracts light.
What does the iris do?
Controls how much light enters the eye
What does the lens do?
Focuses light onto the retina
What does the retina do
Contains light receptors
What does the optic nerve do?
Carried impulses between the eye and the brain
How is temperature controlled by negative feedback?
The receptors received a stimuli and sends it to the thermoregulatory centre, which sends it to the effector.
What are hormones?
Chemical messengers sent in the blood, made by endocrine glands
What are found in the endocrine system?
Pituitary Gland: produces hormones to regulate body temp.
Thyroid: produces thyroxine, which regulates metabolism, heart rate and body temp.
Adrenal Gland: produces adrenaline
Pancreas: produces insulin, regulates blood glucose levels
Ovaries: produces oestrogen
Testes: produces testosterone
What does our eyes do to look at near objects?
The ciliary muscles tighten and the suspensory muscles relax, making the lens curved and refracts more light.
What are some alternatives to glasses?
Contact lenses, laser eye surgery and replacement lens surgery
How is body temperature controlled by negative feedback?
The receptors detect the temperature change and send i to the thermoregulatory centre (the CNS), which triggers the effectors and the effectors produces a response.
What happens when you’re too hot?
Your hairs lie flat, your sweat glands produce sweat, and your blood supply dilates to transfer energy to the environment.
What are hormones?
Chemical messengers sent in the blood to organs and they are made in pancreas.
What are the parts in the endocrine system?
Pituitary Gland: produces hormones to regulate body conditions.
Thyroid Gland: produces thyroxine to regulate metabolism, heart rate and temperature.
Adrenal Gland: produces adrenaline
Pancreas: produces insulin to regulate blood glucose level.
Ovaries: produces oestrogen
Testes: produces testosterone
What’s the difference between a nerve and a hormone?
A nerve is fast, acts for a short time and works in a precise area whilst a hormone is slower. acts for a longer time, and works in general area.
What is excess glucose converted to?
Glycogen in the liver and muscles
What removes glucose from the blood?
Exercise and metabolism
What happens when the blood glucose level is too low/ high?
Low; The pancreas releases glucagon to the blood
High: The pancreas secretes insulin.
What is type 1 Diabetes?
A condition where the pancreas releases no/little insulin.
What are 2 treatments of Type 1 Diabetes?
[0 glucose.
Limiting foods rich in carbohydrates.
What’s Type 2 Diabetes?
A condition when your body cells don’t respond to insulin properly.
What are some factors of getting Type 2 Diabetes?
Age, obesity and lack of exercise
What do kidneys do?
Take waste products out of the blood via filtration.
What substances are removed from the body?
Urea, ions and water
How does negative feedback control water content?
The receptor in the brain detects a change and sends an impulse to the coordination centre which sends a response to the pituitary gland.
What’s dialysis?
The patient’s blood flows in a dialyzer surrounded by dialysis fluid.
The dialysis fluid and blood have the same concentration of nutrients and ions so no useful ions are lost and only waste products can diffuse into the fluid.
What’s the male and female reproductive hormones?
Male: Testes which makes testosterone
Female: Ovaries which make oestrogen
What are the 4 hormones that control the menstrual cycle and where are they produced?
FSH: causes an egg to mature every 28 days and is produced in the pituitary gland
LH: stimulates the egg’s release and is produced in the pituitary gland
Oestrogen and Progesterone maintains the uterus’ lining and are both produced in the ovaries
What are the stages of the menstrual cycle?
Stage 1: period - the uterus lining breaks down
Stage 2: the uterus lining thickens
Stage 3: An egg develops and leaves the ovary
Stage 4: If the egg isn’t fertilised, then the cycle starts again.
What are contraceptions and what are the advantages and the disadvantages?
The pill: a pill taken to stop the egg from maturing A - easy D - forgetfulness and side effects. The patch, the infection and the implant: stop eggs maturing and releasing from the ovary A: last longer D: needs replacement Spermicides: kills sperm A: readily available D: not effective Barrier Methods (eg. condoms): A: no side effects D: can break and need to be fitted properly IUD: prevent early embryos from developing A: effective and long lasting D: uncomfortable Surgery (eg. tubes tied) A: permanent D: requires anaesthetic Abstinence: A: no side effects D: risky
What factors cause infertility?
Low sperm count
Faulty oviducts
Age
Obesity/ Anorexia
What is the process of IVF
Patient is given fertility drugs
The eggs are then extracted for fertilisation and is mixed with sperm.
Then the eggs are placed back in the uterus.
What’s auxin and where is it produced?
A plant hormone controlling growth and is produced in the tips
What happens when the shoot tip is exposed to the light?
Auxin accumulates on the shaded area so the shoot grows and bends towards the light.
What direction do shoots and roots grow due to gravity?
Shoots: upwards, away from gravity
Roots: downwards, towards gravity
How do you investigate plant growth towards light?
Put 10 cress seeds on each of 3 petri dishes with moist filler paper and shine a light at it at different directions and then leave it there for a week and find the results.
What are the uses of auxin?
Killing weeds
Growing from root powder
Growing cells in tissue culture
What are used of gibberellin?
Growing dormancy
Growing larger fruit
Inducing flowering
What are the uses of ethene?
Stimulates the ripening of fruit
