Homeostasis and Response Flashcards
Define Homeostasis.
Homeostasis is the regulation of internal conditions
What does Homeostasis regulate?
- Internal temperature
-Blood glucose concentration
-Water levels
What are the 5 components of the Nervous System?
- Stimulus - a change in an organism’s environment
- Receptors - detects change and converts stimulus into electrical signals in nerve cells
- Coordination centre - receives and procceses electrical impulses from receptors
- Effectors - bring about responses to the stimulus
- Response - could be a muscular contraction or release of a hormone (glands)
Name the 3 neurones and their functions.
Sensory neurones - carry electrical impulses from receptor to coordination centre
Relay neurones - carry electrical impulses within the coordination centre
Motor neurones - carry electrical impulses from coordination centre to effector
What is a synapse?
A junction between two neurones across which electrical signals pass.
The human body has 500 trillion
What is a reflex?
They are rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain.
In the reflex arc the signal bypasses the brain - much quicker
Describe the reaction time practical.
- Drop ruler between finger and thumb
- Measure distance fallen before caught, repeat, calculate mean
- Independant variable:
Stimulant (e.g. energy drink) increases neurotransmission
Depressant (e.g. alcohol) decrease neurotransmission
What is the Endocrine System?
A system of glands that secrete hormones to send signals to effectors, transported via blood (slower than nervous system)
What does the pituitary gland (master gland) produce?
Produces hormones in response to stimuli that travel to other glands in the body in order for them to start producing certain chemicals
What hormones does the pancreas produce?
Secrets insulin (and glucagon) to control blood sugar
What does the thyroid gland do?
Controls growth, metabolism and more
What do the adrenal glands produce?
Release adrenaline
What do the ovaries and testes do?
Ovaries - release eggs and secrete hormones
Testes - produce sperm
What happens when your blood glucose levels are too high?
1 - Pancreas detects high blood glucose.
2 - Pancreas releases insulin.
3 - Insulin stimulates cells to absorb glucose from the blood.
4 - The liver and muscle cells convert glucose to glycogen for storage.
5 - Blood glucose level decreases.
What happens when your blood glucose levels are too low
1 - Pancreas detects low blood glucose.
2 - Pancreas releases glucagon.
3 - Glucagon tells liver to convert glycogen into glucose.
4 - Glucose diffuses into the blood.
5 - Blood glucose level increases.
Describe Type I and Type II Diabetes.
Type I:
Pancreas can’t produce (enough) insulin - injections are needed
Type II:
Cells don’t absorb glucose as they should - Obesity increases risk of developing
Describe the menstrual cycle.
- FSH (from pituitary gland in the brain) - Causes an egg to mature in the ovary. Stimulates the ovary to produce oestrogen.
- Oestrogen (from ovaries) - Thickens the uterus lining (gets it ready for a fertilised egg). Inhibits FSH (so only one egg matures). Stimulates LH release.
- LH (Pituitary gland) - Triggers ovulation (the release of a mature egg from the ovary).
- Progesterone (Ovaries) - Maintains the uterus lining (so it’s ready for a fertilised egg).
Inhibits FSH and LH (stops more eggs from being released).
When progesterone levels drop, the lining breaks down → period starts.
What does adrenaline do?
Increases blood flow and breathing rate, to prepare you for fight or flight
What does thyroxine do?
Released from thyroid gland
- Controls metabolic rate
What happens when your thyroxine is too low?
Hypothalamus in brain releases TRH which causes pituitary gland to release TSH which causes thyroid to release more thyroxine
