Homeostasis and Response Flashcards
What is homeostasis?
The maintenance of a constant internal environment.
What is a receptor?
A specialised cell which creates an electrical impulse when stimulated.
What is a reflex action?
An automatic action, doesn’t involve thought.
What is the purpose of reflex actions?
To protect from danger.
What is a synapse?
A gap between two neurons.
How do electrical impulses move across synapses?
The impulse stimulates the release of a chemical which diffuses across the gap, then converted back into an electrical impulse.
What happens in a reflex arc?
- Receptor detects stimulus
- Impulse travels through sensory neuron
- Relay neuron
- Motor neuron
- Response is carried out by effector
What is a gland?
An organ that releases a chemical
(hormone/enzyme)
What is the effect of insulin?
Glucose in converted to glycogen which is then stored in the liver and muscles.
What is the effect of glucagon?
Causes glycogen stored in the liver to converted into glucose and released into the blood stream.
What is the cause of type 1 diabetes?
The pancreas stopping insulin and glucagon production.
What is the cause of type 2 diabetes?
Cells becoming resistant to insulin as a result of obesity, poor diet, or lack of exercise.
What 4 hormones control the menstrual cycle?
- FSH (Follicle Stimulating Hormone)
- Oestrogen
- LH (Luteinizing Hormone)
- Progesterone
Where is FSH produced?
Pituitary gland.
Where is oestrogen produced?
Ovaries.
Where is LH produced?
Pituitary gland.
Where is progesterone produced?
Egg follicle.
What is the role of FSH?
Stimulates the egg to mature in the ovary.
What is the role of oestrogen?
Stimulates the uterus lining to thicken.
What is the role of LH?
Stimulates ovulation.
What is the role of progesterone?
Maintains the uterus lining.
Why do contraceptives contain oestrogen?
It inhibits FSH.
What hormones are used in contraceptives?
Oestrogen and progesterone.
How does an IUD work?
- Releases progesterone
- Contains copper (kills sperm)
What are the 3 stages of IVF?
- Artificial FSH causes lots of eggs to mature
- Eggs are fertilised in the lab
- Embryos are then implanted into the uterus
Where is adrenaline produced?
In the adrenal gland.
What is the effect of adrenaline?
- Increased heart and breathing rate
- Glycogen converted to glucose (in liver)
- Pupils dilate
- Mental awareness increases
- Blood is diverted form digestive system
What does thyroxine control?
Base metabolic rate
- The rate that substances are built up and broken down
- Level of oxygen used by tissues
- Development of children’s brains
How are thyroxine levels controlled?
Changes in thyroxine levels are detected by the brain, and the appropriate level of TSH is released from the pituitary gland.
