Homostasis Flashcards
What does homeostasis control
Blood glucose concentration
Body temp
Water levels
What do all control systems have
Receptor- cells that detect stimuli
Coordination centres-proceses the information received from the receptors
Effectors-bring about responces to to bring the conditions in body back to optimum
Procces of the nervous system
Receptor cells convert a stimulus into an electrical impulse.
2. This electrical impulse travels along cells called sensory neurons to the central nervous system (CNS).
3. Here, the information is processed and the appropriate response is coordinated, resulting in an electrical impulse being sent along motor neurones to effectors.
4. The effectors carry out the response
Path of a reflex arc
A stimulus is detected by receptors.
2. Impulses are sent along a sensory neuron.
3. In the CNS the impulse passes to a relay neuron.
4. Impulses are sent along a motor neuron.
The impulse reaches an effector resulting in the appropriate response.
Properties of synapses
Synapses are the gaps between two neurons.
• When the impulse reaches the end of the first neuron, a chemical is released into the synapse.
• This chemical diffuses across the synapse.
• When the chemical reaches the second neuron, it triggers the impulse to begin again in the next neuron.
What is a reaction time
reaction time is how long it takes you to respond to a stimulus.
What are all the glands
Pituitary gland
The master gland
• Secretes hormones into the blood to either have an effect on the body or act on other glands to stimulate them to produce different hormones
• Pancreas
• Secretes insulin
• Controls blood glucose levels
• Thyroid
• Secretes thyroxine
• Controls metabolic rate, heart rate and temperature
• Adrenal gland
• Secretes adrenaline
• Involved in the ‘fight or flight response (the body’s response to stressful situations)
• Ovary
• Secretes ostrogen
• Is involved in the menstrual cycle and the development of female secondary sexual characteristics (different features that develop during puberty that distinguish a female from a male)
• Testes
• Secretes testosterone
• Is involved in the production of sperm and the development of male secondary sexual characteristics
How are hormones transported to the areas
The blood transports the hormone to a target organ or tissue where it has an effect.
What happens if you eat to much glucose
• If the glucose levels are too high, the pancreas produces the hormone insulin
• Insulin binds to cell in target organs (muscles and liver) causing:
• 1) Glucose to move from the blood into muscle cells for respiration
• 2) Excess glucose to be converted into glycogen which is stored in the liver
• The blood glucose concentration is reduced
What happens when you exersize
• If glucose levels decrease, the pancreas produces the hormone glucagon
• Glucagon binds to to the liver cells causing glycogen to be broken down into glucose
Glucose is released into the blood, increasing the blood glucose concentration
How is blood glucose kept constant in a negative feedback loop
• When blood glucose levels increase/decrease, a hormone is secreted to oppose the change.
• The action of this hormone cannot occur continually because when the blood arrives at a certain glucose concentration the other hormone is produced, resulting in the opposite effect.
Type 1 diabetes
Type 1 diabetes: the pancreas cannot produce enough insulin
• Blood glucose level can rise to a fatal amount
• Glucose is excreted with urine and lots of urine is produced leaving the individual very thirsty
• It is treated with insulin injections at meal times, which results in glucose being taken up from the bloodstream
• It is also advised to limit the intake of simple carbohydrates which contain lots of glucose
• Doctors are attempting to cure diabetes with pancreas and pancreatic cell transplants, and genetically engineering pancreatic cells from mice to make insulin
Type 2 diabetes.
Type 2 diabetes: the body cells no longer respond to insulin
• Blood glucose levels can rise to a fatal amount
• Obesity is a risk factor for this disease
• Treatments include reducing the number of simple carbohydrates in diet, losing weight and increasing exercise
• There are also drugs to make insulin more effective on body cells, help the pancreas make more insulin or reduce the amount of glucose absorbed from the gut
Properties of testosterone and oestrogen
The main male reproductive hormone is testosterone.
• Produced by the testes
Stimulates sperm production
The main female reproductive hormone is estrogen.
• Produced in the ovary
• Produces physical changes and is involved in the menstrual cycle
All 4 hormones in the menstrel cycle
Follicle stimulating hormone (FSH) causes the maturation of an egg in the ovary, within a structure called a follicle
Produced in the pituitary gland
Stimulates the ovaries to produce estrogen
2. Oestrogen causes the lining of the uterus to grow again
• Produced in the ovaries
Secreted as a result of FSH
• Stimulates the production of LH and inhibits the secretion of more
FSH
3. Luteinising hormone (LH)
• Produced in the pituitary gland
• Produced as a result of the hormone estrogen
• Its release results in ovulation
4. Progesterone
• Produced in the ovaries and secreted from the egg follicle.
• Maintains the lining of the uterus, and supports a pregnancy if the egg is fertilised
• Inhibits the release of both FSH and LH
