Topic B5- Homeostasis and Response Flashcards
What is homeostasis?
Maintaining a stable internal environment
What are three main components, which work together to maintain a steady condition in the body?
Receptors, CNS and effectors
Explain the three steps of negative feedback, when the level of something in the body gets too high?
1) receptor detects a stimulus - level is too high
2) the coordination centre receives and processes the information, then organises a response.
3) effector produces a response which counteracts the change and restores the optimum level -the level decreases.
What is a stimulus?
A change in the environment
What does the central nervous system consist of in vertebrates?
The Brain and spinal cord
What are the receptors?
The cells that detect stimuli
What do the sensory neurons do in the body?
Carry information as electrical impulses from the receptors to the CNS
What do the motor neurons do in the body?
Carry electrical impulses from the CNS to effectors
What are the effectors?
All the muscles and glands, which respond to nervous impulses
How do muscles and glands respond to nervous impulses?
Muscles contract, whereas glands secrete hormones
What does the central nervous system do with the information from the receptors?
Coordinates a response
What is the synapse?
The connection between two neurons. The nerve signal is transferred by chemicals which diffuse across the gap.
What are reflexes?
Rapid and automatic responses to certain stimuli that don’t involve the conscious part of the brain-they can reduce the chances of being injured
What is a reflex arc?
The passage of information in a reflex from receptor to effector
What are the four steps of the reaction time practical?
1) Person being tested to sit with the arm resting on the edge of a table. Make sure that the zero and the ruler are level with a thumb and finger, then let go without giving any warning.
2) Person being tested should try to catch the room as quickly as we can.
3) Reaction time is measured by the number on the ruler where it’s caught. The further down the ruler is caught, the slower their reaction time.
4) Repeat the test several times and calculate the mean distance that the ruler fell.
The person being tested should have a caffeinated drink after 10 minutes, repeat steps 1 to 5.
What does the liver and muscles do with excess glucose?
Stores it as glycogen
What is added when the blood glucose level is too high?
Insulin secreted by pancreas
What is added when the blood glucose level is too low?
Glucagon secreted by pancreas
How can type 1 diabetes be controlled?
Several injections of insulin throughout the day,most likely at mealtime
How can type 2 diabetes be controlled?
By eating a carbohydrate-controlled diet and getting regular exercise
What are the four stages of the menstrual cycle?
1) The uterus lining breaks down for about four days
2) The uterus lining builds up again, from day 4 to day 14
3) An egg develops and is released from the ovary at day 14
4) The wall is then maintained until day 28
What does oestrogen and progesterone do?
Oestrogen- causes the lining of the uterus to grow
Progesterone- Maintains the lining of the uterus during the second half of the cycle
What does FSH and LH do?(produced in pituitary gland)
FSH- Causes an egg to mature
LH- Stimulates the release of an egg at day 14
