Biology Paper 2: Homeostasis And Response Flashcards
Why do cells carry out respiration?
To release energy from glucose- uses enzymes
What do enzymes need in order to work?
Very stable conditions- enzymes cannot work well if the conditions around them change to much
What is homeostasis?
The regulation of internal conditions of a cell or organism to maintain optimum enzyme and cell function
How is homeostasis used in the human body?
To keep the blood glucose concentration, the body temperature and water levels constant
What does homeostasis consist of?
Automatic control systems making sure that the internal conditions of the body stay as constant as possible
What can the automatic control systems in the human body involve?
The nervous system or endocrine system
What do receptors do?
Detect changes in environment (the stimulus)
What does the coordination centre do and what parts of the body does it involve?
.Receives and processes the information from receptor cells
.includes the brain, spinal cord and pancreas
What do the effectors do and what parts of the body are involved?
.Carries out a response
.muscles or glands
What does the nervous system consist of?
The CNS and other nerves running to and from the nervous system
What does the CNS consist of?
The brain and spinal cord
What is the key role of the nervous system?
Enables humans to react to their surroundings and coordinate behaviour, which is done from the reflex arc
What happens when we touch a hot object?
.first the stimulus is detected by a receptor (in this case the receptor is the skin
.electrical impulses now pass along a sensory neurone to CNS
.at the end of the sensory neurone is a junction called a synapse, a chemical is released and this chemical diffuses across to a relay neurone in the CNS, where it triggers an electrical impulse
.The electrical impulse now passes along the relay neurone and reaches another synapse and a chemical is released again
.this chemical triggers an electrical impulse in a motor neurone
.the electrical impulse now passes down the motor neurone to an effector (in this case the effector is a muscle)
.the muscle now contracts and pulls the hand away from the heat
.pulling the hand away from the heat is the response
What do reflexes do?
Because they are rapid, reflexes help protect us from danger
What is the process for the reaction time required practical?
.person 1 sits on a still with good posture
.person 1 then places their forearm of their dominant arm across the table, with their hand overhanging the edge
.now person 2 holds a ruler vertically
.The 0cm mark should be between person 1s thumb and first finger
.person 2 then drops the ruler at a random time
.person 1 has to catch the ruler with their thumb and first finger as quickly as possible
.person 2 now records the measurement on the ruler that is level with the top of person 1s thumb
.test is repeated multiple times and a mean is calculated
.From these experiments, we can convert our results to a reaction time using a conversion table
.At the end the two people switch places to see the different reaction times
What is the independent variable (changed) for reaction time require practical?
.person having their reaction time tested
What is the dependent variable (measured) in three reaction time required practical?
Reaction time
What are the three control variables (stay the same) in the reaction time required practical?
Starting distance between thumb and finger should be kept constant
.always measure the ruler at the top of the sun
.keep conditions on the room the same
What happens if we allow any of our control variables to change?
It will affect our reaction time
other variables that could affect reaction time:
.practice- the more someone does the experiment the better they could become at it
.trying the experiment with a different hand
What is the body controlled by?
Chemicals called hormones- endocrine system
What does the endocrine system consist of?
Glands that secrete hormones directly into the bloodstream
How are hormones carried through the body
Through the bloodstream
.nervous system uses electrical impulses which travel neurones
.endocrine system uses hormones which are chemicals that are carried in the bloodstream
.signalling in the nervous system is very fast whereas the endocrine system has a slower more long lasting effect
