Homeostasis & Stimuli
What is homeostasis?
This is the process of maintaining a stable internal environment despite changes inside or outside the body.
The organ that acts as the body's command centre is the ______.
Brain
What is negative feedback?
Returns the body to its normal set point (counteracts the stimulus)
During exercise, your HR increases to deliver more ____ to the working muscles.
Oxygen
What is Alzheimer's disease?
This disease damages the brain and causes memory loss over time.
What is a stimulus?
A change in the internal or external environment that causes an organism to respond.
This part of the Nervous System carries messages between the brain and the rest of the body.
Spinal cord.
What is an example of negative feedback?
Sweating on a hot day. Blood sugar control (insulin lowers high glucose). Heart rate slows down when pressure is too high (blood pressure regulation). Muscles shiver on a cold day.
Name two body responses that help cool you during exercise.
Sweating and vasodilation (widening of blood vessels)
What is Motor Neuron Disease (MND)?
This disorder causes motor neurons to gradually stop working, leading to progressive muscle weakness and loss of movement.
Name the three parts of a stimulus-response pathway in order
Receptor -> control centre -> effector
Put these in order: sensory neuron, receptor, motor neuron, effector, interneuron.
Receptor → Sensory neuron → Interneuron → Motor neuron → Effector.
What is an example of positive feedback?
Childbirth because contractions become stronger until birth occurs
During exercise, muscles produce more ____ that must be removed.
Carbon dioxide.
What is Multiple Sclerosis (MS)?
This disorder occurs when the immune system attacks the protective covering (myelin) of nerve fibres in the central nervous system.
Your skin feels cold and you begin shivering. Identify the stimulus and the response
Stimulus = drop in body temperature; Response = muscles contract (shivering) to generate heat.
Why is a reflex action faster than a voluntary response?
Because the signal is processed in the spinal cord before reaching the brain, allowing a rapid response.
Explain one difference between positive and negative feedback loops.
Negative feedback reverses a change to restore balance; positive feedback amplifies a change until an event is complete.
Explain how homeostasis helps keep body temperature stable during intense exercise.
The hypothalamus detects increased temperature and triggers sweating and vasodilation to cool the body and return temperature to normal.
List the components of a motor neuron.
Dendrites, cell body (soma), nucleus, axon, myelin sheath, nodes of Ranvier, axon terminals.