Homeostasis and Response Flashcards
What is homeostasis?
The regulation of the internal conditions of a cell or organism in response to internal and external changes.
What does homeostasis control?
Blood glucose concentration.
Body temperature.
Water and Ion levels.
Nervous and chemical (hormonal) responses.
What do control systems include?
Receptors (detect stimuli).
Coordination centres.
Effectors (responders).
What are examples of coordination centres?
Brain, spinal cord, pancreas.
What are examples of effectors?
Muscles, glands.
What is negative feedback?
A control mechanism where upon a receptor detecting a change in stimulus, the coordinating centre compares the stimulus to a set point, then causes the effector to produce a response to correct any difference from the set point.
Basically, maintains amounts of things in the body. Like blood sugar.
What is the central nervous system (CNS)?
The brain and spinal cord.
What is the purpose of the CNS?
Coordinates the response of effectors.
Describe a reflex arc.
Receptors detect stimuli. Sensory neurone carries impulse to CNS. Impulse passes through relay neurone. Motor neurone carries impulse to receptor. Effector responds.
In what order, in the reflex arc, do neurones appear?
Sensory, relay, motor.
How do neurones communicate?
Synapses.
How do electrical impulses travel?
Through the neurones: once it reaches the synapse, a chemical is released which diffuses across the gap between the two neurones, which causes the electrical impulse to be generated in the second neurone.
What is the endocrine system?
Made up of glands which secrete hormones directly into the blood.
What are hormones?
Chemical messengers, carried in the blood, which target an organ where they produce an effect.
What is the pituitary gland?
The ‘master gland’ which secrete hormones in response to body conditions.