B5 Flashcards
What is the nervous system?
The nervous system protects organisms from harm by responding to changes in the environment.
This is achieved by coordinating communication between different parts of organisms.
The components of the nervous system are:
Brain
Spinal cord
Neurones (nerve cells) - Neurones carry electrical impulses (signals) between receptors, the CNS and effectors.
What is CNS?
The brain and spinal cord are part of the central nervous system (CNS).
The CNS coordinates the response of effectors. Effectors are muscles or glands that act in response to a change in the internal or external environment.
what are Synapses?
Synapses are gaps between neurones.
When an electrical impulse reaches the end of a neurone, a chemical called a neurotransmitter is released into the synapse. Neurotransmitters diffuse (move down a concentration gradient) across the synapse and bind to receptors on the next neurone.Reflex actions allow us to respond to dangerous situations rapidly and automatically, without conscious thought.
Examples include blinking and sneezing.
The nervous system responds to stimuli (events or things) via a reflex arc. A reflex arc consists of:
Stimulus → Receptor → Neurones → Effector → Response
What is A stimulus?
A stimulus is any change in the environment to which the body needs to respond. Stimuli are detected by receptors. They initiate the signalling process in the body. The signal is picked up by a neuron.
There are three types of neurones:
Sensory neurone - carries the electrical impulse from receptor to the CNS.
Relay neurone in the CNS - relays the electrical impulse from the sensory neurone to the motor neurone.
Motor neurone - carries the electrical impulse from the CNS to an effector.
What are Effectors?
Effectors bring about a response. A response that is a reflex can be any action that helps the organism to avoid the harmful situation.
Why is glucose essential for life?
Glucose is essential for life because it is used in respiration to release energy that can be used by organisms. This means it is important for an individual to keep its blood glucose levels within a small, optimal range. If blood glucose levels are too low, there is insufficient glucose for respiration.
If there is not enough glucose, an organism cannot produce enough energy.If blood glucose levels are too high, the concentration of water in the bloodstream will decrease.
This can have a negative impact on an organism because excess water will diffuse out from the cells, causing them to shrink.
how does your the body respond to an increase in blood glucose levels?
The body responds to an increase in blood glucose levels by releasing a hormone called insulin. If the blood glucose levels are too high, insulin is released from the pancreas. The liver and muscle tissues detect the presence of insulin and convert the excess glucose into glycogen to reduce the blood glucose levels.
