definitions Flashcards
acquired reflex
a response to a stimulus that has been learnt through practice
axon
an extension of the cell body of a nerve cell, carries nerve impulses away from the cell body
axon terminal
the end of a branch of the axon
bipolar neuron
a neuron with two processes- one axon and one dendrite, arising from opposite sides of the cell body, these neurons are sensory, such as the neurons found in the retina of the eye
cell body
the part of a neuron that contains the nucleaus
dendrite
an extension of the body of a nerve cell, carries nerve impulses into the cell body
extracellular fluid
fluid outside the body cells, includes tissue fluid and blood plasma
innate reflex
a response to a stimulus that is acquired genetically and is therefore present at birth
interneuron
a nerve cell in the brain or spinal cord that carries messages between other nerve cells, also called association neuron, connector neuron or relay neuron
intercellular fluid
the fluid inside cells
ion
a charged atom or molecule
motor neuron
a nerve cell that carries messages from the brain or spinal cord to effector organs (muscles and glands) also called an effector neuron
multipolar neuron
a nerve cell with one axon and many dendrites, the most common type of neuron
myelin sheath
a white, fatty sheath that surrounds some nerve fibres
myelinated fibre
a nerve fibre that has a myelin sheath
nerve
a bundle of nerve fibres
nerve fibres
a projection from a nerve cell body with its associated coverings, usually refers to an axon
nerve impulse
the electrochemical change that travels along the membrane of a nerve cell, the message carried by a nerve
neuromuscular junction
the junction between branches of a motor nerve cell and a muscle fibre, also called the motor end plate
neuron
a nerve cell, the basic structural and functional unit of a nervous system
neurotransmitter
a molecule that carries a nerve impulse across the small gap between branches of adjacent nerve cells
node of Ranvier
a gap in the myelin sheath of a nerve fibre
pain receptor
a receptor that is stimulated by damage to tissue
pseudounipolar neuron
a neuron with a single process that splits into two, the cell body is to one side of the axon, in humans, such neurons are sensory and carry messages to the spinal cord
receptor
a structure that detects a stimulus
reflex
a rapid, automatic response to a change in the external or internal environment, tries to restore homoestasis
reflex arc
the pathway travelled by nerve impulses from receptor to effector in a reflex
Schwann cell
a cell that wraps around a nerve fibre, forming the myelin sheath
sense organ
receptors grouped into a discrete organ such as the eye
sensory neuron
a nerve cell that carries messages from receptors to the brain or spinal cord, also called a receptor neuron
spinal reflex
a reflex carried out by the spinal cord without involvement of the brain
spinal reflex arc
the pathway travelled by a nerve impulse from receptors to effector in a spinal reflex
stimulus
any changes, internal or external that causes a response
synapse
the junction between the branches of adjacent neurons
threshold
the potential after which an all or none response occurs
touch receptor
a receptor sensitive to touch
unipolar neuron
a neuron with a single process, an axon does not occur in humans
unmyelinated fibre
a nerve fibre that has no myelin sheath
homeostasis
the maintenance of a relatively constant internal environment despite fluctuations in the external environment
glycogenesis
the process whereby glucose molecules are chemically combined in long chains to form glycogen molecules
glycogenolysis
the process of converting glycogen back to glucose
gluconeogenesis
the process of producing glucose molecules from lipids and amino acids
herd immunity
a type of group immunity that occurs when such a high proportion of people in a population are immunised that those who are not immune are protected
thermoregulation
the regulation of body temperature, the balance of heat gain and heat loss in order to maintain a constant internal body temperature independent of the environmental temperature.
metabolic rate
the rate at which energy is released to the body by the breakdown of food
what are plasma cells
a cell that develops from B-cell and produces antibodies
