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39 Cards in this Set
- Front
- Back
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stimulus |
A stimulus is any change in the environment that causes a response |
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response |
A response in a change in behaviour or physiology as a result of a change in the environment |
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excrete |
The removal of waste products from the body so that there is not an accumulation in the blood |
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epithelial |
surface/skin any animal tissue that covers a surface, or lines a cavity |
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metabolic |
Cellular activites that use up substances and produce products |
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substrate |
the substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate(s). In the case of a single substrate, the substrate bonds with the enzyme active site, and an enzyme-substrate complex is formed. |
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hormone |
a signal released from an endocrine organ |
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enzyme |
biological catalysts - catalysts are substances that increase the rate of chemical reactions without being used up. Enzymes are also proteins that are folded into complex shapes that allow smaller molecules to fit into them. The place where these substrate molecules fit is called the active site. |
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homeostasis |
Is the maintenance of the internal environment in a constant state despite external changes 1. maintenance of internal environment 2. constant 3. despite changes |
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negative feedback |
Is a process that brings about a reversal of any change in conditions. It ensures that an optimum steady state can be maintained, as the internal environment is returned to its original set of conditions after any change. It is essential for homeostasis. |
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positive feedback |
Is less common than negative feedback. When positive feedback occurs thae response is to incease the original change. Destabilising the system and is usually harmful. |
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oxytocin |
a hormone which increases uterine contractions, which stretches the cervix more. This causes more oxytocin to be released |
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stress response |
- usually involves the release of adrenaline -it has a wide range of target organs - prepares the body for activity - fight or flight - women also release oxytocin (tend and protect) - children are then also considered |
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ectotherm |
An ectotherm is an organism that relies on external sources of heat to regulate its body temperture DO NOT SAY THAT THEY ARE COLD-BLOODED some maintain high body temperatures |
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endotherm |
Endotherms can maintain the temperature of their body within fairly strict limits. They are largely independent of the external temperature. DO NOT SAY THAT THEY ARE WARM-BLOODED |
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light-senstitive cells |
rods and cones in the retina of the eye energy changes detected = light intensity and range of wavelengths (colour) |
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olfactory |
cells lining the inner surface in the nasal cavity energy changes detected = presence of volatile chemicals |
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taste buds |
In the tongue, hard palate, epiglottis and start of oesophagus energy changes detected = presence of soluble chemicals |
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Pacinian corpuscles |
pressure receptors on the skin energy changes detected = pressure on the skin |
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Cochlea |
sound receptors in the inner ear energy changes detected = vibrations in air |
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Proprioceptors |
found in muscle spindles energy changes detected = length of muscle fibres |
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polarised |
a polarised membrane is one that has a potential difference across it. This is the resting potential |
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depolarisation |
Is the loss of polarisation across the membrane. It refers to the period when sodium ions are entering the cell making the inside less negative with respect to the outside. |
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generator potential |
a small change in potential caused by one or two sodium ion channels opening is called a generator potential. is a small depolarisation caused by sodium ions entering the cell. |
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action potential |
An action potential is acheived when the membrane is depolarised to a value of about +40mV. It is an all-or-nothing response. In the events leading up to an action potential, the membrane depolarises and reaches a threshold level, then lots of sodium ions enter the axon and an action potential is reached. Depolarisation of the cell membrane so that the inside is more positive that the outside, with a potential difference across the membrane of +40mV. This can be transmitted along the axon or dendron plasma membrane. |
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sensory neurone |
Sensory neurones carry the action potential from a sensory receptor to the CNS |
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motorneurone |
Motor neurones carry an action potential from the CNS to an effector such as a muscle or gland |
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relay neurones |
connect sensory and motor neurones |
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resting potential |
is the potential difference or voltage across the neurone cell membrane while the neurone is at rest. IT IS ABOUT -60mV inside the cell compared with the outside. |
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voltage-gated channels |
are channels in the cell membrane that allow the passage of charged particles or ions. they have a mechanism called a gate which can open and close the channel. In these channels the gates respond to changes in the potential difference across the membrane. |
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threshold potential |
is the potential difference across the membrane OF ABOUT -50mV. If the depolarisation of the membrane does not reach the threshold potential then no action potential is created. |
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refractory period |
For a short period of time after each action potential it is impossible to stimulate the cell membrane to reach another action potential. It allows the cell to recover after an action potential. |
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local currents |
local currents are the movements of ions along the neurone. The flow of ions is caused by an increase in concentration at one point, which causes diffusion away from the region of higher concentration. |
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myelin sheath |
is an insulating layer of fatty material sodium and potassium ions cannot diffuse through this fatty layer action potentials are faster as a result of jumping between the node of Ranvier |
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saltatory |
saltatory conduction means "jumping conduction". It refers to the way that the action potential appears to jump from one node of Ranvier to the next. |
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neurotransmitter |
A neurotransmitter (transmitter substance) is a chemical that diffuses across the cleft of the synapse to transmit a signal to the postsynaptic neurone. |
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cholinergic synapses |
those that use acetylcholine as their transmitter substance |
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synaptic knob |
is a swelling at the end of the presynaptic neurone |
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post synaptic membrane |
contains specialised sodium ion channels that can respond to the transmitter substances |
