A2 Biology Unit 4 Module 1 Communication and Homeostasis definitions

Definition flashcards, gives names for different synapse functions and summations that are not given in the textbook. Reasonably Hard.

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A change in behaviour or physiology as a result of a change in the environment.
A Response
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The hormone, released from the pancreas, that causes blood glucose levels to go down.
Insulin
2 of 60
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
Negative feedback
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An organism that relies on external sources of heat to regulate its body temperature.
An Ectotherm
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The maintenance of the internal environment in a constant state despite external changes.
Homeostasis
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One presynaptic neurone might diverge to several postsynaptic neurones. This allows signals to be transmitted to several parts of the nervous system, useful in a reflex arc.
Multifunction
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A membrane that has a potential difference across it. This is the resting potential.
A Polarised Membrane
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Carry the action potential from a sensory receptor to the central nervous system.
Sensory neurone
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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.
Depolarisation
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A change in the environment that causes a response.
A Stimulus
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Carry an action potential from the central nervous system to an effector.
Motor Neurone
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It is achieved when the membrane is depolarised to a value of about +40mV. It is an all-or-nothing response. Only ever goes in one direction.
An Action Potential
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Molecules that are released by endocrine glands directly into the blood. They act as messengers, carrying a signal from the endocrine gland to a specific target organ or tissue.
Hormones
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The movement 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.
Local Currents
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The hormone, released from the pancreas, that causes blood glucose levels to rise.
Glucagon
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A chemical that diffuses across the cleft of the synapse to transmit a signal to the postsynaptic neurone.
A neurotransmitter
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A swelling at the end of the presynaptic neurone.
The Synaptic knob
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It refers to the way that the action potential appears to jump from one Node of Ranvier to the next.
Saltatory conduction (means "jumping conduction")
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An organism that can use internal sources of heat, such as heat generated from metabolism in the liver, to maintain its body temperature.
An Endotherm
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An enzyme in the synaptic cleft. It breaks down the transmitter subatance acetylcholine.
Acetylcholinesterase
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The potential difference across the neurone cell membrane while the neurone is at rest. It is about -60mV inside the cell compared with the outside.
Resting Potential
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Refers to the fact that a neurone either conducts an action potential or does not. All action potentials are of the same magnitude, +40mV.
All-or-nothing
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A term that refers to the way that several small potential changes can combine to produce one larger change in potential difference across the membrane.
Summation
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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. The gates respond to changes in the potential difference across the membrane.
Voltage-gated channels
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A muscle tissue that can initiate its own contractions, e.g. Cardiac muscle.
Myogenic
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Synapses ensure that signals are transmitted in the correct direction- only the presynaptic knob contains vesicles of acetylcholine.
Unidirectional
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A gland that secretes hormones directly into the blood. These glands have no ducts.
Endocrine Gland
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The creation of specific pathways within the nervous system is thought to be the basis of conscious thought and memory.
Memory Formation
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A gland that secretes molecules into a duct that carries the molecules to where they are used.
Exocrine Gland
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Cells that possess a specific receptor on their plasma membrane. The shape of the receptor is complementary to the shape of the hormone molecule.
Target Cells (grouped to form a target tissue)
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An enzyme associated with the receptor for many hormones, including adrenaline. It is found on the inside of the cell surface membrane.
Adenyl Cyclase
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Several presynaptic neurones might converge to one postsynaptic neurone. This allows signals from different parts of the nervous system to create the same response.
Spatial Summation
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A small depolarisation caused by sodium ions entering the cell.
A Generator Potential
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Transmits a signal inside the cell, e.g. cAMP
The second messenger
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After repeated stimulation a synapse may run out of vesicle containing the neurotransmitter. The synapse is said to be fatigued, hence the nervous system no longer responds to the stimulus. This is why we can get used to a smell etc.
Acclimatisation
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A low-level stimulus can generate several successive action potentials in the presynaptic neurone, the release of many vesicles of acetylcholine over a short period of time can combine to produce an action potential.
Temporal Summation
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A process that increases any change detected by the receptors. It tends to be harmful and does not lead to homeostasis.
Positive feedback
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Small patches of tissue in the pancreas that have an endocrine function.
The islets of Langerhans
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A disease in which blood glucose cannot be controlled effectively.
Diabetes Mellitus
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Secrete the hormone glucagon. Found in the islets of Langerhans.
a cells (alpha)
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Connect sensory and motor neurones.
Relay neurone
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Liver cells. They are specialised to perform a range of metabolic functions.
Hepatocytes
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Secrete the hormone insulin. Found in the islets of Langerhans.
B cells (Beta)
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The state in which the blood glucose concentration is too high.
Hyperglycaemia
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A synapse that uses acetylcholine as its transmitter substance.
Cholinergenic synapse
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If a low-level stimulus creates an action potential in the presynaptic neurone it is unlikely to pass across the synapse to the next neurone because several vesicles of acetylcholine must be released to create an action potential in the next neurone.
Habituation
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Bacteria in which the DNA has been altered.
Genetically Engineered Bacteria
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The state in which the blood glucose concentration is too low.
Hypoglycaemia
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Unspecialised cells that have the potential to develop into any type of cell.
Stem Cells
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Insulin-dependent diabetes.
Type 1 diabetes
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The result of all the chemical reactions taking place in the cytoplasm.
Cell Metabolism
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A region of tissue in the right atrium wall that can generate an impulse and initiates the contractions of the chambers.
Pacemaker
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A nerve that causes a decrease in heart rate, runs from the medulla oblongata to the heart.
Vagus nerve
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A specific region of the medulla oblongata that receives sensory inputs about levels of physical activity, blood carbon dioxide concentration and blood pressure. It sends nerve impulses to the SAN to alter the frequency of excitation waves.
The Cardiovascular centre
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Insulin -independent diabetes
Type 2 diabetes
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A tube that collects all the secretions from the exocrine cells in the pancreas and carries the fluid to the small intestine
The Pancreatic Duct
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A nerve that causes an increase in heart rate, runs from the medulla oblongata to the heart.
Accelerator nerve
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Found at the base of the brain, it is the region of the brain that coordinates the unconscious functions of the body such as breathing rate and heart rate.
Medulla Oblongata
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The hormone that transmits a signal around the body.
The first messenger
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A potential difference across the membrane of about -50mV. If the depolarisation of the membrane does not reach this value then no action potential is created. If this value of is reached, then an action potential is created.
The Threshold potential
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Other cards in this set

Card 2

Front

The hormone, released from the pancreas, that causes blood glucose levels to go down.

Back

Insulin

Card 3

Front

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

Back

Preview of the front of card 3

Card 4

Front

An organism that relies on external sources of heat to regulate its body temperature.

Back

Preview of the front of card 4

Card 5

Front

The maintenance of the internal environment in a constant state despite external changes.

Back

Preview of the front of card 5
View more cards

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