Control and communication within the body involves the..
The nervous system is built from nerve cells called ____ which have a ___ containing the ___ and the bulk of the ___ .
neurones | nucleus | body | cytoplasm
neurones | body | nucleus | cytoplasm
neurones | body | nucleus | electrical impulses
Neurones are specialised for the transmission of information in the form nerve impulses.
An ___ is a ___ reversal in the ___ in the ___ of neurone.
impulse | momentary | electrical potential difference | membrane
impulse | permanent | electrical potential difference | cytoplasm
shock | momentary | electrical difference | membrane
In mammals the transmission of an impulse along a fibre occurs at speed between 100 -120 mps only.
Neurones are grouped together to form a ___ which consist of the ___ and ___ . To and from this run nerves of the ___ .
central nervous system | brain | spinal cord | peripheral nervous system
peripheral nervous system | heart | spinal cord | central nervous system
central nervous system | brain | rib-cage | secondary nervous system
The three types of neurone are:
Neurones have many fine ___ that bring impulses toward the ___ and a single long ___ which carried the impulse away from that.
axons | nucleus | myelin sheath
dendrites | cell body | axon
motor end plates | node of Ranvier | axon
The function of the motor neurone is to carry impulses from the ___ to a ___ which are also known as ___ .
peripheral nervous system | muscle | effectors
central nervous system | muscle | effectors
central nervous system | gland | effectors
central nervous system | muscle | sensors
One of the supporting cells that surrounds a neurone is a ___ which becomes wrapped around the ___ of ___ neurones and form a structure called a ___ .
schwann cell | axon | relay | myelin sheath
schwann cell | axon | sensory | myelin sheath
myelin sheath | axon | motor | schwann cell
Myelin consists of largely ___ and has a ___ electrical resistance; frequent junctions also occur along the sheath between individual ___ called ___ .
lipid | low | schwann cells | nodes of Ranvier
protein | high | schwann cells | nodes of Ranvier
carbon | high | schwann cells | nodes of river
lipid | high | schwann cells | nodes of Ranvier
An impulse is a momentary reversal in the electrical potential difference in the membrane - a change in the position of ___ between the inside and outside of the membrane of the nerve fibres.
The resting potential is the ___ across a nerve cell ___ when it is ___ -normally about ___ .
difference in charged ions | membrane | not being stimulated | 70mV
potential difference | membrane | not being stimulated | -70mV
potential difference | cytoplasm | being stimulated | 80mV
potential difference | membrane | being stimulated | -70mV
When the nerve fibre has been ___, we mean that the ___ has been ___ across the neurone ___ after a nerve impulse has been transmitted.
repolarised | potential difference | re-established | membrane
re-established | electrical difference | depolarised | membrane
resting | potential difference | re-established | cytoplasm
The resting potential is the product of the active transport of potassium ions in across the membrane and sodium ions out across the membrane only.
The active transport of ___ in across the membrane & ___ out occurs by a ___ using energy from ___ .
potassium ions | sodium ions | K+/Na+ pump | ATP
sodium ions | potassium ions | K+/Na+ pump | ATP
potassium ions | sodium ions | K+/Na+ pump | ADP
Facilitated diffusion of ___ out and ___ back in occurs after an impulse has passed, but since the membrane is far more permeable to ___ flowing ___ than ___ it causes the tissue fluid ___ the neurone to contain many more ___ than are present in the ___ .
potassium | sodium | potassium | back out | sodium ions flowing in | outside | positive ions | cytoplasm inside
potassium | sodium | potassium | back out | sodium ions flowing in | inside | positive ions | cytoplasm outside
sodium | potassium | sodium | back out | potassium ions flowing in | outside | positive ions | cytoplasm inside
The ___ is the potential difference produced across the ___ of the nerve cell when stimulated, reversing the resting potential from from about ___ to ___ .
resting potential | plasma membrane | 40mV | -70mV
action potential | plasma membrane | -70mV | 40mV
action potential | cytoplasm | 70mV | -40mV
An action potential is triggered by a stimulus received at a receptor cell or sensitive nerve ending. The energy of the stimulus causes a temporary and local reversal of the resting potential -brief depolarisation.
During a ___ the ___ located along the membrane are ___ .
resting potential | ion channels | closed
resting potential | globular protein channels | open
resting period | ion channels | closed
The transfer of energy of the stimulus first ___ the gates of the ___ in the ___ and ___ ___ ___, down their electrochemical gradient.
opens | sodium channels | plasma membrane | sodium ions | diffuse | in
opens | potassium channels | plasma membrane | potassium ions | diffuse | in
closes | sodium channels | plasma membrane | sodium ions | are carried across | into the cytoplasm
The electrical properties of an ion are due to its charge and its attraction to the opposite one; the chemical properties are due to concentration in the solution.
When the ___ channels first open, the ___ becomes more ___ in comparison to the ___ of the neurone.
sodium | cytoplasm | positive | outside
potassium | cytoplasm | positive | outside
sodium | outside | positive | inside
potassium | cytoplasm | negative | outside
When the charge in a neurone has been ___ an ___ has been created. It then runs the length of the neurone fibre before a ___ begins to be ____ .
re-established | action potential | resting potential | established
reversed | resting potential | action potential | re-established
reversed | action potential | resting potential | re-eestablished
After the action potential has passed, the ___ channels close and the ___ channels open, allowing ___ to exit the cell into the fluid tissue outside down their electrochemical gradient. The inside of the cell becomes less ___ again and finally the potassium channels close and the ___ potential is ___ .
potassium | sodium | potassium | negative | resting | established
sodium | potassium | potassium | positive | resting | re-established
potassium |sodium | sodium | positive | action | re-established
Following the passage of the resting potential, the neurone fibre is no longer excitable for about 5 - 10 milliseconds and this is called the refractory period.
The all or nothing principle refers to the fact that a stimulus must be at or above the minimum intensity known as the minimum threshold of stimulation, in order to initiate an action potential.
As the intensity of the stimulus increases, the frequency at which the action potentials pass along the fibre increases.
The ___ is the link point between two neurones.
Node Of Ranvier
A synapse consists of the ___ of the axon of a ___ and the ___ of a ___ .
synaptic node | pre-synaptic neurone | nucleus | post-synaptic neurone
synaptic knob | pre-synaptic neurone | cell body | post-synaptic neurone
synaptic knob | post-synaptic neurone | cell body | pre-synaptic neurone
synaptic knob | pre-synaptic neurone | dendrite | post-synaptic neurone
At the synapse neurones have direct contact.
Between neurones there is a tiny gap called a synaptic cleft.
Action potentials can only pass through a synaptic cleft via chemicals known as ___ .
Transmitter substances are produced in the ___ in the synaptic knob.
Rough Endoplasmic Reticulum
Commonly occurring transmitter substances are..
Acetyl coenzyme A
The arrival of an action potential at the synaptic knob opens up ___ channels in the ____ membrane and these ions flow in from the synaptic cleft.
sodium | post-synaptic
potassium | pre-synaptic
calcium | pre-synaptic
calcium | post-synaptic
The calcium ions cause ___ of transmitter substances to fuse with the ___ synaptic membrane and release transmitter substances into the ___ .
vesicles | pre | synaptic cleft
sacs | pre | post-synaptic neurone
vesicles | post | synaptic cleft
The transmitter substance then diffuses across the synaptic cleft and binds with ___ in the ___-synaptic neurone membrane.
transmitter proteins | post
receptor proteins | post
The attachment of a transmitter molecule onto its receptor instantly opens the ion channel.
When a molecule of ACh attaches to its receptor site, a potassium channel opens.
As sodium ions rush in ___ of the __-synaptic neurone happens.
depolarisation | post
polarisation | post
depolarisation | pre
repolarisation | pre
As more and more molecules of ACh bind to receptor site and more sodium ion channels are opened, it is increasingly likely that depolarisation will reach the threshold level and generate an action potential.
The process of build up in pre-synaptic membranes is called fascination.
After some time enzyme action inactivates transmitter substances on receptors and this causes the ion channels to close, allowing a resting potential to be re-established in the post-synaptic neurone.
The inactivated products from the transmitter substances re-enter the ___ and are re-synthesised into transmitter substance.
Hormones are chemical substances produced and secreted from the cells of ___ or ___ ___ .
ductless | exocrine | glands
ductless | endocrine | glands
ductless | endocrine | tissues
duct | endocrine | organs
Hormones are transported indiscriminately in the blood stream and act only at specific sites called target zones.
Hormones are broken down in the ___ and the products are excreted in the ___ .
liver | kidneys
liver | gut
kidneys | liver
duodenum | lungs
A Hormone circulates in the blood stream only briefly, so to be effective long-acting hormones must be secreted continuously.
A hormone released from the pancreas that regulates blood glucose is..