Nerves, Hormones & Homeostasis { 6 }

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Control and communication within the body involves the..

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The nervous system is built from nerve cells called __ which have a _ containing the _ and the bulk of the _ .

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Neurones are specialised for the transmission of information in the form nerve impulses.

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An _ is a _ reversal in the _ in the _ of neurone.

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In mammals the transmission of an impulse along a fibre occurs at speed between 100 -120 mps only.

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Neurones are grouped together to form a _ which consist of the _ and _ . To and from this run nerves of the _ .

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The three types of neurone are:

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Neurones have many fine _ that bring impulses toward the _ and a single long ___ which carried the impulse away from that.

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The function of the motor neurone is to carry impulses from the _ to a _ which are also known as ___ .

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One of the supporting cells that surrounds a neurone is a _ which becomes wrapped around the _ of _ neurones and form a structure called a _ .

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Myelin consists of largely _ and has a _ electrical resistance; frequent junctions also occur along the sheath between individual _ called _ .

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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.

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The resting potential is the _ across a nerve cell _ when it is _ -normally about _ .

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When the nerve fibre has been _, we mean that the _ has been _ across the neurone _ after a nerve impulse has been transmitted.

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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.

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The active transport of _ in across the membrane & _ out occurs by a _ using energy from _ .

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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 _ .

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The _ is the potential difference produced across the _ of the nerve cell when stimulated, reversing the resting potential from from about _ to _ .

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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.

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During a _ the _ located along the membrane are ___ .

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The transfer of energy of the stimulus first _ the gates of the _ in the _ and _ _ _, down their electrochemical gradient.

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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.

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When the _ channels first open, the _ becomes more _ in comparison to the _ of the neurone.

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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 __ .

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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 _ .

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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.

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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.

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As the intensity of the stimulus increases, the frequency at which the action potentials pass along the fibre increases.

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The ___ is the link point between two neurones.

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A synapse consists of the _ of the axon of a _ and the _ of a _ .

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At the synapse neurones have direct contact.

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Between neurones there is a tiny gap called a synaptic cleft.

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Action potentials can only pass through a synaptic cleft via chemicals known as ___ .

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Transmitter substances are produced in the ___ in the synaptic knob.

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Commonly occurring transmitter substances are..

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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.

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The calcium ions cause _ of transmitter substances to fuse with the _ synaptic membrane and release transmitter substances into the ___ .

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The transmitter substance then diffuses across the synaptic cleft and binds with _ in the _-synaptic neurone membrane.

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The attachment of a transmitter molecule onto its receptor instantly opens the ion channel.

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When a molecule of ACh attaches to its receptor site, a potassium channel opens.

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As sodium ions rush in _ of the -synaptic neurone happens.

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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.

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The process of build up in pre-synaptic membranes is called fascination.

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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.

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The inactivated products from the transmitter substances re-enter the ___ and are re-synthesised into transmitter substance.

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Hormones are chemical substances produced and secreted from the cells of _ or _ ___ .

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Hormones are transported indiscriminately in the blood stream and act only at specific sites called target zones.

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Hormones are broken down in the _ and the products are excreted in the _ .

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Chapter 7, Part 6.

Nerves, Hormones & Homeostasis { 6 }

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 are specialised for the transmission of information in the form nerve impulses.

An ___ is a ___ reversal in the ___ in the ___ of neurone.

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 ___ .

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.

The function of the motor neurone is to carry impulses from the ___ to a ___ which are also known as ___ .

One of the supporting cells that surrounds a neurone is a ___ which becomes wrapped around the ___ of ___ neurones and form a structure called a ___ .

Myelin consists of largely ___ and has a ___ electrical resistance; frequent junctions also occur along the sheath between individual ___ called ___ .

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 ___ .

When the nerve fibre has been ___, we mean that the ___ has been ___ across the neurone ___ after a nerve impulse has been transmitted.

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 ___ .

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 ___ .

The ___ is the potential difference produced across the ___ of the nerve cell when stimulated, reversing the resting potential from from about ___ to ___ .

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 ___ .

The nervous system is built from nerve cells called __ which have a _ containing the _ and the bulk of the _ .

An _ is a _ reversal in the _ in the _ of neurone.

Neurones are grouped together to form a _ which consist of the _ and _ . To and from this run nerves of the _ .

Neurones have many fine _ that bring impulses toward the _ and a single long ___ which carried the impulse away from that.

The function of the motor neurone is to carry impulses from the _ to a _ which are also known as ___ .

One of the supporting cells that surrounds a neurone is a _ which becomes wrapped around the _ of _ neurones and form a structure called a _ .

Myelin consists of largely _ and has a _ electrical resistance; frequent junctions also occur along the sheath between individual _ called _ .

The resting potential is the _ across a nerve cell _ when it is _ -normally about _ .

When the nerve fibre has been _, we mean that the _ has been _ across the neurone _ after a nerve impulse has been transmitted.

The active transport of _ in across the membrane & _ out occurs by a _ using energy from _ .

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 _ .

The _ is the potential difference produced across the _ of the nerve cell when stimulated, reversing the resting potential from from about _ to _ .

During a _ the _ located along the membrane are ___ .

The transfer of energy of the stimulus first _ the gates of the _ in the _ and _ _ _, down their electrochemical gradient.

When the _ channels first open, the _ becomes more _ in comparison to the _ of the neurone.

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 __ .

A synapse consists of the _ of the axon of a _ and the _ of 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.

The calcium ions cause _ of transmitter substances to fuse with the _ synaptic membrane and release transmitter substances into the ___ .