The School of Biomedical Sciences Wiki - User contributions [en]

Hippocampal synaptic plasticity

2018-10-18T11:17:57Z

170172349:

Hippocampal synaptic plasticity is the relationship between the neuronal memory & cellular mechanisms and synaptic plasticity of the hippocampus <ref>https://www.ncbi.nlm.nih.gov/pubmed/16678906</ref> . There are studies present which indicate that suggest hippocampal functions are important for higher cognitive function (e.g. impairment leads to cognitive problems in Huntingtons) <ref>https://www.nature.com/articles/s41467-018-06675-3</ref> . However, approaches are being brought in to help repair and improve damage to hippocampal synaptic plasticity - for example, Leptin-deficient mice have shown to have imparired hippocampal synaptic plascity. Increasing Leptin levels made long-term potentiation possible and improved the memory of the deficient mice <ref>https://www.ncbi.nlm.nih.gov/pubmed/16678906</ref> .

=== References ===

<references />

Hippocampal synaptic plasticity

2018-10-18T11:17:19Z

170172349:

Hippocampal synaptic plasticity

2018-10-18T11:16:43Z

170172349: Created page with " Hippocampal synaptic plasticity is the relationship between the neuronal memory & cellular mechanisms and synaptic plasticity of the hippocampus <ref>https://www.ncbi.n..."

Hippocampal synaptic plasticity is the relationship between the neuronal memory & cellular mechanisms and synaptic plasticity of the hippocampus
<ref>https://www.ncbi.nlm.nih.gov/pubmed/10475982</ref>
. There are studies present which indicate that suggest hippocampal functions are important for higher cognitive function (e.g. impairment leads to cognitive problems in Huntingtons)
<ref>https://www.nature.com/articles/s41467-018-06675-3</ref>
. However, approaches are being brought in to help repair and improve damage to hippocampal synaptic plasticity - for example, Leptin-deficient mice have shown to have imparired hippocampal synaptic plascity. Increasing Leptin levels made long-term potentiation possible and improved the memory of the deficient mice
<ref>https://www.ncbi.nlm.nih.gov/pubmed/16678906</ref>
.

Muscle contraction

2017-12-06T12:58:10Z

170172349:

[[Voluntary movement|Voluntary]] and involuntary movements in animals are mainly by contraction of muscles, namely the [[Skeletal muscle|skeletal muscle]] (voluntary, striated and multinucleated), [[Smooth muscle|smooth muscle]] (involuntary, non-striated and uninucleated) and [[Cardiac muscle|cardiac muscle]] (involuntary, in the heart and branched).

[[Image:Muscles.jpg]]<ref>THREE TYPES OF MUSCLE TISSUE - IILyear4 [Internet]. Sites.google.com. 2017 [cited 5 December 2017]. Available from: https://sites.google.com/site/iilyear4/three-types-of-muscle-tissue</ref>

Skeletal muscle fibres are made up of many [[Myofibrils|myofibrils]], which are the basic contractile elements of the muscle cell. Myofibrils are made up of repeating units known as [[Sarcomeres|sarcomeres]], which cause [[Striated muscle|striation]] in the fibre.

Each [[Sarcomere|sarcomere]] consists of overlapping thick and thin filaments respectively known as [[Myosin|myosin]] and [[Actin|actin]]. The sliding of actin and myosin filaments changes the degree of overlap between them and causes contraction. During contraction, the sarcomere shortens considerably but the length of the actin and myosin filaments stays the same.

The stimulus impulse arrives at the neuromuscular junction (a synapse between a motor neurone and muscle cell) causing calcium voltage gated channels to open and calcium enters the synapse. The calcium causes the vesicles containing the neurotransmitter, Acetylcholine, to move towards the presynaptic membrane and fuse with the membrane by exocytosis. The Acetylcholine diffuses across the synaptic cleft and attaches to nicotinic cholinergic receptors on the post synaptic membrane. The binding of Acetylcholine to these receptors causes the membrane to be more permeable to sodium meaning that depolarisation and the creation of an action potential is more likely to occur.When an action potential is triggered in the [[Sarcoplasmic membrane|sarcoplasmic membrane]], it travels down the [[T tubules|T tubules]], activating [[Calcium channel|Ca2+ channels]] in the [[Sarcopalsmic reticulum|sarcopalsmic reticulum]]. There is an influx of Ca2+ ions in the [[Cytosol|cytosol]], which initiates the contraction of the [[Myofibrils|myofibrils]].

The actin filament has two associated proteins, [[Tropomyosin|tropomyosin]] and [[Troponin|troponin]].Tropomyosin binds along the groove of the actin helix. Troponin is trimeric and made up of [[Troponin T|troponin T]], [[Troponin I|I]] and [[Troponin C|C]]. Troponin T and I are inhibitory and bind to actin and tropomyosin, blocking the myosin binding sites on the actin molecule. Troponin C binds to Ca2+ molecules and causes troponin T and I to release their hold on actin.The tropomyosin molecule moves to reveal the myosin binding sites and the myosin heads bind and rotate using energy from [[ATP|ATP]] hydrolysis, to cause contraction<ref>Albert et al., 5th edition, Garland Science, pages 1026-1030</ref>.

However, in smooth muscle the [[Troponin|troponin]] on the actin filament is replaced by a protein called [[Calmodulin|calmodulin]]. When activated by the Ca2+ ions (4 Ca2+ per calmodulin molecule) [[Calmodulin|calmodulin]] activates "myosin light chain kinase". This [[Phosphorylation|phosphorylates]] the globular heads which in turn activates the ATPase enzymes in the globular head and thus the cross-bridge between the myosin globular head and the actin binding site can form. Myosin phosphatase stops the actin-myosin cross-bridge by [[Dephosphorylation|dephosphorylation]] of the myosin head<ref>David Sadava et al. 2006. Life: The science of Biology 8th Edition. Page-1012. Sunderland U.S.A. Sinauer Associates Inc</ref>.

=== References ===

<references />

File:Neuro junction.jpg

2017-12-06T12:55:23Z

170172349:

Muscle contraction

2017-12-06T12:52:53Z

170172349:

Muscle contraction

2017-12-05T17:08:53Z

170172349:

Voluntary and involuntary movements in animals are mainly by contraction of muscles, namely the [[Skeletal muscle|skeletal muscle]] (voluntary, striated and multinucleated), [[Smooth muscle|smooth muscle]] (involuntary, non-striated and uninucleated) and [[Cardiac muscle|cardiac muscle]] (involuntary, in the heart and branched).

[[Image:Muscles.jpg]]<ref>THREE TYPES OF MUSCLE TISSUE - IILyear4 [Internet]. Sites.google.com. 2017 [cited 5 December 2017]. Available from: https://sites.google.com/site/iilyear4/three-types-of-muscle-tissue</ref>

Skeletal muscle fibres are made up of many [[Myofibrils|myofibrils]], which are the basic contractile elements of the muscle cell. Myofibrils are made up of repeating units known as [[Sarcomeres|sarcomeres]], which cause striation in the fibre.

Each sarcomere consists of overlapping thick and thin filaments respectively known as [[Myosin|myosin]] and [[Actin|actin]]. The sliding of actin and myosin filaments changes the degree of overlap between them and causes contraction. During contraction,the sarcomere shortens considerably but the length of the actin and myosin filaments stays the same.

When an action potential is triggered in the [[Sarcoplasmic membrane|sarcoplasmic membrane]], it travels down the [[T tubules|T tubules]], activating [[Calcium channel|Ca2+ channels]] in the [[Sarcopalsmic reticulum|sarcopalsmic reticulum]]. There is an influx of Ca2+ ions in the [[Cytosol|cytosol]], which initiates the contraction of the myofibrils.

The actin filament has two associated proteins, [[Tropomyosin|tropomyosin]]  and [[Troponin|troponin]].Tropomyosin binds along the groove of the actin helix. Troponin is trimeric and made up of [[Troponin T|troponin T]], [[Troponin I|I]] and [[Troponin C|C]]. Troponin T and I are inhibitory and bind to actin and tropomyosin, blocking the myosin binding sites on the actin molecule. Troponin C binds to Ca2+ molecules and causes troponin T and I to release their hold on actin.The tropomyosin molecule moves to reveal the myosin binding sites and the myosin heads bind and rotate using energy from ATP hydrolysis, to cause contraction <ref>Albert et al., 5th edition, Garland Science, pages 1026-1030</ref>.

However in smooth muscle the [[Troponin|troponin]] on the actin filament is replaced by a protein called [[Calmodulin|calmodulin]]. When activated by the Ca2+ ions (4 Ca2+ per calmodulin molecule) calmodulin activates "myosin light chain kinase". This phosphorylates the globular heads which in turn activates the ATPase enzymes in the globular head and thus the cross-bridge between the myosin globular head and the actin binding site can form. Myosin phosphatase stops the actin-myosin cross-bridge by dephosphorylation of the myosin head.<ref>David Sadava et al. 2006. Life: The science of Biology 8th Edition. Page-1012. Sunderland U.S.A. Sinauer Associates Inc</ref>

=== References ===

<references />

<references />

Muscle contraction

2017-12-05T17:03:18Z

170172349:

Voluntary and involuntary movements in animals are mainly by contraction of muscles, namely the [[Skeletal muscle|skeletal muscle]] (voluntary, striated and multinucleated), [[Smooth muscle|smooth muscle]] (involuntary, non-striated and uninucleated) and [[Cardiac muscle|cardiac muscle]] (involuntary, in the heart and branched).

[[Image:Muscles.jpg]][3]

Skeletal muscle fibres are made up of many [[Myofibrils|myofibrils]], which are the basic contractile elements of the muscle cell. Myofibrils are made up of repeating units known as [[Sarcomeres|sarcomeres]], which cause striation in the fibre.

Each sarcomere consists of overlapping thick and thin filaments respectively known as [[Myosin|myosin]] and [[Actin|actin]]. The sliding of actin and myosin filaments changes the degree of overlap between them and causes contraction. During contraction,the sarcomere shortens considerably but the length of the actin and myosin filaments stays the same.

When an action potential is triggered in the [[Sarcoplasmic membrane|sarcoplasmic membrane]], it travels down the [[T tubules|T tubules]], activating [[Calcium channel|Ca2+ channels]] in the [[Sarcopalsmic reticulum|sarcopalsmic reticulum]]. There is an influx of Ca2+ ions in the [[Cytosol|cytosol]], which initiates the contraction of the myofibrils.

The actin filament has two associated proteins, [[Tropomyosin|tropomyosin]]  and [[Troponin|troponin]].Tropomyosin binds along the groove of the actin helix. Troponin is trimeric and made up of [[Troponin T|troponin T]], [[Troponin I|I]] and [[Troponin C|C]]. Troponin T and I are inhibitory and bind to actin and tropomyosin, blocking the myosin binding sites on the actin molecule. Troponin C binds to Ca2+ molecules and causes troponin T and I to release their hold on actin.The tropomyosin molecule moves to reveal the myosin binding sites and the myosin heads bind and rotate using energy from ATP hydrolysis, to cause contraction <ref>Albert et al., 5th edition, Garland Science, pages 1026-1030</ref>.

However in smooth muscle the [[Troponin|troponin]] on the actin filament is replaced by a protein called [[Calmodulin|calmodulin]]. When activated by the Ca2+ ions (4 Ca2+ per calmodulin molecule) calmodulin activates "myosin light chain kinase". This phosphorylates the globular heads which in turn activates the ATPase enzymes in the globular head and thus the cross-bridge between the myosin globular head and the actin binding site can form. Myosin phosphatase stops the actin-myosin cross-bridge by dephosphorylation of the myosin head.<ref>David Sadava et al. 2006. Life: The science of Biology 8th Edition. Page-1012. Sunderland U.S.A. Sinauer Associates Inc</ref>

=== References ===

<references />

 https://sites.google.com/site/iilyear4/three-types-of-muscle-tissue [3]

Muscle contraction

2017-12-05T17:02:33Z

170172349:

Voluntary and involuntary movements in animals are mainly by contraction of muscles, namely the [[Skeletal muscle|skeletal muscle]] (voluntary, striated and multinucleated), [[Smooth muscle|smooth muscle]] (involuntary, non-striated and uninucleated) and [[Cardiac muscle|cardiac muscle]] (involuntary, in the heart and branched).

[[Image:Muscles.jpg]]

Skeletal muscle fibres are made up of many [[Myofibrils|myofibrils]], which are the basic contractile elements of the muscle cell. Myofibrils are made up of repeating units known as [[Sarcomeres|sarcomeres]], which cause striation in the fibre.

Each sarcomere consists of overlapping thick and thin filaments respectively known as [[Myosin|myosin]] and [[Actin|actin]]. The sliding of actin and myosin filaments changes the degree of overlap between them and causes contraction. During contraction,the sarcomere shortens considerably but the length of the actin and myosin filaments stays the same.

When an action potential is triggered in the [[Sarcoplasmic membrane|sarcoplasmic membrane]], it travels down the [[T tubules|T tubules]], activating [[Calcium channel|Ca2+ channels]] in the [[Sarcopalsmic reticulum|sarcopalsmic reticulum]]. There is an influx of Ca2+ ions in the [[Cytosol|cytosol]], which initiates the contraction of the myofibrils.

The actin filament has two associated proteins, [[Tropomyosin|tropomyosin]]  and [[Troponin|troponin]].Tropomyosin binds along the groove of the actin helix. Troponin is trimeric and made up of [[Troponin T|troponin T]], [[Troponin I|I]] and [[Troponin C|C]]. Troponin T and I are inhibitory and bind to actin and tropomyosin, blocking the myosin binding sites on the actin molecule. Troponin C binds to Ca2+ molecules and causes troponin T and I to release their hold on actin.The tropomyosin molecule moves to reveal the myosin binding sites and the myosin heads bind and rotate using energy from ATP hydrolysis, to cause contraction <ref>Albert et al., 5th edition, Garland Science, pages 1026-1030</ref>.

However in smooth muscle the [[Troponin|troponin]] on the actin filament is replaced by a protein called [[Calmodulin|calmodulin]]. When activated by the Ca2+ ions (4 Ca2+ per calmodulin molecule) calmodulin activates "myosin light chain kinase". This phosphorylates the globular heads which in turn activates the ATPase enzymes in the globular head and thus the cross-bridge between the myosin globular head and the actin binding site can form. Myosin phosphatase stops the actin-myosin cross-bridge by dephosphorylation of the myosin head.<ref>David Sadava et al. 2006. Life: The science of Biology 8th Edition. Page-1012. Sunderland U.S.A. Sinauer Associates Inc</ref>

=== References ===

<references />

3. https://sites.google.com/site/iilyear4/three-types-of-muscle-tissue

Muscle contraction

2017-12-05T17:02:18Z

170172349:

Voluntary and involuntary movements in animals are mainly by contraction of muscles, namely the [[Skeletal muscle|skeletal muscle]] (voluntary, striated and multinucleated), [[Smooth muscle|smooth muscle]] (involuntary, non-striated and uninucleated) and [[Cardiac muscle|cardiac muscle]] (involuntary, in the heart and branched).

[[Image:Muscles.jpg]]

Skeletal muscle fibres are made up of many [[Myofibrils|myofibrils]], which are the basic contractile elements of the muscle cell. Myofibrils are made up of repeating units known as [[Sarcomeres|sarcomeres]], which cause striation in the fibre.

Each sarcomere consists of overlapping thick and thin filaments respectively known as [[Myosin|myosin]] and [[Actin|actin]]. The sliding of actin and myosin filaments changes the degree of overlap between them and causes contraction. During contraction,the sarcomere shortens considerably but the length of the actin and myosin filaments stays the same.

When an action potential is triggered in the [[Sarcoplasmic membrane|sarcoplasmic membrane]], it travels down the [[T tubules|T tubules]], activating [[Calcium channel|Ca2+ channels]] in the [[Sarcopalsmic reticulum|sarcopalsmic reticulum]]. There is an influx of Ca2+ ions in the [[Cytosol|cytosol]], which initiates the contraction of the myofibrils.

The actin filament has two associated proteins, [[Tropomyosin|tropomyosin]]  and [[Troponin|troponin]].Tropomyosin binds along the groove of the actin helix. Troponin is trimeric and made up of [[Troponin T|troponin T]], [[Troponin I|I]] and [[Troponin C|C]]. Troponin T and I are inhibitory and bind to actin and tropomyosin, blocking the myosin binding sites on the actin molecule. Troponin C binds to Ca2+ molecules and causes troponin T and I to release their hold on actin.The tropomyosin molecule moves to reveal the myosin binding sites and the myosin heads bind and rotate using energy from ATP hydrolysis, to cause contraction <ref>Albert et al., 5th edition, Garland Science, pages 1026-1030</ref>.

However in smooth muscle the [[Troponin|troponin]] on the actin filament is replaced by a protein called [[Calmodulin|calmodulin]]. When activated by the Ca2+ ions (4 Ca2+ per calmodulin molecule) calmodulin activates "myosin light chain kinase". This phosphorylates the globular heads which in turn activates the ATPase enzymes in the globular head and thus the cross-bridge between the myosin globular head and the actin binding site can form. Myosin phosphatase stops the actin-myosin cross-bridge by dephosphorylation of the myosin head.<ref>David Sadava et al. 2006. Life: The science of Biology 8th Edition. Page-1012. Sunderland U.S.A. Sinauer Associates Inc</ref>

=== References ===

<references />

https://sites.google.com/site/iilyear4/three-types-of-muscle-tissue

File:Muscles.jpg

2017-12-05T16:55:34Z

170172349: