Neurons, Action potentials and Synapses Flashcards
(78 cards)
1
Q
Common elements found in humans?
A
Oxygen O
Carbon C
Hydrogen H
Nitrogen N
Calcium C
Phosphorus P
Potassium P
Sulfur S
Sodium Na
Clorine Cl
Magnesium Mg
Iron Fe
2
Q
What are atoms composed of, what 2 are in the nucleus and what is in the surrounding area?
A
Protons (positive)
Neutrons (neutral)
Electrons (negative)
Protons and neutrons
3
Q
What is an ion?
A
An atom that has lost of gained more than one electron.
4
Q
Chemical bonds and example?
A
Ionic bonds - transfer of positive and negative electrons to form new compound.
Example: Sodium and Chloride. Sodium atoms lose one electron each, and Chloride atoms gain one electron each. The result: positively charged sodium ions Na+ and negatively charged Chlorine Cl-
Covalent bonds - rather than transfering electrons, pairs of atoms share electrons
Example, H20. The oxygen atoms share a pair of electroncs with each hudrogen atom.
5
Q
Types of carbon atom bonds and their properties?
A
Carbon atoms form covalent bonds with hydrogen, oxygen and a number of other elements. They also form covalent bonds with other carbon atoms.
Types: Share one pair, two pair or three pairs of electons.
6
Q
What are the two types of cell in the nervous system?
A
Neurons and Glia
7
Q
What do mitochondria do?
A
Mitochondria are structures that perform metabolic activities: providing the energy that the cell needs for all other activities. Mitochondria require fuel and oxygen
8
Q
What do Ribosomes do?
A
- Ribosomes are the site at which the cell synthesizes new protein molecules.
o Some ribosomes float freely with the cell.
o Others are attached to the endoplasmic reticulum – a network of thin tube that transport newly synthesised proteins to other locations
9
Q
What are the 3 types of neruons?
A
- Sensory neurons (afferent) carry information from sensory receptors in the body (e.g. skin, organs) to the CNS. They are highly sensitive to certain stimulus, e.g. light, sound, touch.
- Motor neurons (efferent) transmit signals from the CNS to effector organs e.g. muscles or glands, initiating movement
- Interneurons (association neurons) connect sensory and motor neurons within the CNS, playing a key role in processing and integration of information. The cell’s dendrites and axon are completely contained within a single structure.
10
Q
What are the components of a motor neuron?
A
- Nucleus
- Dendrites
- dendrite spines (which increase surface area available for synapses)
- Soma (cell body)
- Axon (surrounded by myelin sheath)
- Axon hillock (point between start of axon and the soma)
- Presynaptic terminals
- Muscle fibre
11
Q
What are the components of a sensory neuron?
A
- Nucleus
- Dendrites
- Soma (cell body)
- Axon (surrounded by myelin sheath)
- Sensory endings
- Skin surface
12
Q
What are the fuctions of components on a neuron?
A
- Dendrites surface is lined with specialised synaptic receptors which receive information from other neurons.
- Soma (cell body) contains the nucleus, ribosomes and mitochondria [most metabolic activity occurs here]
- Axon is a thin fibre that conveys information via an impulse towards other neurons of muscles. Many vertebrate axons are covered by myelin sheath with interruptions (nodes of Ranvier)
- Presynaptic terminals (the swollen ends of the axon) which transmit singals.
13
Q
Types of Glia and their function?
A
- Astrocytes: star shaped, wrap around presynaptic terminals.
o Helps synthesize activity of neurons by taking up ions released by axons then releasing them back to axon, enabling them to send messages in waves.
o Remove waste material when neurons die
o control blood flow in each brain area
o Dilate blood vessels to bring in more nutrients to that area
o Absorn glutamate released by neuron, convert to glutamine and release back to neuron for re-use (recycling) - Microglia: very small, remove waste materials, viruses, fungi and other microorganisms.
- Oligodendrocytes: located in CNS, build the myelin sheath on axons
- Schwann cells: located in PNS, build the myelin sheath on axons
- Radial glia: guide migrtation of neurons during embryonic development. Once complete, differentiate into neurons, astrocytes and oligodendrocytes.
14
Q
What is the blood-brain barrier and why is it necessary?
A
- Brain needs blood but cannot afford for infected neurons to be killed by immune system in normal way as these are not easily replaceable. Thus, the blood-brain barrier acts to keep out most viruses, bacteria and harmful chemicals.
- Relies on endothelial cells that form the walls of capillaries, join so tightly almost nothing passes between them.
15
Q
What chemicals are permitted through the blood-brain barrier and how?
A
o Small charged molecules, such as O2 and CO2 pass freely
o Some molecules dissolve in fat of membrane e.g. Vitamin A and D, as well as drugs that affect the brain, antidepressants, heroin etc.
o Active transport: protein mediated activity that expends energy to pump chemicals from blood into the brain. These include glucose (the brain’s main food), amino acids, purines, cholines, iron, some vitamins and certain hormones.
16
Q
How do vertebrate neurons nourish themselves?
A
Vertebrate neurons depend almost entirely on glucose (a sugar). Metabolic pathways that use glucose require oxygen; thus, neurons need a steady flow of oxygen and the brain accounts for 20% of oxygen use. Glucose is the only nutrient other than Ketones that passes the blood-brain barrier and is produced in ample amount by the liver converting carbs, amino acids and glycerol (breakdown product of fat)
17
Q
Resting potential of neurons
A
- The resting potential of a neuron is voltage before any action, typically -70 millivolts.
- The resting potential prepares neurons to respond rapidly.
- The neuron inside the membrane has a slightly negative electric potential due to the proteins inside the cell.
18
Q
What is the sodium-potassium pump and how does it function?
A
- The sodium-potassium pump is an active transport protein complex that repeatedly pumps 3 sodium ions out of the cell and 2 potassium ions into the cell. As a result, sodium ions are 10x more concentrated outside the membrane, and potassium ions are more concentrated inside.
o Its efficacy works because of the selective permeability of the membrane which prevents sodium ions there were pumped out of the neuron from leaking back in.
o Some potassium ions pumped into the neuron leak out. The leaks increases the electrical gradient across the membrane. - When a neuron is at rest sodium is pushed into the cell. Inside of the cell is negatively charged and thus attracts the positively charged sodium (electric gradient). The concentration gradient, the difference in distribution of ions across the membrane, mean as sodium is more abundant outside the membrane, sodium is more likely to enter the cell than to leave it. As sodium channels are closed when the membrane is at rest, almost no sodium flows expect for the sodium pushed out by the potassium-sodium pump.
- Potassium is pulled in by the electric gradient and driven out by the concentration gradient. The sodium-potassium pump pulls more potassium into the cell as fast as it flows out of the cell, so the two gradients cannot completely balance.
19
Q
What is an action potential and how does it work?
A
- Messages sent by axons are called action potentials
- Action potentials require the flow of sodium and potassium.
- Action potentials occur at -50mv and above.
20
Q
How does local anaesthetic work?
A
Local anaesthetic works by attaching to the sodium channels of the membrane, preeing sodium ions from entering. The axons can’t transmit the pain message to the brain despite the pain receptions activating as sodium is needed for the action potentials
21
Q
What is the all-or-none law?
A
The all-or-none law is that the amplitude and velocity of an action potential are dependent on the intensity of the stimulus that initiated it. That is, unless the threshold is met, an action potential will not occur.
22
Q
What are the refractory periods and what are their mechanisms?
A
- Immediately after an action potential the cell is in a refractory period in which it resists the production of further action potential.
- Absolute refractory period: The membrane cannot produce an action potential regardless of the stimulus.
- Relative refractory period: A stronger than usual impulse is necessary to initiate an action potential.
- The two refractory period mechanisms are closed sodium channels and potassium flowing out of the cell faster than normal.
23
Q
What is the propogation of the action potential?
A
Transmission of the action potential down the axon. Due to release of positive ions which flow to neighbouring areas and depolarise the next membrane, causing it to reach its threshold and open its sodium channel, therefor the membrane regenerates the action potential at that point in the next neuron.
24
Q
What is the relationship between myelin sheath and saltatory conduction?
A
- Myelin sheaths (found only in vertebrates) are an insulating material made of fats and proteins that increases the speed at which messages are sent along the axon.
- In most cases the action potential starts at the axon hillock but in some cases starts are the nodes of Ranvier
- Axon messages would otherwise stop at nodes of Ranvier if not for the sodium release which activates the next action potential in the next portion of the axon. The jumping of action potentials from node to node is known as saltatory conduction.
- Saltatory conduction allows for rapid conduction of impulses and conserves energy.
- Rather than using the potassium-sodium pump, myelin sheaths admit sodium only at its nodes.
25
What are local neurons and how do they function?
- Axons produce action potentials. However, many small neurons have no axon. These local neurons exchange information only with their closest neighbours. Because they do not have an axon, they do not follow the all-or-none law.
- When a local neuron receives information from other neurons, it has a graded potential, a membrane potential that varies in magnitude in proportion to the intensity of the stimulus.
26
What is a synapse?
A synapse is the junction between nerve cells (neurons) that allows a neuron to pass chemical (or occasionally electric signals) to another neuron or gland / muscle (effector) cell by diffusion of neurotransmitters.
27
What are the mechanisms of flexion reflex?
- In leg flexion reflex, a sensory neuron excites a second neuron, which in turn excites a motor neuron which excites a muscle
- The spinal cord controls the flexion and extension reflexes (as demonstrated by severing the brain and spinal cord and still rendering a reflexive response to touch).
28
What is the process, speed of reflex and transmission of the synapse?
- When touched, an impulse has to travel up an axon from the skin receptor to the spinal cord, and then an impulse has to travel from the spinal cord back to the leg muscle (a delayed response)
- The speed of conduction along an axon is about 40 m/s
- The speed of conduction through a reflex arc is slower and more variable, around 15 m/s or less.
29
What is spacial summation?
- Spatial summation: summation over space. Synaptic inputs from several nearly simultaneous stimulation at several synapses combine their effects on a neuron.
- Multiple sensory stimulation at different sensory neurons converge onto a neuron in the spinal cord
- Spatial summation ensures that a sensory stimulus stimulates neurons enough to activate them.
30
What is temporal stimulation?
- Repeated stimulus (rapid repetitive pinching at a single point) evokes an action potential because the subthreshold of excitation in the postsynaptic neuron decays, but further impulse accumulate to produce an action potential.
- Graded potentials: Unlike action potentials, which are always depolarisations, graded potentials may be depolarisations (excitatory) or hyperpolarisations (inhibitory).
- A graded potential is known as an excitatory postsynaptic potential (EPSP)
31
What are inhibitory postsynaptic potentials (IPSPs)?
- Inhibitory postsynaptic potentials (IPSP) occur when synaptic input selectively opens the gates of potation ions to leave the cell (carrying a positive charge) or chlorine ions to enter the cell (carrying a negative charge) thus causing hyperpolarisation moving it further from the threshold and decreasing the probability of an action potential.
- A pinch on the foot sends a message along a sensory neuron to an interneuron (intermediate neuron) in the spinal cord which in turn excites the motor neurons connected to the flexor muscles of that leg.
32
What is a neuron spontaneous firing rate?
- Most neurons have a spontaneous firing rate: a periodic production of action potentials even without synaptic input. In such cases, EPSPs increase the frequency of action potentials above the spontaneous rate, where is IPSPs decrease it.
33
What is the sympathetic nervous system, which brain area controls it, how, and what effect does it have?
-he sympathetic nervous system (a set of nerves) plays a key role in releasing adrenaline (epinephrine) during times of stress or perceived danger. When the sympathetic nervous system is activated, the hypothalamus sends signals to the adrenal glands (indirectly via the pituitary gland), which then release adrenaline into the bloodstream to accelerates the heartbeat, relax the stomach muscles, dilate the pupils and regulate other organs.
34
What is the sequence of chemical events in the synapse?
1. Neurons synthesize chemicals that serve as neurotransmitters. Smaller Neurotransmitters are synthesised in the axon terminal, and neuropeptides in the cell body.
2. Action potentials travel down the axon. At the presynaptic terminal, an action potential enables calcium to enter the cell. Calcium releases neurotransmitters from the terminals into the synaptic cleft (the space between the pre and postsynaptic neurons)
3. The released chemicals diffuse across the cleft, attach to receptors, an alter the activity of the postsynaptic neuron.
4. The neurotransmitter molecules separate from their receptors
5. The neurotransmitter molecules make be taken back into the presynaptic neuron for recycling (reuptake) or they may diffuse away.
6. Some postsynaptic cells send reverse messages to control the further release of neurotransmitters by the presynaptic cells.
35
What are the main types of neurotransmitters?
- Around 100 neurotransmitter chemicals
- Amino acids: glutamate, GABA, glycine, aspartate and others)
- Monoamines: chemicals formed by a change in certain amino acids
- Neuropeptides: chain of amino acids
- Purines: a category of chemicals including adenosine and its derivatives
- Gases: nitric oxide [poisonous in large quantitites] and possibly others
36
What does nitric oxide do?
- Neurons release nitric oxide when stimulated which sends a message so that blood flows to an area that has become active by dilating blood vessels.
37
How do neurons synthesise neurotransmitters?
- Neurons synthesise nearly all neurotransmitters from amino acids, which the body obtains from proteins in the diet.
38
Main types and pathways of neurotransmitters?
Pathways (each begin with substances found in the diet)
- Acetyl coenzyme A (from metabolism) + Choline (from metabolism or diet) > Acetylcholine
- Phenylalanine (from diet) > Tyrosine > Dopa > Dopamine > Norepinephrine > epinephrine [collectively compounds known as catecholamines because they contain a catechol group and an amine group]
- Tryptophan (from diet) > 5-hydroxytrptophan > Serotonin (5-hydrocytryptamine)
o The amino acid tryptophan crosses the blood-brain barrier by a special transport system that is shares with other amino acids. Thus, the amount of tryptophan in the diet controls the amount of serotonin in the brain.
39
Storage of neurotransmitters?
Most neurotransmitters are synthesised in the presynaptic terminals, near the point of release. The presynaptic terminal stores high concentrations of neurotransmitter molecules in vesicles (tiny spherical spheres). The presynaptic terminal also maintains many neurotransmitter molecules outside the vesicles.
MAO (Mono-amine oxidase) is an enzyme that breaks down over accumulated neurotransmitter chemicals such as serotonin, dopamine and norepinephrine.
40
What is Exocytosis?
Exocytosis: At the end of the axon, the action potential itself does not release the neurotransmitter. Rather, the depolarisation caused by the entrance of calcium opens the voltage-dependent gates in the presynaptic terminal which causes the release of neurotrasmitters from the presynaptic neuron to the synaptic cleft.
41
How many neurotransmitters do neurons typically produce / receive?
- Most neurons release 2 or more chemicals
- Most neurons can receive almost all chemicals from different synapse
42
What is the effect of activating a receptor of a postsynaptic cell?
The effect of a neurotransmitter depends on the receptor on the postsynaptic cell. When the neurotransmitter attaches to its receptor, the receptor may open a channel exerting an ionotropic effect or it may produce a slower but longer metabotropic effect.
43
Ionotropic effects, transmission, and uses?
- Ionotropic effects are when neurotransmitters exert a brief on/off effect.
- When the neurotransmitter binds to an ionotropic receptor, it twists the receptor open enough to open its central cannel to let particular ions through
- The channels controlled by a neurotransmitter are transmitter-gated or ligand gated (a ligand is a chemical which binds to another chemical). When the neurotransmitter attaches it opens a channel.
- Well suited to conveying visual information and anything else that needs to be updated quickly as they begin rapidly with a half-life of 5ms.
44
Chemicals used in excitatory and inhibitory ionotropic synapses?
- Most of the brain’s excitatory ionotropic synapses use the transmitter glutamate (the most abundant transmitter in the nervous system) or Acetylcholine.
- Most inhibitory ionotropic synapses use GABA (gamma-amino-butyric-acid) [which allows chlorine ions to enter the cell more rapidly] and Glycine (common in the spinal cord).
45
Metabolic effects, transmission, and uses?
- Metabotropic effects initiate a sequence of metabolic reactions that are slower and longer lasting than ionotropic effects.
- Effects emerge 30ms or more after release of transmitter.
- Typically last a few seconds.
- Best suited for longer lasting effects such as taste, smell and pain.
- Also important for aspects of arousal, attention, pleasure and emotion
46
Main chemicals used in Metabolic effects?
Mainly use dopamine, serotonin and norepinephrine but also GABA and glutamate.
47
Metabolic effects on secondary messenger systems?
- When a neurotransmitter attaches to a metabotropic receptor, it bends the receptor protein that goes through the membrane of the cell. The other side of the receptor is attached to the G protein (protein group called Guanosine triphosphate [GTP], an energy storing molecule). Bending the receptor protein detaches that G protein which si then free to take its energy elsewhere in the cell. The result is the release of a second messenger inside the cell which communicates information to many areas of the cell and can cause ion channels to open or close, or activate a portion of a chromosome.
- Unlike ionotropic synapses which are localised to one area of the cell, metabotropic synapses influence much or all of the cell by way of the second messenger.
48
What are the features of neruopeptides?
- Synthesised in the cell body and slowly transported to other parts of cell
- Released mainly by dendrites (rather than axon terminals), and the cell body and sides of the axon
- Whereas a single action potential can release other neurotransmitters, neuropeptides require repeated stimulation.
- Neurons containing neuropeptides do not release them often, but hen they do they release substantial amounts by priming other nearby dendrites to release the same neuropeptide
- Diffuse widely, affecting many neurons in their region of the brain
- (Many) exert effect by altering gene activity, thus effects are long-lasting. 20 minutes+.
- Important for hunger, thirst, intense pain and other long-term changes in behaviour and experience
49
What is a hormone?
A hormone is a chemical that’s is secreted by one cell and released into the bloodstream to influence another cell.
50
Where are hormones produced?
Hormones are produced by endocrine glands
- Pituitary gland:
- Pineal gland:
- Thyroid gland:
- Parathyroid glands:
-Thymus:
- Adrenal glands:
- Pancreas:
- Ovaries (females) / Testes (males):
51
Types of hormones?
Types of hormones: Protein hormones and peptide hormones composed of chains of amino acids. They attach to the membrane receptors where they activate second messengers within the cell
52
Brain use of hormones, brain regions and chemicals produced?
- Hormones secreted by the brain control many other hormones
- The hypothalamus, consisting of the anterior and posterior pituitary glands release sets of hormones. Neurons in the hypothalamus synthesize hormones oxytocin and vasopressin. These are then released to the posterior pituitary which releases them into the blood.
- The hypothalamus maintains fairly constant circulating levels of certain hormones through a negative feedback system. When thyroid hormone is low, the hypothalamus releases TSH-releasing hormone, which stimulates the anterior pituitary to release TSH, which causes the thyroid gland to secrete more thyroid hormones.
53
Inactivation and reuptake of neurotransmitters
- After acetylcholine releases is broken down by an enzyme into fragments of acetate and choline. Choline is reuptaken by the presynaptic neuron and added to the existing store of acetate to for acetylcholine again.
- Serotonin and the catecholamines do not breakdown at the postsynaptic membrane and simply detach from the receptor.
o In some cases, the presynaptic neuron reuptakes the whole neurotransmitter and reuses them, a process facilitated by a special membrane protein called transporters.
o In brain areas where fewer transporters are present, excess dopamine is broken down by the enzyme COMT (catechol-o-methyltransferase) into inactive chemicals than cannot activate the dopamine receptor and wash away.
54
Negative feedback from postsynaptic cell
- Yes I got your message, do not send it again"
- Auto receptors: Many presynaptic terminals have receptors sensitive to the same neurotransmitter they release. They respond to the detection of the released chemical by inhibiting further synthesis and release
- Some post-synaptic neurons respond to stimularion by releasing special chemicals that travel back to the presynaptic terminal where they inhibit further release fof the transmitter. One example is nitric oxcide.
55
Electric synapses
A few special-purpose synapses operate electrically.
- Electrical transmission is much faster than chemical transmission
- Electrical synapses have evolved in synchrony between two cells
- At an electrical synapse, the membrane of one neuron comes into direct contact with another, called the gap junction. Large pores of the membrane of one neuron line up precisely with similar pores in the other cell and are large enough for sodium and other ions to pass readily, and they remain open constantly.
- Some of the cells that control rhythmic breathing are synchronised by electrical synapses (it’s important to breath on the left and right side at the same time)
56
What is depolaraisation?
When a neuron receives a stimulus, such as a chemical signal from another neuron, it opens it's Ion channels allowing positive sodium ions to enter, which temporarily decreases it's negativity towards 0.
-
57
What is the threshold potential?
When postively charged ions change the resting potential of a neuron to above -50 milivolts
58
What are neurons covered in?
- Neurons are covered by an inner and outer layer of fatty acids and phosphates (phospholipid molecules).
- Embedded along the phospholipids are cylindrical protein molecules with control which chemicals flow between the inside and outside of the cell
59
Membranes: what passes freely, what cannot pass, and what passes via membrane gates/channel?
- Membranes are selectively permeable surface of the cell, a structure that separates the inside of the cell from the outside environment (to avoid depolarization).
- It is composed of two layers of fat molecules that are free to flow around one another.
- They allow oxygen, carbon dioxide, urea and water to cross freely.
- Most large or electrically charged ions do not cross at all.
- Biologically important ions, sodium, potassium, calcium and chloride pass through membrane channels (gates) (specific protein channels) that’s are sometimes open and sometimes closed/
60
What is polarisation, depolorisation and hyperpolarisation?
- Polarisation – the changing in electrical charge from positive to negative within a neuron.
- Depolarisation: a decrease in the negative charge within a cell.
(When the membrane is depolarised, sodium and potassium channels are open.
- Hyperpolarization: increased negative charge within a cell.
61
What are voltage-gated channels?
Voltage-gated channels: these protein channels permit specific ions, such as sodium, to pass based on the voltage in across the membrane.
- At rest, sodium channels are closed and potassium are almost entirely closed.
- As a membrane is depolarised both potassium and sodium gates open. Due to electric gradient and concentration gradient, sodium ions are pushed into the cell/neuron more rapidly than potassium, until the electric potential across the membrane passes beyond zero to a reversed polarity.
62
What happens at peak action potential?
- At peak action potential, sodium gates snap shut for 1 millisecond. As membrane opens potassium channels during depolarisation, many sodium ions cross the membrane and the inside of the cell because positively charged. At this point both concentration gradient and electrical gradient drive potassium out of the cell, taking with them a positive charge through the axon, causing temporary hyperpolarisation.
63
What is repolorisation?
The action potential doesn't stay at its peak for long. Sodium channels close, and potassium channels open, allowing K= ions to flow out of the cell, reversing depolorisation and causing the neuron to return to its resting potential.
64
How is multiple sclerosis affected by the immune system?
In MS, the immune system attacks myelin sheaths meaning it lacks sodium and most action potentials die resulting in various impairments from vision to poor muscle coordination.
65
Calcium and synapse
An influx of calcium is essential for the release of neuro transmitters.
66
Difference between agonist and antagonist drugs?
Antagonists block neurotransmission, agonists mimics of increases the effects.
67
What are drugs effect on synapse?
Drugs can increase or decrease the synthesis of a neurotransmitter, decrease its reuptake, block its breakdown or act on postsynaptic receptors.
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What three chemicals are often share effects with illicit drugs?
Dopamine, serotonin and norepinephrine
69
Which area of the brain is filled with dopamine when taking drugs or performing pleasurable activities?
What are the effects of liking and wanting?
Nucleus accumbens.
70
What is the effect of the nucleus accumbens and which activities activate which parts?
- The nucleus accumbens is central to reinforcing experiences of all types
- Small parts of the nucleus accumbens respond to pleasure (liking)
- Large parts of the nucleus accumbens respond to motivation (wanting)
71
Amphetamine effects?
- Amphetamines and cocaine stimulate dopamine synapses in the nucleus accumbus and in the presynaptic terminal.
- Amphetamines and cocaine block reuptake, prolonging the effects of released dopamine
- Amphetamines have similar effects on serotonin and norepinephrine
72
What receptor family / brain area does nicotine affect?
Stimulates a family of acetylcholine receptors which cause dopamine to be released in the nucleus accumbus
73
Effects and chemical actions of opiates?
- Relax people, decrease attention and decrease sensitivity to pain
- The brain releases the neuropeptides endorphins, a contraction of endogenous morphines which react to receptors on the brain.
- Receptors common in medulla and can cause overdose
- Endorphins indirectly activate dopamine release
- Endorphins inhibit synaptic release of GABA
74
Where are cannabis receptors and what affect does it have on synapses?
- The brain has cannabinoid receptors in many areas of the mammalian brain (especially hypothalamus and hippocampus) but not the medulla.
- Unusually the receptors are located on the presynaptic receptors, which assumes it had sent signals and stop. As a result both excitatory and inhibitory messages from neurons are blocked.
75
Chemical effects of hallucinogenics?
- Chemically resemble serotonin
- Attach to serotonin 2A (5HT2a) receptors
- MDMA use leads to destruction of serotonin receptors increasing depression, anxiety and impairing learning and memory
76
What are the genetic causes of alcoholism?
- One gene action on Dopamine 4 receptor. The long form is less sensitive and people with long form report stronger cravinds for additional alcogool after having 1 drink.
- One gene controls COMT. People that have more actie COMT enzyme so they get less dopamine tgus seek more alcohol to compensate
76
What receptors does alcohol affect and what is the behavioural response?
- Facilitates response at the GABA receptor (brain’s main inhibitatory site)
- Block actitiy at the gulatamte receptor (brain’s main excitatory site)
o As such decreases brain areas responsible for inhibiting risky behaviour
77
What is a protein and their use?
Protein is a vital macronutrient molecules made up of amino acids that plays a key role in the body's structure and function. It's a building block for muscles, bones, skin, cartilage, and blood, and also for hormones, enzymes, and vitamins.
They are essential for virtually every cellular process, including building and repairing tissues, catalyzing biochemical reactions, and transporting molecules.
