Synapses, Neurotransmitters, Hormones Flashcards by Eliza Konomanyi

What is synaptic transmission?

How neurones communicate with each other

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What is a synapse?

The gap between neurones where signals are passed from one to another

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What are the two types of synapses?

Electrical and chemical

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What are the characteristics of an electric synapse?

Small gap between two neurones (2-4nm), large channels to allow ions to move directly from one neurone to another, process is similar to propagation of an action potential, fast, prevalence in PNS due to muscle contraction

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How are action potential propagated in electric synapses?

From the pre-synaptic neurone to the post-synaptic neurone

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What are the characteristics of a chemical synapse?

Specialised structures to transmit chemical signals, larger gap (20-40nm), slow transmission, high prevalence in neurones (1000)

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What is the process in chemical synapses with action potential?

Action potential arrives at pre-synaptic membran3
VG Ca 2+ channels open
Ca 2+ diffuses into the cell
Synaptic vesicles fuse with the membrane
Neurotransmitters released into the synaptic cleft
Neurotransmitter binds to the postsynaptic receptor, opening the ion channels

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What is the fusion process of vesicles?

Lipid membrane forms a large opening for release into the cleft

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What is the criteria for neurotransmitters?

Must be synthesised in the pre-synaptic neurone, present in the axon terminal and released in a calcium dependant manner upon depolarisation of the pre-synaptic neurone

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What do amino acid transmitters do?

Fast transmission such as glutamate with the related amino acid aspartate

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What are examples of biogenic amines?

Noradrenaline, adrenaline, dopamine

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How are biogenic amines produced?

By the amino acid tyrosine and then decarboxylation occurs

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How do neuropeptides work?

They have long term neuromodulatory effects due to interaction with metabotropics

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What are the three groups of neuromodulator peptides

Enkephalins, endorphins, dynorphins

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What is a property of enkephalins?

Pain relieve

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What are properties of endorphins and dynorphins?

Pain relief and euphoria

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What happens if the synapse is excitatory?

NA + channels open, depolarisation occurs leading to an excitatory postsynaptic potential (EPSP)

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What happen if the synapse is inhibitory?

Cl- channels open, hyperpolarisation occurs leading to an inhibitory postsynaptic potential (IPSP)

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What are receptors?

Membrane proteins that bind neurotransmitters in a lock and key principle so each receptor type can bind only to a specific neurotransmitter

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What are ionotropic receptors?

Receptors that lead to the opening or closing of an ion channel so there is a change in the ion channel permeability for a flow of ions across the cell membrane

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What are ionotropic receptors responsible for?

Fast, brief and precise synaptic transmission

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What is the structure of an ionotropic receptor?

Ligang-gated ion channel, receptor site is apart of the ion channel protein

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What are metabotropic receptors?

Receptors where the binding of neurotransmitters activates a G protein

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What does a G protein do?

Bind to an ion channel which will influence opening or closing or activate secondary messengers

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What do metabotropic receptors allow?

Slower and prolonged signalling

What are neurotransmitters?

A chemical released that will transmit signals between neurones

What are characteristics of neurotransmitters?

Synthesised in the pre-synaptic neurones, localised to vesicles in the pre-synaptic neurone, released from the pre-synaptic neurones, removed by the synaptic cleft, binds to receptor

What happens to neurotransmitters when the signal is transmitted?

It is either recycled in the cleft by reuptakers or neutralised by enzymes

What are 4 excitatory neurotransmitters?

Acetylcholine, glutamate, norepinephrine, serotonin

What is acetylcholine's role?

Muscle control

What is glutamate's main role?

Learning and memory

What is norpinephrine's main role?

Fight or flight response and arousal

What is serotonin's main role?

Mood, appetite, sensory perception

What are 2 inhibitory neurotransmitters?

Dopamine and GABA

What is dopamine's main role?

Reward, motivation, movement

What is GABA's main role?

Calmness and relaxation

How do SSRIs work?

Blocking the reuptake so serotonin can bind to nerve cells

What is a neuromodulatory system?

A set of neural networks and at the core a small number of neurones in the brainstem

How are neurotransmitters secreted?

By a small group of neurones in large areas of the nervous system

What is the noradrenergic locus coeruleus involved with?

Regulation of attention, arousal, learning, memory, anxiety, pain, mood

What are the two parts of the serotonergic raphe nuclei?

Caudal nuclei and rostral nuclei

How does the caudal nuclei work?

Innervate the spinal cord for pain related sensation

How does the rostral nuclei work?

Innervares the brain for the sleep wake cycle and regulation of the sleep stages

What is the serotoneric raphe nuclei implicated in?

Control of mood and emotions

What is the cholinergic basal forebrain involved with?

Arousal, sleep wake cycle, learning and memory

How do neurones project in the dopaminergic substantia nigra?

From the substantia nigra to the striatum to control voluntary movement

How does the ventral tegmental area project in the dopaminergic substantia nigra?

To the frontal cortex areas of the limbic system for reward system

What is dopamine involved in?

The reward system associated with pleasure and euphoria increasing the odds that we will repeat the activity

What happens after a period of use for dopamine?

Tolerance and a decrease in dopamine receptors

What are hormones?

Molecules secreted by endocrine glands that travel in the bloodstream to influence organs or glands

What are the features of hormonal communication?

Long lasting effects, produced in small amounts, interaction with other hormones, influence behaviours, many affect different body parts

What is the endocrine system?

The glands of the body where hormones are produced

What does the endocrime system help?

Regulation of organs, maintaining of homeostasis

Where is the hypothalamus located?

Below the thalamus forming the walls of the third ventricle

How is the hypothalamus divided?

Into several nuclei that have specific functions

Where is the pituitary gland?

Connected to the base of the hypothalamus

What are the three zones of the hypothalamus?

Lateral, medial and periventricular

What part of the hypothalamus is the most connected to the pituitary?

The periventricular

What does the hypothalamus control?

Circadian rhythms and organs via the autonomic nervous system

What does the hypothalamus integrate?

The somatic and visceral responses in accordance with the needs of the brain

What is homeostasis?

The maintaining of the body's internal environment in a narrow physiologic range such as temperature, pH and oxygen levels

What does the pituitary gland do?

Production of many hormones to stimulate other glands to produce hormones

What are the pituitary gland two divisions?

Posterior and anterior

How is the posterior pituitary gland connected?

To the hypothalamus

Where are neuro-hormones produced?

In the magnocellular hypothalamus which is release at the pituitary

What is the posterior PG main hormone release?

Oxytocin and vasopressin

What does oxytocin do?

Uterine contractions and lactation

What is oxytocin triggered by?

Somatic, visual or auditory stimuli

What does vasopressin do?

Stimulate ADH

How is vasopressin regulated?

By blood volume and pressure

What hormones are implicated in forming romantic attachments

Oxytocin and vasopressin

How is oxytocin released? (Romantic formation)

In response to social bonding and physical intimacy

What does the release of oxytocin cause? (Romantic formation)

Feelings of trust, closeness, emotional bonding

What is vasopressin linked with? (Romantic formation)

Pair bonding and attachment in humans

How does vasopressin influence people? (Romantic formation)

A person's preference for a specific partner and the commitment to a relationship

What does vasopressin contribute to? (Romantic formation)

The maintenance of a long term relationship

How is the anterior pituitary gland connected?

To the pituitary

What do parvocellular neurosecretory cells release?

Tropic actors to cause the production of hormones

What are examples of hormones produced from tropic actors?

ACTH (adrenal cortex control), FSH (growth of ovary follicles/sperm), growth hormone (growth of cells), LH (increase in testosterone)

What is the main stress response system?

Hypothalamic-pituitary-adrenal axis

What is the process where hormones effect stress?

1. Hypothalamus releases CRH in response to stress. 2. In response to CRH, the pituitary releases ACTH 3. ACTH stimulates the adrenal glands, in response to ACTH the adrenal glands release cortisol into the bloodstream 4. Cortisol prepares the body for the stressor by increasing energy production and suppressing non essential functions 5. Cortisol provides negative feedback to the hypothalamus and pituitary to stop releasing CRH and ACTH

What is the signals, pathways, speed of information, duration of effect, type of action and response and the target for the nervous system?

Electrical (action potentials) Transmission by neurones Fast Short-lived Voluntary or involuntary Localised (to cells connected to neurones)

What is the signals, pathways, speed of information, duration of effect, type of action and response and the target for the endocrine system?

Chemical (hormones) Transported by the blood Slow Short or long-lived Involuntary Distant (many cells can be effected)