L4, Synapses, Neurotransmitters and Hormones

Question 1

What is a synapse? (what are the different types?)

Answer 1

A synapse is the gap between neurons where signals are passed from one neuron to another. An electrical synapse is a fast and small gap opening ion channels (prevalent in PNS) and chemical synapses are larger with a slight time delay (prevalent in the brain)

Question 2

How are chemical synapses initiated?

Answer 2

They are initiated by an action potential arriving at the presynaptic membrage causing voltage-gated ion channels to open, letting sodium diffuse into the cell as synaptic vesicles fuse with the membrane, releasing neurotransmitters into the synaptic cleft, before they bind to the postsynaptic receptors, opening ion channels and allowing the cell to be depolarised.

Question 3

What is spatial-/temporal summation?

Answer 3

Spatial: multiple neurons sending action potentials at once
Temporal: one neuron sending multiple action potentials at once

Question 4

What three types of receptors are there? (related to neurotransmitters/synapses)

Answer 4

Post-synaptic receptors (selectively bind to neurotransmitters), ionotropic receptors (fast & precise synaptic transmission, opening/closing ion-channels), metabotropic receptors (activating intracellular signaling called second messengers)

Question 5

What is a neurotransmitter?

Answer 5

A chemical released by a neuron that plays a crucial role in transmitting signals between neurons. After the “work” of the neurotransmitter is done, they are recycled in the presynaptic cleft by cells called transporters

Question 6

Give an example of an excitatory/inhibitory neurotransmitter

Answer 6

Excitatory: Acetylcholine (muscle control), Glutamate (learning/memory), serotonin (mood, appetite etc)
Inhibitory: Dopamine (reward system), GABA (gamma-aminobutyric acid)

Question 7

What is a neuromodulatory system?

Answer 7

A set of neural networks in the brain

Question 8

What is a hormone?

Answer 8

Molecules secreted by endocrine glands influence the activity of organs or glands.

Question 9

What is homeostasis? where is it regulated?

Answer 9

homeostasis is regulated in the hypothalamus and maintains the body’s internal environment (temp etc.)

Question 10

What is the endocrine system and the pituitary glands?

Answer 10

Endocrine: includes all glands and the hormones they produce
Pituitary: divided into anterior (production of many hormones, prolactin etc) pituitary glands or posterior (production of oxytocin and vasopressin)