Unit 4 Lecture 1 Fundementals of Neuro

What is the main function of the Autonomic Nervous System (ANS)?

Helps with homeostasis. Part of the peripheral nervous system

What are the three divisions of the ANS mentioned in the lecture?

Sympathetic, parasympathetic, enteric

The location of ganglia relative to the spinal cord and target tissue in the sympathetic nervous system.

Project to ganglia outside of the spinal cord and brainstem

Synapses between pre- and post-ganglionic neurons in the sympathetic nervous system.

leave the spinal cord and synapse very close with post-ganglionic neurons and to the spinal cord

characteristics of post-ganglionic axons in the sympathetic nervous system.

unmyelinated and extend long distances to the targets. They also have extensive dendritic branching receiving input from many preganglionic fibers (convergence)

all pre-ganglionic neurons in the sympathetic nervous system are

cholinergic

What are the neurotransmitters typically used by post-ganglionic neurons in the sympathetic nervous system? What is the exception mentioned?

Typically noredrinic. The exception is one cholinergic post-ganglionic neuron in the sweat glands

location of ganglia relative to the spinal cord/brainstem and target tissue in the parasympathetic nervous system.

from the brain stem and spinal cord traveling to ganglia very close to target organs

Compare the lengths of pre- and post-ganglionic axons in the parasympathetic nervous system.

Pre-ganglionic axons are long, post-ganglionic axons are short

characteristics of post-ganglionic neurons in the parasympathetic nervous system regarding dendritic branching and innervation.

Have fewer dendrites and are innervated by one or a few pre-ganglionic cells (more one-to-one than sympathetic)

characteristics of post-ganglionic axons in the parasympathetic nervous system.

unmyelinated and very short

What neurotransmitter(s) are used by pre-ganglionic neurons in the parasympathetic nervous system?

Acetylcholine and some peptides

What neurotransmitter(s) are used by post-ganglionic neurons in the parasympathetic nervous system?

Acetylcholine and some peptides

What organs are innervated by the enteric nervous system?

Gastrointestinal tract

What types of acetylcholine receptors are present in the autonomic nervous system?

Both fast and slow acetylcholine receptors

What type of receptors are used for adrenaline in the autonomic nervous system?

G-protein coupled receptors

Where are nicotinic receptors found in the context of post-ganglionic cells in the autonomic nervous system?

Only at the site of pre-ganglionic neurotransmission to post-ganglionic cells

What type of receptors are commonly found on the target organs of the autonomic nervous system?

G-protein coupled receptors

a key characteristic of post-ganglionic axons in both the sympathetic and parasympathetic nervous systems

They are non-myelinated

hypothalamus' primary role in the context of the neuroendocrine system and homeostasis?

integrator that regulates and coordinates basic functions and regulates internal homeostasis

Where is the hypothalamus located anatomically?

Located below the thalamus — divided by the third ventricle

What types of inputs does the hypothalamus receive?

Direct input from sensory systems

How does the hypothalamus connect to the pituitary gland?

Neurons project to the anterior pituitary via the pituitary portal system

Which two hormones are released from the posterior pituitary? Where are these hormones synthesized?

Oxytocin and vasopressin are released from the posterior hypothalamus (posterior pituitary. They are synthesized in the hypothalamus

Describe the pituitary portal system and its function.

a specialized vascular network that connects the hypothalamus to the anterior pituitary gland. Its function to allow transport of hormones from the hypothalamus to the anterior pituitary through the blood

How are hypothalamic hormones typically released?

in pulses

what is the general three-level hormonal system involving the hypothalamus

hypothalamus → anterior pituitary → target endocrine organ

What type of receptors do the first-level hormones from the hypothalamus typically bind to in the anterior pituitary?

G-protein coupled receptors

Define short-loop and long-loop negative feedback in the context of the hypothalamus-pituitary system.

Short loop: Hormone released by the anterior pituitary can inhibit the hypothalamus.

Long loop: Hormone released by the target organ can inhibit both the hypothalamus and the anterior pituitary

List some potential causes of hormone hypersecretion.

Tumors, lack of negative feedback, inappropriate synthesis/degradation

List some potential causes of real or functional hormone hyposecretion.

Lack of releasing/trophic hormones, lack of synthetic enzymes, lack of receptors

What hormones are involved in the hypothalamus-pituitary-thyroid (HPT) axis?

TRH, TSH, T3 and T4

What hormones are involved in the growth hormone axis

GHRH, GH, IGF-1

What hormones are involved in the stress-brain--pituitary-adrenal axis?

CRH, ACTH/ACSH, Corticosterone

What hormones are involved in the brain-pituitary-gonadal axis?

GnRH, LH and FSH, Progesterone and Estrogen / Testosterone

what hormones are involved in the prolactin axis?

TRH, oxytocin, and dopamine, PRH, and Prolactin

How do steroid and lipophilic hormones typically cross cell membranes?

they are able to diffuse into the cell and out of the cell

How are steroid and lipophilic hormones transported in the bloodstream?

They donʼt travel well in blood since they are lipophilic, so they are transported by carrier proteins.

describe the various actions of a steroid hormone in a cell

diffuse across the cell membrane → binding to intracellular receptors (cytoplasmic or nuclear) → translocation of the hormone-receptor complex to the nucleus (if needed) → binding of the complex to hormone response elements on DNA → regulation of gene transcription → subsequent protein synthesis mediating the hormone’s effects.

What are pro-hormones in the context of steroid hormone action?

It is a mechanism where a precursor of a steroid hormone is transported in the bloodstream and then modified into the final steroid hormone once it is within the target cell.