Subcortical structures are a group of diverse neural formations deep within the brain, which include the diencephalon, pituitary gland, limbic structures and basal ganglia. They are involved in complex activities such as memory, emotion, pleasure, and hormone production. They act as information hubs of the nervous system, as they relay and modulate information passing to different areas of the brain." - Source

Here is a superior view of the subcortical (below-the-cortex) structures, aka, the peach pit. 

https://www.youtube.com/watch?v=Na_4HZLvFiM

The video above reviews the thalamus, hypothalamus, epithalamus, and subthalamus 

The thalamus is going to send sensory information from the sense organs to the appropriate cortical lobe (acting as the switchboard) to make sure sensory information gets where it needs to go. For example, the thalamus will route visual signals from the eyes to the occipital lobe for processing, etc. 

The epithalamus contains the pineal gland. Nuclei within the epithalamus also send signals to the limbic system responsible for emotion. 

The hypothalamus directly controls the release of hormones from the pituitary gland; (it does this by releasing its hormones in a downstream axis. It helps to regulate body temperature (sweating and shivering), the sensation of hunger/satiety, thirst, and the internal clock or circadian rhythm. 

The subthalamus is ventral to the thalamus and, confusingly, contains the subthalamic nucleus as one of its components. Technically, the STN is part of the basal ganglia. We aren't going to go into immense detail - but for now, it is helpful to know that the subthalamus helps to regulate movement.

Maintaining Homeostasis

Four F’s

Endocrine regulations of growth, metabolism, and reproductive organs

Autonomic Regulation

Regulation of circadian rhythms (suprachiasmatic nuclei)

Master gland:

Growth Hormone Releasing Hormone

Growth Hormone Inhibiting Hormone

Thyrotropin Releasing Hormone

Corticotropin Releasing Hormone

Gonadotropin-Releasing Hormone

Prolactin Releasing Hormone

Prolactin Inhibition Hormone

Diabetes Insipidus: The regulation of urine production occurs in the hypothalamus, which produces ADH (Antidiuretic (ADH) in the supraoptic and paraventricular nuclei. After synthesis, the hormone is transported in neurosecretory granules down the axon of the hypothalamic neuron to the posterior lobe of the pituitary gland where it is stored for later release.

Posterior Pituitary Gland

Antidiuretic Hormone (ADH) / Vasopressin

Increases water absorption in the kidneys.

Affects drinking behavior to regulate fluid balance.

Produced by osmoreceptor cells in the Paraventricular and Supraoptic nuclei of the hypothalamus.

Released in the posterior pituitary and transported to target organs via capillaries.

Oxytocin

Induces uterine contractions during childbirth.

Triggers breast milk ejection during lactation.

Released during bonding experiences.

Originates from the hypothalamus and is stored and released by the posterior pituitary gland.

Anterior Pituitary Gland

Thyroid-stimulating hormone (TSH)

Basics

Also known as thyrotropin.

It is stimulated by thyrotropin-releasing hormone (TRH) from the hypothalamus.

It is inhibited by somatostatin from the hypothalamus.

TSH stimulates the thyroid gland to secrete thyroxine (T4) by binding to G-protein-coupled receptors (GPCRs) on thyroid cells.

Disorders

Hyperthyroidism (Graves' Disease):

The immune system attacks the thyroid gland, causing overproduction of thyroxine (T4).

Symptoms: protrusion of eyes, reddish skin on lower legs, fatigue, insomnia, weight loss, increased appetite, excessive urination, and impaired kidney function.

Hypothyroidism (can be caused by autoimmune Hashimoto’s disease, but not always):

Symptoms: fatigue, cold sensitivity, constipation, dry skin, puffy face, brittle nails, hair loss, tongue enlargement, weight gain, muscle and joint pain, weakness, menstrual irregularities, depression, and memory lapses.

Increased TSH - since the APT is trying to send a message to the thyroid to produce more hormones

Some individuals have conversion disorders from T4 —> T3, the active version of the hormone.

Adrenocorticotropic Hormone (ACTH)

Basics

ACTH acts on adrenal cortex cells, stimulating them to produce glucocorticoids (like cortisol), mineralocorticoids (like aldosterone), and androgens (like testosterone).

Glucocorticoids raise blood sugar levels by stimulating gluconeogenesis in the liver.

Cortisol plays a role in glucose metabolism, blood pressure regulation, insulin release, immune function, and inflammatory response.

Effects of Cortisol

Positive Effects (Small increases):

Energy burst, heightened memory, increased immunity, lowered pain sensitivity, maintenance of homeostasis

Adverse Effects (High or Protracted levels):

Impaired cognitive performance, suppressed thyroid function, hyperglycemia, decreased bone density, muscle tissue loss, hypertension, lowered immunity, slow wound healing, increased abdominal fat, risk of heart attacks, strokes, metabolic syndrome, and cholesterol imbalances

Disorders

Cushing Syndrome:

Often caused by hypersecretion of ACTH.

Symptoms: severe fatigue, weak muscles, high blood pressure, high blood glucose, and increased thirst.

Prolactin -lactation

Growth Hormones (GH)

Body growth, insulin-like growth factor 1

Basics

Controlled by Growth Hormone-Releasing Hormone (GHRH) or Growth Hormone-Inhibiting Hormone.

Human Growth Hormone (HGH; also known as somatotropin).

GH-secreting cells are stimulated by the intermittent arrival of GHRH from the preoptic and anterior hypothalamus.

GH promotes body growth by binding to liver cell receptors, stimulating them to release Insulin-Like Growth Factor-1 (IGF-1; also known as somatomedin), which acts directly on the ends of the long bones to promote growth.

Disorders

In Childhood:

Hyposecretion leads to stunted but well-proportioned growth (small stature).

Hindered growth can result from an inability to respond to GH due to:

Mutant genes encoding GHRH or GH receptors.

Homozygosity for a disabling mutation in STAT5b, part of the downstream signaling after GH binds its receptor.

Hypersecretion leads to gigantism.

In Adults:

Hypersecretion of GH or GHRH leads to acromegaly, characterized by enlargement of hands, feet, nose, lips, ears, and a general thickening of the skin. Other symptoms include a thick, deep voice, slowed speech, generalized skull expansion, pronounced brow protrusion, and ocular distension.

Gonadotropins

Luteinizing hormone – ovulation, progesterone, testosterone

Follicle Stimulation hormone – follicle, estrogen, sperm