Chapter 16: The Hypothalamus & Pituitary Gland

The hypothalamus is connected to the ______ by stalk called _____.

Pituitary gland (hypophysis), infundibulum

What are the two major lobes of the pituitary gland?

Posterior pituitary and Anterior pituitary

The posterior pituitary is composed of neural tissue that secretes _____. The Anterior pituitary consists of _____ tissue.

Neurohormones, glandular

How does the posterior lobe maintain neural connection to the hypothalamus?

By the hypothalamic-hypophyseal tract

What does the hypothalamic-hypophyseal tract arise from?

Which two neurohormones are secreted by the parietal lobe?

Oxytocin and ADH

Where are oxytocin and ADH stored in?

Paraventricular produce oxytocin and Supraoptic produce ADH

What does the hypothalamus secrete?

Releasing and Inhibiting hormones to anterior pituitary

The hypothalamus regulates hormone secretion of which hormones?

• GHRH and GHIH

• THR

• CRH

• PIH

• GnRH

How is the anterior lobe connected to the hypothalamus?

By the hypophyseal portal system

The posterior pituitary consist of which hypothalamic neurons

Paraventricular and Supraoptic neurons

What does the Paraventricular neurons produce?

What does the Supraoptic neurons produce?

Oxytoxin and ADH are composed of 9 _____.

amino acids

• differs in two amino acids

What is considered a strong stimulant of uterine contractions released during childbirth?

Oxytocin

• (positive feedback mechanism)

Oxytocin is a hormonal trigger for milk _____.

How does oxytocin act as a neurotransmitter in the brain?

Uses PIP₂ calcium second messenger system

The hypothalamus has osmoreceptors which monitor what?

Solute concentrations

In a Antidiuretic hormone (ADH), what will happen if the concentration is too high?

ADH Secretion

Antidiuretic hormone (ADH) targets the kidney tubules to do what?

What is the release of the antidiuretic hormone (ADH) triggered by?

Pain, drugs, and low blood pressure

What does high concentrations of the antidiuretic hormone cause?

Vasoconstriction (vasopressin)

What is the antidiuretic hormone inhibited by?

Alcohol and diuretics

All six hormones of the anterior pituitary are what?

Peptide hormones

All hormones in the anterior pituitary except the growth hormone activates target cells by what?

cAMP second messenger system

Which hormones does the anterior pituitary secrete?

• FSH

• LH

• ACTH

• TSH

• PRL

• GH

Which hormones are produced and secreted by gonadotropic cells?

FSH and LH

What is another name for Growth Hormone (GH), and where is it produced?

Somatotropin; produced by somatotropic cells.

What are the direct metabolic actions of GH?

• Glucose-sparing

• Triggers liver glycogenolysis

• blood levels of fatty acids for fuel

• Encourages protein synthesis

What are glucose sparing actions?

Decreases rate of cellular glucose uptake and metabolism

• has anti-insulin effects

The GH triggers the liver, skeletal muscle and bone to produce what?

Insulin-like growth factors (IGFs)

What do IGFs stimulate?

• Cellular uptake of nutrients

• Forms collagen and deposition of bone matrix

IGFs stimulate cellular uptake of nutrients used to synthesize what?

DNA and proteins needed for cell division

What major targets does the GH stimulate?

Bone and skeletal muscle.

What is GH release or inhibition regulated by?

Hypothalamic hormones on somatotropin cells

What does the Growth hormone-releasing hormone (GHRH) stimulate and triggered by?

Stimulates GH release

• triggered by low blood GH, low blood glucose, and high amino acid levels

What does the Growth hormone-inhibiting hormone (GHIH) inhibits?

Inhibits release, triggered by increase in GH and IFG levels

What hormone stimulates GH release?

Ghrelin (hunger hormone)

What is hypersecretion of GH caused by?

Anterior pituitary tumor

• tumor fucks up GH and makes them grow tremendsly

What does hypersecretion of GH in children result in?

Gigantism

• reaching heights of 8 feet

What does hypersecretion of GH in adults result in?

Acromegaly

• overgrowth of hands, feet and face

What does hyposecretion of GH in children result in?

Pituitary dwarfism

• reach height of only 4 feet.

What does hyposecretion of GH in adults results in what?

usually doesn’t cause problems

What is the function of Thyroid-Stimulating Hormone (TSH)?

Stimulates normal development & Secretory activity of the thyroid gland

What triggers the release of the thyroid stimulating hormone (TSH)?

Thyrotropin-Releasing Hormone (TRH) from the hypothalamus.

What inhibits thyroid stimulating hormone (TSH) secretion?

Rising blood levels of thyroid hormones (negative feedback) & the Growth Hormone-Inhibiting Hormone (GHIH)

What is another name for Adrenocorticotropic Hormone (ACTH) and where is it produced?

Corticotropin; produced by corticotropic cell

What does the Adrenocorticotropic Hormone (ACTH) stimulate?

The adrenal cortex to release corticosteroids

What does the adrenal medulla secrete?

Epinephrine and Norepinephrine

What triggers the release of ACTH?

Corticotropin-Releasing Hormone (CRH) in daily rhythm, highest levels in the morning.

What internal and external factors can alter the release of CRH?

Fever, Hypoglycemia, and Stress

Which gonadotropins are secreted by the anterior pituitary?

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Which cells secrete FSH and LH?

Gonadotropic cells of the anterior pituitary

What does FSH stimulate in both sexes?

Gametes (egg and sperm)

What does the LH promotes the production of?

Gonadal Hormones

What does LH stimulate in males?

Production of testosterone

What does LH in females help with?

• Helps mature follicles of the egg

• Triggers ovulation and release of estrogen and progesterone

Are LH and FSH present in prepubertal children?

No, they are absent from blood in prepubertal boys and girls

What triggers the regulation of gonadotropin release?

Gonadotropin-releasing hormone (GnRH), especially during and after puberty

What suppresses gonadotropin release?

gonadal hormones (negative feedback)

Which cells secrete prolactin (PRL)?

Prolactin cells of the anterior pituitary

Prolactin _____ milk, while oxytocin stimulates milk ______.

produces, ejection

What does prolactin stimulate in females?

Milk production

What hormone primarily controls prolactin?

Prolactin-inhibiting hormone (PIH), also known as dopamine

• bc prevent from prolactin until end or pregancy

What effect does PIH have on prolactin?

Prevents prolactin release until needed

• decreased levels PIH lead to lactation

What happens when PIH levels decrease?

Lactation occurs

What increases prolactin levels and cause breast tenderness during the menstrual cycle?

Rising estrogen levels

Increased _____ levels stimulate PRL.

Estrogen

Do rising estrogen levels during the menstrual cycle cause milk production?

No, they briefly stimulate PRL but do not lead to milk production

When do blood levels of prolactin rise significantly?

Toward the end of pregnancy

What does suckling stimulate?

PRL release and promotes milk production

What hormones are considered Gonadotropins?

FSH and LH