BMSP 2136 Module 16.1 – 16.2 Flashcards

Flashcards based on lecture notes for BMSP 2136 Module 16.1 and 16.2, covering the endocrine system, hormones, and the hypothalamus-pituitary gland axis.

How do the endocrine and nervous systems compare in maintaining homeostasis?

Both use chemicals to communicate, but the nervous system is faster and shorter-lasting, while the endocrine system is slower and longer-lasting.

How do hormones travel through the body?

Hormones are secreted into the interstitial fluid, diffuse into blood capillaries, travel through the bloodstream, diffuse out of the blood in capillary beds, and bind to receptors on target cells.

What are the three types of chemical signals?

The provided text does not have the answer for chemical signals - needs to be from page 587 figure 16.2

What are the two classes of hormones?

Amino acid-based and steroid hormones.

What determines the categories of amino-acid based hormones?

Size (single amino acids, several amino acids, or complete proteins).

Are most amino-acid based hormones hydrophilic or hydrophobic?

Hydrophilic.

From which chemical are steroid hormones derived?

Cholesterol.

Are steroid hormones hydrophilic or hydrophobic?

Hydrophobic (lipid-soluble).

What are free hormones?

Small, amino acid-based hormones that are hydrophilic and able to freely associate with water.

What are bound hormones?

Hormones that form complexes with binding proteins in plasma, usually hydrophobic.

Which hormones typically require protein carriers?

Usually hydrophobic hormones.

What is the purpose of protein carriers for hormones?

Allows hydrophobic hormones to be transported safely through the watery environment of blood, provides a reservoir of hormones, and extends the lifespan of hormones.

What determines the location of hormone receptors?

Whether the hormone is hydrophilic or hydrophobic. Hydrophilic hormones bind to membrane receptors, hydrophobic hormones bind to intracellular receptors.

What is up-regulation?

When target cells make more receptors for a hormone in response to a decline in the hormone level.

What is down-regulation?

When target cells decrease the number of receptors for a hormone in response to prolonged exposure to a high level of the hormone.

Which class of hormones can enter into a cell?

Hydrophobic hormones.

Which class of hormones require a “second messenger” inside the cell?

Hydrophilic hormones.

Define synergists in relation to hormones.

Hormones that act on the same target cell to exert the same effect.

Define antagonists in relation to hormones.

Hormones that act on the same target cells and have opposite effects.

How are hormones removed from the blood?

By the kidneys (eliminated in urine) or liver (broken down by enzymes).

What is half-life of a hormone?

The amount of time it takes for the plasma concentration of the hormone to reduce to half.

Which class of hormones tends to have a longer half-life?

Hydrophobic hormones.

Which class of hormones tends to have a shorter half-life?

Hydrophilic hormones.

List the three types of stimuli that lead to the release of hormones.

Hormonal stimuli, humoral stimuli, and neural stimuli.

Define tropic hormone.

Hormones that control hormone secretion from other endocrine glands.

Define trophic hormone.

Hormones that induce growth in its target cells.

What connects the pituitary gland to the hypothalamus?

The infundibulum.

What are the two components of the pituitary gland?

Anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis).

What is a portal system?

Where capillaries are drained by veins that lead to another set of capillaries.

Describe the hypothalamic-hypophyseal portal system.

Hypothalamic neurons secrete releasing and inhibiting hormones into the hypothalamic capillary bed. These hormones travel through portal veins in the infundibulum to the anterior pituitary capillary bed, where they bind to receptors on anterior pituitary cells and stimulate or inhibit hormone secretion.

Where is ADH produced?

Hypothalamus

Where is ADH stored?

Axon terminals in the posterior pituitary

What organ secretes ADH?

Posterior pituitary

What is the primary function of ADH?

Water retention (increase water retained in kidneys).

Where is oxytocin produced?

Hypothalamus

What organ secretes oxytocin?

Posterior pituitary

What are the effects of oxytocin?

Support reproduction and milk release; targets mammary glands and smooth muscle cells of the uterus.

What are releasing hormones?

Hormones that stimulate the release of hormones from the anterior pituitary.

What are inhibiting hormones?

Hormones that inhibit the release of hormones from the anterior pituitary.

Where are releasing and inhibiting hormones produced?

Hypothalamus

What is the target of releasing and inhibiting hormones?

Anterior pituitary

How do releasing and inhibiting hormones arrive at their target?

Hypothalamic-hypophyseal portal system.

What is the first tier of feedback control in the anterior pituitary hormonal control?

Hypothalamus - releases hormones.

What is the second tier of feedback control in the anterior pituitary hormonal control?

Anterior Pituitary - releases hormones.

What is the third tier of feedback control in the anterior pituitary hormonal control?

Target organs - release hormones.

TSH

Thyroid-stimulating hormone (Thyrotropin), Source: Anterior Pituitary thyrotroph cells, Stimulus for Release: TRH, cold, stress, Target: Thyroid Gland, Effect: Secretion of thyroid hormones

TRH

Thyroid-releasing hormone, Source: Hypothalamus, Target: Anterior Pituitary, Effect: Release of TSH

Somatostatin

Source: Hypothalamus, Target: Anterior Pituitary, Effect: Inhibits the release of GH and TSH

ACTH

Adrenocorticotropic hormone, Source: Anterior Pituitary, Stimulus for Release: CRH from hypothalamus, stress, Target: Adrenal Cortex, Effect: Growth and development of adrenal cortices and release of adrenal steroids and catecholamines

CRH

Corticotropin-releasing hormone, Source: Hypothalamus, Target: Anterior Pituitary, Effect: Release of ACTH

PRL

Prolactin, Source: Anterior Pituitary, Stimulus for Release: Infant sucking at nipple and PRH, Target: Mammary gland cells, Effect: Milk production and the development of mammary glands

PRH

Prolactin-releasing hormone, Source: Hypothalamus, Target: Anterior Pituitary, Effect: PRL (Prolactin) release

PIF

Prolactin-inhibiting factor, Source: Hypothalamus, Target: Anterior Pituitary Gland, Effect: Inhibition of release of PRL from anterior pituitary

LH

Luteinizing hormone, Source: Anterior Pituitary, Stimulus for Release: GnRH, Target: Ovaries and Testes, Effect: Development of gonads, testosterone production, ovulation, production of estrogens and progesterone

GnRH

Gonadotropin-releasing hormone, Source: Hypothalamus, Target: Anterior Pituitary, Effect: Release of FSH and LH

FSH

Follicle-stimulating hormone, Source: Anterior Pituitary, Stimulus for Release: GnRH, Target: Male/female gonads or ovaries/testes, Effect: Testosterone, estrogens production.

GH

Growth Hormone, Source: Anterior Pituitary, Target: Liver, adipose tissue, muscle tissue, bone, and cartilage, Effect: Gluconeogenesis, fat breakdown (lipolysis), protein breakdown, production of insulin-like growth factor (IGF)

GHRH

Growth hormone-releasing hormone, Source: Hypothalamus, Stimulus for Release: Secretion increases during exercise, fasting, stress, and after the ingestion of protein-rich meal, Target: Anterior Pituitary, Effect: Release of GH.

IGF

Insulin-like growth factor, Source: Liver and other target tissues of GH, Target: Every cell in the body, Effect: Stimulates protein Synthesis, growth, and cell division