Phys 1 Central Endocrine Glands

Endocrine System

A collection of glands that secrete hormones into the blood, regulating physiological processes.

Tropic Hormone

A hormone that stimulates another endocrine gland to release its hormones.

Central Endocrine System

Hypothalamus, anterior pituitary, posterior pituitary.

Factors Affecting Plasma Hormone Concentration

Rate of hormone secretion, rate of hormone removal (metabolism/excretion), binding to plasma proteins, volume of distribution.

Body Mechanisms Changing Plasma Hormone Concentration

1. Negative feedback, 2. Positive feedback, 3. Feedforward mechanisms

Hyposecretion

Insufficient hormone production; can be primary (gland itself is damaged) or secondary (tropic hormone deficiency).

Hypersecretion

Excess hormone production.
Causes include tumors, overstimulation, or genetic disorders.

Hypothalamus

Regulator of the endocrine system; produces hormones that control the anterior pituitary and regulate posterior pituitary hormone release.

Hypophysiotropic Hormone

Hormones produced by the hypothalamus that regulate anterior pituitary hormone secretion.

Posterior Pituitary Hormones

Antidiuretic hormone (ADH), Oxytocin

Vasopressin/Antidiuretic hormone (ADH)

Produced by hypothalamic neurons and stored/released from the posterior pituitary; conserves water by the kidneys and raises blood pressure.

Oxytocin

Produced by hypothalamic neurons and stored/released from the posterior pituitary; Stimulates uterine contraction and milk ejection; plays a role in bonding behavior

Posterior Pituitary Connection

Hormones are produced in hypothalamic neurons and transported along axons for storage and release. An extension of the brain

Anterior Pituitary Connection

Connected via the hypophyseal portal vein system

Anterior Pituitary Regulation

Hypothalamic and target gland hormones

Hypertrophy

increase in cell size

Hyperplasia

increase in cell number

Growth Hormone (GH) Hyposecretion

Causes dwarfism in children

Growth Hormone (GH) Hypersecretion

Causes gigantism in children, acromegaly in adults.

TRH (Thyrotropin-Releasing Hormone)

Produced by the hypothalamus; stimulates the anterior pituitary to release TSH, which then promotes thyroid hormone secretion.

CRH (Corticotropin-Releasing Hormone)

Produced by the hypothalamus; stimulates the anterior pituitary to release ACTH, which then promotes cortisol release from the adrenal cortex.

GHRH (Growth Hormone-Releasing Hormone)

Produced by the hypothalamus; stimulates the anterior pituitary to release GH, promoting growth and IGF-1 production.

Anterior Pituitary Hormone Producing Cells

Somatotrophs, Lactotrophs, Corticotrophs, Thyrotrophs, Gonadotrophs

Posterior Pituitary

stores and releases hormones produced by the hypothalamus (ADH and oxytocin); connected to the hypothalamus via neuronal axons (hypothalamo-hypophyseal tract).

Anterior Pituitary

synthesizes and releases its own hormones (GH, TSH, ACTH, Prolactin, LH, FSH); it is regulated by the hypothalamus via the hypophyseal portal system (capillary network).

Somatotrophs

Anterior pituitary cells that produce Growth Hormone (GH).

Growth Hormone (GH)

Hormone produced by somatotrophs; promotes growth and stimulates IGF-1 release from the liver.

Lactotrophs

Anterior pituitary cells that produce Prolactin.

Prolactin

Hormone produced by lactotrophs; stimulates milk production in the mammary glands.

Corticotrophs

Anterior pituitary cells that produce ACTH (Adrenocorticotropic Hormone).

ACTH (Adrenocorticotropic Hormone)

Hormone produced by corticotrophs; stimulates the adrenal cortex to release cortisol.

Thyrotrophs

Anterior pituitary cells that produce TSH (Thyroid-Stimulating Hormone).

TSH (Thyroid-Stimulating Hormone)

Hormone produced by thyrotrophs; stimulates the thyroid gland to release T3 and T4, regulating metabolism and growth.

Gonadotrophs

Anterior pituitary cells that produce LH (Luteinizing Hormone) and FSH (Follicle-Stimulating Hormone).

Luteinizing Hormone (LH)

Produced by gonadotrophs in the anterior pituitary; in females, triggers ovulation and stimulates estrogen/progesterone production; in males, stimulates testosterone production.

Follicle-Stimulating Hormone (FSH)

Produced by gonadotrophs in the anterior pituitary; in females, stimulates growth and maturation of ovarian follicles; in males, stimulates spermatogenesis.

Cortisol

A steroid hormone produced by the adrenal cortex; Helps regulate metabolism, increase blood glucose, suppress inflammation, and assist the body in responding to stress.