Endocrine Glands And Their Hormones 7M

hormones of anterior pituitary

• hormones synthesized in cells of ant. pituitary (its own)

• hormones secreted: protein

• transported in blood, so have a life span of minutes

• bind to membrane-bound receptors on target cells

• mostly, each hormone is secreted by a diff. cell type

• mostly “tropic hormones”

anterior pituitary list of hormones

1. growth hormone (GH)

2. thyroid-stimulating hormone (TSH)

3. adrenocorticotropic hormone (ACTH)

4. gonadotropins - (LH & FSH)

5. prolactin

6. melanocyte-stimulating hormone (MSH)

growth hormone (GH)

• stimulate bone, muscle, organ growth by increased gene expression

• slows protein breakdown during periods of food deprivation and favors lipid breakdown

• GF increase, insulin-like growth factor (IGF) or somatomedins secretion increase in liver tissue

growth hormone conditions

1. pituitary dwarf - GH deficiency

2. giantism - excess GH before epiphyseal plate close (+ length)

3. acromegaly - excess GH after epiphyseal plate close (+diameter)

thyroid-stimulating hormone (TSH)

• bind to membrane-bound receptors on cells of thyroid gland

• stimulate secretion of thyroid hormones

• stimulate growth of thyroid gland

• decrease TSH smaller thyroid gland, increase TSH enlargement of thyroid gland

• regulated by hormones from hypothalamus

adrenocorticotropic hormone (ACTH)

• bind to membrane-bound receptors on cells of adrenal cortex

• increase secretion of cortisol

• bind to melanocytes on skin

• increase skin pigmentation

• required to keep adrenal cortex from degeneration

• regulated by hormones from hypothalamus

another name for cortisol

hydrocortisone

gonadotropins - (LH & FSH)

• bind to membrane-bound receptors on gonad cells

• regulate growth, development, and function of gonads

• without these, ovaries and testes decrease in size;

• no production of oocytes and sperm cells;

• no hormone secretion

• regulated by hormones from hypothalamus

luteinizing hormone (LH)

in females:

• stimulates ovulation

• promote secretion of estrogen and progesterone

in males:

• stimulate interstitial cells of testes;

• to secrete testosterone

follicle-stimulating hormone (FSH)

in females:

• stimulate development of follicles in ovaries

in males:

• stimulate development of sperm cells in testes

prolactin

• bind to membrane-bound receptors on breasts

• promotes development of breast

• stimulate milk production following pregnancy

• principal control: dopamine/prolactin-inhibiting factor

• plays a role in homeostasis: regulation of ion composition of blood and immune function

• regulated by several substances released from hypothalamus

melanocyte-stimulating hormone (MSH)

• bind to membrane-bound receptors on melanocytes

• stimulate melanin production

• increase skin pigmentation like ACTH

• regulated by hormones from hypothalamus

hormones of the posterior pituitary list

1. antidiuretic hormone (ADH) vasopressin

2. oxytocin

antidiuretic hormone (ADH) vasopressin

• binds to membrane-bound receptors

• increase water reabsorption by kidney tubules

• cause blood vessels to constrict when released in large amounts

• reduced ADH = large amounts of dilute urine

• condition: diabetes insipidus

diabetes insipidus

• production of large amounts of dilute urine

• excess water loss from blood

• increased concentration of body fluids and electrolytes lost ex. Ca²⁺, Na⁺, and K⁺

• alcohol inhibits ADH secretion so drinkers are prone for short-term effect to keep alc in system and water out

oxytocin

• binds to membrane-bound receptors

• cause contraction of smooth muscle cells of uterus

• cause milk letdown from breasts in lactating females

• pitocin

  • commercial preparations of oxytocin

  • given under certain conditions to assist in childbirth to constrict uterine blood vessels following childbirth

thyroid gland

• one of the largest endocrine glands

• lobes are on each side of trachea, inferior to larynx, connected by isthmus in the middle

• highly vascular, surrounded by connective tissue capsule

• contains thyroid follicles, parafollicular cells c cells

• requires iodine to produce thyroid hormones

thyroid gland synthesizes and secretes three (3) hormones

1. triiodothyronine (T₃) - 3 iodine atoms

2. thyroxin tetraiodothyronine (T₄) - 4 iodine atoms

3. calcitonin

thyroid follicles

• small spheres

• walls composed of simple cuboidal epithelium that store and produce thyroid hormones (T3 and T4)

• has protein: thyroglobulin inside

thyroglobulin

a protein inside thyroid follicle where thyroid hormones attach

thyroid hormones

attach to nuclear receptors in their target cells and regulate metabolic rate of the body

parafollicular cells or c cells

• between thyroid follicles are a network of loose connective tissue containing capillaries and scattered (parafollicular cells) yay!

• secrete the hormone calcitonin

thyroid hormone secretion

regulated by BOTH hormones from hypothalamus and pituitary

steps in thyroid hormone secretion

cause: stress and hypothermia

1. hypothalamus secrete TSH-releasing hormone (TRH) to ant. pituitary through hypothalamohypophysial portal system

2. TRH travels to ant. pituitary to stimulate secretion of thyroid-stimulating hormone (TSH)

3. TSH cause synthesis and release of T3 and T4 from thyroglobulin into “general circulation”

4. T3 and T4 act on target tissues to produce a response

5. T3 and T4 have inhibitory effects on secretion of TRH from hypothalamus and TSH from ant. pituitary

goiter

• loss of negative feedback in thyroid hormones

• develops if iodine in diet is too low

• less thyroid hormones used = overcompensation of TRH & TSH causing enlargement of thyroid gland

hypothyroidism

• lack of thyroid hormones

• in infants: result in cretinism

• in adults: decreases metabolic rate = low body temperature; weight gain; reduced appetite; lethargy

cretinism

developmental delay, short stature, abnormally formed skeletal structures

hyperthyroidism

• too much thyroid hormones

• causes an increased metabolic rate, extreme nervousness, chronic fatigue

• Graves Disease: autoimmune disease that causes hyperthyroidism

Graves Disease

• autoimmune disease that causes hyperthyroidism

• occurs when immune system produce proteins similar to TSH = overstimulation of thyroid gland

• accompanied by exophthalmia (bulging of eyes)

calcitonin

• binds to membrane-bound receptors of osteoclasts

• inhibit osteoclast activity reducing bone reabsorption

• prevent elevated blood Ca²⁺ levels