The Pituitary Hormones

Chapter 13

Slide 2(c) 2003 Brooks/Cole - Thomson Learning

Fig 13-1b, pg 410

Hypothalamus

Pituitary stalk

Posterior lobe

Intermediate lobe

Pituitary gland

Anteriorlobe

Optic chiasm

Hypothalamic-Pituitary Systems

The pituitary is controlled largely by the hypothalamus: interaction of the nervous and endocrine system.

Three separate glands

Anterior lobe: endocrine, 6 hormones

Intermediate : minor, 1

Posterior : neuroendocrine, 2

Slide 3(c) 2003 Brooks/Cole - Thomson Learning

Fig 13-3, pg 412

To venous circulation

Arterial blood supply

Posterior pituitary

Supraopticnucleus

Paraventricularnucleus

Hypothalamus

Posterior pituitary contains the axons from the neurons that have their cell bodies in the hypothalamus.

Slide 4(c) 2003 Brooks/Cole - Thomson Learning

Fig 13-4, pg 413

Cell bodies of neurons that produce releasing/inhibiting hormones Hypothalamus

Primary capillaries in median eminence

Arterial flow

Releasinghormones

Anteriorpituitaryhormone

LongPortalveins

ANTERIORPITUITARY

Secretory cells that produce anterior pituitary hormones

Anterior pituitary hormonesVenous outflow

Gonadotropic Thyroid-Proactin hormones stimulating ACTH Growth (FSH and LH) hormone hormone

Hypothalamus releases hormones at median eminence and those hormones are carried to anterior via portal vein.

Slide 5

Oxytocin and ADH are synthesized in soma in hypothalamus and released from nerve terminals in post. Pituitary.

Various inputs influence supraoptic and paraventricular neurons to control secretion.

Arterial inflow

Venous outflow

Supraoptic nucleus

Paraventricular nucleus

Cell bodies of neurons that produce posterior pituitary hormones

Posterior pituitary

capillaries

Slide 6

Hypothalamic releasing hormones travel to ant. pit. and control secretion from cells there.

One hypothalamic hormone may control more than one ant. pit. hormone (stim. or inhibit).

Slide 7

Posterior Pituitary Hormones

Effect: water retention by kidneys

Stimulator: 1) an increase in osmolality in blood and ECF 2) a large decrease in blood volume

Antidiuretic hormone (ADH)

Slide 8

Suckling and other stimuli trigger oxytocin release to transfer milk from alveoli to ducts.

Posterior Pituitary Hormones

Slide 9

Anterior Pituitary Hormones

Somatotropes (50%) = GH

corticotropes (20%) = ACTH

thyrotropes (5%) = TSH

Gonadotropes (5%) = LH and FSH

Lactotropes (variable) = Prolactin

Slide 10

LH and FSH (the gonadotropins) :promote production of sperm, egg, and sex steroids.

Prolactin Stimulation of alveolar cells to make milk.Release is controlled by PRF and PIH (DA)

ACTH is controlled by CRH;

Promotion of the synthesis and secretion of cortisol from adrenal cortex

Anterior Pituitary Hormones

Slide 11

(c) 2003 Brooks/Cole - Thomson Learning

Fig 13-5, pg 418

Sleep

6 AMMidnight6 PMNoon

Time of day

Plasma GHconcentration(relative units)

GH is released in pulses, with a major peak during deep sleep before REM.

Growth Hormone

Slide 12

(c) 2003 Brooks/Cole - Thomson LearningFig 13-6, pg 419

Somatomedins

Liver

Growth hormone

Somatotrophs ofAnterior pituitary

Somatostatin(-)

GHRH (+)

Portalvein

Hypothalamus

Sleep centerIn the brain

Chemicalstimuli

Stress centersIn the brain

GHRH and somatostatin in hypothalamus; final pathway for controlling GH

Growth Hormone

StimulatorDeep sleep, low blood glucose stimulationStress

physical traumainfectionpsychological stress

Amino acid (especially, arginine)

InhibitorREM sleepHigh blood glucose stimulation

Slide 13

GH effects: tissue growth (including bone growth)

Anabolic hormone

Growth Hormone

Insulin-like GH effects: liver and muscle protein synthesis;

anti-insulin: inhibits glucose uptake

Slide 14

(c) 2003 Brooks/Cole - Thomson Learning

Fig 13-7a, pg 420

GROWTH HOMONE

MUSCLE LIVER ADIPOSE

Insulin-likeeffects of GH

Anti-insulineffects of GH

Amino aciduptake

Proteinsynthesis

Glucoseuptake

Lipolysis

Decreased adiposity

RNAsynthesis

Glucoenogenesis

Somatomedinproduction

Proteinsynthesis

Glucoseuptake

Increasedmuscle mass

Growth Hormone

Slide 15Fig 13-7b, pg 420

SOMATOMEDINS

CHONDROCYTES OF BONE MANY ORGANS AND TISSUES

Increased lineargrowth

Increased tissue growthIncreased organ size

Collagen synthesis

Protein synthesis

Cell proliferation

Protein synthesis

RNA synthesis

DNA synthesis

Cell size and number

IGF-IIIGF-I

IGF-I stimulates bone growth by stimulating chondrocytes, which make cartilage.

Growth Hormone

Slide 16

SOMATOMEDINS

CHONDROCYTES OF BONE MANY ORGANS AND TISSUES

Increased lineargrowth

Increased tissue growthIncreased organ size

Collagen synthesis

Protein synthesis

Cell proliferation

Protein synthesis

RNA synthesis

DNA synthesis

Cell size and number

IGF-IIIGF-I

IGF-II stimulates tissue growth and repair by stimulating RNA and protein synthesis.

Growth Hormone

Slide 17

Deficiency

Childhood deficiency results in dwarfismAdulthood: not evident symptom

Growth Hormone

Slide 18

Overproduction

Gigantism is childhood GH excess; acromegaly from adulthood GH excess.

Growth Hormone

Slide 19

TSH: stimulates thyroid cell growth and secretion of thyroid hormone

Thyroid-Stimulating Hormone

Slide 20(c) 2003 Brooks/Cole - Thomson Learning

Fig 13-10, pg 422

Larynx

Thyroid gland

Thyroid isthmus

Trachea

The thyroid gland has two large lobes below the larynx, rich blood supply, and large growth capacity

Weight: 10-20 g

Thyroid-Stimulating Hormone

Slide 21

Thyroid-Stimulating Hormone

The thyroid gland consists of cells that are arranged in follicles. In a healthy adult, there are 3 million follicles.

Slide 22

Each thyroid follicle is filled with colloid and major component of colloid is thyroglobulin.

Thyroid-Stimulating Hormone

Slide 23(c) 2003 Brooks/Cole - Thomson Learning

Fig 13-13, pg 424

Tyrosine

Monoiodotyrosine (MIT) Diiodotyrosine (DIT)

T4 (thyroxine)

T3

Thyroxine (T4) and

triiodothyronine (T3) are its main

products; MIT and DIT are minor.

Slide 24

(c) 2003 Brooks/Cole - Thomson LearningFig 13-14, pg 425

Thyroglobulinsynthesis

Basal surface

Amino acids

Thyrogloblulin

Apical surfaceThyroglob-ulin, the T4

and T3

precursor, is a glyco-protein secreted into the colloid. Interstitial fluid

Slide 25

(c) 2003 Brooks/Cole - Thomson Learning

Fig 13-14, pg 425

Iodinetrap

Coupling

Iodination

Iodideoxidation

Thyrogloblulin

Thyroglobulin tyrosine is iodinated to MIT/DIT and coupled to make bound T3 and T4.

Interstitial fluid

Slide 26

(c) 2003 Brooks/Cole - Thomson Learning Fig 13-14, pg 425

Plasma

T3 T4

Deiodeinase

Phagolysosome

Lysosome

Pinocytosis

Follicle cells endocytose some colloid, fuses it with lysosomes, and releases T3 and T4.

Slide 27(c) 2003 Brooks/Cole - Thomson Learning

Metabolismof

carbohydrates,proteins, and fats

Biologicaleffects

Heatproduction

T3 and T4

Thyroidgland

TSH

I-

Anteriorpituitary

TRH

Hypothalamus

Otherbraincenters

Temperature-regulatoryCenters (hypothalamus)

Environmentalinfluences

Hypothalamic-pituitary-thyroid axis

Low temperature hypothalamus TRH

pituitary TSH

thyroid T4/T3

body.

Slide 28

Iodide deficiency low T4/T3

low feedback inhibition high TSH goiter.

Slide 29

T3 is more potent than T4, and

target cells convert T4 to T3.

Slide 30

Thyroid hormones

•Stimulate calorigenesis

•Increase circulatory sensitivity to sympathetic nervous system.

•Increase oxygenation of blood

•Increase

glucose uptake, glycogen formation, lipolysis,

biphasic protein synthesis

Effects of thyroid hormone

Slide 31

Thyroid hormones

• Promote bone growth

• Promote development of nervous system

1. Neural branching

2. Myelinization of nerve

Effects of thyroid hormone

Slide 32

Excess secretion; Hyperthyroidism

Symptom

high metabolism,

High heart rate;

weight loss;

heat intolerance.

Slide 33

Excess secretion; Hyperthyroidism

Slide 34

Excess secretion; Hyperthyroidism

Slide 35

Slide 36

Slide 37

Hypothyroidism

Deficiency of thyroid hormone

Slide 38

Slide 39