Download presentation
Presentation is loading. Please wait.
Published bySharlene Floyd Modified over 8 years ago
1
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chapter 16 The Endocrine System Part B
2
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Major Endocrine Organs: Pituitary (Hypophysis) Pituitary gland: Two-lobed organ Secretes nine major hormones Neurohypophysis: Posterior lobe (neural tissue) & the infundibulum Receives, stores, & releases hormones (from the hypo- thalamus) Adenohypophysis Anterior lobe, made up of glandular tissue Synthesizes and secretes a number of hormones
3
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Major Endocrine Organs: Pituitary (Hypophysis) Figure 16.6
4
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pituitary-Hypothalamic Relationship: Posterior Lobe: Is a downgrowth of hypothalamic neural tissue Has a neural connection with the hypothalamus (hypothalamic-hypophyseal tract) Nuclei of the hypothalamus synthesize: Oxytocin Antidiuretic hormone (ADH) These hormones are transported to: The posterior pituitary
5
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Anterior lobe: Is an outpocketing of the oral mucosa Has no direct neural contact with the hypothalamus, but Has (with the hypothalamus) a vascular connection called the hypophyseal portal system: The hypophyseal portal system consists of: The primary capillary plexus The hypophyseal portal veins The secondary capillary plexus PLAY Pituitary-Hypothalamic Relationship
6
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pituitary-Hypothalamic Relationships: Anterior Lobe Figure 16.6
7
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adenophypophyseal Hormones The six hormones of the adenohypophysis: GH (Growth hormone) TSH (Thyroid stimulating hormone) ACTH (Adrenocorticotropic hormone) FSH (Follicle stimulating hormone) LH (Luteinizing hormone) PRL (Prolactin)
8
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adenophypophyseal Hormones Four of the six hormones are tropic (turn on) hormones They are the TSH, ACTH, FSH, and LH They regulate the secretory action of other endocrine glands An additional pituitary hormone has been isolated: Pro-opiomelanocortin (POMC) Can be split enzymatically into: ACTH Opiates MSH
9
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Activity of the Adenophypophysis The hypothalamus regulates the anterior pituitary through: Releasing hormones: Stimulate synthesis & release of hormones Inhibiting hormones: Shut off the synthesis & release of hormones
10
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Growth Hormone (GH) Stimulates: Most cells, but targets: Bone Skeletal muscle Promotes: Protein synthesis Encourages: The use of fats for fuel
11
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Growth Hormone (GH) Hypothalamic hormones that regulate GH include: Growth hormone–releasing hormone (GHRH): Stimulates GH release Growth hormone–inhibiting hormone (GHIH): Also called somatostatin Inhibits GH release
12
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Action of Growth Hormone GH stimulates the following tissues to produce insulin-like growth factors: Liver Skeletal muscle Bone Cartilage GH direct action: Promotes lipolysis Inhibits glucose uptake
13
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Action of Growth Hormone (GH) Figure 16.7
14
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Biol2401.5017 Wed, 04/24/’13
15
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thyroid Stimulating Hormone (Thyrotropin) Stimulates: The thyroid secretory activity Triggered by: Hypothalamic thyrotropin-releasing hormone (TRH) Blocked by: Rising blood levels of thyroid hormones (-ve feedback on pituitary & hypothalamus to block TSH release)
16
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adrenocorticotropic Hormone (Corticotropin) ACTH stimulates: The adrenal cortex to release cortico-steroids Triggered by: Hypothalamic corticotropin-releasing hormone (CRH) in a daily rhythm
17
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Gonadotropins Gonadotropins include: Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) FSH stimulates gamete (egg or sperm) production Absent from the blood in prepubertal boys and girls Triggered by: Hypothalamic gonadotropin-releasing hormone (GnRH) (during and after puberty)
18
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Gonadotropins In females LH works with FSH to cause maturation of the ovarian follicle LH works alone to trigger ovulation (expulsion of the egg from the follicle) LH promotes synthesis and release of: Estrogens and Progesterone
19
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Gonadotropins In males LH stimulates: Interstitial cells of the testes to produce testosterone LH is also referred to as: Interstitial cell-stimulating hormone (ICSH)
20
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Prolactin (PRL) In females, stimulates milk production by the breasts Triggered by: Hypothalamic prolactin-releasing hormone (PRH) Inhibited by: Hypothalamic prolactin-inhibiting hormone (PIH) Its blood levels rise toward the end of pregnancy Suckling Stimulates: PRH release Continued milk production
21
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Posterior Pituitary & Hypothalamic Hormones Posterior pituitary: Made of axons of hypothalamic neurons Stores antidiuretic hormone (ADH) and oxytocin ADH and oxytocin: Are synthesized in the hypothalamus ADH: Influences water balance Oxytocin: Stimulates smooth muscle contraction in breasts and uterus
22
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Oxytocin A strong stimulant of uterine contraction Regulated by a positive feedback mechanism: Leads to increased uterine contractions, ending in birth Triggers milk ejection (“letdown” reflex) in lactating women Synthetic and natural oxytocic drugs are used to induce or hasten labor Plays a role in: Sexual arousal and satisfaction in males and non-lactating females
23
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Antidiuretic Hormone (ADH) Helps avoiding dehydration or water overload by: Preventing urine formation Osmoreceptors: Monitor solute concentrations of the blood With high solutes: ADH preserves water With low solutes ADH is not released, thus causing water loss Alcohol: Inhibits ADH release Causes copious urine output
24
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thyroid Gland The largest endocrine gland Located in the anterior neck Consists of two lateral lobes connected by a median tissue mass called the isthmus Composed of follicles lined with follicle cells Follicle cells produce the glycoprotein thyroglobulin Thyroglobulin + iodine form a colloid filling the follicle lumen The colloid is the precursor of the thyroid hormone Parafollicular (endocrine) cells, produce the hormone calcitonin
25
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thyroid Gland Figure 16.8
26
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thyroid hormone: Major metabolic hormone Consists of two related iodine-containing compounds T 4 – thyroxine T 3 – tri-iodothyronine Thyroid Hormone
27
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Effects of Thyroid Hormone TH is concerned with: Glucose oxidation Increasing metabolic rate Heat production TH plays a role in: Maturation and reproductive capabilities
28
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings A peptide hormone Produced by the parafollicular, or C, cells Lowers blood calcium levels in children Antagonist to parathyroid hormone (PTH) Calcitonin
29
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Calcitonin targets the skeleton, where it: Inhibits: Osteoclast activity (and thus bone resorption) The release of calcium from the bone matrix Stimulates: Calcium uptake Calcium incorporation into the bone matrix Regulated by: A humoral (blood Ca 2+ level) negative feedback mechanism Calcitonin
30
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Parathyroid Glands Tiny glands Embedded in the posterior aspect of the thyroid Contains two types of cells arranged in cords The Chief (principal) cells secrete PTH PTH (parathormone): Regulates calcium balance in the blood
31
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Parathyroid Glands Figure 16.11
32
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PTH release increases Ca 2+ in the blood as it: Stimulates osteoclasts to digest bone matrix Enhances the reabsorption of Ca 2+ & the Secretion of phosphate by the kidneys Increases (indirectly) the absorption of Ca 2+ by intestinal mucosal (thru stimulating vit D activation by the kidneys) Rising Ca 2+ in the blood inhibits PTH release Effects of Parathyroid Hormone
33
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Effects of Parathyroid Hormone Figure 16.12
34
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Break Slide 2401.
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.