Endocrine Glands Secretion And Action Of Hormones - University Of Babylon
Endocrine Glands Secretion and Action of Hormones
Classic Definition of a Hormone Hormone - Chemical messenger produced by a ductless gland or tissue and carried in the blood/lymph to a target organ where it effects a change in cellular activity. Effector Cell 1 TargetC ell 2 Capillary
Endocrine Glands Hypothalamus Adrenal Gland Kidney Pituitary Located at base of brain Thyroid Parathyroid Testis in Male Ovary
Higher Centers of Brain Control All Hormonal Functions Cerebrum Hypothalamus Third Ventricle Pineal Body Medulla Oblongata Pituitary Stalk Anterior & Posterior Pituitary Cerebellum
Anatomy of Cow Brain Infundibular Stalk Diaphragma sellae Pituitary Spenoid Bone
Control of Endocrine Gland Function Hypothalamic-Pituitary Interrelationships Secreting neurons: GnRH, CRH, TRH, GHRH Hypothalamus Nerve cells which release peptide hormones: Oxytocin, ADH Superior Hypophyseal Artery Hypophyseal Portal Vessels Pituitary Stalk Posterior Pituitary: Anterior Pituitary Adenohypophysis non-neural tissue Release of LH, FSH, ACTH, PRL, GH, TSH Neurohypophysis Nerve endings come directly from hypothalamus Release of Oxytocin or ADH into circulation
Other forms of endocrine action 1) Paracrine - released from effector cell (E) interact with a different target cell (T1). 2) Autocrine - secreted by E interact with original E cell or similar cell types. 3) Juxtacrine -expressed on surface of E and interacts with target cell (T2) via direct cell-cell contact. 4) Intracrine - is not secreted by E and interacts with an intercellular receptor. E T E E T
Ectocrine Flehmen Pheromones: A chemical substance that is liberated by one animal and causes a relatively specific behavior modification in a recipient animal following its chemoreception Lee-Boot effect: Crowded female mice become anestrous when no males are present. Bruce effect: A newly mated female mouse will abort if placed with a strange male (not the previous mate). Dormitory effect: menstrual synchrony in all-females living groups
Structural Classes Amines: – Hormones derived from tyrosine and tryptophan. NE, Epi, T4. Peptides, Polypeptides and Proteins – Polypeptides Chains of 100 amino acids in length. – ADH. Ex: Adrenalcorticotropic Hormone (ACTH) – 39 amino acids – Peptide - Few - Several amino acids Ex: Gonadotropin Releasing Hormone (GnRH) - 10 amino acids Oxytocin - 8 amino acids – Protein hormones: Polypeptide chains with 100 amino acids. – Growth hormone, Insulin, ACTH. – Prolactin - 198 amino acids
Structural Classes Glycoprotein - Protein hormone with carbohydrate molecules - Steroids - Lipids derived from cholesterol – Are lipophilic (fat loving; can diffuse through plasma membrane) hormones. - Ex – testosterone, estradiol, progesteone, and cortisol
Mineralocorticoids, glucocorticoids and steroids are synthesized from cholesterol Cholesterol C27 Pregnenolone C21 Glucocorticoids C21 Mineralocorticoids C21 Androgens C19 Estrogens C18
Hypothalamus Gland Hormone Chemical Principal class functions Gonadotropin-releasing hormone (GnRH) Prolactin-inhibiting factor (PIF) Prolactin-releasing factor (PRF) Corticotropin-releasing hormone (CRH) Peptide (1) FSH and LH release Peptide (1) Prolactin retention Peptide (1) Prolactin release Peptide (1) ACTH release
Anterior pituitary Follicle-stimulating hormone (FSH) Protein Luteinizing hormone (LH) Protein Prolactin Adrenocorticotropin (ACTH) Protein Polypeptide (1) Follicle growth (2) Estrogen release (3) Spermatogenesis (1) Ovulation (2) Corpus luteum formation and function (3) Testosterone release (1) Milk synthesis (1) Release of glucocorticoid
Posterior pituitary Oxytocin Peptide (1) Parturition (2) Milk ejection
Ovary Estrogens (estradiol) Steroid Progestins ("progesterone) Steroid Relaxin Polypeptide Inhibin Protein (1) Mating behavior (2) Secondary sex characteristics (3) Maintenance of female duct system (4) Mammary growth (1) Maintenance of pregnancy (2) Mammary growth ( 1) Expansion of pelvis (2) Dilation of cervix (1) Prevention of release of FSH
Placenta Adrenal cortex Uterus Glucocorticoids (Cortisol) Steroid Human chorionic Protein gonadotropin (hCG) Pregnant mare serum gonadotropin (P.MSG) Protein Estrogens Progestins Relaxin (1)Parturition (2) Milk synthesis (1) LH-like (l)FSH-like (2) Supplementary corpora lutea in mare (See ovary) Prostaglandin F2 (PGF2 ) Lipid (1) Regression of corpus luteum (2) Parturition
Structural Classes Amines: -Hormones derived from tyrosine and tryptophan. NE, Epi, T 4. Peptides, Polypeptides and Proteins -Polypeptides Chains of 100 amino acids in length. -ADH. Ex: Adrenalcorticotropic Hormone (ACTH) -39 amino acids -Peptide - Few - Several amino acids Ex: Gonadotropin Releasing Hormone (GnRH) - 10 amino acids
7/28/2008 3 Components of the Endocrine System There are two types of glands in the human body 1. Endocrine glands 2. Exocrine glands Endocrine glands are ductless glands which secrete their hormones directly into the bloodstream. Exocrine glands release their secretions through ducts or tubes ie.Sweat gg, yg glands, salivary glands and tear glands.
THE ENDOCRINE GLANDS Endocrine glands are ductless glands made up of clusters of secretory cells supported by a reticular fibre framework. Their secretions (hormones) are passed directly into a rich capillary network. Most endocrine glands are encapsulated (e.g. pituitary and thyroid) and thus separate entities, while others are
the apical surface. These exocrine glands are composed of highly specialized epithelial cells and thus are classified as glandular epithelia. Endocrine Glands - Glands that release their products basally, so the secretion goes through the basal lamina, moves into the underlying connective tissue, and enters the vascular system. Endocrine glands .
organs. These glands are known as ENDOCRINE glands. Endocrine glands do not have ducts. Their secretions (hormones) are secreted into the blood stream. There is a specific 'target' organ that the hormone acts on. They composed of secretory cells and rich network of blood capillary . Cells typically aggregate as: Cords and clumps ,,and as follicles.
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Classification of glands: Glands are generally classified into two major groups: Exocrine glands (Gr. Exo, outside, krinein, to separate) release their products onto an epithelial surface, either directly or through a duct e.g; the salivary glands. Endocrine glands (Gr, endon, within, kr
iii)muscle layer iv)loose connective tissue layer under the muscle v)fibrous tissue layer vi)smooth muscle layer vii)conjunctiva. Glands in the Eyelids The glands of the eyelid are: i) meibomian glands –in the tarsal plate. Their secretion forms the oily part of the tear film. ii) glands of Zeis – sebaceous
synthesize and secrete hormones directly into blood and lymph capillaries. By contrast to exocrine glands, such as the salivary, mammary, and sweat glands, which pour their secretions onto a surface of the body by means of ducts, the endocrine glands have no ducts and are therefore sometimes called the ductless glands.
