Upload
aldous-montgomery
View
224
Download
0
Tags:
Embed Size (px)
Citation preview
Endocrine Glands
• Ductless: deliver peptides (hormones) into blood, lymph or tissue fluid
• Produce hormones at a site distant from effected organ/tissue
• Regulate most of body functions
Peptide-Target Systems
The various ways in which peptides reach their targets. A, Neuroendocrine; B, endocrine; C, neurotransmitter, neuromodulator (action on postsynaptic membrane); D, paracrine (localized hormone action). 1, Bloodstream; 2, target cell; 3, synapse.
Hypophysis/Pituitary/Master Gland
Compare & Save
Median sections of the hypophysis of the horse (A), ox (B), pig (C), and dog (D). The rostral extremity of the gland is to the left. 1, Adenohypophysis; 2, intermediate part; 3, neurohypophysis; 4, hypophysial stalk; 5, recess of third ventricle.
Posterior Lobe (Neurohypophysis)
• Part of the hypothalamus (brain = neuro-)• Stores and releases
– Oxytocin (contraction of smooth muscle of uterus and udder myoepithelial cells)
– Vasopression (Vasoconstriction, promotes fluid reabsorption by the kidneys)
– These are produced by the hypothalamus
• Very vascular
Anterior Lobe (Adenohypophysis)
• Grows up from the developing dorsal mouth• Products regulated by the hypothalamus
– Follicle Stimulating Hormone (FSH)– Luteinizing Hormone (LH)– Adrenocorticotropic Hormone (ACTH)– Thyroid Stimulating Hormone (TSH)– Alpha-Melanocyte Stimulating Hormone (MSH)– Prolactin
Pars Intermedia (Intermediate Lobe)
• Lies between anterior and posterior lobes• Doesn’t really do much
Brain-Pituitary-Organ Axis
Organization of the brain–pituitary–peripheral organ axis. TRH, thyrotropin-releasing hormone; CRH, corticotropin-releasing hormone; DA, dopamine; PIF, prolactin-inhibiting factor; GnRH, gonadotropin-releasing hormone; SS, somatostatin; GRH, growth hormone-releasing hormone; ACTH, adrenocorticotropic hormone; TSH, thyroid-stimulating hormone; GH, growth hormone; LH, luteinizing hormone; FSH, follicle-stimulating hormone; PRL, prolactin. 1, Adrenal cortex; 2, thyroid; 3, liver; 4, ovary; 5, testis; 6, mammary gland; 7, median eminence; 8, anterior lobe of pituitary; 9, intermediate lobe of pituitary; 10, neural lobe of pituitary.
Pineal Gland
• Caudal Dorsal brain (in mammals)• Secretes melatonin
– Circadian rhythms– Taken supplementally for sleep and jet lag
• More dorsal and external in reptiles
Thyroid Gland
Compare & Save
The thyroid gland of the dog (A), horse (B), cattle (C), and pig (D). The inset to D illustrates the subtracheal connection in transverse section in the pig. 1, Isthmus; 2, trachea; 3, cricopharyngeus.
Thyroid Gland
• Located adherent to ventral trachea• Respond to Thyroid Stimulating
Hormone (TSH) produced by anterior lobe of pituitary
• Releases Thyroid hormone (thyroxine)– Regulates metabolism and growth
• Small release of Calcitonin (antagonist to parathormone)
Thyroid Gland• Utilizes iodine to make thyroid hormone
– Iodine deficiency causes goiter
• Dogs are prone to hypothyroidism• Cats are prone to hyperthyroidism
Compare & Save
Parathyroid
• Located near, attached to or embedded in the thyroid glands
• Set of 4 (typically)• Regulate Calcium metabolism
– Absorbtion from the gut– Mobilization from the skeleton– Excretion in the urine
• Governed by plasma calcium concentration
Adrenal Glands
Compare & Save
The topography of the canine adrenal glands. 1, 1 , Right and left adrenal glands; ′2, left kidney; 3, aorta; 4, caudal vena cava; 5, phrenicoabdominal vessels; 6, renal vessels; 7, ovarian vein; 8, ureter; 9, bladder.
Adrenal Gland
• Craniomedial to kidneys– Left wraps around aorta– Right wraps around vena cava
• Cortex and Medulla• Cortex produces mineralocorticoids,
glucocorticoids and some sex steroids• Medulla produces epinephrine and
noreprinephrine (“fight or flight”)
Pancreatic Islet Cells
• Located diffusely throughout the pancreas• Produce insulin and glucagon• Insulin drives glucose and potassium into cells• Glucagon also affects carbohydrate
metabolism• Also produce somatostatin, pancreatic
polypeptides, and gastrin
Testicles
Compare & Save
Compare & Save
Testis (horse). 1, Head of epididymis; 2, body of epididymis; 3, pampiniform plexus.
Testis (dog) (140×). 1, seminiferous tubules (showing spermatogenesis); 2, interstitial tissue with androgen-producing (Leydig) cells.
Testicles
• Affected by LH and FSH• Interstitial (Leydig) cells make androgens
– Male sexual functioning– Accessory sex glands– Secondary characteristics– behavior
• Sustenacular (Sertoli) cells make inhibin and activin, which affects FSH synthesis and release
Ovaries
Compare & Save
Specific and functional variations in ovarian morphology. A, Ovary of a cow (monotocous). 1, Mature follicle.
Specific and functional variations in ovarian morphology. B, Ovary of a bitch in a quiet stage.
Ovaries
• Located in dorsal abdomen• Outer layer contains follicles
– Each follicle contains one egg– Follicle development produces estrogen– Follicle ruptures and releases egg
• “scar” where follicle was becomes corpus luteum• Corpora lutea produce progesterone
Placenta
• Present only during pregnancy• Significant species variation• Source of
– Lactogen (mammary development)– Relaxin (prepare pelvis for parturition, helps oxytocin with
expulsion of fetal membranes)
• Prosteglandin produced by empty uterus; (stimulated by oxytocin) promotes regression of CL and initiating next cycle– In pregnancy, fetus produces factor blocking receptivity to
oxytocin, CL remains and pregnancy persisis