ADSC 2010Exam # 3 Study Guide Lectures: Veterinary Social Work,Reproduction and the Dairy Industry Lecture 22 (March 17)I. Endocrine SystemA. HormonesB. Specific Endocrine Glands1. Pituitary2. Hypothalamus3. Gonads4. Thyroid5. Adrenal Cortex6. Pancreas7. Uterus8. PlacentaII. PituitaryA. Anterior Hormones1. Growth Hormone2. Thyroid Stimulating Hormone3. Adrenocorticotrophic Hormone4. Follicle Stimulating Hormonea. Maleb. Female5. Luteinizing Hormonea. Maleb. Female6. Prolactina. FemaleB. Posterior Hormones1. OxytocinIII. HypothalamusA. Gonadotropin Releasing HormoneB. PIF and PRFC. GHRH and GHIHD. Corticotrophin RHIV. GonadsSteersCull heifersMarket5Herd 1Bull breed AHerd 2Bull breed BReplacement femalesReplacement femalesSteersCull heifersHerd 1Bull breed A1/3 A2/3 B2/3 A1/3 BHerd 3Bull breed COlder cowsCull cows100% of progenyA. Gonadal Hormones1. TestosteroneCurrent Lecture: I. Two Breed Rota-Terminal CrossA. Advantages- Produce replacement females- Heterosis in females- Maximum heterosis in terminal cross calves- Can utilize complementary in terminal cross calvesB. Disadvantages- Only 67% heterosis in females and rotational calves- Requires greater number of animals to implement- Requires greater management inputII. Endocrine System: endocrine glands secrete hormones carried to other parts of the body (target organ/tissues) through the blood-streamA. Hormones: chemical substances that are carried by the blood stream to a target organ and elicit a consistent responseB. Specific Endocrine Glands1. Pituitary (anterior/posterior): base of brain2. Hypothalamus: above pituitary3. Gonads: testes/ovaries4. Thyroid: lobes on sides of larynx5. Adrenal Cortex: close to kidneys6. Pancreas: near duodenum7. Uterus8. PlacentaIII. PituitaryA. Anterior Hormones1. Growth Hormone/GH (protein)- “RBST” (bovine somatrotropin) stimulates growth of bone and muscle2. Thyroid Stimulating Hormone/TSH (glycoprotein)- stimulates thyroid gland3. Adrenocorticotrophic Hormone/ACTH (protein)- stimulates adrenal cortex to secrete corticosteroids (glucorticoids) involved in energy metabolism4. Follicle Stimulating Hormone/FSH (glycoprotein)a. Male- stimulates sertoli cells in testes to initiate spermatogenesis upto secondary spermatocytes b. Female- stimulates granulose cells in ovary to enlarge and develop the follicle on ovary; acts synergistically with luteinizing hormone to stimulate estrogen production5. Luteinizing Hormone/LH (glycoprotein)a. Male- stimulates interstitial cells (leydig cells) of testes to produce testosterone (ICSH) b. Female- stimulates luteal cells on ovary- Ovulation- Formation of corpus Luteum (CL)- Stimulates progesterone production and secretionActs with FSH to produce estrogen6. Prolactin/PRL (Proteina. Female- Initiation and maintenance of lactation (mammary tissue)- Induces maternal behaviorB. Posterior Hormones1. Oxytocin (protein)- stimulates contraction of smooth muscle of uterus and oviduct and thus;- Stimulates transport of sperm and ova- Expulsion of fetus at parturition- Myoepithelial cells in mammary gland to contract and release milk- “milk letdown”IV. Hypothalamus- mainly produces releasing and inhibiting hormonesA. Gonadotropin Releasing Hormone/GnRH (FSHRH/LHRH)- stimulates release of FSH and LH from anterior pituitaryB. PIF and PRF- prolactin inhibiting/releasing hormonesC. GHRH and GHIH (somatostatin)- stimulates release/inhibition of release of growth hormonesD. Corticotrophin RH- stimulates release of ACTH from anterior PituitaryV. GonadsA. Gonadal Hormones: steroid/derived from cholesterol1. Testosterone (T2): produced in leydig cells of testes (interstitial cells)- Stimulates spermatogenesis in the seminiferous tubules- Develops/maintains secondary (accessory) sex glands- Develops secondary sex characteristics- Increases “libido” (sexual desire)- Increase nitrogen retention (^ protein synthesis and muscle growth)Lecture 23 (March 19)I. Gonads ContinuedA. Estrogen (E2): produced in follicles on the ovary and placenta- Stimulates “estrus” behavior: standing heat (receptive to mating)- Maintenance of female secondary sex characteristics- Needed for normal growth of uterus and female reproduction tract- Stimulates duct development in the mammary gland- Interacts with oxytocin and prostaglandin to increase uterine contractibility- Increases nitrogen retention (anabolic effect)B. Progesterone (P4): produced by the corpus Luteum and placenta- Maintenance of pregnancy- Promotes uterine contractions- Acts synergistically with estrogen to stimulate “estrus” behavior- Promotes alveolar growth in the mammary gland- Inhibits LH (ovulation)C. Relaxin: produced by ovary- Relaxation and dilation of cervix during parturition - Relaxation of the pubic symphasis during parturitionII. UterusA. Prostaglandin (PGF2α): causes regression of corpus Luteum and restarts estrous cycleIII. Thyroid GlandA. Triodothyronine (T3) and Thyroxin (T4): needs iodine for normal function- Accelerates all aspects of carb., lipids and protein metabolism- Increase basal metabolic rate and body temperatureIV. Adrenal GlandA. Glucocorticoids: stimulate gluconeogenesis (protein CHO)B. Mineralocorticoids: regulate Na, Ca, and H2O balanceC. Adrenaline (epinephrine) /Noradrenaline (norepinephrine): regulate fight or flight mechanism - Stress energy?V. PancreasA. Insulin and Glucagon- Regulate the passage of glucose in/out of the bloodstream- Diabetes: lack of insulinVI. The Estrous Cycle in Cattle - Ovulation occurs during estrus- Progesterone: blocks estrus cycles in future if pregnant- Dominant follicle grows mid-way through estrus cycle because of FSH peakVII. ChartPuberty (mo.)Estrous cycle Duration of EstrusTime of ovulationlength (d)Cow 6 – 18 21 18 hr 18 – 48 hrEwe 6 – 12 17 30 hr 24 – 27 hr** Mare 20 22 7 days 24 – 48 hrs** Sow 5 – 10 21 60 hr 38 – 42 hr** **prior to end of estrus** Cow ovulates after estrus, everyone else during estrus**REPRODUCTION: MALE ANATOMY**VIII. Testes: two main functionsA. Sperm production: occurs in seminiferous (sertoli cells) tubules/ FSH and T2 regulateB. Androgen (T2) production: occurs in leydig cells / LH regulatesIX. Scrotum: houses and protects testes and regulate temperature- Maintains testicle temperature (3-7°F in bull and 9-13°F lower in ram)- 99-95° ideal for sperm production- Too hot/cold- sperm killed- Tunicadartos (thin muscle of scrotum) and Cremaster
View Full Document