Endocrine and Reproductive System PDF

The Endocrine System The Endocrine System regulates homeostasis on a long time scale by releasing and controlling hormones over hours, days, weeks Hormone: chemical released into the blood to regulate distant target cells Endocrinology: the study of hormones and endocrine organs ...

The Endocrine System The Endocrine System regulates homeostasis on a long time scale by releasing and controlling hormones over hours, days, weeks Hormone: chemical released into the blood to regulate distant target cells Endocrinology: the study of hormones and endocrine organs  Endocrine Processes Overall, the major processes that the Endocrine System can regulate: – Reproduction – Growth and Development – Electrolyte, water, nutrient balance of blood – Cellular metabolism and energy balance – Immune defenses  Endocrine Pineal gland Glands Major Endocrine Glands Hypothalamus Pituitary gland – Hypothalamus Thyroid gland – Pituitary Gland Parathyroid glands Anterior Pituitary Posterior Pituitary – Thyroid Gland Thymus – Parathyroid Glands Adrenal glands – Adrenal Glands – Pineal Gland Pancreas Others with partial endocrine function: Gonads Ovary (female) – Pancreas (endocrine Testis (male) portion) – Thymus – Gonads (ovaries and testes) © 2016 Pearson Education, Inc. The Hypothalamus- Neural input Hormonal input Pituitary Axis of Hypothalamus Control (secretes) Hormone 1 Endocrine “chain Hypophyseal portal system of command” – Hypothalamus Anterior pituitary releasing or (secretes) inhibiting hormones Hormone 2 – Anterior Pituitary Systemic circulation tropic hormones – Peripheral Target endocrine gland Endocrine Gland (secretes) hormones Hormone 3 – Target Cells General circulation change in homeostatic factors Target cells Physiologic effect  Hypothalamus – Pituitary: Functional Connections Hypothalamus → Anterior Pituitary – The Hypothalamus secretes hormones which regulate the anterior pituitary Releasing Hormones: increase release/secretion of anterior pituitary hormones Inhibiting Hormones: decrease release/secretion of anterior pituitary hormones Hypothalamus→ Posterior Pituitary The Hypothalamus produces hormones that are stored and released by the posterior pituitary  Hypothalamus-Posterior Pituitary The Posterior Pituitary does NOT produce any hormones, it only stores and releases 2 hormones produced in the hypothalamus: 1. ADH/Vasopressin Hypothalamus 2. Oxytocin Posterior pituitary  ADH/Vasopressin 1. ADH/vasopressin is produced in the hypothalamus, released by the posterior pituitary Target: kidneys, arterioles Function: – conserve water by preventing water release V a s into urine o p r e – contract arteriole smooth s s i n muscle (vasoconstriction) to increase blood pressure Regulation: osmoreceptors in Nephrons Increases A C r a Permeability of t u distal and e s in kidneys r e Collecting i s o V tubules to H2O l a e s s o -t h c r o o n u s tg rh io u c t ib o d n y hypothalamus, atrial (heart) blood volume receptors  Oxytocin – Oxytocin is produced in the hypothalamus, released by the posterior pituitary Target: uterus, mammary O glands, brain x y t Function: o c i – stimulate uterine n contraction during childbirth – promote milk release during breastfeeding Uterus Stimulates S M ta im uterine m m u la r contractions a ty g e l s m a in ld k s e j e c t i o n d u r – maternal behavior, i n g b r e a s t - f e e d i n g bonding, attachment Regulation: birth canal reflexes  Supraoptic nucleus Neurosecretory neuronal cell bodies in hypothalamus 1 (produce vasopressin and oxytocin) Hypothalamus 2 Axons Neuronal terminals in Hypothalamic posterior posterior pituitary (release pituitary stalk vasopressin and oxytocin Capillary into systemic blood) Anterior pituitary 3 Posterior pituitary KEY Systemic = Vasopressin = Oxytocin Systemic venous blood arterial blood in out Vasopressin Oxytocin Hypothalamus- Posterior Pituitary Nephrons in kidneys Arterioles throughout Uterus Mammary glands body Increases Permeability of Causes Stimulates Stimulates distal and Vaso- uterine milk ejection Collecting constriction contractions during breast- tubules to H2O feeding Fig. 18-4, p. 663 Hypothalamus-Anterior Pituitary The Hypothalamus releases 7 hormones that regulate the release of anterior pituitary hormones releasing hormones: increase release of target hormones in the anterior pituitary inhibiting hormones: decrease release of target hormones in the anterior pituitary 1. Thyrotropin- releasing hormone (TRH) 2. Corticotropin-releasing hormone (CRH) 3. Gonadotropin-releasing hormone (GnRH) 4. Prolactin Releasing hormone (PRH) 5. Dopamine/Prolactin Inhibiting Hormone (PIH) 6. Growth Hormone Releasing Hormone (GHRH) 7. Somatostatin/Growth Hormone Inhibiting Hormone (GHIH)  Anterior Pituitary The Anterior Pituitary produces and releases 6 tropic hormones that regulate other endocrine glands 1. Growth Hormone (GH) 2. Thyroid Stimulating Hormone (TSH) 3. Adrenocorticotropic Hormone (ACTH) 4. Follicle Stimulating Hormone (FSH) 5. Luteinizing Hormone (LH) 6. Prolactin (PRL)  Anterior Pituitary Hormones – Growth Hormone (GH): Target: bone and soft tissues, liver Function: growth, protein metabolism, fat breakdown, blood glucose increase – Thyroid Stimulating Hormone (TSH) Target: thyroid gland Function: stimulate T3 & T4 production – Adrenocorticotropic Hormone (ACTH) Target: adrenal cortex Function: stimulate cortisol secretion – Follicle Stimulating Hormone (FSH) Target: ovaries, testes Function: ovarian follicle maturation, estrogen secretion, sperm production – Luteinizing Hormone (LH) Target: ovaries, testes Function: ovulation, estrogen & progesterone secretion, testosterone secretion – Prolactin (PRL) Target: mammary glands Function: breast development, milk secretion  Regulation of Growth Growth of the whole body requires the synthesis of proteins, lengthening of bones, and increasing size and number of cells In children and adolescents, growth is regulated by growth hormone Other hormones can influence growth: – thyroid hormone – insulin – sex hormones (androgens, estrogens) Also influenced by: – genetics – diet – level of stress/chronic disease  Growth Hormone Growth hormone (somatotropin) is a hormone that increases growth and metabolism – amino-acid based produced and released: anterior pituitary Functions: – metabolic functions (throughout life): fat breakdown increased blood glucose – growth functions protein synthesis (muscle mass, cellular growth) bone growth increased cell division Regulation: – hormonal: GHRH, GHIH from hypothalamus, negative feedback of IGF-I and GH – neural: diurnal rhythms (increase with sleep)  Growth Hormone & IGF’s Growth hormones actions to promote growth are mediated by IGF’s (insulin-like growth factors), also called somatomedins IGF’s: peptide hormones – IGF-I: mainly released into blood by liver, local production by individual tissues stimulates soft tissue cell number and cell size stimulates long bone growth negative feedback to anterior pituitary to decrease GH – IGF-II: fetal development, adult role unknown  Growth Hormone Pathway Stimulus: GHRH (hypothalamus) Production & Release: Growth Hormone made and released by anterior pituitary Targets: – liver: produce IGF’s, breakdown glycogen → glucose stimulates soft tissue cell number and cell size stimulates long bone growth – adipose tissue: breakdown fats → fatty acids – all body cells: growth and metabolism, increase amino acid uptake & protein synthesis, reduce glucose uptake (more glucose in blood), increase fatty acid uptake Regulation: – IGF’s → negative feedback on anterior pituitary – GH → negative feedback on anterior pituitary – GHIH (hypothalamus)  Hypothalamus Figure 16.5 secretes growth Growth- Feedback Inhibits GHRH release hormone–releasing promoting hormone (GHRH), and Stimulates GHIH release Anterior and metabolic pituitary GHIH (somatostatin) actions of Inhibits GH synthesis growth and release hormone (GH). Growth hormone (GH) Indirect actions Direct actions (growth- (metabolic, promoting) anti-insulin) Liver and other tissues Produce Insulin-like growth factors (IGFs) Effects Effects Fat Carbohydrate Skeletal Extraskeletal metabolism metabolism Increases, stimulates Reduces, inhibits Increased protein Initial stimulus Increased cartilage Increased Increased blood synthesis, and formation and fat breakdown glucose and other Physiological response cell growth and skeletal growth and release anti-insulin effects proliferation Result © 2016 Pearson Education, Inc. Regulation of growth hormone Factors stimulating GHRH. – Hypoglycemia – Increased amino acids in the blood. – Deep sleep – Increased activity of the sympathetic nerves Factors stimulating GHIH. – Hyperglycemia. – Emotional deprivation – Obesity  Growth Hormone Syndromes hypersecretion of growth hormone: gigantism (whole body enlarged) or acromegaly (enlarged extremities) hyposecretion of growth hormone: dwarfism growth hormone replacement therapy is effective if diagnosed before epiphyseal plate closure GH abuse: bodybuilders, athletes, elderly – minimal evidence for muscle strength or stature increase in adults, can cause fluid retention, joint and muscle pain, © 2016 Pearson Education, Inc. diabetes, cancer  Thyroid Hormone Thyroid Hormones: T3 and T4 are the major metabolic hormones of the body – lipid-soluble, plasma protein bound – T4: tetra-iodothyronine; stored and secreted form – T3: tri-iodothyronine; more potent, biologically active form Produced and released: Thyroid Gland: bow-tie shaped organ located below the larynx Function: increased metabolic rate, increased heat production, increased growth and CNS development, increased SNS activity (stress) Regulation: – hormonal: TRH (Hypothalamus), TSH (Anterior Pituitary), negative feedback – neural: body temperature, stress  Thyroid Hormone Pathway Stimulus: TRH (hypothalamus), TSH (anterior pituitary) Production & Release: made and released by the thyroid gland Targets: – all body cells: – increased metabolism & heat production – increased tissue growth and development – blood vessels: increased SNS receptors to maintain blood pressure Regulation: – T and T negative feedback to hypothalamus and 3 4 anterior pituitary – hormonal inhibition: GHIH, dopamine, glucocorticoids – neural: cold (in infants), stress  Hypothalamus Figure 16.7 Regulation of thyroid hormone secretion. TRH Anterior pituitary TSH Thyroid gland Thyroid hormones Stimulates Target cells Inhibits © 2016 Pearson Education, Inc.  Thyroid Hormone Synthesis Thyroid Hormone is made from the amino acid tyrosine and iodide (I-) Synthesis STEPS: 1) Thyroglobulin with tyrosines synthesized in follicular cells colloid 2) iodide actively transported into follicular cells 3) iodide converted to iodine 4) iodine attached to tyrosine in colloid 5) T3 and T4 made in colloid by attaching to thyroglobulins 6) T3-thyroglobulins and T4 – thyroglobulins back into follicular cells 7) T3 and T4 cleaved from thyroglobulins diffuse into blood follicular cells  Figure 16.9 Synthesis of thyroid Thyroid follicular cells hormone. Colloid 1 Thyroglobulin is synthesized and discharged into the follicle lumen. Tyrosines (part of thyroglobulin molecule) Capillary 4 Iodine is attached to tyrosine in colloid, forming DIT and MIT. Golgi apparatus Rough Thyro- ER Iodine globulin 3 Iodide DIT MIT colloid is oxidized to iodine. Iodide (I−) 2 lodide (I−) is trapped (actively transported in). T4 5 Iodinated tyrosines are T3 linked together to form T3 Lysosome and T4. T4 6 Thyroglobulin colloid is endocytosed and combined T3 with a lysosome. 7 Lysosomal enzymes cleave T4 and T3 from Colloid in T4 thyroglobulin and hormones lumen of T3 diffuse into bloodstream. follicle To peripheral tissues © 2016 Pearson Education, Inc.  T4 to T3 conversion T4 – tetra-iodothyronine: – T4 is the major form of thyroid hormone that is stored and secreted by the thyroid T3 – tri-iodothyronine: – 80% of T3 is made from T4 by removing and iodide in the liver or kidneys, 20% is secreted as T3 by the thyroid gland – T3 is 10 times more potent and the more biologically active form Regulation of thyroid hormones Exposure of cold stimulates the secretion of TRH. Ca2+ ions and diacylglycerol, which eventually leads to TSH release. TSH stimulates cAMP for the production of T3 and T4. Excitement and anxiety greatly stimulate the sympathetic nervous system cause an acute decrease in secretion of TSH.  Thyroid disorders Hyperthyroidism Hypothyroidism T3 and T4 high; TSH is T3 and T4 low ; TSH is low high Symptoms Symptoms – Extreme weight loss. – Extreme somnolence – – Mental sluggishness Inability to sleep – Deepening of voice – Psychic disorders – Endemic Colloid Goiter Muscle weakness. – Deficiency of iodine cause – Tremor of hands. swelling of thyroid gland. Graves’ Disease. Myxedema (adults) – Auto antibodies against – Bagginess under the eyes TSH receptor. and swelling of the face. Exophthalmos Cretinism (infants). – Protrusion of eyeballs – Failure of body growth and by mental retardation.  Thyroid Hormone Syndromes Hyperthyroidism: excess T3 and T4 due to autoimmune disease, tumors. In adults causes high metabolism, sweating, tachycardia, irregular heartbeat, anxiety, protruding eyeballs – Grave’s disease (autoimmune) bulging eyes Hypothyroidism: low T3 and T4 due to lack of iodine in diet, TRH/TSH deficiency, thyroid gland disease in adults causes low metabolism, cold, sluggish, dry skin, puffy eyes, edema – myxedema, cretinism (mental disability) – goiter: enlarged thyroid gland due to iodine deficiency goiter: enlarged thyroid  Calcitonin Calcitonin: reduces blood calcium levels Produced and released: by thyroid gland parafollicular cells Function: inhibits bone breakdown, stimulates calcium storage in bones, reduces blood calcium Regulation: – blood (humoral): increased blood calcium NOTE: not required in humans, if thyroid is removed, little to no effect on patient calcium homestasis  Parathyroid Hormone Parathyroid Hormone: increases calcium in the blood Produced and released: by Parathyroid Glands, 3-4 tiny glands on the posterior side of thyroid Function: increase plasma Ca2+, decreased plasma PO43-, stimulates Vitamin D Regulation: Thyroid – blood (humoral): Ca2+ levels gland in blood, thyroid gland (calcitonin) Parathyroid glands NOTE: required for calcium homeostasis, removal can be fatal  Parathyroid Hormone Pathway Stimulus: low blood calcium Target: – Bone: increase in Ca2+ release from bone fluid to ECF via calcium pumps in osteocytes and osteoblasts increase in bone breakdown, Ca2+ and PO4 release via stimulation of osteoclasts – Kidneys: increase in blood calcium retention via kidneys decrease in blood phosphate via kidney elimination increase in Vitamin D activation by kidneys – Small intestine (Vitamin D needed for calcium absorption in diet) Regulation: – blood (humoral): high Ca2+ in blood directly inhibits parathyroid hormone production and release  Hypocalcemia (low blood Ca2+) Figure 16.12 Effects of parathyroid hormone on bone, the kidneys, and the intestine. PTH release from parathyroid gland Osteoclast activity Ca2+ reabsorption Activation of in bone causes Ca2+ in kidney tubule vitamin D by kidney and PO43– release into blood Ca2+ absorption from food in small intestine Initial stimulus Physiological response Ca2+ in blood Result © 2016 Pearson Education, Inc. Ricketts Mainly occurs in children's. – calcium level slightly depressed. – phosphate level greatly depressed. – Deficiency of vitamin D. Pot belly, bow legs, knock knee, enlarged skull, Pigeon chest and hepatosplenomegaly. Extreme osteoclastic resorption of bone  Adrenal Glands Adrenal Glands: small, capped Adrenal Adrenal glands above the kidneys medulla cortex 1. Adrenal Cortex: outer region 2. Adrenal Medulla: middle region  Adrenal Medulla: Catecholamines Adrenal Medulla: middle region of the adrenal glands Hormones: epinephrine, norepinephrine Target: SNS organ targets Adrenal medulla Functions: enhance sympathetic effects, stress regulation, blood pressure Regulation: sympathetic nervous system Catecholamines (epinephrine and norepinephrine)  Adrenal Cortex: Steroids Adrenal Cortex: outer region of the adrenal glands Steroid Hormones: Adrenal 1) mineralocorticoids cortex (aldosterone) Mineralocorticoids 2) glucocorticoids (cortisol) (aldosterone) 3) sex hormones (androgens) Glucocorticoids (cortisol) and sex hormones (dehydro- epiandrosterone)  Mineralocorticoids (Aldosterone) Mineralocorticoids- primarily aldosterone Fluid Balance: – increases Na+ in the blood, retained from urine – decreases K+ in the blood, eliminated in urine – Water balance follows Na+ increase, blood volume increases, blood pressure increases Aldosterone deficiency is FATAL, due to loss of blood volume. Aldosterone Mineralocorticoid (adrenal cortex hormone)  Gonadocorticoids (Sex Hormones) Sex Hormones: are androgens adrenal cortex is a secondary site of production, gonads are primarily responsible for sex hormones, other tissues can also produce androgens (adipose tissue) – DHEA – mainly from adrenal cortex - weak precursor to testosterone, mainly involved in secondary sex characteristics in females during puberty (growth spurt, hair patterns, sex drive) Dehydroepiandrosterone masculinizing effect in excess (adrenal cortex hormone) – estrogen – mainly from ovaries – testosterone – mainly from testes Androgens Androstenedione (male sex hormones) Testosterone E s t r o ia n d o lie o l  Glucocorticoids (Cortisol) Glucocorticoids: primarily Cortisol Metabolism: – increase blood glucose Cortisol – sequester blood glucose for the brain – increase protein breakdown Glucocorticoid (adrenal cortex hormone) – increase fat breakdown Stress Response: – permissive vasoconstriction via epinephrine/norepinephrine – other effects? Immune Suppression: – blocks inflammation pathways – blocks antibody production  Cortisol Cortisol: maintains blood glucose during fasting, enhances the stress response during trauma and inhibits the immune system – steroid-based hormone Adrenal gland Cortex Medulla Produced and released: by Cortex Adrenal Cortex Function: increases Kidney gluconeogenesis, breakdown of fats to increase fatty acids, breakdown Medulla of protein to increase amino acids, anti-inflammatory and anti-immune effects Regulation: – hormonal: CRH by hypothalamus and ACTH by anterior pituitary – neural: stress  Melatonin Pineal Gland melatonin: induces sleep at night (or in the dark) Produced and released by: The Pineal Gland Function: induces sleep Other Proposed functions: inhibits reproduction, seasonal changes in behavior, antioxidant defenses, anti-aging, increased immune function Regulated – neural: light/dark input from the retina produces melanopsin, cells signal to hypothalamus  Insulin insulin: lowers blood glucose by allowing cells to transport glucose Produced and released by: pancreas Functions: glucose uptake in muscle and fat cells, glycogen storage, inhibit glucose production Regulation: Pancreas – blood (humoral): levels of nutrients in blood – neural: PSNS post-eating (inhibited by SNS) – hormonal: increased by glucagon, epinephrine, thyroxine, glucocorticoids, decreased by somatostatin Fig. 19-15, p. 709 Pancreatic Cells Endocrine portion: Islets of Langerhans are 1% of the pancreas – alpha (α) cells - glucagon – Beta cells (β) - insulin – delta cells (D) - somatostatin – F cells – pancreatic polypeptide Exocrine portion: 99% – acinar cells - digestive enzymes – duct cells – NaHCO3 solution  Insulin Effects Insulin increases during absorptive, post-digestive state of high nutrient intake and facilitates nutrient use and storage – lowers blood glucose production and storage of glycogen in liver and muscle increase glucose transport into cells inhibit glycogen breakdown and gluconeogenesis in liver – lowers fatty acids → storage of fat production and storage of triglycerides increase transport fatty acids into adipose tissue inhibit triglyceride breakdown – lowers amino acids → storage of protein production and storage of protein increase transport of amino acids into cells inhibit protein breakdown  Type I and Type II Diabetes Mellitus Type I Diabetes: lack of insulin secretion from pancreas – can be treated with injected insulin Type II Diabetes: normal insulin secretion, lack of target cell response to insulin, high blood glucose – insulin treatment does not help – diet, exercise high blood glucose due to lack of storage and use of glucose in body cells high glucose elimination in urine, polyuria, dehydration, reduced blood volume, reduced blood flow to brain, other tissues polyphagia – excessive hunger, food intake due to lack of nutrients IN body cells  Glucagon glucagon: increased blood glucose – amino-acid based Produced and released by: pancreas Functions: glucose synthesis, Pancreas glucose release, glycogen breakdown Regulation: – blood (humoral): low levels of blood glucose – neural: stimulated by SNS – hormonal: inhibited by insulin and somatostatin  Glucagon opposes Insulin Glucagon Effects Oppose Insulin: glucagon is increased between meals, during “fasting” states, ensuring brain receives enough glucose – increased blood glucose decreased glycogen production and storage increase gluconeogenesis and glycogenolysis in liver – increased fatty acids and ketones increased lipolysis in adipose tissue increased ketogenesis – decreased protein synthesis inhibit liver protein synthesis increased protein degradation in liver NO effect on muscle protein, NO increase in blood amino acids Regulation of insulin and glucagon Normoglycemia – 80 - 120 mg of glucose per 100 ml of blood. Hypoglycemia – If glucose level decreased to less than 70 mg/100 ml Hypergycemia – When glucose level increased more than 120 mg/100ml Glycosuria – Appearance of glucose in urine due to Hyperglycemia.  Control of Blood Glucose Insulin and glucagon act as antagonistic hormones to control blood glucose levels Most of the time both of these hormones are found in the blood, it is the ratio of the two that determines which is dominant Reproductive Systems  Function of reproductive system Male reproductive system – Spermatogenesis – Synthesis of sex hormones. – Storage. – Transport. Female reproductive system – Oogenesis – Synthesis of sex hormones. – Fertilization. (zygote) – Pregnancy. – Birth. – Lactation. Reproductive system includes Gonads, ducts, accessory glands and external genitalia.  Spermatogenesis Each day about 120 million sperm complete the process of spermatogenesis. A small quantity of these can be stored in the epididymis, but most are stored in the vas deferens.  Sperm Sperm divided into two parts Head – Acrosome hyaluronidase and proteases for penetration of secondary oocyte. – Nucleus 23 highly condensed chromosomes Tail (Divided into four parts) – Neck Contains centrioles form the microtubules for the tail portion to provide locomotion. – Middle piece Contains mitochondria provide energy for motility and metabolism. – Principal piece longest portion of the tail – End piece Terminal portion of tail  Male sex hormones During puberty hypothalamic neurosecretory cells increase their secretion of gonadotropin-releasing hormone (GnRH). Stimulates gonadotrophs of anterior pituitary to increase their secretion of two gonadotropins. luteinizing hormone (LH) (produce principal androgens) – Stimulates Leydig cells to secrete testosterone. Follicle-stimulating hormone (FSH). (necessary for sperm maturation) – FSH and testosterone act synergistically on Sertoli cells to stimulate secretion of androgen-binding protein (ABP). – ABP binds to testosterone, keeping its concentration high in testes. – When sufficient spermatogenesis is achieved, sertoli cells secrete the hormone inhibin to inhibit the secretion of FSH. Function of Androgens – Before birth, it stimulates male pattern of development of reproductive system ducts and the descent of the testes. – Increase muscular mass and skeletal growth. – Wide shoulders and narrow hips. – Growth of facial and chest hair. – increased sebaceous (oil) gland in face (acne formation). – Enlargement of larynx and deepening of the voice. – Anabolic action cause heavier muscle and strong bones.  Function of Accessory Glands Seminal Vesicles (contribute 60% of semen ) – secrete an alkaline, viscous fluid contains fructose, prostaglandins and clotting proteins (fibrinogen). – Prostaglandins contribute to sperm motility, viability and stimulate smooth muscle contractions in female reproductive tract. Prostate gland (contribute 30% of semen) – Secretes a milky, slightly acidic fluid (pH 6.5) contains citric acid, calcium and phosphate ions. Citric acid used for production of ATP in sperm. – Proteolytic enzymes like - prostate specific antigen , pepsinogen, lysozyme, amylase and hyaluronidase. For break down the clotting proteins from the seminal vesicles. Bulbourethral Glands – Secrete an alkaline fluid to neutralize acids from urine in urethra. – Secrete mucus that lubricates the penis and the lining of the urethra.  Properties of Semen Semen is mixture of sperm and seminal fluid. – Volume 2.5 – 5.0 ml. – 50–150 million sperm per mL. (less than 20 million is infertile). – pH of 7.2–7.7 the higher pH due to larger volume of fluid from the seminal vesicles. – Prostatic secretion gives semen a milky appearance. – Bulbourethral glands give it a sticky consistency. Once ejaculated, liquid semen coagulates within 5 minutes due to clotting proteins from seminal vesicles. After 20 minutes, semen reliquefies proteolytic enzymes produced by the prostate to break down the clot. – Abnormal or delayed liquefaction of clotted semen cause complete or partial immobilization of sperm.  Male sexual act Penile erection is the first effect of male sexual stimulation. – The degree of erection is proportional to the degree of stimulation, whether psychic or physical. visual, tactile, auditory, olfactory or imagined. During sexual stimulation, – The parasympathetic impulses, promoting erection. – Parasympathetic stimulation produce nitric oxide cause vasodilation of penile arteries. – the bulbourethral glands to secrete mucus. Ejaculation – Powerful release of semen from urethra to exterior, by sympathetic reflex – smooth muscle sphincter at the base of the urinary bladder closes. The entire period of ejaculation is called the male orgasm.  Function of female reproductive system Female gonads – ovaries – Produce secondary oocytes and hormones, including progesterone and estrogens (female sex hormones), inhibin, and relaxin – Held by ovarian and suspensory ligaments. Uterine or fallopian tube or oviducts. – Transport a secondary oocyte to uterus and normally are the sites where fertilization occurs. The uterus – The site of implantation of a fertilized ovum, development of the fetus during pregnancy and labor The vagina – Receives the penis during sexual intercourse and is a passageway for childbirth. Mammary glands – Synthesize, secrete, and eject milk for nourishment of the newborn  Puberty The period when secondary sexual characteristics begin to develop and potential for sexual reproduction is reached. – Onset of puberty is marked by pulses or bursts of LH and FSH secretion, triggered by a pulse of GnRH. – The hormone, leptin play a crucial role in triggering GnRH. – As puberty advances, hormone pulses occur during day as well as at night, continued for 3-4 years, until adult pattern is established. In females, reproductive cycle occurs once each month from menarche , the first menses to menopause, the permanent cessation of menses.  ovarian cycle Ovum production Occurs in monthly ovarian cycle Part of ovarian cycle – Take place in the time of 28 days. – Follicular phase (preovulatory phase – 14 days) Formation of 1°, 2° and 3° follicles. Ovulation phase – Luteal phase (Post ovulatory phase – 14 days) Formation and degeneration of corpus luteum Degradation of corpus luteum.  Uterine cycle Repeating series of changes in endometrium Continues from menarche to menopause – Have three different phases. Menses (menstrual phase) – Degeneration of endometrium – Menstruation Proliferative phase – Restoration of endometrium Secretory phase – Endometrial glands enlarge and accelerate the rate of secretion.  Structure of uterus The secretory cells of the mucosa of the cervix produce a secretion called cervical mucus, a mixture of water, glycoproteins, lipids, enzymes, and inorganic salts.  Role of hormones GnRH stimulates the release of FSH and LH from anterior pituitary. Follicle stimulating hormone (FSH) – Initiates follicular growth luteinizing hormone (LH) – Stimulates further development of ovarian follicles. – At mid of the cycle, it triggers ovulation and then promotes formation of the corpus luteum. Both FSH and LH stimulate ovarian follicles to secrete estrogens. Stimulated by LH, corpus luteum produces and secretes estrogens, progesterone, relaxin, and inhibin. Hormones involved in ovarian cycle  Phases of Reproductive cycle Duration of cycle is 28 days divided into 4 phases The menstrual phase (Menstruation). – By influence of FSH, Primordial follicles develop into primary follicles and then into secondary follicles. – Menstrual flow from uterus consists of 50 - 150 mL of blood and epithelial cells of endometrium. – Decreased level of estrogen and progesterone stimulate prostaglandins to constrict uterine arteioles – Shedding of entire stratum functionalis of uterus The preovulatory phase (menstruation- ovulation) – Secondary follicle became dominant follicle called mature (graafian) follicle. (follicular phase) – Secretion of estrogen and inhibin decrease the FSH. – Estrogen repair the endometrium produce new stratum functionalis. (Proliferative phase) Ovulation phase Estrogen stimulate GnRH, which stimulate LH and FSH. After the peak of LH surge, causes rupture of the graafian follicle and expulsion of a secondary oocyte into pelvic cavity. Ovulated oocyte usually swept into uterine tube  Postovulatory Phase In ovary (Time between ovulation and onset of next menses) – The mature follicle collapses, with minor bleeding of ruptured follicle, becomes corpus hemorrhagicum. – Theca interna cells and granulosa cells mix and transformed into corpus luteum cells under the influence of LH. Corpus luteum secrete estrogens, progesterone, relaxin and inhibin. (luteul phase). In uterus – Secretory activity of the endometrial glands, which begin to secrete glycogen (Secretory phase). – If Fertilization not occur, levels of progesterone and estrogens decline due to degeneration of the corpus luteum. Menstrual cycle  Pregnancy Sequence of events that begins with fertilization, proceeds to implantation, embryonic and fetal development, ends with birth about 38–40 weeks later, after last menstrual period. Prenatal development is the time from fertilization to birth. – Includes both embryological and fetal development. Divided into three periods of three calendar months. 1. First trimester – The rudiments (incompletely developed) of all major organ systems appear. 2. Second trimester – The nearly complete development of organ systems. 3. Third trimester – A period of rapid fetal growth.  Hormones of Pregnancy hCG detected in blood of a pregnant woman in 6 days after conception It has the similar function like the luteinizing hormone  Labor or Giving birth or Parturition Process by which the fetus is expelled from the uterus through the vagina. End of gestation, levels of estrogens in mother’s blood rise sharply stimulate oxytocin and relaxin and prostaglandins from placenta. – Oxytocin stimulates uterine contractions. Contract myometrium more forcefully. – Relaxin increase the flexibility of pubic symphysis and dilate the uterine cervix. – Prostaglandins, induce production of enzymes that digest collagen fibers in cervix, causing it to soften. True labor can be divided into three stages  Three stages of labor Stage of Dilation (6-12 hrs). – Contractions of the uterus, rupturing of amniotic sac and complete dilation (to 10 cm) of the cervix. Stage of expulsion (10 minutes to several hours). – The time from complete cervical dilation to delivery of baby is the stage of expulsion. Placental stage (5–30 minutes). – The time after delivery until the placenta or “afterbirth” is expelled by powerful uterine contractions.  Lactation Secretion and ejection of milk from mammary glands. Prolactin levels increase as pregnancy progresses, no milk secretion occurs because progesterone inhibits the effects of prolactin. After delivery, levels of estrogens and progesterone decreased and the inhibition is removed. Suckling initiates nerve impulses from stretch receptors in the nipples to hypothalamus to release of prolactin. First few days after birth, the mammary glands secrete a cloudy fluid called colostrum. – Contains less lactose, no fat and maternal IgA antibodies. – Lactation often blocks ovarian cycles for the first few months following delivery. Regulation of lactation CLASS DISMISSED THANK YOU !!!