Ch. 13 and Ch. 22 (Male Reproductive Notes Only)
Ch. 13 and Ch. 22 (Male Reproductive Notes Only) BISC-227
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91315 Ch 13 Endocrine System VocabularyKey terms Endocrine system composed of endocrine glands that secrete hormones into the internal environment Endocrine internal secretion Hormones chemical messengers that diffuse from interstitial tissue into the blood stream and act on target cells Paracrine secretions affect only neighboring cells Autocrine secretions affect only secreting cells Exocrine glands secretions that enter tubesducts that lead to the body surface released externally Receptors are proteins or glycoproteins With binding sites for a specific hormone Glycoproteins proteins that contain glycan chains carbohydrate plus protein Steroid hormones lipids that include complex rings of carbon and hydrogen atoms Upregulation increase in the number of receptors due to prolonged decrease in the level of a hormone Downregulation decrease in the number of receptors due to prolonged increase in specific hormone levels Hormonereceptor complex when a steroid or thyroid hormone binds with a protein receptors in the nucleus Aldosterone stimulates sodium First messenger a hormone that combines with the binding site causing the receptor s activity site to interact With other membrane proteins Second messenger biochemical in cell that induces change recognized as a response to a hormone Cyclic adenosine monophosphate CAMP secondary messenger for nonsteroidal hormones Protein kinase activated by CAMP to transfer phosphate groups from ATP to protein substrate molecules Phosphodiesterase deactivates cAMP so cAMP s effects are short lived Diacylglycerol DAG is like CAMP by activating protein kinase leading to a cellular response second messenger Inositol triphosphate 1P3 second messenger that increases calcium ion concentration by stimulating the transport of calcium ions Prostaglandins a paracrine substance that is potent and present in small amounts Halflife indicates the rate of removal of a hormone by the time it takes for half of the hormone molecule to be removed from the plasma Tropic hormones stimulate other endocrine glands to release hormones Neurosecretory cells axons Whose endings enter the posterior lobe of the pituitary gland and secrete into the bloodstream ADH and OT ADH antidiuretic OT oxytocin Somatotrops secretory cell of pituitary gland that releases GH Mamatropes secretory cell of the pituitary gland that releases PRL Thyrotropes secretory cell of the pituitary gland that releases TSH Cortiocotropes secretory cell of the pituitary gland that releases ACTH Gomadotropes secretory cell of the pituitary gland that releases FSH and LH Growth Hormone GH and somatotropin protein that stimulates cells to enlarge and more rapidly divide Somatostatin inhibits secretion of growth hormone Prolactin PRL produces milk Thyroidstimulating hormone thyrotropin controls secretions of certain hormones from thyroid gland Adrenocorticotropic hormone ACTH controls manufacture and secretion of certain hormones from the adrenal gland Corticotropicreleasing hormone CRH released in response to low concentrations of ACTH Folliclestimulating hormone FSH and gonadotropin act on gonads growth and development of follicles that house egg cells in the ovaries and secrete estrogen in males stimulate production of sperm cells in testes Luteinizing hormone LH and gonadotropin promotes secretion of sex hormones in both males and females for essential purposes to release eggs in females GnRH gonadotropinreleasing hormone Antidiuretic vasopressin reduces volume of water that the kidneys excrete Osmoreceptors sense changes in body uids Vasoconstriction blood vessels constrict Oxytocin contracts uterus walls and lets down milk in the breast of a woman Follicular cells singe cuboidal cells of the thyroid gland that line the follicle cavities Colloid clear viscous substance that fills follicle cavities of the thyroid gland Thyroglobulin makes up colloid Extra follicular cells hormonesecreting cells on the outskirts of the thyroid gland cells Thyroxine tetradothyronine T4 secreted by the thyroid Triiodothyronine T3 secreted by the thyroid Calcitonin controls blood calcium and phosphate ions by decreasing the rate at which they leave the bones and enter extracellular uid by inhibiting osteoclasts released by thyroid gland Osteoclasts bone cell that resorbs bone tissue Osteoblasts bone cells that secrete the matrix for bone formation Parathyroid hormone Para hormone increases blood calcium and lowers phosphate in bones kidneys and intestines DIHydroxycholesterol pro vitamin D Hydroxycholecalciferol what vitamin D is first changed to Dihydroxycholecalciferol second edition of vitamin D Adrenal medulla inner layer of the adrenal gland Chromaffin cells cells of the medulla modified postganglionic neuron and preganglionic autonomic nerve fibers that lead directly to CNS Adrenal cortex outer layer of adrenal gland that is divided into 3 layers Epinephrine adrenalin catecholamine that is produced from norepinephrine released by adrenal cortex Norepinephrine noradrenalin catecholamine that is released by the adrenal cortex Corticosteroids steroids produced by the adrenal cortex Aldosterone mineralocorticoid because it regulates concentration of mineral electrolytes like Na and K corticosteroid Reninangiotensin system system that regulates aldosterone secretion Renin enzyme released in reninangiotensin system that reacts with angiotensinogen Angiotensinogen used in reninangiotensin system to regulate aldosterone secretion combines with renin to release angiotensin I Angiotensin II converted from angiotensin I to stimulate release of aldosterone Adrenal androgens sex hormones released by adrenal cortex Pancreatic islets cells of the pancreas Alpha pancreatic hormonesecreting cell that secretes glucagon Beta pancreatic hormone secreting cell that secretes insulin Delta pancreatic hormonesecreting cell that secretes somatostatin Glucagon stimulates liver to breakdown glycogen into glucose Glycogen lysis break down of glycogen Gluconeogenesis building of glucose Insulin promotes facilitated diffusion of glucose through the membranes of cells bearing insulin receptors Somatostatin inhibits secretion of glucagon and insulin Pineal gland secretes melatonin synthesized from serotonin Thymosins affect production and differentiation of certain white blood cells Atrial nature tic peptide hormone secreted by the heart antagonist to aldosterone o Erythroprotein hormone secreted by kidneys that deals With red bloods cell production 0 Stressor causes loss of homeostasis 131 339 Endocrine system release hormones into the bloodstream gt Hormones move to specific target cells gt What do endocrine glands do 132 0 Endocrine glands regulate metabolic processes How 0 0 Control rates of certain chemical reactions 0 Aid in transporting substrates through membranes 0 Regulate water balance 0 Regulate electrolyte balance 0 Regulate blood pressure 0 Play a vital role in reproduction development and growth Larger endocrine glands include pituitary gland thyroid gland parathyroid glands adrenal glands and the pancreas v The two types of hormones are Steroid and Nonsteroidal gt Steroid Hormones These are lipids that include complex rings of carbon and hydrogen atoms They differ by the types and number of atoms attached to the rings and the way they are joined All are derived from cholesterol gt Nonsteroidal Hormones Amines 0 Norepinephrine and epinephrine o Derived from tyrosine 0 Synthesized in the adrenal medulla Protein hormones 0 Composed of links of amino acids folded into molecular structures 0 Include hormones secreted by the parathyroid gland and some from anterior pituitary gland Glycoproteins 0 Certain other hormones secreted from the anterior pituitary gland that consist of carbohydrates joined 0 proteins Peptide hormones 0 Short chains of amino acids O 09 0 Include hormones associated with the posterior pituitary gland and some produced by the hypothalamus I Prostaglandins o Paracrine substances 0 Lipids o Produced in the liver kidneys heart lungs thymus pancreas brain and reproductive organs Actions of hormones gt Exert effects by altering metabolic processes I EX Change enzyme activity or change the rate at which a chemical is transported through a cell membrane gt A greater hormone response is due to more binding gt The receptor number on a target cell can change I Upregulation increase in the number of receptors due to prolonged decrease in the level of a hormone I Down regulation decrease in the number of receptors due to prolonged increase in specific hormone levels Steroid and Thyroid Hormones gt gt Carried in bloodstream but weakly bound to plasma proteins in a way that they are released in quantities sufficient to affect target cells gt Soluble in lipids I Diffuse into cells easily I Enter any cell in the body Insoluble in water gt Slower than nonsteroidal hormones but long lasting gt How steroid and thyroid hormones enter and activate I 1 Once in a cell they will bind with protein receptors usually in nucleus hormone receptor complex I 2 This HR complex binds to specific DNA sequences to activate or repress genes I 3 Transcription of mRNA I mRNA directs protein synthesis Nonsteroidal Hormones gt Bind with a receptor molecule that includes binding to an active site I First messenger a hormone that combines with the binding site causing the receptor s activity site to interact with other membrane proteins I Second messenger biochemical in the cell that induces changes recognized as response to a hormone 0 Use of cyclic adenosine monophosphate as second messenger o Amplified because fewer receptors are needed and enzymes activated can be repeatedly catalyzed quicker gt Sequence of Actions of Nonsteroidal hormone using CAMP I 1 Endocrine gland secretes nonsteroidal hormone I 2 Hormone is carried to target cell I 3 Hormone combines With receptors on the membrane of a target cell to activate G proteins I Adenylate cyclase molecule is activated in the target cell s membrane I 5 Adenylate cyclase converts ATP into cAMP by removing 2 phosphates I 6 cAMP activates protein kinase I 7 Protein kinase activate protein substrates in the cell that change metabolic processes I 8 Cellular changes produce the hormone s effects gt Cellular responses to second messenger activation include altering membrane permeability activation enzymes promoting synthesis of proteins stimulatinginhibiting metabolic pathways promoting cellular movement and initiating secretion of hormones or other substances gt Phosphodiesterase deactivates cAMP so effects are short lived I Means continuing response in a target cell requires a continuing signal from hormone molecules binding receptors to target cells gt Hormones Whose actions require cyclic AMP include releasing hormones from I Hypothalamus I TSH thyroid stimulating hormone I ACTH adrenocorticotropic hormone I FSH follicle stimulating hormone I LH luteinizing hormone from the pituitary gland I ADH antidiuretic hormone from the posterior pituitary gland I PTH parathyroid hormone from the parathyroid gland I Norepinephrine and epinephrine form the adrenal gland I Calcitonin from the thyroid gland I Glucagon from the pancreas gt Nonsteroidal hormones that don t use cAMP as a second messenger are I Diacylglycerol DAG I Inositol triphosphate 1P3 0 Increases calcium ion concentration 0 Stimulates transport of calcium ions inward through the cell membrane inducing the release of calcium ions from cellular storage sites via 1P3 0 The calcium ions Will bine With protein calmodulin and cause alterations I Cyclic guanosine monophosphate 339 Prostaglandins gt Paracrine substances gt Potent and present in small amounts gt Rapidly inactivated and not stored gt Effects of prostaglandins I Dilate blood vessels I Contract smooth muscle of walls of the uterus causing menstrual cramps I Stimulate secretions of hormones from adrenal cortex and inhibit secretion of hydrochloric acid from the walls of the stomach I In uence movements of sodium ions and water in the kidneys I Regulate blood pressure I Male and female reproductive physiology I Promote in ammation 134 Control of Hormonal Secretions 0 v Halflife indicates the rate of removal of a hormonetime is takes for half of a hormone molecule to be removed from the plasma gt Hormones With short halflife usually control functions that turn on and off quickly 339 Hormones are secreted constantly in the urine and broken down by enzymes primarily in the liver gt An increase or decrease in blood levels requires and increase or decrease in secretion of a hormone 339 Control Sources of Hormones gt Hormones are mainly control by negative feedback gt Hypothalamus controls the anterior pituitary gland s release of tropic hormones gt Hypothalamus receives information about the internal environment from neural connections in the cerebrospinal uid because it is located near the thalamus and third ventricle gt The nervous system Will directly stimulate some glands like the adrenal medulla 135 Pituitary Gland 339 Located at the base of the brain v Anterior and Posterior Lobes 339 Anterior lobe secretes GH TSH ACTH FSH LH and PRL v Posterior lobe secretes antidiuretic and oxytocin by neurosecretory cells axons Whose endings enter posterior lobe parts v Hypothalamus and Anterior Pituitary Glands are connected by the hypophyseal portal vein so substances released into the blood by the hypothalamus go directly to the anterior lobe gt Hypothalamus is an endocrine gland that controls other endocrine glands I The only inhibiting hormones released by control of the hypothalamus are prolactin releaseinhibitor hormone and somatostatin v Epithelial tissue of pituitary gland has 5 types of secretory cells gt Somatotropes secrete GH gt Mamatropes secrete PRL gt Thyrotropes secrete TSH gt Corticotropes secrete ATCH gt Gomadotropes secrete FSH and LH I LH in males is sometimes called interstitial cellstimulating hormone ICSH because it affects cells of the testes I Growth Hormone somatotropin is a protein that stimulates cells to enlarge and more rapidly divide Enhances movements of amino acids through cell membrane Increases the rate of protein synthesis Decreases the rate at which cells use carbohydrates Increases the rate at which cells use fats Peak during sleep Controlled by two biochemical from the hypothalamus 0 Growth hormonereleasing hormone stimulates secretion of GH 0 Somatostatin inhibits secretion of GH If there is a high protein deficiency and abnormally low blood glucose concentrations that GH will be secreted I Prolactin Produces milk Too much can disrupt sexual functions in both sexes Under inhibitory control by dopamine from the hypothalamus prolactin release inhibiting hormone When released they hypothalamus likely releases more than one prolactin releasing factor PRF I Thyroidstimulating hormone thyrotropin Glycoprotein Controls secretions of certain hormones from the thyroid gland 0 Can stimulate growth of gland and cause enlarged glands goiter O Adrenocorticotropic hormone controls manufacture and secretion of certain hormones from the cortex of the adrenal gland ACTH gt Regulated by corticotropin releasing hormone CRH which the hypothalamus releases in response to low ACTH I Stress can increase secretion of ACTH by stimulating the release of CRH I Folliclestimulating hormone and Luteinizing hormone Gonadotropins FSH 0 0 9 0 Controls growth and development of follicles that house egg cells and stimulate production of sperm in testes 0 Also stimulate secretion of estrogen LH O Promotes secretion of se hormones in both male and females for the essential purpose to release eggs in females GnRH gonadotropinreleasing hormone starts being secreted at puberty Posterior Pituitary Hormones gt Antidiuretic and Oxytocin I Antidiuretic Reduces the volume of water that the kidneys excrete Helps regulate uids of the body Sufficient concentration contracts certain smooth muscles including blood vessels 0 Antidiuretic is a vasopressin Affects possible because it can bind to 2 different receptors on target cells 0 VI increased concentration of second messenger triphosphate causes an increase in intracellular calcium ions in smooth muscle of the blood vessel walls cause vasoconstriction 0 V2 parts of the kidney s microscopic tubules called collecting ducts bind and activate cAMP causing collecting ducts to resorb water 0 Osmoreceptors sense change in body uids Blood volume also affects ADH secretion 0 A high blood volume stretches walls of certain blood vessels cause volume receptors that signal hypothalamus to inhibit the release of ADH ADH can also be stimulated so that the secretion increases and the kidneys conserve water countering further volume loss Ch 136 Thyroid Gland O 09 Thyroid gland gt 2 large lateral lobes separated by a broad isthmus gt Below larynx gt Anterior to trachea gt Removes iodine from the blood Structure of the gland gt Capsules of connective tissues cover the gland made up of secretory parts I Follicles gt Follicular cells single cuboidal cells that line the follicles I Produces and secretes hormones that are either stored in the colloid or released into nearby capillaries gt Cavities are filled with a clear viscous substance called colloid which consist of thyroglobulin v Thyroid hormones gt 3 gt Affect the cellular metabolic rates of carbohydrates lipids and proteins I Thyroxine tetraodothyronineT 4 I TridothynonineT 3 I Calcitonin discussed later on in notes gt Specifically T4 and T3 hormones increase the rate at which cells release energy from carbohydrates enhance rate of protein synthesis and stimulate breakdown and mobilization of lipids I Maj or determiner of calorie intake needed to maintain homeostasis gt TSH from the anterior pituitary gland controls the levels of thyroid hormones gt Follicular cell hormone production I Require iodine salts I Iodine with amino acid tyrosine is used to synthesize T4 and T3 gt Thyroglobulin production I Includes tyrosine which have iodine attached I T3 has increased free concentrations so it Is more important I T4 makes up 95 percent of concentration of these two hormones 0 T3 is more potent 0 T4 converted into T3 gt 3rd Hormone produced by the Thyroid gland I Calcitonin antagonist to parathyroid gland 0 Controls blood calcium and phosphate ions by decreasing the rate at which they leave bones and enter extracellular uids by inhibiting osteoclasts 0 Increase the rate at which calcium and phosphate ions are deposited in bone matrix by stimulating osteoblasts 0 Increase excretion of calcium ions and phosphate ions by the kidneys 0 Increase blood calcium concentrations 0 Helps prevent prolonged elevation of calcium after meals 137 Parathyroid Gland 339 Secretes hormones that regulate the concentration of calcium and phosphate ions in the blood 339 Structure gt Small yellowbrown gt Secretes parathyroid hormone I Increases blood calcium levels and decreased phosphate in bones kidneys and intestines 0 Stimulates bone resorption by osteoclast and inhibits activity of osteoblasts 0 As bone resorption increases calcium and phosphate are released into the blood Causes kidneys to conserve blood calcium ions and excrete more phosphate ions into the urine Indirectly stimulates absorption of calcium in the intestine by in uencing metabolism of vitamin D 0 Vitamin D from food is stored as pro vitamin D dehydroxycholestorol until the UV rays change it into vitamin D 0 Liver Will change vitamin D into hydroxycholecalciferol store in tissues 0 When PTH is present hydroxycholecalcifereol is changed in the kidneys to active vitamin D dihydroxycholecalciferol Which controls absorption of calcium ions from the intestines 138 Adrenal Glands 0 v 2 parts to each adrenal gland found on each kidney gt Adrenal medulla Cells Within the medulla are connected With the sympathetic division of the autonomic nervous system Chromaffin cells cells of the medulla are modified post and pre ganglionic autonomic nerve fibers that lead them directly to the central nervous system gt Adrenal cortex 3 layers 339 Hormones of the Adrenal Medulla gt Epinephrine and norepinephrine Both types of amine called catecholamine gt Synthesis of catecholamine 0 Begin With amino acid tyrosine Enzyme tyrosine hydroylase in secretory cells catalyzes a reaction that then converts tyrosine into dopa Dopa decarboxylase enzyme catalyzes a reaction that modifies dopa into dopamine Dopamine betahydroxylase catalyzes a reaction that alters dopamine to form norepinephrine Phenylethanolamine Nmethyl tranferase converts norepinephrine into epinephrine o Norepinephrine is mostly stored changed v Hormones of the Adrenal Cortex gt 30 different steroids and several hormones called corticosteroids Aldosterone cortisol and adrenal androgens Aldosterone 0 Mineralocorticoid because it regulates concentrations of mineral electrolytes of potassium and sodium 0 Control of aldosterone secretion is indirectly linked to plasma sodium levels by reninangiotensin system 0 J uxtaglomerular cells respond to changes in blood pressure and plasma sodium concentrations 0 If either is low the enzyme renin will be released and react with the blood protein angiotensinogen to release peptide angiotensin O Angiotensin converting enzyme is found primarily in the lungs blood vessels catalyzed a reaction that converts angiotensin I to angiotensin II 0 When II reaches adrenal cortex it will stimulate the release of aldosterone O ACTH is necessary for adrenal gland to respond to this and other stimuli O Aldosterone is conserving sodium ions and indirectly retaining water by osmosis and thus maintaining both blood sodium concentrations and blood volume I Cortisol o Helps keep blood glucose concentrations within normal range between meals 0 Involves hypothalamus anterior pituitary gland and adrenal cortex 0 Hypothalamus secretes corticotrophinreleasing hormone into the hypophyseal portal veins which carry CRH to anterior pituitary gland to stimulate it to secrete ACTH o ACTH stimulate adrenal cortex to release cortisol O Inhibits release of CRH and ACTH 0 Sex hormones O Adrenal androgens 139 Pancreas 339 Duodenum attaches pancreas to first section of small intestine to transport digestive uids gt Pancreatic islets cells grouped gt 3 hormonesecreting cells I Alpha glucagon I Beta insulin I Delta somatostatin gt Hormones I Glucagon 0 Stimulate liver to breakdown glycogen into glucose glycogenolysis 0 Converts noncarbs like amino acids into glucose gluconeogenesis 0 Stimulates breakdown of fats into fatty acids and glycerol I Insulin 0 Promotes facilitate diffusion of glucose through the membranes of cells bearing insulin receptors adipose tissue skeletal muscles cardiac muscle 0 Increase protein synthesis 0 Store fat 0 Neurons are not dependent of insulin I Somatostatin 0 Inhibit secretion of glucagon and insulin 1310 Other Endocrine Glands 339 Pineal gland gt Secretes melatonin synthesized from serotonin I Melatonin part of the regulation of circadian rhythm patters of repeated actiVities associated With cycles of day and night sleepwake Thymus gt Secrets group of thymosins I Affect the production and differentiation of certain White blood cells 0 Immunity v Ovaries Testes Placenta 339 Heart gt Secretes atrial natriuretic peptide I Lower blood pressure I Antagonist to aldosterone v Kidneys gt Erythropoietin red blood cell production Ch 22 Reproductive Systems VocabularyKey terms 0 Synapsis pairing of chromosomes during Prophase I 0 Spermatozoa sperm cells 0 Cryptorchidism the testes do not drop and cause infertility o Tunica albudinea capsule that encloses each testis o Rete testis channel network of lobules o Epididymis tube for sperm cell maturation 0 Primary spermatocyte first gamete 0 Spermatogenesis formation of sperm cell 0 Spermatids mature into sperm cells divided from primary spermatocytes 0 Spermiogenesis sperm cell maturation o Actosone protrusion at the end of the head of a sperm 0 Hyaluronidase enzyme that enables a sperm to penetrate oocyte layers 0 Citrate nutrient for sperm Within the prostate gland secretion 0 Prostatespeci c antigen PSA enzyme that liquefies semen following ejaculation 0 Corpora cavernos pair of columns located dorsally on the shaft of the penis 0 Corpus spongiosum single ventral area that encloses the urethra 0 Glans penis Where the corpus spongiosum enlarges at the end of the penis 0 Emission movement of uids Within the penis o Inhibin inhibits anterior pituitary by negative feedback Ch 221 Introduction 0 v Reproductive organs produce and nurture sex cells gametes and transport them to sites of fertilization gt Malesperm gt Femaleoocytes 339 Sex cells each have 23 chromosomes compared to 46 found in the rest of the body cells somatic cells 222 Meiosis 0 v Includes 2 divisions 339 First and second meiotic divisions gt First meiotic division meiosis 1 separates homologous pairs different variations but the same genes gt Each homologous pair is replicated into DNA chromatids gt Each chromatid has genetic information associated With that chromosome gt Meiosis II produces haploid cells 339 Frist Meiotic Division gt Prophase I I Microtubules build spindles that will separate homologous pairs 0 Synapsis pairing of chromosomes I Often the chromatids will shareexchange parts leaving chromatids that have genes from both the mother and father gt Metaphase I I Two chromosomes4 chromatids line up with respect to maternal and paternal relations and split gt Anaphase I I Chromosomes split I Halving the chromosome number gt Telophase I I Original cell is divided into 2 I Nuclear membrane from around chromosomes I Nucleoli reappear 339 Second Meiotic Division gt Chromatids become chromosomes gt Malesgametes become 4 sperm cells gt Females 3 cells cast aside as polar bodies and 1 becomes an egg 223 Organs of the Male Reproductive system 0 v Primary sex organs gonads 2 testes 339 Sperm cellsspermatozoa 0 v Secondary sex organs gt Testes I Suspended by a spermatic cord in the scrotum I Descent of Testes 0 Originate from the masses of tissue near the kidneys 0 Month or two before birth the testes will descent tothrough abdominal wall to the scrotum 0 Testosterone stimulates this 0 Gubernaculum cord that aids in dropping the testes 0 Each testes has a ductus vasdeferens blood vessels and nerves which later form the spermatic cord 0 Cryptorchidism the testes do not drop and cause infertility gt Structure of the Testes I Tunica albuginea capsule that encloses each testis 0 Thin layers of connective tissue septa pass into the testis to form 250 lobules by subdividing 0 Each lobule 14 contains coiled seminiferous tubules approximately 70 cm long 0 Unite to form channel network rete testis gt Gives rise to ducts that join to form epididymis gt Epididymis is coiled on the outer surface of testis and becomes ductus deferens O Seminiferous tubules are lined with spermatogenic cells 0 Interstitial cells lie between the seminiferous tubules and producesecrete male sex hormones gt Formation of sperm cells I Also include sustentacular cells sertoli cells 0 Support nourish and regulate spermatogenic cells I Male embryo contains spermatogonia cells which have 46 chromosomes for most somatic cells I Hormones stimulate spermatogonia to go through mitosis and give rise to two cells one that becomes a body cell and the other a primary spermatocyte 0 Spermatogenesis formation of sperm cell 0 Stops at this stage until puberty when new spermatogonia form 0 Puberty is when testosterone causes dividing in primary spermatocytes which then divide into 2 spermatids that mature into sperm cells 0 Sperm cells collect in lumen of each seminiferous tubule then pass through rete testis to epididymis to accumulate and mature gt Structure of sperm cell I Spermiogenesis sperm cell maturation 0 Head of sperm contains nucleus and highly packed chromatin of 23 chromosomes 0 Protrusion at the anterior end called actosone contains enzyme hyaluronidase to penetrate oocyte layers 0 Mid piece has a filamentous core and mitochondria in a spiral 0 Tail has microtubules in the cell membrane 0 Mitochondria provide ATP for tail movement gt Male Internal Reproductive Organs I Epididymis o Tightly coiled tubes 0 Connected to ducts in the testis o Emerges from the top of the testis 0 Secrete glycogen and other substances to support sperm cells and their maturation 0 When immature sperm cells reach the epididymis they are no motile until they travel through the epididymis by rhythmic peristaltic contractions to mature O Sperm do not usually move independently until after ejaculation I Ductus Deferentia o Muscular tube 0 Originates at the lower end of the epididymis to become part of the spermatic cord 0 Ej aculatory duct prostate gland and seminal vesicle unite to form this I Seminal Vesicles 0 Saclike structures each attached to the ductus deferens at the base of the urinary bladder 0 Glandular tissue line the walls that secrete alkaline uid to regulate pH of tubular contents while the sperm travel to the outside 0 Also neutralize acidic secretions 0 Also contains fructose to provide energy to sperm cells and prostaglandins to stimulate muscle contraction of female reproductive organs aiding in movement of sperm cells toward egg cells gt Contents dump into ejaculatory ducts as the sperm move through which increases the volume of uid that is discharged I Prostate Gland 0 Surrounds proximal portion of urethra 0 Just below the bladder 0 Ducts of the gland open into the urethra 0 Secretes milky uid slightly acidic 0 Contains citrate nutrient for sperm prostatespecific antigen PSA an enzyme to liquefy semen following ejaculation I Bulbourethral Gland 0 Secrets mucous from sexual stimulation 0 The mucous cleanses the urethra to get rid of the urine before ejaculation happens I Penis 0 Shaft composed of 3 columns of erectile tissue 0 Pair of dorsally located corpora cavernous and a single ventral corpus spongiosum gt Corpus spongiosum through which the urethra extends enlarges at the end of the shaft to form the glans penis I External urethral orifice o Prepuce foreskin originates posterior to the gland to cover it 0 Circumcision will remove this foreskin 0 Corpus spongiosum enlarges between the cura as the bulb of the penis 339 Erection Orgasm and Ejaculation gt Sexual stimulation gt Parasympathetic neurons release nitric oxide gas by small dilations of small arteries to the penis I Veins are compressed reducing blood ow away from the penis 0 Blood accumulates in vascular spaces within the erectile tissues of the penis O Erection gt Emission movement of all uids within penis I Response to sympathetic impulses 0 Contractions in smooth muscle walls of testicular ducts epididymis ductus deferentia and ejaculatory ducts I As urethra fills with semen sensory impulses are stimulated and erectile columns and contracted 0 Pressure in erectile tissues aids in forcing semen out 0 At the time of ejaculation the posterior pituitary gland releases a burst of oxytocin to aid in movement of sperm by stimulating the epididymis seminiferous tubules and prostate gland 0 Sequence of events happens so bulbourethral glands expel liquid first then prostate then sperm cells finally ejection of uid from seminal vesicles 224 Hormonal Control of the Male reproductive Functions 0 v Hypothalamus and Pituitary Hormones gt FSH stimulates sustentacular cells of the seminiferous tubules to proliferate grow mature and respond to effects of testosterone I Then in presence of FSH and testosterone cells stimulate spermatogenic cells to undergo spermatogenesis to create sperm cells 0 Also secret hormone inhibin inhibiting anterior pituitary by negative feedback preventing the over secretion of FSH gt Male Sex Hormones I Androgens 0 Most interstitial cells of testes produce them but small amounts are produced by adrenal cortex 0 Any androgen that does not reach the target cell goes to the liver to be turned into a form to then be excreted I Testosterone is secreted during fetal development and continues for several weeks after birth then stops and picks back up after puberty gt Actions of Testosterone I First to develop organs I Then to drop testes I Enlarge testes I Secondary characteristics 0 Body hair 0 Enlargement of larynx and thickening of vocal cords With lowering pitch 0 Skin thickens 0 Increased muscular growth 0 Thickening and strengthening of bones 0 Also increases rate of cellular metabolism and red blood cell production by stimulating erythroprotein gt Regulation of Male Sex Hormones I Male climacteric leads to a decrease in sexual function With age