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Case 4 Slideshow

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Case 4 Slideshow

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Quick Islamic ReminderHypothalamic-Pituitary-Gonadal Axis Leptin Kisspeptin (Arcuate Nucleus + Periventricular Nucleus) GnRH LH + FSH 3 Main Goals: 1). Testosterone 2). DHT 3). Spermatogenesis- LH = Acts on Leydig cells - to produce testosterone - FSH = Acts on Sertoli Cells - to produce DHT and for spermatogenesisTestosterone and DHT Production Cholesterol Testosterone Pregnenolone enzyme 5- 17-hydroxypregnenolone reductase DHEA Estrone aromatase Androstenedione DHT Estra17-beta oestradiol aromatase TestosteroneTestosterone and DHT Functions Testosterone: - Libido - Stimulates muscle and bone growth - Voice deepening - Sebum production/ acne - Spermatogenesis DHT: - Most DHT is produced in liver - Facial and body hair growth - Prostate enlargement - Very important for development of accessory glands - Deficiencies in DHT can lead to androgenic alopeciaSeminiferous Tubules = Site of Spermatogenesis ● Myoid cells = contractile cells that push sperm into the lumen ● Blood-Testis barrier - between basal compartment and adluminal compartment ● Provide nutrients and chemical stimuli that promote the development and differentiation of spermatids to spermatozoa ● Sertoli cells release inhibin (-ve feedback) Spermatogenesis Spermatogonia undergoes 4 rounds of mitosis to produce: - Spermatogonium (remains as a precursor) - Primary spermatocyte (travels towards lumen) Meiosis 1 - Diploid primary spermatocyte → Haploid secondary spermatocyte Meiosis 2 - Haploid Remember - testosterone is secondary spermatocyte needed at all stages of → Spermatid spermatogenesis (come from Leydig cells) Spermiogenesis - FSH needed for thisSpermatozoa Anatomy Contains enzymes needed to penetrate oocyte for fertilisation - acrosin and hyaluronidasesMale Accessory Glands ● Epididymis ○ Spermatozoa mature fully here, and start to acquire (some) motility ● Seminal Glands ○ Fructose ○ Prostaglandins ● Prostate Gland ○ Plasmin - proteolytic enzyme and other proteases ● Bulbourethral glands ○ Thick alkaline mucus (neutralise urinary acids)Quick Questions let’s gooo 👀 The function of the acrosome is to: A). Block polyspermy C). Help propel the sperm to ovum D). Nourish the mitochondria of the spermatazoonGrowth Hormone GHRH Growth-Hormone Releasing Hormone from the hypothalamus Growth Hormone Anterior pituitary gland (somatotrophs) Target Tissues: 1. Stimulate liver to produce IGF-1 2. Stimulate bone to produce IGF-1 3. Adipose Tissue 4. MusclesInsulin-Like Growth Factor (IGF-1) Growth Hormone Travels in bloodstream to liver GH GH GHR Bone Liver Releases IGF-1 Releases IGF-1 Target Tissues Target Tissues 1. Bone 1. Acts within bone itself 2. Adipose Tissue 3. Muscles PARACRINE ENDOCRINEGrowth Hormone Signalling Cascade GH GH GH G G G G G G H H H H H H R R R R R R JAK2 JAK2 stat5 stat5IGF-1 PI3K pathway Cell Survival and Metabolism IGF IGF 3 = cell is free to live (ie survival) I I I I G G G G F F F F R R R R MAP pathway Pi Pi Cell Proliferation World map always expanding = proliferating Sorry for the terrible mnemonics idk how else u could remember it Iodide (from diet) Thyroid Hormone THRH Thyroid-Hormone Releasing Hormone from the hypothalamus peroxidase Iodide → Iodine TSH Iodide + Tyrosine residues = Ante(thyrotrophs)y gland monoiodotyrosine monoiodotyrosine + iodine = diiodotyrosine Target Tissues: 1. Thyroid gland T3 T4Effects of GH, IGF1, Thyroid Hormone and Oestrogen Growth Hormone IGF-1 Thyroid Hormone Oestrogen (from gonads) Peptide hormone (already Peptide hormone (receptor Lipophilic so acts on Lipophilic so acts on discussed) tyrosine kinase) nuclear hormones nuclear hormones Stimulates the chondrocytes In the bone: increases Stimulate hypertrophy of Causes apoptosis of in the epiphyseal plate - osteoblastic and osteoclastic chondrocytes in the progenitor cells in the allows long bone to grow action hypertrophic zone of epiphyseal plate - so once epiphyseal plate ie bone they have all been used up, growth bone stops growing Muscle hypertrophy - Muscle hypertrophy - Stimulates amino acids Stimulates amino acids uptake uptake Increases lipolysis - so more Increases lipogenesis free fatty acids in blood for energyA few qsssMale Puberty ● Testicular changes ○ First sign of puberty = increase in testicular v3mL (measured using orchidometer ○ Seminiferous tubules enlarge in diameter and form tight junctions for blood- testis barrier ○ Onset of spermatogenesis ● Voice break ● Facial, body and axillary hair ● Growth spurtFemale Puberty ● First sign of puberty = formation of breast buds ● Menarche (periods start) approx 12 years ● Activation of the HPA-gonadal axis leads to development of one primordial follicle into a large antral Graffin follicle once a month. This leads to the first ovulation. ● Pubic and axillary hair ● Growth spurtInvestigations ● Growth chart ● Bone age ■ X-ray is taken of non-dominant hand ■ Check for presence of epiphysial growth plates ● Basal and peak LH and FSH - see if HPG axis is intactGrowth Charts ● Midparental Height is calculated by: (Mother’s Height + Father’s Height) / 2 ● If male +7 ● If female - 7 Normal Growth Needs investigationShort Stature ● Short stature = height of more than 2 SD below the mean ● Causes of Short Stature: ○ Constitutional Delay of Puberty/ Growth ○ Hypergonadotrophic hypogonadism ○ Hypogonadotropic hypogonadism ■ I’ll explain don’t freak out :0 ○ GH deficiency (short stature + adiposity) ○ HypothyroidismConstitutional Delay of Puberty/ Growth ● Bone age is lower than chronological age ● Child has “always been short” ● Parents are of normal height ● Normal growth velocity on the growth chart ● Management: ○ Reassurance of patient that they will ‘catch-up’Hyper vs Hypogonadotrophic Hypogonadism - ikr what even Hypergonadotropic Hypogonadotropic Kallmann syndrome - Turner’s Syndrome defective migration of (one missing X GnRH neurones. Patient chromosome) also has loss of sense of smell Klinefelter’s syndrome (XXY)- tall but delayed puberty 🤓 More Quick Questions The hormone that initiates puberty is: A). Growth hormone B). FSH C). Kisspeptin D). IGF-1 E). TestosteroneQuick Bone AnatomyEndochondral Ossification - last thing I PROMISEEpiphyseal Plate Zones - learn this!Good Luck Everyone ! InshaAllah you’ll all smash the exams :)