B8 W3 Flashcards
White, fibrous capsule on testes
Tunica albuginea
Tunica vaginalis
Layer of serous membrane covering the testis derived from peritoneum.
Cells that for inner epithelia of seminiferous tubules
Sertoli cells
Where does spermatogenesis occur within seminiferous tubule?
Gaps between sertoli cells
Where does spermatogenesis occur within seminiferous tubule?
Gaps between sertoli cells
What prevents passage of spermatoza into blood?
Junctions between sertoli cells
Sustencular cells
Cells which support gamete devElopment
Male sustencular cells
Sertoli cells
Female sustencular cells
Granulosa cells
Phases of spermatogenesis
Mitotic proliferation, meoitic proliferation, cytodifferentation
Produced at the end of mitotic proliferation of spermatogenesis
Resting primary spermatocytes
Resting primary spermatocytes
Cells which breach the tight junctions of sertoli cells and move into luminal compartments
Produced at the end of meiosis
Spermatid
Production of secondary spermatocyte
Meiosis- two divisions. First division has genetic shuffling to produce secondary spermatocyte. Second division to generate four haploid spermatid
Cytodifferentiation
Cytoplasmic bridges break open and release spermatids into seminiferous tubule
Number of clones of spermatids from 1 A1 spermatogonium
25
Final stage of spermatogenesis
Spermiogenesis. Golgi apparatus migrates to the poles and forms vesicle. Formation of streamlined spermatozoa
What forms the acrosome?
Occurs during spermiogenesis by action of golgi apparatus giving rise to glycoprotein rich granules which coalesce
What forms the flagella of sperm?
Centrioles
Interval cycle in spermatogenesis
16 days
What initates germ cell development?
Specification of primordial germ cells in endoderm
Where do primordial germ cells colonise?
The gonadal ridge
Origin of sertoli cells
Coelomic epithelia in medulla
Roles of testis
Spermatogenesis and hormone production
What forms the blood testis barrier?
Tight junctions between Sertoli cells
What blood-testis barrier?
Testosterone produced by Leydig cells
Epididymis
Long, coiled duct where sperm mature, are concentrated and testore. Develops from collecting tubules of the mesonephros
Structures where the epididymis develops
Collecting tubules of mesonephros
First Site of steroidogenesis
Mitochondria- conversion of cholesterol into pregnenolone
Main site of steroidogenesis
Smooth endoplasmic reticulum
How is testosterone converted to 5-alpha-dihydrotestosterone?
By reductase enzyme
How is testosterone converted into oestradiol?
Aromatase enzyme
What carries testosterone to the seminiferous tubules?
Blood
What carries testosterone to accessory sex glands?
Lymph
Seminal vesicle
Site of fructose, vitamin C, prostaglandins and ph semen
Prostate
Secretes ions to maintain osmotic balance-also priduces prostate specific antugen and citric acid
How much semen is produced by the prostate?
20-30%
Drugs for treating prostate cancer
GnRH antagonists
Finasteride
Reductase inhibitor
Bicalutamide
Androgen receptor antagonist
Oligozoospermia
Low sperm count
Asthenozoospermia
Low sperm motility
Teratospermia
Abnormal sperm morphology
Temperature that testis work
35 degree
Cycle of erection
Flaccid, tumescence, erection, detumescence, flaccid
What cleaves cGMP to GMP?
Phosphodiesterase 5
Alprostadil
Vasodilator which agonises prostaglandin E1 to treat erectile dysfunction
Apomorphine
Dopamine receptor for erectile dysfunction via indirectly relaxatioin of smooth muscle
Where are Leydig cells in testis?
interstital tissues of testis
What hormones control sertoli cells?
Tesotsterone and FSH
Morbidly obese BMI
40+
Prevalence of overweight
Men greater than women
Prevalence of obesity
Women is greater than men
Doubly Labelled water method
Collecting samples of urine and saliva to measure disappearance of isotopes and measure energy output
Redundancy
Neural and molecular signals with strong “drive to eat”
Effect on melanocortin stimulating hormone on appetite
Suppresses appetite by acting on hypothalamus receptors. Effect is enhanced by leptin.
Peptide YY
Satiety hormone released from intestines
Glucagon like peptide 1
Satiety hormone released from intestines
External factors influencing appetite
Convenience of food, price, availability, mood
What regions of the hypothalamus respond to appetite?
Acruate and ventromedial nuclei- responds to leptin, insulin, ghrelin and gluose
Paraventricular nuclei
region of the hypothalamus mediates autonomic and neuroendocrine responses for energy homeostasis?
Tractus solitarius
Region of hindbrain for short-term control of satiety- peptide YY, cholecystokinin and GLP-1