Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
45 Cards in this Set
- Front
- Back
How is gender expressed in an embryo? |
SRY gene - sex determining region of Y - produces testis determining factor (TDF) Expressed - forms testis Not expressed - forms ovaries |
|
Where is testosterone produced and what does it do embryologically? |
Produced in Leydig cells Maintains Wolffian duct system |
|
Where is Mullerian Inhibiting Hormone (MIH) produced and what does it do embryologically? |
Produced in Sertoli cells Regressed Mullerian ducts |
|
What is the pampiniform plexus? |
A venous network surrounding the testicular artery that causes countercurrent heat exchange. |
|
What are the roles of the seminiferous tubule, rete testis, efferent duct and epididymus in sperm production? |
Seminiferous tubule - spermatogenesis Rete testis - spermatozoa collected Efferent duct - reabsorb fluid and concentrate sperm Epididymus - mature and store sperm |
|
At what phase are the sperm in at mitosis, meiosis, differentiation and spermiation? |
Spermatogonia, spermatocyte, round spermatid, elongated spermatid, spermatozoa |
|
What process differentiates spermatids to spermatozoa? |
Spermiogenesis |
|
Where are spermatogonial stem cells found in the seminiferous tissue? |
Near the basal membrane. |
|
What are the junctional complexes between Sertoli cells? |
Blood-testis barrier. |
|
What do Sertoli cells produce? |
Seminiferous tubular fluid, androgen binding protein and inhibin |
|
What functions do Sertoli cells have to do with hormones? |
Mediate effects of FSH and testosterone on spermatogenesis. |
|
Describe the phases of spermiogenesis. |
Golgi - polarisation Cap - enzyme fulled cap sythesised Acrosomal - acrosome formed Maturation - cytoplasm becomes phagocytosed |
|
Describe sperm motility. |
ATP and Ca2+ dependent.
|
|
What ways can ATP be synthesised in sperm and which species use each method? |
Oxidative phosphorylation (midpiece) - bull Glycolytic ATP production - mice |
|
What do Sertoli and Leydig cells produce? |
Sertoli cells - oestrogens (major in boar and stallion), cytokines - inhibin, activin, MIH during development Leydig - androgens (mostly testosterone), oxytocin |
|
What is testosterone converted to and why? |
DHT - more biologically active |
|
What is the cause of boar taint? |
Androsterone - sexually attractive to pigs |
|
What is the function of Myoid cells? |
Maintain functional integrity and contractility of tubules. |
|
What stimulates Leydig cells to produce testosterone? |
LH and FSH |
|
What does FSH with androgens do to Sertoli cells? |
Permissive effect on spermatogenesis Produce ABP, inhibin, activin, transferrin |
|
What types of GnRH pulses cause release of FSH and LH? |
FSH - irregular, low amplitude LH - high frequency |
|
What controls FSH and testosterone production? What prevents LH surges? |
Inhibin inhibits FSH production. Testosterone production controlled by long loop negative feedback at hypothalamus and pituitary. Exposure to androgens masculinises hypothalamus. |
|
How is testosterone transported? |
Venous blood Lymph Seminiferous tubular fluid bound by androgen binding protein ABP |
|
What are some examples of masculinisation due to androgens? |
Female rodent between two males in utero - masculinised and produce male biased litters Freemartins - infertile and culled |
|
Define puberty in the male. |
Able to produce enough sperm to impregnate a female. |
|
Why does puberty happen? |
Continued sensitivity of GnRH neurone to peptide neurotransmitter kisspeptin. |
|
What happens if there is a lack of kisspeptin? |
Puberty failure and hypogonadotropic hypogonadism. |
|
What is the difference between developmental effects and activational effects of androgens? |
Developmental - totally or partly irreversible Activational - reversible |
|
Why does castration after puberty not remove all behaviours? |
Some are learned. |
|
Is singing in birds activational or determinative in birds? |
Canaries - activational Zebrafinch - determinative |
|
What is the action of oxytocin in relation to spermiation? |
Produced by Leydig cells Enhances contractility of seminiferous tubule via action on myoid cells. |
|
What is fluid absorption dependent on? |
Oestrogen in tubular fluid (Sertoli cells) |
|
What happens during sperm maturation in the epididymus? |
Sperm begin to swim in straight lines. Middle and last section - secrete fructose and glycoproteins. Dependent on androgen stimulation (DHT) |
|
Ehat happens during sperm storage in the epididymus? |
Fluid absorbed Oxytocin increases sperm release Stored in cauda for 3-13 days depending on species |
|
What is the function of the ductus deferens? |
Extragonadal sperm reserves. Sperm build up prevented by phagocytosis and/or leakage through epididymal wall |
|
What two factors could cause activation of sperm? |
Factors in seminal fluid. Dilution of epididymal inhibition factors when added to seminal fluid. |
|
What are some of the components in seminal fluid? |
Fructose/sorbitol Citric acid Buffers Proteins Paracrine agents e.g prostaglandins STDs! |
|
What types of seminal plugs are there? |
Fibrous plug - block others from mating Gelatinous plug - retention in vagina |
|
What part of the hypothalamus controls male mating behaviour? |
Medial preoptic area |
|
What is the reflex associated with psychogenic stimuli called? |
Bulbocavernosus reflex |
|
What is priapism? |
Persistant penile erection. |
|
Why is sensory feedback from glans important? |
Confirms intromission has occured. Spines - may induce ovulation. |
|
What is emission and how is it controlled? |
Delivery of sperm and fluid to urethra. Parasymp - secretion from accessory sex glands and ductus deferens Symp - contraction of smooth muscle to propel fluid and sperm forward and to close bladder sphincter to prevent retrograde ejaculation |
|
What is ejaculation and how does it occur? |
Expulsion of sperm from penis due to prolonged sexual arousal. Rhythmic contraction of smooth muscle of urethra and straited muscle (bulbospongiosum). Motor output coordinated by central pattern generator in lumbosacral spinal cord. Stimulation in paraventricular nucleus. |
|
What happens after ejaculation? |
Symp activity increases - reduced blood flow. Penis retractor muscle pulls penis back into prepuce. Refractory period. |