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Flashcards in GU Phys 2 Deck (45)
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1
Q

Spermatogenesis

  • define
  • where does it occur
A
  • male gamete formation via meiosis

- occurs in seminiferous tubules

2
Q

Spermatogenesis

  • what stimulates it
  • when does it start
  • how much per day
A
  • testosterone
  • starts at puberty (~14 yo)
  • continues through life
  • produce 100m sperm daily
3
Q

Meiosis I and II

A

review :)

4
Q

Spermatogonia

  • location
  • what type of cell
  • action
A
  • outermost cells of seminiferous tubules near basal lamina
  • stem cell
  • divide by mitosis to produce clonal diploid cells
5
Q

Spermatogonia divide into what two types of cells

A

A: remain at basal lamina as spermatogonium (pluripotent)
B: move toward lumen, differentiate into primary spermatocyte

6
Q

Spermatogenesis Meiosis

- primary vs. secondary spermatocyte

A
  • Primary: undergo meiosis I to produce secondary spermatocytes
  • Secondary: undergo meiosis II to form spermatids
7
Q

Spermatids

  • describe
  • location
A
  • immature sperm
  • round, small cells, large nuclei
  • near the lumen
8
Q

When do sperm become motile?

A

when they exit the body

9
Q

Spermiogenesis

- describe process

A
  • process by which spermatids mature into sperm (not yet motile or fertile)
  • Golgi packages acrosomal enzymes, positioned anterior to nucleus
  • cytosol sloughs off to streamline the cell
  • multiplication of mitochondria, position proximal to the tail
  • microtubules form flagellum
10
Q

Sertoli Cells

  • location
  • role
A
  • surround developing sperm
  • deliver nutrients
  • tight junctions open and close as spermatocytes move toward lumen
  • secrete testicular fluid
  • dispose of sloughed cytosol
  • produce ABP
11
Q

What is ABP

A
  • Androgen binding protein
  • androgen is testosterone
  • allows testosterone to be held in close proximity to spermatogenesis
12
Q

Capacitation

- describe

A
  • final phase of maturation
  • produces motile, fertile sperm
  • occurs post ejaculation
13
Q

How does the female body effect capacitation

A

sterol binding proteins, enzymes

14
Q

FPP

A

Fertility promoting peptide

  • part of capacitation
  • secreted by prostate
  • increases cAMP in sperm cell, Ca2+
  • leads to motility
15
Q

Acrosomal reaction in capacitation

A
  • destabilizes the acrosome

- acrosomal enzymes degrade the bona pellucid coat of ovum

16
Q

What are the four main parts of the penis

A
  • root
  • shaft
  • glans
  • foreskin
17
Q

What are the three columns of erectile tissue

A
  • connective tissue
  • smooth muscle
  • vascular spaces
18
Q

Corpus spongiosum

  • location/anatomy
  • muscle
A
  • midline, surrounds urethra
  • expands distally to form the glans
  • secured to the urogenital diaphragm
  • proximally forms root covered by bulbospongiosus muscle
19
Q

Corpus cavernosa

  • location/anatomy
  • muscle
A
  • two paired bodies
  • proximal end form crura
  • anchors to the pelvic arch
  • each crux surrounded by ishiocavernosus muscle
20
Q

Unstimulated penis

- state of blood vessels

A

arterioles supplying erectile tissue (cavernous) are constricted

21
Q

Stimulated penis

- state of blood vessels

A
  • vasodilation causes engorgement

- erectile reflex

22
Q

Erection reflex

- initiated by what

A
  • physical receptors on skin of glans
  • emotional, visual, mental activity
  • 2nd-4th sacral segments of spinal cord
23
Q

CNS response in erection reflex

  • PNS
  • sensory/somatic fibers
A
  • parasympathetic nerves of pelvic splanchnic to nerves serving penis
  • sensory and somatic fibers of pudendal nerve serve skin and muscle, including pelvic sphincters and pelvic floor
24
Q

What is effect of parasympathetic input in the erection reflex

A
  • causes vasodilation of internal pudendal arteries (engorgement and expansion)
  • pressure from 35-100 mmHg
  • compression of veins prevents outflow
25
Q

What is contained in the parasympathetic fibers of the pelvic plexus

A

NOS

nitric oxide synthase

26
Q

What does the release of NO do?

A
  • inhibits phosphodiesterase (PDE) breakdown of cGMP which is necessary for vasodilation
  • NO is a PDE inhibitor
  • creates and prolongs erection
    (also the ED drugs)
27
Q

What happens when stimulus ends or ejaculation occurs?

A
  • sympathetic tone reduces blood flow and blood pressure
  • venous flow increases
  • detumescence occurs
28
Q

Ejaculation

- neural input from where

A
  • SNS from T10-L2
  • to lumbar splanchnic nerves
  • strong and rhythmic contraction
29
Q

Ejaculation

- result of neural input

A
  • acts on smooth muscle along entire tract
  • leads to contraction of ducts and glands
  • propels sperm forward to urethra
  • contraction of pelvic floor helps propel semen to exterior
30
Q

Ejaculation

- what prevents urine back flow?

A
  • urinary sphincter
31
Q

What are the systemic effects of SNS input during ejactulation

A
  • pleasure

- elevated HR, BP, Resp Rate

32
Q

The brain-testicular axis:

  • GnRH
  • source
  • target
  • action
  • inhibited by what
A
  • Gonadotropin releasing hormone
  • produced and released by hypothalamus
  • anterior pituitary
  • prompts release of anterior pituitary gonadotropins (LH and FSH)
  • inhibited by testosterone
33
Q

Luteinizing Hormone

  • source
  • target
  • action
A
  • anterior pituitary
  • targets gonads via circulation, receptor on interstitial cells of Leydig
  • testosterone production
    (under influence of GnRH)
34
Q

Follicle stimulating hormone (FSH)

  • source
  • target
A
  • anterior pituitary
    Target:
  • gonads via circulation
  • influences Sertoli cells to secrete ABP (androgen binding protein)
  • binds testosterone and DHT
  • concentrates hormones within the luminal fluid of tubules (where needed for spermatogenesis)
35
Q

FSH

- action

A
  • stimulates spermatogenesis in seminiferous tubules

- stimulates sperm maturation in the epididymis

36
Q

Testosterone

- source

A
  • synth from cholesterol in interstitial cells

- also formed/secreted by adrenal cortex

37
Q

Testosterone

- transport

A

protein bound for transport

  • 65% to GBG (gonadal-steroid binding globulin)
  • 30% to albumin
  • 5% free
38
Q

Testosterone

- elimination

A
  • converted to ketosteroid and eliminated in urine
39
Q

Testosterone

- action

A
  • binds to intracellular receptor
  • moves to nucleus
  • affects transcription of multiple genes
40
Q

Testosterone

- action

A

Testes
- enhances spermatogenesis

Systemic

  • anabolic (protein synthesis, decreases degradation)
  • increases/maintains bone and muscle mass
  • sebum and hair production
  • maintains adult size/fn of genital organs
  • masculinization of brian (sexual behavior and territoriality)
41
Q

Testosterone at puberty

- what causes increase in T?

A
  • decreased inhibition of GnRH by hypothalamus
  • increased GnRH results in increased testosterone release
  • takes 3 years to reach adult levels
  • results in masculinization of body (enlarged genitals, hair distribution, behavior)
42
Q

Effects of testosterone at puberty

A

The list is VERY long, second to last slide

43
Q

Inhibin

  • where produced
  • stimulated by what
  • target
  • action
  • inhibited by what
A
  • produced by Sertoli cells
  • stimulated by FSH
  • targets anterior pituitary
  • inhibits release of FSH
  • inhibited by GnRH
44
Q

DHT (dihydrotestosterone)

  • how made
  • where located
A
  • 5% of testosterone is converted to DHT by 5alpha-reductase

- predominant in scalp, prostate, genital tissue

45
Q

DHT

- action

A
  • binds T receptor, forming a more stable complex (kind of like super T)
  • results in higher T activity
  • male pattern baldness
  • prostate growth