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What are the three ways to determine sex
- Chromosomal sex
- Gonadal sex
- Phenotypic sex
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What are the germ cells in males, and female
- Males - Spermatogonia
- Female - Oogonia
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From the indifferent stage of male production to the male genitalia, what degenerates
- Mullerian ducts
- Caused by the secretion of antimullerian hormone from Sertoli cells
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In the absence of what is a female produced
SRY gene & Dihydrotestosterone (DHT)
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What cells releases Testosterone
Leydig cells
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What is the effect of testosterone released in a male during development
Testosterone is converted to DHT via 5-alpha reductase helping develop the external and internal genital features
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How does testosterone cycle through out life
- There is a large surge during fetal development
- A drop just prior to birth
- A spike during the first year
- No testosterone till puberty
- A decrease around 70 years old
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What inhibts the release of GnRH during pre-puberty
- GABA neurons
- Endorphins
- Melatonin
- Neuropeptide Y (NPY)
- Testosterone
- Estrogen
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What happens to the levels of hormones during male puberty
- Increase in LH, Testosterone, FSH, and Leptin
- Decrease in NPY, Melatonin, and GABA
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Spermarchy
Nocturnal emission of sperm
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What are some secondary characteristics effected by male puberty
- Body hair
- Pitch in voice
- Skeletal muscle increase
- Thicker longer bones
- Thickness of skin
- BMR increase
- Increase blood volume
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What do spermatozoa contain that assist in energy
GLUT 5 fructose transporters and mitochondria
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How long does a spermatazoa survive in the epididymis
6 weeks (under the best conditions)
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What influences the motility and life of sperm
- High temp increases motility
- Neutral-Alkaline medium increases motility
- Acidic environment kills the sperm
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Why does increase in temperature decrease the lifespan of sperm
It increases the metabolic rate and therefore utilizes the energy stores
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What effects the rate of spermatogenesis
It is constant, not accelerated by androgens or gonadotropins
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What are the primary roles of the Sertoli cells
- Secrete Androgen binding protein
- Secrete plasmin
- Spermiation (remove excess organelles ect.)
- Blood testes barrier
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What is the comparison of daily sperm production as it relates to the age of the male
- 20 year old - 6.5 million sperm
- 50-90 year old - 3.8 million sperm
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How many days does it take to make sperm
65-75 days
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What is found in the head of the sperm, and how is it important
Acrosome which is filled with enzymes to break through the walls of the oocyte
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What inhibits the hypothalamus from releasing GnRH
- Dopamine and Endorphins
- Inhibin (released from gonads)
- Testosterone and Estrogen
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What inhibits the release of FSH and LH from the Pituitary gland
- Follistatin (released from gonads)
- Inhibin (released from gonads)
- Testosterone and Estrogen
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What triggers the release of GnRH from the hypothalamus
Norepinephrine
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What triggers the release of FSH and LH from the pituitary
- GnRH (released from the hypothalamus)
- Activin (released from the gonads specifically causes the release of FSH)
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POMC
- Pro-Opiomelanocortin
- When broken down it yields ACTH (Corticotropin), MSH (melanocyte stimulating hormone), Endorphins, and Lipotropin
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Testosterone and Estrogen have what effects during puberty
They increase body growth, Growth hormone (GH), and Insulin like growth factor (IGF)
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Insulin like growth factor (IGF) has what effect during puberty
- Increase in GnRH
- Increase in Gonadal function
- Enhances testosterone and estrogen synthesis
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What causes the growth of Leydig cells
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LH has its primary action in males on Leydig cells through what pathway
G protein stimulation, Adenylyl cyclase, then cAMP to stimulate testosterone production
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What facilitates LH effects on Leydig cells
- FSH
- Prolactin (increases the amount of LH receptors)
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LH stimulates testosterone synthesis by its action at what enzyme, on what cell
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What are the effects of FSH on Sertoli cell functions
- Stimulates the maturation of germ cells
- Increases glucose metabolism of Sertoli cells
- Stimulates the synthesis of Inhibin B, Activin, and other growth factors
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What receptors do Sertoli cell lack
LH
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What receptors do Leydig cell lack
FSH
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Aromatase
Enzyme used in the conversion of testosterone to estradiol in the Sertoli cells as well as other cells
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Sertoli cells produce
- Androgen Binding Protein (ABP)
- Anti-Mullerian hormone
- Activin
- Inhibins
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What is the role of Estrogen receptors on Leydig cells
- They decrease the proliferation and activity of Leydig cells
- "Ester stops Leydi's"
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LH receptors on the Leydig cells can respond to what during gestation
hCG
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In the Leydig cells, what series of products cause testosterone poduction
Cholesterol to Pregnenolone to Testosterone
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Testosterone secreted from the Leydig cells has what effect on the Sertoli cells
- Formation of Estradiol
- Formation of Androgen binding protein which is secreted in to the seminiferous tubule
- Protein formation
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Estradiol secreted from the Sertoli cells has what effect on the Leydig cells
Causes the formation of proteins
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What effect does testosterone have on the kidneys
- Stimulates erythropoietin synthesis
- Stimulation of renal sodium reabsorption
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How does Testosterone effect the liver
- Increase VLDL and LDL
- Decrease HDL
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What is the result of a male lacking 5 alpha-reductase
They have female phenotype at birth but rising testosterone levels at puberty produce a more male phenotype
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What is the effect of Estradiol on the efferent ductules
It causes them to concentrate sperm for the final ejaculation
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What hormone is associated with closing the epiphyseal after puberty
Estradiol
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What nerve is important in the initiation of an erection
Pudendal nerve
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What are the five phases of a male erection
- Flaccid phase
- Tumescence phase
- Full erection
- Rigid phase
- Resolution phase
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What nervous system dominates in the flaccid stage of an erection
Sympathetic nervous system dominates
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What is the driving action of the Tumescence stage of an erection
- Release of NO and Prostaglandin E1 increasing intracellular cGMP.
- These relax the cavernosa vascular smooth muscle causing initial erection
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What happens in the rigid phase of the an erection
- Cavernosa pressure exceeds systolic blood pressure
- Ejaculation occurs by sympathetic innervation
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What muscles are important to ejaculation
- Ischiocavernosa
- Bulbocavernosa
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What happens in the resolution phase of an erection
Sympathetic activity constricts supplying arteries decreasing blood flow and reversing the erectile process
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What is the role of the sympathetic and parasympathetic nervous systems in an erection
- Para - mediates the arteriole vasodilation
- Symp - Mediates constriction of the arterial venous anastomoses
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What are the four stages of the male sexual act and what causes them
- Excitement (Parasympathetic)
- Plateau (Parasympathetic)
- Orgasm (Sympathetic L1-2, Somatic L1-S4)
- Resolution (Sympathetic L1-2)
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What helps determine the amount of consistency of semen
Parasympathetic stimulation
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What do the seminal vesicles contribute to semen
- Fructose
- Citric acid
- Prostaglandins
- Fibrinogen
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What does the prostate gland contribute to semen
- Citric acid
- Calcium phosphate
- Clotting enzyme
- Fibrinolysin
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What does the Cowpers gland add to the semen
Mucus
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What is the pH of semen
7-8
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During what phase of the male sexual act does the bulbourethral gland (cowpers) secrete fluid
Excitement
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What artery constricts reducing the blood to the penis in the resolution phase
Internal pudendal
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What causes the ejaculate to coagulate and then liquify after an hour
Clotting enzyme released from the prostate gland
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