Male Reproductive System Flashcards
Where does Spermatogenesis occur?
In the seminiferous tubules within the testes
What is the typical Rate of Sperm Cell Production?
300-600 Sperm Cells per Gram of Testis Tissue per Second
What are the 3 Phases of Spermatogenesis?
- Mitotic Division
- Meiotic Division
- Cytodifferentiation
What Germ Cells to do with Spermatogenesis are activated at the start of Puberty in Males?
Spermatogonial Stem Cells
When the Spermatogonial Stem Cells are activated, what type of Cell Division do they undego? What is the result of this Cell Division?
Mitotic Cell Division, to create one undifferentiated Spermatogonial Stem Cell and one Spermatogonium which will eventually end up as sperm cells
How many Chromosomes do Spermatogonium have?
46
Where do the Mitotic Divisions of Spermatogonial Stem Cells occur?
In the basal compartment of the seminiferous tubules
Where do Spermatogonium move after arising from Spermatogonial Stem Cells? What do they move between?
They move into the adluminal compartment of the seminiferous tubules, moving between adjacent sertoli cells
Once Spermatogonia move into the Adluminal Compartment of the Seminiferous Tubule, what are they called?
Primary Spermatocytes
How many Chromosomes do Primary Spermatocytes have?
46
Primary Spermatocytes divide into ___ Spermatocytes and have ___ Chromosomes
Primary Spermatocytes divide into Secondary Spermatocytes and have 23 Chromosomes
Secondary Spermatocytes undergo ___, giving rise to 4 daughter cells called ___, having ___ Chromosomes each
Secondary Spermatocytes undergo Meiosis II, giving rise to 4 daughter cells called Spermatids, having 23 Chromosomes each
What is another name for Cytodifferentiation?
Spermiogenesis
What Shape are Spermatids?
Round
What occurs in the process of Cytodifferentiation/Spermiogenesis?
The transformation and shape changing of round spermatids into spermatozoa (sperm)
What is the Primary Function of a Sperm Cell?
To swim through the female reproductive tract to deliver genetic information to the Oocyte
What are the 3 Parts of a sperm cell?
The head, midpiece and tail
What is in the Mid Piece of a Sperm Cell? Why?
Mitochondria to power the tail for swimming
What does the Head of a Sperm Cell contain?
DNA
What is the Head of the Sperm Cell covered with?
The Acrosome
What is inside the Acrosome?
Enzymes which are required for egg penetration
What happens to the Excess Cytoplasm in a Spermatid during Cytodifferentiation/Spermiogenesis?
It is “shed” into a structure called the residual body that is later phagocytosed by sertoli cells after the sperm leaves
In Males, where does Luteinising Hormone (LH) act?
On the interstitial Leydig cells
Upon being acted upon by Luteinising Hormone (LH), what Hormone do Leydig Cells produce?
Testosterone
In Males, where does Follicle Stimulating Hormone (FSH) act?
Sertoli cells inside the seminiferous tubules
Upon being acted upon by Follicle Stimulating Hormone (FSH) what do Sertoli Cells Produce?
Androgen Binding Protein and Inhibin
What does Androgen Binding Protein do?
It binds to testosterone and allows it to be transported around the body through the bloodstream or to trap testosterone within the seminiferous tubules to help support sperm production
What happens to Sperm Production in the absence of Testosterone?
Spermatogonia will not be able to undergo the last phase of Cytodifferentiation/Spermiogenesis to produce spermatozoa
As Testosterone levels increase, what happens to Gonadotrophin Releasing Hormone (GnRH), Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH) production?
They decrease as they recieve the negative feedback
What does Inhibin do?
Provide negative feedback to Follicle Stimulating Hormone (FSH) production
What is a typical Sperm Count?
Around 20 million sperm/ml of ejaculate
What is Oligospermia?
A sperm count lower than 20 million sperm/ml of ejaculate
What is Azoospermia?
When there is no sperm in ejaculate
What does it mean if Sperm Cells are Immotile?
They can’t swim
What is a Treatment for Oligospermia?
IVF (In Vitro Fertilisation), when approximately 50,000 sperm are placed in droplets with an Oocyte
What is a treatment for Azoospermia and Immotile Sperm?
ICSI (IntraCytoplasmic Sperm Injection), in which a sperm is injected directly into an Oocyte. The sperm can be collected directly from a biopsy of the testes
Identify the Spermatogonium
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Identify Primary Spermatocytes
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Identify Secondary Spermatocytes
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Identify the Spermatids
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Identify the Sperm Cells
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Identify the Sertoli Cells
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Identify the Leydig Cells
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Identify the Mid Piece and Mitochondria
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Identify the Nucleus
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Identify the Acrosome
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What is Cryptorchidism?
When the testes don’t descend into the scrotum before birth
Are Cryptorchid individuals Fertile?
No
How many Seminiferous Tubules are in each Testis?
Approximately 80 in each testis
From the Seminiferous Tubules, what is the next area Sperm Cells move into?
The Rete Testis
From the Rete Testis, where do Sperm Cells move to?
The Epididymis
How long do Sperm Cells spend in the Epididymis?
Around 10-14 days
From the Epididymis, where do Sperm Cells move to?
The vas deferens
What happens to Sperm Cells in the Epididymis?
They acquire the ability to swim and fertilize
What does the Epididymis do to the liquid around the Sperm Cells?
Reabsorbs it to concentrate the sperm
How long can Sperm stay in the Vas Deferens?
Several months
How long is the Vas Deferens?
Approximately 45cm long
Where does the Vas Deferens lead to from the Epididymis?
The ejaculatory duct
Where do the Seminal Vesicles empty into?
The ejaculatory duct
Where does the Ejaculatory Duct join the Urethra?
At the prostate
What does the Ampulla of the Vas Deferens allow for?
It allows for a greater capacity for sperm storage
What are the Characteristics of the Seminal Vesicle Secretions?
- Mucoid (sticky)
- Alkaline
- Contains Fructose
- Contains Prostaglandins
- Contains Clotting Proteins
What is the Purpose of the Fructose in the Seminal Gland Secretion?
To provide energy to the sperm as it swims through the female reproductive tract
What is one of the Hypothetical Purposes of the Prostaglandins in the Seminal Gland Secretion?
To cause contractions within the female reproductive tract to assist the movement of sperm towards the fallopian tubes
What is the Purpose of the Clotting Proteins in the Seminal Vesicle secretion?
To create a plug that stops sperm from leaving the female reproductive system
Is the Seminal Vesicle secretion ejected into the Ejaculatory Duct before or after Sperm Cells?
After, as it washes the sperm down the ejaculatory duct
What Shape is the Prostate Gland?
A donut shape the size of a golf ball
Is Prostatic Fluid secreted behind or ahead of Sperm Cells during Ejaculation?
Ahead
Does the Urethra pass under, over or through the Prostate Gland?
Through
What are the Characteristics of the Prostatic Fluid?
- It is slightly acidic (pH 6.5)
- Contains citrate
- It is milky in colour
- Contains phosphate and calcium
- Contains Prostate Specific Antigen (PSA) and other enzymes
What is the Purpose of the Citrate in the Prostatic Fluid?
To provide materials for ATP production in the Sperm Cells
Why is Prostatic Fluid a milky colour?
Because it contains phosphate and calcium
What is the Purpose of the Prostatic Specific Antigen (PSA) and other enzymes in the Prostatic Fluid?
To break down the coagulum formed by the seminal vesicle secretion after 10-15 minutes
When the Prostatic Fluid and Seminal Vesicle Secretion interact, the different pH levels do what?
Neutralise each other
What is the Composition of Semen?
- Sperm (10%)
- Seminal Vesicle Fluid (60%)
- Prostatic Fluid (30%)
- Other Secretions (Small Amounts)
What is the pH of Semen?
Approximately 7.5
Why is the pH of Semen 7.5?
To provide a survivable environment for sperm cells, as if they were directly exposed to the vaginal environment (pH approx 4.5) they would quickly die
What is the average Ejaculatory Volume?
2-5ml
What is Benign Prostatic Hyperplasia?
Excessive growth of the prostate
What is a Common Symptom of Benign Prostatic Hyperplasia?
Difficulty voiding the bladder
What can Benign Prostatic Hyperplasia cause?
Weakening of the bladder and urinary tract and kidney infections
What is the Incidence of Benign Prostatic Hyperplasia across different age groups?
<40: Rare
50-59: 17%
60-69: 27%
70-79: 35%
>85: 90%
What are some Treatments for Benign Prostatic Hyperplasia?
- Surgery
- Specific 5 α-reductase inhibitors
What do 5 α-Reductase Inhibitors do?
Stop the prostate enlarging or shrink it
What are 2 Different 5 α-Reductase Inhibitors? What are their Half Lives?
Finasteride: 5-7 hours
Duasteride: 5 Weeks
How do 5 α-Reductase Inhibitors work?
They prevent 5 α-Reductase from converting Testosterone into the twice as potent 5 α Dihydrotestosterone. The prostate grows at a slower/lesser rate when acted on by Testosterone than 5 α Dihydrotestosterone
Prostate Cancer can typically be Detected through elevated levels of what in the bloodstream?
Prostate Specific Antigen
What are the 3 Main Structures present in the Penis?
- Corpora Cavernosa (x2)
- Corpus Spongiosum
- Penile Urethra
Sexual Stimulation in a Male results in the release of what?
Nitric oxide and prostaglandin E1
What do Nitric Oxide and Prostaglandin E1 cause?
The relaxation of smooth muscle in the Corpora Cavernosa, resulting in blood filling the Corpora Cavernosa (up to 8x more than usual)
What is the function of the Corpus Spongiosum?
To prevent the obstruction of the urethra during an erection
For the Smooth Muscles in the Corpora Cavernosa to relax, and to thus achieve an erection, ___ is needed. ___ breaks this down
For the Smooth Muscles in the Corpora Cavernosa to relax, Guanosine Monophosphate (cGMP) is needed. Phosphodiesterase breaks this down
How does Viagra work?
It inhibits phosphodiesterase, increasing cGMP levels and allowing for smooth muscle relaxation within the corpora cavernosa and thus allowing for an erection to occur