Male Reproduction Flashcards
What is our soul purpose in life?
- Our sole purpose in life is to reproduce
- Passage of genetic material
- A species “fitness” is defined as its success at producing offspring
What does sexual reproduction require?
- Sexual reproduction requires the union of egg and sperm (called gametes)
- Sperm male gamete, “DNA with a propeller”
- Egg female gamete, large and nutrient rich
- Offspring is a genetic combination from both parents
- Gametes are produced by gonads
What is the female gonad?
A. Ovary
B. Vagina
C. Uterus
What is the male gonad?
A. Penis
B. Testes
C. Scrotum
A. Ovary
B.Testes
How many chromosomes does a human have?
- Humans have 23 pairs of chromosomes in most cells
- Linear structures that organize DNA
- One from mother and one from father
- When most cells in our body divide, 46 chromosomes are maintained mitosis
How many chromosomes do gametes have?
- Gametes only have 23 chromosomes (unpaired)
- Egg or sperm
Represents DNA from one parent
During production the pairs of chromosomes are separated meiosis
Join during fertilization (23 + 23 = 46)
What happens during mitosis?
- Chromosomes copy (or replicate) to make “X-like” structure
- During mitosis, all 46 chromosomes line up in the middle of the cells
- Copied chromosomes separate from each other and cell divides
- Daughter cells have 46 chromosome (23 pairs) not replicated at this point
- Occurs in all cells except gametes
What occurs during meiosis?
- Chromosomes copy (or replicate) to make “X-like” structure
- During meiosis 1, each chromosome matches with its pair
- Pairs line up in the center of the cell
- During this time, pieces of DNA can “swap” between the pairs
- Remember chromosomes from each parent have the same genes
- Swapping information leads to diversity (Ex. blue vs. brown eyes)
- Pairs separate from each other and cell divides
- Meiosis 2 continues the same as mitosis
- Replicated chromosomes separate
Blue whales have 22 pairs of chromosomes. How many chromosomes are found in one blue whale gamete (egg or sperm)?
A. 22
B. 44
C. 11
D. 66
A. 22
What is the gross anatomy of the male reproducctive system?
- Gross anatomy includes: testes, epididymis, vas deferens, penis, seminal vesicle, prostate gland, and bulbourethral gland
How are the testes constructed?
- Divided into lobes
- Lobe contain seminiferious tubules
- Site of sperm production
What are the three main cell types in the testes?
- Three main cells types
- Interstitial (Leydig) cells between the tubules
- Germ cells divide to become sperm (like stem cell)
- Sustentacular (Sertoli) cells protect the germ cells
- Rest of cells are developing sperm
What does spermatogenesis start with and what surrounds it?
- Starts with immature sperm cells (spermatogonia)
- Found on the edge of tubules (furthest from lumen)
- Sustentacular cells surround developing sperm
- Provide nutrients and waste removal for developing
How are four sperm cells produced and how is it regulated?
- As the spermatogonium travels towards the lumen, it undergoes meiosis I and II
- Mature sperm develops a flagellum (tail) and loses most of its cytoplasm
- Fast and lightweight for travel in the female
- A single spermatogonia produces four sperm cells
- Regulated by hormones called gonadotropins
- GnRH (gonadotropin-releasing hormone) is released from hypothalamus
- Stimulates _____ from pituitary
A. Testosterone
B. Inhibin
C. FSH only
D. FSH and LH
- FSH stimulates _____ to secrete ________.
- LH stimulates ______ to secrete ________.
- What does testosterone directly inhibit?
A. LH B. FSH C. GnRH
D. FSH and LH
- sustentacular cells (androgen binding peptide)
- Intertistial cells (testosterone)
- ABP + testosterone stimulate the production of sperm cells
- C. GnRH
- Inhibin inhibits FSH
What is the role of testosterone?
- Triggers puberty
- Maintains sex organs (primary sex characteristics)
- testis
- penis
- associated ducts that carry sperm
- Maintains secondary sex characteristics
- deep voices
- body hair
- facial hair
- increased muscle mass
- Stimulates spermatogenesis
- Provides negative feedback to hypothalamus
- Testosterone levels decline after 50
- Male climacteric hormone changes
- Mood, hot flashes, illusions of suffocation
What is the sperm strructure?
- Process from meiosis to maturation is a continual process
- Contain head, midpiece (body), and tail region
- Head houses acrosome and nucleus
- Acrosome is a “pocket” of enzymes to dissolve egg’s covering
- Midpiece houses mitochondria
- Tail motion in the ocean! (NOT FULLY FUNCTIONAL UNTIL IN FEMALE)
What is the epididymis structure?
- Functions in sperm maturation and storage
- Single tube about 18 feet long
- Sperm starts at the head of the epididymis and is mature at the tail
- Tail joins with the vas (ductus) deferens
- Unused sperm is absorbed by the body
A scientist extracts sperm from the lumen of a seminiferous tubule and injects into a tube with several eggs. Will it successfully fertilize one of the eggs?
A. Yes B. No
B.No
What is the vas deferens?
- Muscular tube which functions to carries sperm to ejaculatory duct
- During orgasm, peristalisis moves sperm from epididymis to vas deferens
- Vas deferens is part of the spermatic cord
- Cord of connective tissue that leaves the scrotum
- Also include blood vessels, nerves, and lymph vessels
- Cremaster muscle
- SHRINKAGE
What does the Accessory Glands do for the male reproduction?
- Supply fluids of semen
- Seminal vesicle (~60%)
- Sticky, yellow fluid that cause sperm to “stick” to walls of the vagina
- Prostate gland (~30%)
- Thin, milky fluid that helps breakdown seminal vesicle fluid so sperm can swim
- Sperm (~10%)
- Bulbourethral gland
- Slippery liquid preejaculatory
- Reduces acidity of residual urine
What is the penis?
- Functions to deliver sperm to vagina
- Contains three cylinders of erectile tissue
- Smooth muscle, connective tissue, blood vessels
- Erectile tissue contains small pockets of blood vessels (sinuses) in muscle tissue
- During erection, increased blood flow fills pockets
- After erection, blood flow decreases and the pockets empty
What is the male sexual response?
- Excitement (Erection)
- Controlled by the parasympathetic system
- Initiated by sensory stimuli or thoughts
- Increase of heart rate, blood pressure and respiratory rate
- Vasocongestion
- To penis and testes
- Nervous system triggers release of nitrous oxide
- Smooth muscle of blood vessels relaxes they can easily fill (vasodilation)
- Viagra side note
- Erection angles penis for intercourse
- Bulbourethral gland secretes fluid
What are the stages of the sxual male response?
- Plateau
- Orgasm – Emmision
- 3-15 seconds
- Sympathetic control
- Peristalsis of vas deferens moves sperm from epididymis to urethra
- Prostate and seminal vesicles secrete fluid
- Orgasm – Expulsion
- Sympathetic control
- Urethral sphincter contracts (block flow of urine)
- Muscles contract and compress root and shaft of penis to expel semen
- Resolution
- Blood vessels constrict to reduce blood flow
Smooth muscle of penis contracts to force blood from erectile tissue
Penis becomes detumescent
Refractory period
10 minutes to a few hours
Impossible to attain another erection
Due to chemicals needed for vasodilation
