Chapter 17 - The reproductive system - mitosis, meiosis, male reprod. Flashcards
- What is the diploid chromosome number?
- total number of chromosomes in the nucleus of each body cell is the same (except for reproductive cells)
- Always an even number - chromosomes occur in pairs)
- Sex chromosomes are designated as either _____ or _____.
X or Y
- XX means?
female
- XY means?
male
- What is reduction division?
- total number of chromosomes in each of the daughter cells is reduced to half the number of the parent cells
- Haploid chromosome number includes?
- reduction division
- ensures that the fertilized ovum from the union of spermatozoa and ova has diploid number
- haploid chromosome number in the reproductive cells results from meiosis
- Gamate is either a _________ or a ___________
ova or sperm
- Mitosis always = _________ pairs
chromosome
9 What is mitosis?
- Most body cells divide after the cell first makes a duplicate copy of its chromosomes
- half the chromosomes go to one daughter cell and half go to the other
- genetic makeup of the two daughter cells is exactly the same as each other and as the parent cell
10.What is Meiosis?
- chromosomes do not produce duplicate copies of themselves before daughter cells divide
- half of the total chromosomes go to each daughter cell (one from each diploid chromosome pair and one sex chromosome
- which chromosomes go to which daughter cell is entirely random
- What is spermatogenesis?
- production of male sex cells
- occurs in seminiferous tubules of the testes
- produce continuously and in very large numbers
- What are the changes that spermatocytes undergo?
- primary spermatocyte divides by meiosis into secondary spermatocytes - that creates a haploid number
- secondary spermatocytes divide by mitosis into 4 spermatids
- spermatids grow tails and undergo physical changes that convert them to spermatozoa
- when spermatozoa is fully developed, they detach and are carried to the epididymis for storage before ejacuation
- half the spermatozoa produced have an X sex chromosome and half have a Y chromosome
- What is Oogenesis?
- production of female sex cells
- occurs in ovarian follicles
- female has fixed number of primary oocytes at or soon after birth
- oogenesis produces small number of ova at a time
- Process of Oogenesis is?
- primary oocyte divides by meiosis into a large secondary oocyte and a small polar body
- each has a haplid chromosome number
- the secondary oocyte and the first polar divide by mitosis into an ovum and 3 polar bodies
- Polar bodies are essentially garbage cans for excess chromosomes which are not ________.
functional - they will not develop into ova
- What does male reproductive system do?
- produces male sex hormones
- develops spermatozoa
- delivers the male spermatozoa to the female system at the appropriate time
- What do the testes do?
- produce sperm and hormones
- usually located outside the abdomen in the inguinal region
- housed in a sac of skin - the scrotum
- What is the scrotum?
a sac of skin that houses the testes
- helps regulate temperature of testes
- What is the structure of the spermatozoa?
- Head
- midpiece
- tail
- What is the head of the spermatozoa?
- contains the nucleus of the cell
- covered by the acrosome (cap-like structure)
- contains digestive enzymes that helps the spermatozoon penetrate the ovum
- What is the midpiece of the spermatozoa?
- a large concentration of mitochrondria arranged in a spiral pattern (the “power plant”)
- What is the tail of the spermatozoa?
- contains muscle like contractile fibrils
- produces a whip-like movement of the tail and propels the cell forward
- What is cryptorchidism?
testes are still up in the abdomen
- What is a gubernaculum?
a band of connective tissue that attaches testes to the scrotum
- What are inguinal rings?
openings in abdominal muscles through which testes decend
- What is the cremaster muscle?
passes down through the inguinal ring and attaches to the scrotum
- also adjusts the position of the testes relative to the body depending on temperature
- What is the vas deferens?
- a muscular tube that runs from the tail of the epididymis to the pelvic urethra
- thick smooth walls
- also known as the ductus deferens
- passes through inguinal ring as part of the spermatic cord.
- Once inside the abdomen it separates from spermatic cord and connects with urethra
- What is the spermatic cords?
- blood and lymphatic vessels, nerves, and the vas deferens
- pampiniform plexus
- What is pampiniform plexus?
- meshwork of veins that surrounds testicular artery
- maintains testes at temperature slightly lower than body temperature
- it warms blood back to the body temperature before it returns to the abdomen
- What are tunics?
- they are connective tissue that forms a sheath-like layers around the testes and spermatic cord
- visceral vaginal tunic
- parietal vaginal tunic
- tunica albuginea
- What is visceral vaginal tunic?
- very thin inner layer
- lies next to the organ or viscera
- deepest tunic
- What is parietal vaginal tunic?
- thick outer layer and it forms a fiborus sac around each testis and spermatic cord
- What is tunica albuginea?
- fiborus connective tissue capsule surrounding each testes beneath tunics
- What is seminiferous and where are they located?
site of spermatogenesis
- a long convoluted U-shaped tube attached at both ends to system of ducts (rete testis)
- What are interstitial cells?
endocrine cells between the seminiferous tubules produce androgens
- What are Sertoli cells?
cells
supports developing spermatids
- in retained testicals they produce estrogen
- After detaching from the Sertoli, spermatozoa enter the ________?
rete testis
- What is the rete testis?
carries sperm from the seminiferous tubules to the efferent ducts.
- What is the duct system?
that’s where the spermatozoa develop and then gets transported to the epididymis via the efferent ducts of the testes
40.What is the epididymis?
ribbonlike structure that lies along the surface of the testis
it is divided into 3 regions:
- “head” region - site where spermatozoa enter from efferent ducts
- “body” region - lies along surface of testis
- “tail” region - continues on as the vas deferens
- functions as a storage site for spermatozoa
- What is the function of the vas deferens?
propels sperm quickly from epididymis to urethra at the time of ejaculation
- In the vas deferens what is the ampulla?
- if present in some species, it is the enlargement of the vas deferens that occurs just before joining the urethra
- the ampulla may contain glands that contribute material to semen
- What 2 functions does the urethra have in the male?
- carries urine from the urinary bladder outside the body (urinary function)
- urine flow temporarily blocked when ejaculation occurs (ejaculation function)
- What 2 portions does the urethra have?
pelvic portion and penile portion
- What is the pelvic portion in the urethra?
- entry point of vas deferens and accessory reproductive glands
- What is the penile portion in the urethra?
runs down the length of the penis
- Spermatozoa from the vas deferens make up only a small portion of the total volume of _______. The majority is made up of secretions from the various ________ _________ glands.
semen
accessory reproductive glands
- What are the male accessory reproductive glands?
seminal vesicles
prostate gland
bulbourethral glands
- What are some facts about accessory reproductive glands?
- ducts of all accessory reproductive glands enter pelvic portion of the urethra
- different species have different combinations of accessory reproductive glands
- produce alkaline fluid that helps counteract the acidity of the female reproductive tract
- What does the prostrate gland do?
- surrounds the urethra
- multiple ducts carry secretions into urethra
- What are the bulbourethral glands?
- also known as cowper’s gland
- ducts enter urethra near caudal border of pelvis
- secrete mucinous fluid just before ejaculation that clears and lubricates the urethra
- all common domestic animals have these glands except for the dog
- What is the penis?
- composed of muscle, erectile tissue, and connective tissue
- large blood supply and many sensory nerve endings
- three main parts of the penis - the roots, the body, and the glans
53, What are the roots of the penis?
bands of connective tissue (crura) that attach penis to the brim of the pelvis
- What is the body of the penis?
- largest part
- two bundles of erectile tissue
corpus cavernosum urethrae (smaller)
corpus cavernosum penis - (larger)
- What is the glans of the penis?
- the tip or distal end; numerous sensory nerves
- What is the prepuce of the penis?
sheath of skin that encloses the penis when it is not erect
- inner portion is smooth, moist mucous membrane
- varies in species
- What is the os penis in a dog?
it is the bone (and an erectile structure) that causes the male and female to remain stuck together after breeding is complete - the bone in the penis is the os penis
- What is the bulb of the glans in the dog?
enlargement toward the rear of the glans
- engorges with blood; reaches full size after
ejaculation
- remains clamped in place by contractions of
muscles surrounding vagina and vulva
- erection of the bulb subsides in 15 - 20 minutes
- What is the sigmoid flexure?
- s shape of nonerect penis of the bull, ram, and boar
- higher proportion of connective tissue to erectile tissue than any other species
- erection results from straightening of the sigmoid flexure from internal hydraulic pressure
- causes the penis to protrude from the prepuce for breeding
- What are the reproductive functions of the penis?
erection
ejaculation
61, One of the reproductive functions is erection, what is this?
results from a parasympathetic reflex triggered by sexual stimuli
- often involves olfactory cues and behavioral
changes (visual and smelling)
- arteries dilate and increase blood flow into penis
- veins are compressed against brim of the pelvis
by contractions of muscles in roots of the penis
- Another one of the reproductive functions is ejaculation, what is this?
reflex expulsion of semen
- semen moves from accessory reproductive
glands into pelvic portion of the urethra
- rhythmic contractions of the urethra, pump the
semen out into the female reproductive tract
