reproduction

Question 1

functions of gonads (ovaries or testes)

Answer 1

produce gametes (spermatozoa or ova)

produce steriod “sex” hormones (mostly testosterone in males; mostly estradiol and progesterone in females)

Question 2

testosterone belongs to a group of similar hormones having similar masculinizing actions called ____

Answer 2

androgens

Question 3

in males, most of the testosterone is made by the ____ ; other less potent androgens are made by the ____ ____

Answer 3

testes

adrenal cortex

Question 4

estradiol belongs to a group of similar hormones called ____ that are secreted in large amounts by the ____ and ____

Answer 4

estrogens

ovaries and placenta

Question 5

estrone is an estrogen produced:

estriol is produced:

estrogens are produced:

Answer 5

by the ovaries and placenta

by the placenta, and is usually found only in pregnant women

from androgens by the enzyme aromatase

Question 6

males produce ____ amounts of estrogens

females produce small amounts of ____ , most of which come from the ____ ____

Answer 6

small

androgens

adrenal cortex

Question 7

progesterone is produced by the ____ and ____

it is an intermediate in the synthetic pathways for:

Answer 7

ovaries and placenta

adrenal steroids, estrogens, and androgens

Question 8

all steroid hormones act via

Answer 8

intracellular receptors to alter the rate of formation of particular mRNAs and thus intracellular proteins

Question 9

accessory reproductive organs

Answer 9

the system of ducts through which sperm or ova are transported and the glands lining or emptying into them (also included here are breats in females)

Question 10

secondary sexual characteristics

Answer 10

the external differences between males and females (characteristic body shape, hair distribution, average adult height, etc.)

Question 11

chain of hormones that largely controls reproductive function:

• ____ is released from the hypothalamus into the portal blood vessel leading to the anterior pituitary, where it stimulatess the relase of ……
• ____ ( ____ ____ and ____ ____ ) these travel in the blood to the gonads, resulting in ….
• the maturation of ____ or ____ and the stimulation of sex hormone secretion which exert many effects on all parts of the reproductive system (including the gonad from which they came) and on other body parts too
• the gonadal steriods exert feedback effects on the secretion of ____ , ____ , and ____
• gonadal protein hormones such as ____ also exert feedback effects on the anterior pituitary

Answer 11

• gonadotropin-releasing hormone (GnRH)
• gonadotropins (luteinizing hormone and follicle-stimulating hormone)
• sperm or ova
• GnRH, LH, and FSH
• inhibin

Question 12

germ cells

Answer 12

cells that will develop or are developing into gametes

Question 13

first stage of gametogenesis:

• primordial, undifferentiated germ cells (called ____ in males and ____ in females) first proliferate by ____ in which each of the two daughter cells resulting from the cell division receives a full set of ____ chromosomes identical to those of the original dividing cell
• this provides a supply of identical germ cells for the next stage (that is, it provides more spermatogonia or oogonia, some of which will eventually be called ____ spermatocytes or oocytes)
• in females, this mitosis occurs during ____ development; in males, it starts after ____ and continues throughout the rest of life

Answer 13

• spermatogia oogonia mitosis 46
• primary
• fetal
• puberty

Question 14

second stage of gametogenesis:

• primary spermatocyte or oocyte divides by ____ which involves
• two successive divisions (with meiosis I producing two secondary ____ or one secondary ____ and one polar body, and meiosis II producing two ____ from each secondary spermatocyte or one ____ and another polar body from the secondary oocyte

Answer 14

• meiosis
• spermatocytes oocyte spermatids ovum

Question 15

in meiosis I, the ____ chromosomes are dealt to the two cells being produced, so that each secondary spermatocyte or secondary oocyte contains ____ chromosomes

Answer 15

46

23

Question 16

in meiosis II, a cell with ____ chromosomes gives rise to two spermatids with ____ each or an ovum with ____ and a polar body with ____

Answer 16

23

23

23

Question 17

after meiosis II, the resulting sperm and ova are not genetically ____ to one another nor to the ____ germ cell that gave rise to them; thus the siblings from the same parents are far from being genetically identical

Answer 17

identical

primordial

Question 18

seminiferous tubules

the walls of each tubule are formed from

Answer 18

sites of spermatogenesis in the testes

develop germ cells and sertoli cells

Question 19

leydig (interstitial) cells

Answer 19

are in the connective-tissue spaces between the tubules

synthesize and release testosterone

Question 20

the mitoitc cell division by spermatogonia in the walls of seminiferous tubules to produce primary spermatocytes begins

Answer 20

at puberty and continues throughout the rest of life

Question 21

each stem cell spermatogonium undergoes a specified number of mitotic divisions to produce a clone of ____ ; a little differentiation occurs along the way, and cells resulting from the final mitotic division are called:

Answer 21

spermatogonia

primary spermatocytes

Question 22

if all the cells in the clone produced by each stem cell spermatogonium followed the differentiation pathway, the spermatogonia would disappear, as all of them would be converted to:

this is prevented by, at an early point, one of the cells of each clone “dropping out” of the mitosis-differentiation cycle to:

Answer 22

primary spermatocytes

remain a stem cell spermatogonium (which will enter its own full sequence of divisions)

Question 23

in spermatogenesis, meiosis I and II produce

Answer 23

4 enlarged spermatids from one primary spermatocyte

Question 24

• in the final step of spermatogensis, spermatids differentation into ____ (sperm) ; this involves cell remodeling, including ____ :
  
  • the sperm cell head is almost all ____ and contains the DNA; the tip of the nucleus is covered by the ____ , and protein- filled vesicle containing enzymes needed in fertilization
  • most of the tail is a ____ (contractile filaments that produce movements capable of propelling the sperm)
  • the body (midpiece) of the sperm contains ____ that provide the energy for movement

Answer 24

• spermatozoa elongation
  
  • nucleus acrosome
• flagellum
• mitochondria

Question 25

_participation of sertoli cells:_ * each sertoli cell extends from the base of the ____ \_\_\_\_ (where there is a basement membrane) all the way to the tubule's \_\_\_\_ * sertoli cells send out extensions that join the extensions of other sertoli cells; ____ \_\_\_\_ are between the extensions of adjacent cells * the ring of sertoli cells interconnected by tight junctions forms a ____ \_\_\_\_ ____ , which prevents the movement of many chemicals from the blood into the tubule lumen and thereby ensures proper conditions for germ cell development and differentation * mitosis of spermatogonia occurs at the ____ of the seminiferous tubule; the primary spermatocytes then migrate through the tight junctions to eventually gain entry into the tubule's \_\_\_\_ * when sperm formation is complete, the sertoli cells cytoplasm around the sperm \_\_\_\_, and the sperm are released in the \_\_\_\_

Answer 25

* seminiferous tubule lumen * tight junctions * blood testis barrier * base lumen * retracts lumen

Question 26

_other functions are sertoli cells:_ * serve as the route by which _____ reach developing germ cells * secrete most of the ____ found in the tubule lumen * in response to ____ and to local ____ produced by leydig cells, secrete a variety of chemical messengers that function as paracrines to stimulate differentiation of the germ cells * secrete the hormone \_\_\_\_ * secrete paracrines that affect ____ cell function * ____ defective sperm * secrete, during embryonic life, a substance that causes the primordial ____ duct system to regress

Answer 26

* nutrients * fluid * FSH testosterone * inhibin * leydig * phagocytize * female

Question 27

from the seminiferous tubules, sperm travel through the ____ \_\_\_\_ , a network of interconnected tubes formed by the convergence of seminiferous tubules from different testicular areas

Answer 27

rete testis

Question 28

after leaving the rete testis, sperm move into ____ \_\_\_\_ , which empty into the ____ , which is loosely attached to the testicular surface

Answer 28

efferent ductules epididymis

Question 29

the epididymis leads to the ____ \_\_\_\_ , a thick-walled tube lined with smooth muscle, which is bound together with blood vessels and nerves to form the ____ \_\_\_\_

Answer 29

vas deferens spermatic cord

Question 30

inguinal canal

Answer 30

slit-like opening that allows the spermatic cord to pass between the scrotum and abdominopelvic cavity

Question 31

on each side of the body, the duct from a large, glandular ____ \_\_\_\_ joins the vas deferens to form an ____ \_\_\_\_ , which travels through the ____ \_\_\_\_ to join the ____ (which is coming from the urinary bladder and enters the penis after emerging from the prostrate

Answer 31

seminal vesicle ejaculatory duct prostate gland urethra

Question 32

in addition to fluid and sperm from the vas deferens, semen contains large amounts of fluid from the two ____ \_\_\_\_ and the ____ \_\_\_\_ , and small amounts from mucous glands, especially the two ____ \_\_\_\_

Answer 32

seminal vesicles prostate gland bulbourethral glands (cowper's glands)

Question 33

in addition to sperm, semen contains

Answer 33

nutrients buffers for protecting sperm against the acidic vaginal secretions chemicals that increase sperm motility fibrinogen prostaglandins

Question 34

sperm are nonmotile early in the pathway, and movement as far as the ____ results from:

Answer 34

epididymis the pressure created by fluid secretion from the Sertoli cells

Question 35

fluid absorption as fluid travels through the epididymis

Answer 35

concentrates the sperm

Question 36

peristaltic contractions of ____ and ____ \_\_\_\_ smooth muscle tissue propel the semen forward

Answer 36

epididymis vas deferens

Question 37

penis consists mostly of

Answer 37

three cylindrical, vascular compartments that run its entire length

Question 38

during sexual excitement, erection occurs as neural input to the arteries supplying the vascular compartments causes

Answer 38

the arteries to dilate, and the compartments become engorged with blood under high pressure

Question 39

in male sexual excitement, the engorgement of blood passivley compresses

Answer 39

the veins draining the compartments, further increasing the local pressure

Question 40

before erection, the main neural input to the arteries is ____ released from ____ neurons

Answer 40

norepinephrine sympathetic

Question 41

during erection, the sympathetic input is inhibited, and ____ neurons to the arteries that release the unusual transmitter ____ \_\_\_\_ become active; nitric oxide relases the arterial ____ \_\_\_\_

Answer 41

parasympathetic nitric oxide smooth muscle

Question 42

the main receptors that initiate the erection reflex are ____ in the genital region, especially in the head of the penis

Answer 42

mechanoreceptors

Question 43

during erection, sensory neurons carry impulses from the mechanoreceptors to the inferior parts of the spinal cord; interneurons here control

Answer 43

the outflow of neural signals to the penile arteries

Question 44

ejaculation is a reflex initiated by sensory pathways from

Answer 44

penile mechanoreceptors traveling to teh spinal cord centers

Question 45

_ejaculaiton:_ * a patterned sequence of impulses in ____ neurons leading from the spinal cord results in * ____ , ____ \_\_\_\_ , ____ \_\_\_\_ , ____ , and ____ \_\_\_\_ smooth muscle contraction as a result of stimulation by ____ neurons; this empties semen into the urethra ( ____ ) * semen's being expelled from the urethra by a series of rapid contractions of ____ smooth muscle and skeletal muscle as the base of the ____ ( the latter is controlled by somatic motor neurons)

Answer 45

* efferent * epididymis, vas deferens, ejaculatory duct, prostate, and seminal vesicle sympathetic emission * urethral penis

Question 46

the GnRH-secreting neuroendocrine cells of the ____ fire a burst of action potentials about every 90 minutes to secrete pulses of GnRH

Answer 46

hypothalamus

Question 47

GnRH reaches the ____ \_\_\_\_ via the portal blood vessels connecting the two structures, and triggers the release of both ____ and ____ from the same cell type; thus these hormones are released in pulses

Answer 47

anterior pituitary LH and FSH

Question 48

FSH acts mainly on the ____ cells to stimulate the secretion of paracrines required for \_\_\_\_

Answer 48

sertoli spermatogenesis

Question 49

LH acts mainly on the ____ cells to trigger ____ secretion

Answer 49

leydig testosterone

Question 50

testosterone secreted by leydig cells enters the blood to act hormonally/systemically, but it also acts locally, in a paracrine manner, by diffusing from the ____ \_\_\_\_ into the ____ \_\_\_\_ ; it enters ____ cells, where it facilitates \_\_\_\_

Answer 50

interstitial spaces seminiferous tubules sertoli spermatogenesis

Question 51

_negative hormonal feedback effects:_ * testosterone inhibits ____ secretion by * acting on the ____ to decrease ____ secretion * and acting directly on the ____ \_\_\_\_ to decrease the ____ response to GnRH * ____ released by sertoli cells, acts directly on the anterior pituitary to decrease ____ secretion

Answer 51

* LH * hypothalamus GnRH * anterior pituitary LH * inhibin FSH

Question 52

other effects of testosterone

Answer 52

* induces differentiation of male accessory reproductive organs and maintains their functions * induces male secondary sex characteristics; opposes action of estrogen on breast growth * stimulates protein anabolism, bone growth, and cessation of bone growth * required for sex drive and may enhance aggressive behavior * stimulates erythropoietin secretion by kidneys

Question 53

_some hormones must undergo changes within target cells to be effective; this is true for testosterone in many of its target cells:_ in adult prostate cells, testosterone is converted to ____ catalyzed by the enzyme 5 alpha-reductase) in certain other targets cells (for example in the brain), testosterone is converted to ____ (catalyzed by aromatase)

Answer 53

dihydrotestosterone estradiol

Question 54

some males lack 5 alpha-reductase or aromatase in some tissues, in such a case, they will exhibit

Answer 54

certain signs of testosterone deficiency but not others

Question 55

the fetal differentiation and later growth and function of the entire male duct system, glands, and penis all depend on testosterone, following the loss of testicular function, what occurs

Answer 55

accessory organs decrease in size, the glands markedly reduce their secretion rates, the smooth muscle activity of the ducts is diminished, and sex drive - erection - and ejaculation are usally impaired

Question 56

during childhood, the hypothalamus does not secrete significant amounts of ____ , for reasons not yet understood, at the time of ____ , GnRH secretion begins

Answer 56

GnRH puberty

Question 57

most if not all of the observable changes that occur at puberty depend on ____ or its metabolite \_\_\_\_

Answer 57

testosterone DHT