Chapter 11 Flashcards
1
Q
What are the two roles of the testes?
A
(1) Synthesis of sperm (spermatogenesis) (2) Secretion of male sex hormones into the blood stream
2
Q
Site of spermatogenesis within the testes
A
Seminiferous tubules;
3
Q
Sustentacular cells
A
Walls of the seminiferous tubules are formed by cellls called sustentacular clues They protect and nurture the developing sperm, both physically and chemically
4
Q
What are important cells found in the testicular interstitium?
A
Interstitial cells (also known as Leydig cells); They are responsible for androgen (testosterone) synthesis
5
Q
Where does the seminiferous tubule empty into?
A
Epididymis; a long coiled tube located on the posterior of each testicle
6
Q
Where does the epididymis from each testicle empty?
A
Into a duct deferens which leads to the urethra
7
Q
What path does the duct deferens travel to get to the urethra?
A
It enters the inguinal canal –>joins the duct of the seminal versicle to form the ejaculatory duct –> joins the urethra
8
Q
Seminal vesicles
A
A pair of glands located on the posterior surface of the bladder that nourish sperm They secrete about 60 percent of the total volume of the semen into the ejaculatory duct
9
Q
What are the three glands that produce semen?
A
The seminal vesicles, the prostrate and the bulbourethral glands Collectively called accessory glands
10
Q
Prostate gland
A
Nourishment, allows semen to coagulate after ejaculation
11
Q
Bulbourethral glands
A
Lubricate urethra, neutralize acids in the male urethra and female vagina
12
Q
Erectile tissue
A
Composed of modified veins and capillaries surrounded by a connective tissue sheath Blood accumulates at high pressures
13
Q
Three compartments contain erectile tissue
A
The corpora cavernosa (two of these) and the Corpus spongiosum (one of these)
14
Q
Three stages of the male sexual act
A
Arousal, orgasm and resolution
15
Q
The sexual act events are controlled by an integrating center in the spinal chord, how is it activated/inactivated?
A
The cerebral cortex can activate this integrating center (in sexual arousal during sleep) or inhibit it (anxiety with sexual function)
16
Q
What is arousal dependent on?
A
The parasympathetic nervous input and can be subdivided into two stages: erection and lubrication
17
Q
Erection
A
Involves dilation of arteries supplying the erectile tissue. This results in swelling which obstructs venous outflow and causes the erectile tissue to become pressurized with blood
18
Q
Lubrication
A
Function of the parasympathetic system. Bulbourethral glands secrete a viscous mucous which serves as a lubricant
19
Q
What is required for an orgasm?
A
Stimulation by the sympathetic nervous system which can be divided into two stages: emission and ejaculation
20
Q
Emission
A
Propulsion of semen into the urethra by contraction of smooth muscles
21
Q
Ejaculation
A
Semen is propelled out of the urethra by rhythmic contractions of muscles surrounding the base of the penis
22
Q
Resolution (2-3 minutes)
A
Or “returning to normal”, unstimulated state, is also controlled by the sympathetic nervous system Caused by a constriction of erectile arteries which results in decreased blood flow to the erectile tissue and allows veins to carry away trapped blood
23
Q
Gametogenesis
A
Process by which diploid germ cells undergo meiotic division to produce haploid gametes
24
Q
Syngamy
A
Fusion of sperm with the egg. The gametes produced by males and females differ dramatically in structure but contribute equally to the genome of the zygote
25
Spermatogenesis
Sperm synthesis. It begins at puberty and occurs in the testes throughout adult life
26
What is the site of spermatogenesis?
In the seminiferous tubule Spermatogenesis occurs with the aid of the specialized sustentacular cells found in the walls of the seminiferous tubule
27
Where are immature sperm precursors found?
The outer wall of the tubule
28
Where are nearly-mature spermatozoa's deposited?
In the lumen and the they are transported into the epididymis
29
Germ cells
Give rise to male and female spermagonia Can germinate and give rise to full organisms
30
Spermatogonium Job
(1) Mitotically reproduce prior to meiosis (2) Replicate DNA in S phase of meiosis "SpermatoGONium is GONNA become a sperm"
31
Primary spermatocyte job
Meiosis I "Any gamete precursor (male or female) with "cyte" undergoes a meiotic division"
32
Secondary spermatocyte job
Meiosis II "The secondary spermatoCYTE undergoes the second meiotic division"
33
Spermatic Job
Turn into a spermatozoan "The spermatid's a kid, almost mature"
34
Spermatozoan Job
Finish maturing: (1) in seminiferous tubule (2) in epididymis "Just remember that a mature sperm is called a spermatozoan"
35
Where do the final stages of sperm maturation occur?
In the epididymis
36
Where do spermatids develop?
Spermatids develop into spermatozoa in the seminiferous tubules with the aid of sustentacular cells
37
Acrosome
Contains lytic enzymes needed for penetration of the ovums protective layers
38
Bindin
Protein that allows for attachment to receptors on the zone pecullia surrounding the ovum
39
Process by which spermatids develop into spermatozoa?
(1) DNA condenses and cytoplasm shrinks to from a head (contains haploid nucleus) (2) Flagellum forms tail (3) Neck region carries mitochondria
40
Testosterone
Plays the essential role of stimulating division of spermatogonia
41
Luteinizing hormone (LH)
Stimulates the interstitial cells to secrete testosterone Secreted by anterior pituitary gland and uses systematic circulation to reach its target
42
Follicle stimulating hormone (FSH)
Stimulates the sustenacular cells which support and nourish sperm in seminiferous tube
43
Inhibin
Is secreted by sustenacular cells; its role is to inhibit FSH release
44
Wolffian ducts
Can develop into male internal genitalia (epididymis, seminal vesicles, and ductus deferens) Can develop into either genitalia
45
Müllerian ducts
That can develop into female internal genitalia (uterine tubes, uterus and vagina) Müllerian ducts are the default
46
Although external genitalia is also default, it is not
Derived from the Müllerian ducts
47
Genetic information on Y chromosomes leads to the development of
Testes, which cause male internal and external genitalia to develop by producing testosterone and Müllerian inhibiting factor (MIF)
48
Müllerian inhibiting factor (MIF)
Causes regression of Müllerian ducts
49
Dihydrotesterone
Testosterone enters the systemic circulation and is converted into dihydrotestosterone in target tissues in order to exert its effects.
50
Three main fetal precursors of the reproductive organs are
Wolffian ducts, Müllerian ducts and the gonads Structures arising from these ducts tend to have the same function
51
Analogous structures
Wolffian ducts and Müllerian ducts arise from different precursors
52
Homologous structures
Derived from the same underdeveloped structure i.e. Gonads
53
Androgens
All hormones involved in the development and maintenance of male characteristics
54
Estrogens
All hormones involved in development and maintenance of female characteristics
55
What happens to testosterone after birth
levels of testosterone fall to negligible levels until puberty, at which time increases and remains high for the remainder of adult life
56
Secondary sexual characteristics
Maturation of the geneticist,male distribution of facial and body hair, deepening of the voice and increased muscle mass. Pubertal growth spurt and fusion of the epiphyseal also results
57
Why is estrogen required at the beginning of puberty?
Required to regulate the uterine cycle and for the development and maintenance of female secondary sexual characteristics Maturation of the genitalia, breast development, wider hips and public hair
58
Gonadotropin releasing hormone (GnRH)
From the hypothalamus stimulates the pituitary to release the gonadotropins. Stimulates release of FSH and LH
59
What is the role of FSH and LH in females
FSH stimulates the granulosa cells to secrete estrogen and LH stimulates the formation of the corpus luteum and progesterone secretion
60
Labioscrotal swellings
Testosterone causes a pair of skin folds to grow and fuse, forming the scrotum In women they form the labia majora of the vagina
61
Urethral opening
Where urine exits the body
62
Labia minora
Surrounding the urethral opening is another pair of skin folds
63
Where is the opening o the vagina?
Between the labia minora
64
Endometrium
The inter most lining of the uterus (closest to the lumen) Role is to nourish a developing embryo and if pregnancy does not occur it is shed once a month
65
Myometrium
Surrounds the endometrium. Thick layer of smooth muscle compromising the wall of the uterus
66
Uterine tubes
The uterus ends here and then extends into the pelvis on either side
67
Fimbriae
Uterine tube ends at this bunch of finger like structures
68
Cervix
Separates vagina and uterus
69
Female stages of the sexual act
Arousal, orgasm and resolution
70
Arousal stage
Erection and lubrication
71
Lubrication in females
Controlled by the parasympathetic nervous system, the clitoris and labia minora become encouraged in blood
72
What is lubrication in females provided by
Lubrication is provided by mucus secreted by greater vestibular glands and by the vaginal epithelium
73
Orgasm in the female
controlled by the sympathetic nervous system and involves muscle contraction
74
What is different between the female sexual act and the male?
Females do not experience ejaculation
75
Oogenesis
Begins prenatally. In the female ovary, germ cells divide mitotically to produce many orgo is and enter the first phase of meiosis and stops at prophase I (primary oocytes) Male mitotic division occurs in adult stage not in the womb
76
1st mitotic division after puberty
results in a larger 2nd locution containing all the cytoplasm and organelles. Followed by a polar body (cell is haploid)
77
2nd mitotic division
Occurs only if the primary oocyte is fertilized by sperm. Unequal division resulting in a large ovum and small 2nd polar body
78
What happens if fertilization occurs?
The nuclei from the sperm and egg do not fuse immediately. They must wait for the secondary oocyte to release the second polar body and finish maturing to an ootid and then ovum Finally, the two nuclei fuse and the diploid (2n) zygote is formed
79
Primary Oocyte
Not an isolated cell. Found in a clump of supporting cells called granulosa cells and the entire structure is known as a follicle
80
Granulosa cells
Assist in maturation. Surrounds an immature primary oocyte and forms primordial follicle
81
Zone pellucida
Oocyte itself forms a protective later of mucopolysaccharides
82
Fate of the follicle
Insert picture
83
Estrogen
Made and secreted by the granulosa cells (with help from the thecal cells) during the first half of the menstrual cycle
84
Steroid hormones in females
Estrogen and Progesterone
85
Progesterone
is involved in the hormonal regulation of the menstral cycle and pregnancy
86
Stages in the ovarian cycle
Follicular phase, ovulatory phase, luteal phase
87
Follicular phase
Primary follicle matures and secrets estrogen controlled by FSH
88
Ovulatory phase
2nd oocyte is released from the ovary due to LH and what is left of the follicle becomes the corpus lutem
89
Luteal phase
Full formation of the corpus luteum. Secrets both estrogen and progesterone
90
Uterine Cycle
Preparation of the endometrium for potential implantation of a fertilized egg Menstruation, proliferative phase and secretory phase
91
Mensturation
Degeneration of the corpus luteum and drop in estrogen and progesterone. The lining then sloughed out "bleeding"
92
Proliferative phase
Follicle produces estrogen which causes production of a new endometrium LH levels peak
93
Secretory phase
Development of endometrium increases
94
GnRH from the hypothalamus
Stimulates the release of FSH and LH from the anterior pituitary
95
What happens when estrogen reaches its threshold?
It's effects on LH become positive
96
Stimulation of LH
Causes ovulation and turns the follicle into the corpus luteum which. Secrets estrogen and progesterone and marks the start of the secretory phase
97
What happens if pregnancy does not occur
High levels of estrogen and progesterone feedback to inhibit FSH, LH and GnRH
98
What happens when LH secretions drop
The corpus luteum regresses and mesntration occurs
99
How is ovulation prevented during pregnancy?
Constant high levels of estrogen and progesterone seen during pregnancy to inhibit secretion of LH by the pituitary No LH surge no ovulation
100
If fertilization occurs
The embryo implants itself in the endometrium and the placenta begins to develop
101
Chorion
Portion of the placenta derived from the zygote takes LH's place and secrets HCG which maintains the corpus luteum
102
When the secondary oocyte is ovulated and enters the uterine tube
Is it surrounded by the corona radiation and the zone pellucida. The oocyte will remain fertile for about a day. When intercourse occurs sperm becomes capacitance and survive 2-3 days to swim to the 2nd oocyte
103
Sperm capacitation
Involved the dilution of inhibitory substances present in semen
104
Fertilization
Occurs in the uterine tube usually. The fusion of spermatozoan with the secondary oocyte
105
Acrosome
Large vesicles in the sperm head contains hydrolytic enzyme which are release by exocytosis.
106
Once the corona radiation is penetrated
the acrosomal process containing actin elongates towards the zone pellucida
107
Embryogenesis
Begins within hours of fertilization, but proceeds slowly in humans. 1st stage is cleavage: Zygote undergoes many cell divisions to produce a morula (ball of cells)
108
Morula
Same size as the zygote: dividing cells spend most of their time in S phase and M phase they skip G1 & G2
109
When division continues the morula is transformed into
The blastocyst through blastulation
110
Tropohblast
Secrets protease that lyses the endometrium cells and allows the blastocyst to burrow into the endometrium and become engulfed in it. Absorbs nutrients through trophoblast into the inner cell mass Gives rise to chorion which gives rise to the placenta
111
Blastocyst
Travels to uterus and implants a week after fertilization
112
Inner cell mass
Will become the embryo
113
Where does cleavage occur in animals?
In a very small portion of the yolk at the animal pole (the side of the egg with the least amount of yolk)
114
Meroblastic cleavage
Incomplete division in animals partial part of the yolk
115
What does the trophoblast secrete?
Protease that lyse the endometrial cells
116
Secretory phase of endometrial cycle
Occurs so the endometrium can uptake glycogen, lipids and other nutrients
117
Placenta
Specialized to facilitate exchange of nutrients, gases and even antibodies between the maternal and embryonic bloodstreams
118
Why is hCG essential?
For maintenance of the endometrium In the 1st 3-months of pregnancy until placenta forms
119
Placental villi
Chorionic projections extending into the endometrium, into which fetal capillaries will grow This surrounds sinuses which contain maternal blood
120
A minion
Surrounds fluid-filled cavity which contains the developing embryo
121
Yolk Sac
Important in reptiles and birds because it contains the nourishing yolk Mammals do not store yolk, our yolk sac is the 1st sire of red blood cell synthesis
122
Allantois
Develops from the embryonic gut and forms the blood vessels of the umbilical cord, which transport blood between embryo and placenta
123
Gastrulation
When the three primary germ layers (the ectoderm, the mesoderm and the endoderm) become distinct
124
Ectoderm
Entire nervous system, pituitary gland (both lobes), adrenal medulla, cornea and lens, epidermis of skin and derivatives (hair, nails, sweat glands, sensory receptors), nasal, oral, anal epithelium
125
Mesoderm
All muscle, bone and connective tissue Entire cardiovascular and lymphatic system, including blood Urogenital organs (kidneys, uterus, gonads, reproductive ducts) Dermis of skin
126
Endoderm
GI tract epithelium (except mouth and anus) GI glands (liver, pancreas, etc) Respiratory epithelium Epithelial lining of urogenital organs and ducts Urinary Bladder
127
Neurulation
Formation of the nervous system. Layer of the ectoderm invaginates and pinches on the back of the embryo to form the dorsal neural groove which leads to neural tube and then leads to the brain and spinal chord
128
Notochord (mesodermal origin)
Gives instructions for neural tube formation which leads to the vertebral column
129
Organogenesis
Development of organ systems By the 8th week all organs are present and embryo turns into the fetus
130
Differentiation
Specialization of cell types during development. Cells become better at performing a particular task, but less adept to other tasks
131
Totipotent cells
Primitive (stem) cells in an early embryo have the potential to become any cell types Determination comes before differentiation
132
Determined
Point in development of a cell at which the cell fate becomes fixed
133
How does determination happen
Determination can be preprogrammed or induced by a cells environment
134
Parturition
Technical term for birth. Dependent on contraction of muscles in the uterine wall
135
Labor contractions
Increased pressure on the cervix passes a threshold that makes the anterior pituitary secrete oxytocin
136
Steps on birth
(1) Dilation of the cervix (2) Birth, involves contractions and movement of body down the cervix and birth canal (3) Expulsion of the placenta
137
Result of increased levels of estrogen and progesterone secreted by the placenta during pregnancy
Causes further development of glandular and adipose breast tissue. These fall after parturition and allow for prolactin the be released and milk production to begin
138
What happens when sucking occurs
The pituitary gland is stimulated by the hypothalamus to release a large surge of prolactin. Sucking prolongs secretion of prolactin and production of milk
139
Oxytocin
Posterior pituitary hormone Necessary for milk-let down Released when suckling occurs
140
Animalistic is split into
(1) Parazoa: animals that lack true tissue (2) Eumetazoa: radial and bilateral symmetry
141
How many germ laters do radial animals have?
2 germ layers
142
Bilateral animals have how many germ layers?
3
143
Acelomates
Solid bodies; flat worms
144
Coelomates
Fluid filled body that separates digestive tract
145
Coelomates can be divided into two distinct lines of evolution
Protostomes: annelids, mollusks and arthropods. Mouth first Deuterostomes: echinoderms and chordates. Anus first
146
What kind of cleavage do protostomes undergo?
Spiral, determinate cleavage, while deuterostomes undergo radial, indeterminate cleavage
147
Spiral Cleavage
This results in smaller cells that lie in grooves between larger cells
148
Radial Cleavage
Cells align on top of one another
