Reproductive Physiology Flashcards
What is the function of the reproductive system?
Production of gametes
Organs for mating
Fertilization
What are the organs of the reproductive system?
Gonads
Pathway of gamete transport
Accessory reproductive organs/glands
What is the function of gonads?
Gamete production
Secrete sex hormones
What are the male gonads?
Testes
What is the scrotal sac?
Outside of the body
Testes, blood vessels, nerves
Has concurrent blood flow to regulate temperature in this region
How do the testes descend?
First found in the abdominal cavity and descend to their final position in the scrotum
During 8 and 12 weeks, the testes move down towards the inguinal canal
Between the 7th and 9th months, the testes pass through the inguinal canal and come to rest in the scrotum
What are the testes?
Male gonads
250-300 compartments
Has seminiferous tubules that are important for sperm production
What are the seminiferous tubules?
Spermatogenic cells, site of sperm production
Spermatogenesis begins at puberty
400 million sperm/3 mL of ejaculated volume
What are the cells of the testes?
Leydig cells
Sertoli cells
Smooth muscle (myoid cells)
What are Leydig cells?
Secrete testosterone
Found in the connective tissues surrounding the seminiferous tubules
What are Sertoli cells?
Support sperm development
What are the myoid cells?
Just outside of the basement membrane
Muscle-like cells
have contractile properties to help with peristalsis to move the sperm forward
What forms the blood-testis barrier?
Tight junctions
Luminal compartment
Basal compartment
What are the functions of Sertoli cells?
Support sperm development
Secrete luminal fluid for sperm housing
Secrete androgen-binding protein
Acts as target cells for testosterone and follicle-stimulating hormone
-secrete paracrine factors that stimulate spermatogenesis
Secrete inhibin
-hormone of negative feedback loop for FSH
Phagocytosis of old and damaged sperm
Site of immunosuppression
Why do testosterone and FSH use Sertoli cells?
As their target and help in sperm development
What is testosterone?
Steroid hormone synthesized from cholesterol
Produced by the adrenal cortex and gonads
What is progesterone?
An intermediary hormone synthesized from cholesterol and produced in the adrenal gland
Depending on the enyzmes present, progesterone is converted to mineralocorticoids, glucocorticoids, or androgens
Where are testosterone receptors generally located?
In intracellular locations
Testosterone is lipophilic and can diffuse across membranes and bind to intracellular receptors to exert its function
Acts by influencing gene transcription and affecting protein synthesis
How are male hormones synthesized in Leydig cells?
Cholesterol to pregnenolone to progesterone
Progesterone produce androgens
What happens when testosterone enters the bloodstream?
Maintains the lifelong male reproductive capacity
Converted to DHT and maintains tissues or sexual characteristics
Converted to estrogen
What happens during puberty?
Onset of male hormone synthesis
Sexual maturation
Reproductive organs mature
Secondary sexual characteristics develop
What is the pattern of male reproductive activity over the human lifespan?
Continually produce sperm over the lifespan
What is the hypothalamic-pituitary-Leydig cell axis?
Cues to initiate firing of the cells that produce the hormone gonadotropin-releasing hormone
What are the effects of androgens?
Stimulate spermatogenesis
Promote development of secondary sex characteristics during puberty and maintenance of these characteristics in adult life
Increase sex drive
Promote protein synthesis in skeletal muscle
Stimulate growth hormone secretion, promotes bone growth
Promote development of male reproductive structures during embryonic life
What is spermatogenesis?
The formation of the male gamete or the sperm
Where does the formation of sperm begin?
Close to the basement membrane in the seminiferous tubule and then goes to the lumen
Why does one daughter cell remain spermatogonia?
To ensure that resources are not depleted from the stockpile of spermatogonia
Where does spermatogenesis occur in relation to the Sertoli cells?
Occurs in the space between adjacent Sertoli cells
What is the final step of spermatogenesis?
Must undergo differentiation to form the final sperm structure
How long does spermatogenesis take?
64 days
What is spermiogenesis?
The last stage within spermatogenesis
Spermatids mature into motile spermatozoa
Flagella forms
Takes 24 days
What is the structure of the head of sperm?
Contains the nucleus
Contains an acrosome
What is an acrosome?
A vesicle positioned close to the plasma membrane at the tip of the sperms head with enzymes necessary for fertilization
What is the mid-piece of sperm?
Many mitochondria which generate ATP needed for movement of the tail
What is the tail of sperm?
Whip-like movements propel the sperm
Where are spermatozoa released?
Into the lumen of the seminiferous tubules where they remain immotile for 20 days
How does the sperm get to the epididymis?
Pressure generated by the fluid secreted from the Sertoli cells pushes the sperm and fluid to the epididymis
What happens in the epididymis (sperm)?
Resides there for 6-12 days
Acquires mobility with an initial wave-like tail movement
Most of the fluid is reabsorbed
Sperm is concentrated?
How does sperm get to the vas deferens?
By peristalsis
How long does sperm stay in the vas deferens?
Until ejaculation
How does FSH control male reproduction?
Stimulates spermatogenesis
How does LH control male reproduction?
Stimulaters androgen secretion
What is the pulse generator?
GnRH
The pulse generator stimulates the anterior pituitary to release FSH which stimulates the Sertoli cells to secrete androgen binding protein and inhibin
What is inhibin?
Peptide hormone
Regulate the axis at the level of the anterior pituitary to decrease secretion of FSH
Does not act at the hypothalamic level
What does LH act on?
The Leydig cells
How is LH release controlled?
Testosterone released from Leydig cells inhibits the secretion of LH at the level on the anterior pituitary and at the level on the hypothalamus
What does FSH act on?
Sertoli cells
How is FSH release controlled?
Release of FSH from the anterior pituitary is inhibited by inhibin released from the Sertoli cells
Inhibin acts on the level of the anterior pituitary
What are the functions of seminal fluid?
Dilution of sperm
Provision of energy
Formation of semen clot
Where does seminal fluid come from?
Seminal vesicle
Prostate gland
Bulbourethral gland
What are seminal vesicles?
Secrete alkaline fluid with fructose, enzymes, and prostaglandins
- enzymes for semen clot
- alkaline to balance acidic environment in female genital tract
- prostaglandins to cause contraction of female tract for sperm to move forward
What is the prostate gland?
Secretes citrate and enzymes (PSA)
Hypertrophy is a biomarker for cancer
What are the bulbourethral glands?
Secrete viscous fluid with mucous
What makes up semen?
Sperm + seminal fluid
What is the male sexual response controlled by?
The autonomic nervous system
Involves spinal reflexes
What are the phases of the male sexual response?
Erection phase
Emission phase
Ejaculation phase
What is the erection phase?
Controlled by parasympathetic nervous system
Increased blood flow
What is the emission phase?
Sympathetic stimulation to the smooth muscle of the ducts
What is the ejaculation phase?
Rapid contraction of skeletal muscle for semen expulsion which is under somatic control
What is the parasympathetic control of an erection during and erection?
Activity in the sympathetic neurons decreases
Activity in the parasympathetic neurons to the penile structures increases, causing relaxation of the smooth muscle which increases blood flow
What is parasympathetic control of an erection?
Activation of the parasympathetic nerve causes the release of nitric oxide
NO stimulates production of cyclic GMP
Increased cGMP acts on smooth muscle of the blood vessels to cause vasodilation
cGMP is broken down by phosphodiesterarse and the erection stops
What is erectile dysfunction?
Treated with Viagra
Viagra is an inhibitor of phosphodiesterase
Whaat is the fallopian tube?
Site where fertilization occurs
Only low numbers reach the fallopian tube due to the high acidity in the female reproductive tract
What is capacitation?
Occurs as sperm moves through the female reproductive tract
A functional maturation process of the sperm cell membranes
Receptors are made available through the removal of the glycoprotein layer
The area of the acrosomal cap is altered during capacitation so that the acrosomal reaction can take place
What is the acrosomal reaction?
Oocytes have an outer layer called the zona pellucida
Sperm must penetrate the zona pellucida to gain access to the egg
Binding of the sperm with the zona pellucida triggers the acrosomal reaction
Allows acrosomal enzymes to be releases by exocytosis that allow the sperm to digest a path through the zona pellucida for fertilization to occur
What are some characteristics of the female reproductive system?
Cyclic changes in activity -menstrual cycle Restricted periods of fertility -ovulation Limited gamete production -pool established at birth
What are the patterns of female reproductive activity?
Onset of puberty (menarche)
Female reproductive system cycles (menstruation)
Menopause
What are the female gonads?
Ovaries
What composes the female reproductive tract?
The uterus, uterine tube, vaginal canal
What is the site of ova maturation?
The ovaries
Are the ovaries directly linked to the uterine tubes?
No, they are suspended by ligamentous tissue in the peritoneal cavity
What are the uterine tubes (fallopian tubes, oviducts)?
Transports the ova from ovaries to uterus
Fimbria stick out and sit close to the ovary and contain hair cells that move help move the egg
What is the infundibulum?
A cup-shaped structure that captures the egg from the ovary
How does the ovum move through the uterine tube?
Initially by peristaltic contraction
Mostly ciliary actions
How long does it take to get to the uterus from the uterine tubes?
4 days
What is the perimetrium?
The outer layer of the uterus
Epithelial cells and connective tissue
What is the myometrium?
Middle layer
Thickest layer
Smooth muscle
What is the endometrium?
Inner layer of the uterus
Layer of epithelial cells and connective tissue
Numerous glands that contains things like glycogen
What is the site of fetal development?
Body = upper portion
Cervix = canal leading to vagina
Cervix + vagina = birth canal
What are follicles in female reproduction?
Densely packed shells of cells containing an immature oocyte at all stages prior to ovulation
What is the structure of the ovary?
Covered by a capsular structure
Contains follicles
Contains blood vessels
What is the corpus luteum?
Formed in the ovary at the site of a follicle, or sac, which has matured and released its egg
Remains for a while and acts as an endocrine gland
What is the hormonal-ovarian-uterine cycle?
The 3 different cycles in the female body
Cyclical change is on average 28 days
What is the first phase of the ovarian cycle?
Follicular phase = first 14 days
Development of the follicles in which the eggs are growing
Ovulation occurs on the 14th day
What is the second phase of the ovarian cycle?
Luteal phase = the last 14 days
The structure from which the egg is released and it is related to a secretory gland known as the corpus luteum
What is the first phase of the uterine cycle?
Menstrual phase
Day 1 = first day of menstrual bleeding of shedding the surface of the endometrial layer
4 to 5 days of menstrual bleeding
What is the second phase of the uterine cycle?
Proliferative phase
Phase of development or growth
Layers become wider in the endometrium and the blood vessels are growing
Function layer of the endometrium develops
What is the third phase of the uterine cycle?
Secretory phase
Further vascularization and development of uterine glands
What uterine and ovarian phases coincide?
Menstrual + proliferative phases and the follicular phase
Secretory phase and the luteal phase
What is oogenesis?
The development of the oocyte
What is folliculogenesis?
The maturation of the ovarian follicle
What does each follicle contain?
1 oocyte
What are primordial follicles?
A single oocyte surrounded by a single layer of epithelial cells (granulosa cells)
What is theca?
Internal and external
Differentiated granulosa cells that form layers