The Reproductive System Flashcards
What are the three cylindrical columns of erectile tissue in the penis?
-
Corpora cavernosa
- 2 columns
- deep artery embedded
-
Corpus spongiosum
- erectile tissue
- around urethra
- more elastic fibres
What are the three cells contained in each testis?
-
Leydig cells
- produce sex hormones
-
Spermatogenic cells
- make sperm
-
Sertoli cells
- mechanical and nutritional support
What are the steps in spermatogenesis starting from germ cells (spermatogonia)?
- Spermatogonia divide by mitosis
- Differentiate into primary spermatocytes
- Undergo meiosis I to form secondary spermatocytes
- Undergo meiosis II to form spermatids
- Differentiates into spermatozoa/sperm
Describe the properties of mature sperm
- Lacks intracellular structures
- Reduces sperm size and mass
- Absorbs nutrients (fructose) from surrounding fluid
- Mitochondrial spiral provides ATP
- Energy to move flagellum
- Movement (swim)
Describe the functions of the fluid secreted by Sertoli cells
- Secretes fluid rich in PENBIA
- P: Proteins
- E: Enzymes
- N: Nutrients
- B: Bicarbonate ions
- I: Ions
- A: Androgens
- Fluid enters lumen
- Nourish developing sperm
- Flushes sperm into epididymis
- Damaged spermatogonia engulfed by sertoli cells
Describe the functions of the proteins synthesized by Sertoli cells
-
Androgen-binding protein
- Binds to testosterone to increase its concentration
-
Inhibin
- Stimulates pituitary gland to inhibit FSH secretion
Describe the hormonal control of spermatogenesis
-
Testosterone
- Stimulated by LH
- Secreted by Leydid cells
- Promotes meiosis and early spermatid maturation
-
FSH
- Promotes spermatogenesis
- Direct: Acts on Sertoli cells to influence no. of germ cells
- Indirect: More ABP to concentrate testosterone levels
Why is the incidence of bladder infections in males lower than in females?
-
Longer urethra in males
- Lower chance of bacteria reaching bladder
- Male urinary tract has natural defenses to infection
- Seminalplasmin, an antibiotic
- Male urethra separated from rectum
Describe the overall effects of testosterone
- Maintains spermatogenesis
- Enlarges penis and testes
- Wrinkles and pigments scrotal skin
- Grows facial, pubic, and body hair
- Enlarges vocal cords and larynx
- Increases body growth
- Increases muscle mass
- Grows long bones
- Forms red blood cells
Describe the pathway of sperm from production to ejaculation
- Seminiferous tubules
- Rete testis
- Efferent ductules
- Epididymis
- Ductus deferents
- Ejaculatory duct
- Urethra
Describe the features and functions of the epididymis
- Lined with smooth muscle
- Secretes fluid with nutrients, enzymes, hormones
- Site of sperm maturation and storage
Describe the functions of the seminal vesicle, a male accessory sex organ
- Produces 60% of semen volume
- Contains fructose
- Prostaglandins (fatty acids) to stimulate smooth muscle contractions
- Fluid is alkaline to neutralize vaginal acids
Describe the functions of the prostate gland, a male accessory sex organ
- Produces ~20% of semen volume
- Acidic
- Contains seminalplasmin, a protein with antibiotic properties
Describe the functions of Cowpers gland, a male accessory sex organ
- Secretes thick mucus
- Alkaline to neutralize urinary acids in the urethra
- Lubricates penis tip
Describe what triggers an erection
- Parasympathetic (POINT)
- Nitric oxide released
- Arteries dilate
- Increased blood flow
Describe what triggers ejaculation
-
Emission prior
- movement of semen into urethra
- Sympathetic (SHOOT)
- Contraction of smooth muscle
- Seminal vesicle, prostate, muscles at penis base
- Semen expelled
Describe the four main functions of the uterus
- Mechanical protection
- Nutritional support
- Removes waste for developing embryo
- Uterus wall contracts during labor
What is capacitation of sperm?
- Maturation process
- Sperm stays in female tract for hours
- Sterols and glycoproteins removed
- Increased membrane permeability to calcium ions
- Increased intracellular cAMP levels
- Increased motility
- Ability to penetrate ovum
Why do only 0.1% of sperm reach the uterine tubes?
- 50% is lost due to abnormal shape or reduced motility
- Destroyed by acidic vaginal secretions
- Blocked by cervix mucus
Describe the process of fertilization
- In fallopian tubes
- Acrosome reaction: for sperm to enter oocyte
-
Calcium ions released
- Prevents other sperm from entering
- Activates oocyte to complete meiosis
- Diploid zygote forms 12 hours later
Describe the process of implantation
- Blastocyst releases chorionic gonadotropin (hCG)
- Keeps corpus luteum alive
- Continued release of estrogen and progesterone
- Maintains thick endometrium
- Increased vascularization
Describe molecule exchange between the fetus and the mother
- Umbilical cord connects fetus and placenta
- Umbilical arteries deliver fetal blood to placental vessels
- Umbilical veins return fetal blood
- Molecules diffuse across placental tissue
- From maternal to fetal: Oxygen and nutrients
- From fetal to maternal: Carbon dioxide and wastes
Describe the process of parturition (delivery)
-
Dilation
- > 8 hours
- Labor contractions every 10-30 minutes
- Amniochorionic membrane ruptures
-
Expulsion
- <2 hours
- Cervix dilates (hormonal) with pressure (physiological)
- Labor contractions every 2-3 minutes
-
Placental
- Muscle tension
- Tears connection between endometrium and placenta
- Afterbirth: Placenta expelled
- Contraction of uterine vessels restrict blood loss
