Unit 2 of 3 · B.Sc MLS Sem 3
Unit 2: Urinary and genital systems
Human Anatomy & Physiology-II notes · PTU syllabus (BMLS303-18)
3 min read7 topics10 exam questions
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Unit summary
The kidneys clean the blood and the reproductive system continues the species. This unit covers the kidney and nephron, urine formation, other excretory organs, the male and female reproductive systems, gametogenesis, the menstrual cycle, the placenta and extra-embryonic membranes.
After this unit you can
- Describe the kidney and nephron
- Explain the formation of urine
- Describe the male and female reproductive systems and gametogenesis
- Explain the menstrual cycle and the placenta
PTU syllabus topics
- Structure and function of the kidney and nephron
- physiology of excretion and urine formation
- additional excretory organs
- structure of the male and female reproductive systems
- gametogenesis
- menstrual cycle
- placenta and extra-embryonic membranes
- 1Glomerular filtration
Bowman's capsule
- 2Proximal tubule
Reabsorbs glucose, salts, water
- 3Loop of Henle
Concentrates urine
- 4Distal tubule
Fine-tunes salts; secretion
- 5Collecting duct
Water reabsorbed under ADH
1
Topic 1
The kidney and nephron
- Two bean-shaped kidneys lie behind the peritoneum; each has an outer cortex, inner medulla with pyramids, and a pelvis draining to the ureter → bladder → urethra.
- 1Bowman's capsule around the glomerulus — filtration
- 2Proximal convoluted tubule — reabsorbs glucose, amino acids, most Na⁺ and water
- 3Loop of Henle — concentrates urine (countercurrent)
- 4Distal convoluted tubule — aldosterone-regulated Na⁺ and K⁺ exchange
- 5Collecting duct — ADH-regulated water reabsorption
2
Topic 2
Physiology of urine formation
- Glomerular filtration
- Blood pressure filters plasma (minus proteins and cells); GFR about 125 mL/min (180 L/day)
- Tubular reabsorption
- About 99% of filtrate reabsorbed; glucose fully unless above the renal threshold (about 180 mg/dL)
- Tubular secretion
- H⁺, K⁺, creatinine, drugs added
- Concentration
- ADH and the loop of Henle produce 1–1.5 L urine daily
- Other functions: acid–base balance, erythropoietin, vitamin D activation, renin (blood pressure). Other excretory organs: skin (sweat), lungs (CO₂), liver (bile pigments), intestine.
- Normal urine: pH about 6, specific gravity 1.003–1.030, no glucose or protein (trace).
3
Topic 3
The male reproductive system
- Testes
- In the scrotum; seminiferous tubules make sperm; Leydig cells make testosterone
- Epididymis
- Sperm maturation and storage
- Vas deferens and ejaculatory duct
- Carry sperm
- Accessory glands
- Seminal vesicles (fructose), prostate, bulbourethral glands
- Penis and urethra
- Deliver semen
- Normal semen (WHO 2021 lower limits): volume 1.4 mL, sperm concentration 16 million/mL, total motility 42%, normal forms 4%.
4
Topic 4
The female reproductive system
- Ovaries
- Produce ova, oestrogen and progesterone
- Fallopian tubes
- Site of fertilisation
- Uterus
- Endometrium for implantation; myometrium
- Cervix and vagina
- Birth canal
- Mammary glands
- Milk production
5
Topic 5
Gametogenesis
Spermatogenesis
Oogenesis
Site
Seminiferous tubules
Ovary
Begins
Puberty; continuous
Before birth; arrested until puberty
Products per cell
Four sperm
One ovum and polar bodies
Duration
About 74 days
Months to decades
6
Topic 6
The menstrual cycle
Menstrual cycle (about 28 days)
1Menstrual phase
2Follicular (proliferative) phase
3Ovulation
4Luteal (secretory) phase
5If no pregnancy
- 1. Menstrual phase: Days 1–5: endometrium shed
- 2. Follicular (proliferative) phase: FSH grows follicles; oestrogen rebuilds endometrium
- 3. Ovulation: Around day 14 after an LH surge
- 4. Luteal (secretory) phase: Corpus luteum secretes progesterone; endometrium prepares
- 5. If no pregnancy: Corpus luteum degenerates; hormones fall; menstruation
- Pregnancy test: detects hCG made by the placenta, in urine or serum.
7
Topic 7
Placenta and extra-embryonic membranes
- Placenta: disc-shaped organ linking mother and fetus; exchanges gases, nutrients and wastes; produces hCG, progesterone, oestrogen and human placental lactogen; passes IgG antibodies to the fetus.
- Amnion
- Encloses amniotic fluid that cushions the fetus
- Chorion
- Forms the fetal part of the placenta
- Yolk sac
- Early blood cell formation
- Allantois
- Forms umbilical blood vessels
Key terms
- Nephron
- Functional unit of the kidney
- GFR
- Volume of plasma filtered per minute by the glomeruli
- Renal threshold
- Blood level above which a substance appears in urine
- Ovulation
- Release of an ovum from the ovary
- hCG
- Placental hormone detected in pregnancy tests
Quick revision
- Kidney regions; nephron parts and functions.
- Filtration, reabsorption, secretion; GFR 125 mL/min; renal threshold for glucose.
- Male organs; semen reference values.
- Female organs; spermatogenesis vs oogenesis.
- Menstrual cycle phases and hormones; placenta functions; amnion, chorion, yolk sac, allantois.
Important exam questions
Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).
Short-answer questions
- Q1.Name the parts of a nephron.
- Q2.What is the normal GFR?
- Q3.What is the renal threshold for glucose?
- Q4.Which cells produce testosterone?
- Q5.What triggers ovulation?
- Q6.Name two hormones made by the placenta.
Long-answer questions
- Q1.Describe the structure of the nephron and urine formation.
- Q2.Describe the male and female reproductive systems.
- Q3.Compare spermatogenesis and oogenesis.
- Q4.Explain the menstrual cycle and the functions of the placenta.
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