2.4 Musculoskeletal, Urinary & Reproductive Systems
Key Takeaways
The adult skeleton has 206 bones divided into the axial skeleton (skull, spine, ribcage) and appendicular skeleton (limbs, shoulders, pelvis)
The three types of muscle tissue are skeletal (voluntary), smooth (involuntary, organ walls), and cardiac (involuntary, heart only)
The kidneys filter blood, producing approximately 1-2 liters of urine daily; the nephron is the functional unit of the kidney
Normal urine output is 30-50 mL/hour in adults; oliguria (<400 mL/day) and anuria (<100 mL/day) indicate kidney dysfunction
The female reproductive cycle averages 28 days with four phases: menstrual, follicular, ovulation, and luteal
Common musculoskeletal conditions include osteoarthritis, osteoporosis, rheumatoid arthritis, fractures, and sprains/strains
Musculoskeletal System
Skeletal System:
- 206 bones in the adult skeleton
- Functions: Support, protection, movement, mineral storage (calcium, phosphorus), blood cell production (hematopoiesis in red bone marrow)
| Division | Components | Examples |
|---|---|---|
| Axial skeleton (80 bones) | Skull, vertebral column, rib cage, hyoid | Cranium, mandible, cervical/thoracic/lumbar vertebrae, sternum |
| Appendicular skeleton (126 bones) | Upper limbs, lower limbs, shoulder girdle, pelvic girdle | Humerus, radius, ulna, femur, tibia, fibula, scapula, clavicle |
Vertebral Column:
- Cervical (C1-C7) — Neck region; C1 is atlas, C2 is axis
- Thoracic (T1-T12) — Upper back; attach to ribs
- Lumbar (L1-L5) — Lower back; largest vertebrae
- Sacrum (S1-S5 fused) — Posterior pelvis
- Coccyx (3-4 fused) — Tailbone
Joint Types:
| Type | Movement | Examples |
|---|---|---|
| Synovial | Freely movable | Knee, shoulder, hip, elbow |
| Cartilaginous | Slightly movable | Vertebral discs, pubic symphysis |
| Fibrous | Immovable | Skull sutures |
Common Musculoskeletal Conditions:
- Osteoarthritis — Degenerative joint disease; wear and tear of cartilage
- Rheumatoid arthritis — Autoimmune; systemic joint inflammation
- Osteoporosis — Decreased bone density; increased fracture risk
- Fracture — Bone break (closed/simple vs. open/compound)
- Sprain — Ligament injury (connects bone to bone)
- Strain — Muscle or tendon injury (connects muscle to bone)
- Herniated disc — Disc material pressing on spinal nerves
- Carpal tunnel syndrome — Compression of median nerve in the wrist
Urinary System
| Structure | Function |
|---|---|
| Kidneys (2) | Filter blood, produce urine, regulate fluid/electrolyte balance, acid-base balance, blood pressure (renin), red blood cell production (erythropoietin) |
| Ureters (2) | Transport urine from kidneys to bladder via peristalsis |
| Bladder (1) | Stores urine (capacity ~500 mL) |
| Urethra (1) | Transports urine from bladder to outside the body |
The Nephron (functional unit of the kidney): Each kidney contains about 1 million nephrons that filter blood and produce urine:
- Glomerulus — Capillary network that filters blood
- Bowman's capsule — Collects the filtrate
- Proximal convoluted tubule — Reabsorbs glucose, amino acids, sodium, water
- Loop of Henle — Concentrates urine; reabsorbs water and sodium
- Distal convoluted tubule — Fine-tunes electrolyte balance
- Collecting duct — Collects final urine; influenced by ADH
Urine Output:
| Term | Definition |
|---|---|
| Normal output | 30-50 mL/hour (1,000-2,000 mL/day) |
| Polyuria | Excessive urine output (>2,500 mL/day) |
| Oliguria | Decreased urine output (<400 mL/day) |
| Anuria | Absent urine output (<100 mL/day) |
| Hematuria | Blood in the urine |
| Proteinuria | Protein in the urine |
| Glycosuria | Glucose in the urine |
Common Urinary Conditions:
- UTI — Urinary tract infection; most common in females; burning urination, frequency
- Kidney stones (nephrolithiasis) — Mineral deposits; severe flank pain
- Chronic kidney disease — Progressive loss of kidney function
- Incontinence — Involuntary loss of urine (stress, urge, overflow types)
Reproductive System
Male Reproductive System:
| Structure | Function |
|---|---|
| Testes | Produce sperm and testosterone |
| Epididymis | Sperm maturation and storage |
| Vas deferens | Transports sperm from epididymis |
| Seminal vesicles | Produce fructose-rich fluid (60% of semen) |
| Prostate gland | Produces alkaline fluid to protect sperm |
| Urethra | Passageway for semen and urine (not simultaneously) |
| Penis | Delivers sperm; urination |
Female Reproductive System:
| Structure | Function |
|---|---|
| Ovaries | Produce eggs (ova), estrogen, and progesterone |
| Fallopian tubes | Transport eggs from ovary to uterus; fertilization site |
| Uterus | Site of embryo implantation and fetal development |
| Cervix | Lower portion of uterus; opening to vagina |
| Vagina | Birth canal; receives sperm |
Menstrual Cycle (~28 days):
| Phase | Days | Events |
|---|---|---|
| Menstrual | 1-5 | Uterine lining sheds; bleeding occurs |
| Follicular | 1-13 | Follicle matures in ovary; estrogen rises; endometrium thickens |
| Ovulation | Day 14 | Mature egg released from ovary; LH surge triggers ovulation |
| Luteal | 15-28 | Corpus luteum produces progesterone; endometrium maintained; if no fertilization, progesterone drops and menstruation begins |
Common Reproductive Conditions:
- Benign prostatic hyperplasia (BPH) — Enlarged prostate; urinary difficulty in older males
- Prostate cancer — Most common cancer in males; PSA screening
- Endometriosis — Uterine tissue grows outside the uterus; painful periods
- Polycystic ovary syndrome (PCOS) — Hormonal imbalance; irregular periods, ovarian cysts
- Cervical cancer — Often caused by HPV; detected by Pap smear screening
- Sexually transmitted infections — Chlamydia, gonorrhea, syphilis, HIV, herpes, HPV
Lymphatic/Immune System
The lymphatic system works closely with the cardiovascular system and plays a crucial role in immunity:
| Component | Function |
|---|---|
| Lymph nodes | Filter lymph fluid; trap pathogens; contain lymphocytes |
| Spleen | Filters blood; removes old RBCs; stores blood; produces lymphocytes |
| Thymus | T-cell maturation (most active in childhood) |
| Tonsils | Trap pathogens entering through mouth/nose |
| Bone marrow | Produces all blood cells including lymphocytes |
Immunity Types:
- Innate (natural) immunity — Non-specific; present at birth (skin, mucous membranes, inflammation, fever)
- Adaptive (acquired) immunity — Specific; develops after exposure to pathogens or vaccination
- Active immunity — Body makes its own antibodies (infection or vaccination)
- Passive immunity — Receiving antibodies from another source (maternal antibodies, immunoglobulin injections)
Which of the following correctly describes the difference between a sprain and a strain?
A sprain involves a muscle injury; a strain involves a ligament injury
A sprain involves a ligament injury; a strain involves a muscle or tendon injury
A sprain involves a bone fracture; a strain involves a joint dislocation
A sprain and a strain are the same type of injury
The functional unit of the kidney responsible for filtering blood and producing urine is the:
Glomerulus
Nephron
Ureter
Loop of Henle
On approximately what day of the menstrual cycle does ovulation typically occur?
Day 1
Day 7
Day 14
Day 28
Active immunity is developed when:
A patient receives antibodies from another source
A newborn receives antibodies through breast milk
The body produces its own antibodies after infection or vaccination
A patient receives an immunoglobulin injection
Oliguria is defined as:
Excessive urine output (>2,500 mL/day)
Blood in the urine
Decreased urine output (<400 mL/day)
Glucose in the urine
Sections you finish are checked off in the contents.