(Systems of the body 3 )

📌 Part 1: The Respiratory System
🖇 Division
Upper Respiratory Tract: Nasal cavity, Nostril, Oral cavity.
Lower Respiratory Tract: Pharynx, Larynx, Trachea, Right & Left main bronchi, Lungs, Diaphragm.
🟠 Pharynx
3 Parts (top → bottom):
1. Nasopharynx: behind nasal cavity.
2. Oropharynx: behind oral cavity.
3. Laryngopharynx: connects to larynx.
🟣 Larynx (Voice Box)
Function: Voice production.
Location: From C3 → C6 vertebrae.
Structure: Cartilaginous framework (Thyroid cartilage = Adam’s apple).
Key parts: Soft palate, Epiglottis, Cricoid cartilage.
🟠 Trachea
Continuation of larynx.
Wall: 15–20 C-shaped cartilaginous rings.
Ends at T4 (divides into R & L main bronchi).
Carina: point of division.
🟣 Bronchi
Right main bronchus: shorter, wider, more vertical → common site for foreign body impaction.
Left main bronchus: longer, narrower, more oblique → less common for impaction.
🟠 Lungs
Shape: Cone-shaped (Apex ↑, Base ↓).
Right lung: 3 lobes (Superior, Middle, Inferior) + 2 fissures (Oblique, Horizontal).
Left lung: 2 lobes (Superior, Inferior) + 1 fissure (Oblique) + Cardiac notch (medial surface).
🚨 Clinical Importance
Right bronchus → common site of aspiration.
Carina → sensitive; irritation triggers cough reflex.
Cardiac notch → accommodates heart.
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📌 Part 2: The Genital (Reproductive) System
🖇 A. Male Genital System
🟠 Primary Sex Organs
Testes:
2 in number, inside scrotum.
Function: Sperm production.
🟣 Secondary Sex Organs (Duct System)
Ducts for sperm transport & maturation:
Vasa efferentia
Epididymis: stores & matures sperm.
Vas deferens: conducts sperm.
Ejaculatory duct: final duct before urethra.
Urethra: passage for sperm & urine.
🟠 Accessory Glands
Seminal vesicle: base of urinary bladder.
Prostate gland: below bladder neck.
Bulbo-urethral gland: opens into urethra below prostate.
Function: Provide sperm nutrition.
🟣 External Genitalia
Penis: delivers ejaculate → posterior fornix of vagina.
🚨 Clinical Importance
Right testis slightly lower.
Prostate enlargement → urinary obstruction.
Vasectomy: cutting vas deferens (contraception).
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🖇 B. Female Genital System
🟠 Primary Sex Organs
Ovaries:
2 in number, in lateral pelvic wall.
Functions:
Produce ova (eggs).
Secrete female hormones.
🟣 Secondary Sex Organs
🔹 Uterine (Fallopian) Tube:
Parts (lateral → medial):
1. Infundibulum (fimbriae at end).
2. Ampulla: site of fertilization.
3. Isthmus
4. Intramural (in uterine wall).
Functions:
Carries ovum → uterus.
Carries sperms → ovum.
Fertilization in ampulla.
Transports zygote → uterus.
🔹 Uterus:
Parts:
Fundus (above tubes).
Body (middle; lower part = isthmus).
Cervix (cervical canal with internal & external os).
Wall Layers:​
Perimetrium: outer.
Myometrium: muscular middle.
Endometrium: inner epithelial lining.
🔹 Vagina:
Upper part surrounds cervix → forms 4 fornices (anterior, posterior, 2 lateral).
Posterior fornix → site of ejaculation.
Opens externally behind urethra & in front of anal canal.
🟣 External Genitalia
Includes: Clitoris, Labium minus, Labium majus, Vaginal orifice.
🚨 Clinical Importance
Ampulla → site of ectopic pregnancy.
Endometrium → changes during menstrual cycle.
Posterior fornix → used for culdocentesis (clinical procedure).