Overview
This lecture provides a detailed recap of essential topics for exam revision: the female reproductive system, the eye, and the ear, focusing on their structures, functions, and common exam pitfalls.
Female Reproductive System (Ovarian and Uterine Cycle)
- The ovarian cycle starts with primary follicles growing under follicle-stimulating hormone (FSH).
- Mature follicles (Graafian follicles) secrete estrogen, which maintains the endometrium (lining of the uterus).
- Ovulation occurs around day 14, triggered by peaks in FSH and luteinizing hormone (LH).
- After ovulation, the empty follicle becomes the corpus luteum, maintained by LH.
- The corpus luteum secretes progesterone, which further thickens and maintains the endometrium for possible pregnancy.
- If pregnancy does not occur, progesterone and estrogen levels drop, causing the endometrium to shed (menstruation).
Hormonal Regulation and Feedback Loops
- FSH and LH are pituitary hormones; FSH stimulates follicle growth, LH triggers ovulation.
- Estrogen peaks twice: once during follicle development and again just before menstruation.
- Progesterone peaks after ovulation, maintaining the endometrium.
- Negative feedback: High estrogen/progesterone inhibit FSH/LH; when estrogen/progesterone fall, FSH/LH rise to start a new cycle.
The Eye: Key Structures and Functions
- Cornea is the transparent front bulge; conjunctiva lies behind it.
- Suspensory ligaments attach to the lens, changing its shape during accommodation.
- Retina contains rods and cones for vision; choroid is the vascular layer.
- Blind spot: where the optic nerve exits, no vision due to absence of rods/cones.
- Yellow spot (fovea) is the area of highest visual acuity due to many cones.
- Vitreous humor is the thick gel behind the lens; aqueous humor is the watery fluid in front.
- Accommodation: lens becomes flatter to see distant objects, fatter for near objects.
- Myopia (short-sightedness): corrected with concave lenses; hypermetropia (long-sightedness): corrected with convex lenses.
- Pupil reflex: radial muscles contract in dim light (pupil dilates), circular muscles contract in bright light (pupil constricts).
The Ear: Hearing, Balance, and Equilibrium
- Cochlea is the snail-shaped structure responsible for hearing.
- Sound pathway: pinna → auditory canal → tympanic membrane → ossicles → oval window → cochlea → organ of Corti → brain.
- Organ of Corti converts fluid vibrations in cochlea into nerve impulses.
- Semicircular canals (with cristae) maintain balance in three planes.
- Utriculus and sacculus (with macula) detect head posture relative to gravity.
- Oval window receives sound; round window allows excess sound to exit, preventing echoing.
Key Terms & Definitions
- FSH (Follicle Stimulating Hormone) — stimulates follicle growth in the ovary.
- LH (Luteinizing Hormone) — triggers ovulation and supports corpus luteum.
- Estrogen — hormone that repairs/maintains the endometrium.
- Progesterone — hormone that maintains pregnancy by thickening endometrium.
- Graafian Follicle — mature ovarian follicle before ovulation.
- Corpus Luteum — structure formed from empty follicle, secretes progesterone.
- Accommodation — lens changing shape to focus on near or distant objects.
- Vitreous Humor — thick gel behind the lens in the eye.
- Aqueous Humor — watery fluid in front of the lens in the eye.
- Organ of Corti — hearing receptor in the cochlea.
- Crista — balance receptor in semicircular canals.
- Macula — posture receptor in utriculus and sacculus.
Action Items / Next Steps
- Review all labeled diagrams of the ovary, eye, and ear.
- Memorize the hormonal cycles and feedback loops.
- Practice identifying and explaining common exam errors in diagram labeling.
- Learn and rehearse the pathway of sound and the process of accommodation.
- Use bullet-point summaries to answer typical exam questions on these topics.
- Consult the cheat sheet or study guide for concise model answers.