A&p2
Organs within the urinary system:
- Kidneys: Located in the posterior abdominal wall, retroperitoneal.
- Urinary tract: Ureters, urinary bladder, and urethra (male urethra is longer and has three parts: prostatic, membranous, and spongy).
2. How is the urethra different in males and females?
- Male urethra: ~20 cm long, divided into prostatic, membranous, and spongy parts, serves urinary and reproductive functions.
- Female urethra: ~4 cm long, shorter and serves only urinary function.
3. Functions of the urinary system:
- Elimination: Metabolic wastes (e.g., urea, uric acid).
- Regulation: Blood ionic composition, pH, blood volume, and blood pressure.
- Hormonal functions: Erythropoiesis via erythropoietin, activation of Vitamin D.
4. External anatomy of the kidneys:
- Bean-shaped, covered by protective layers (renal fascia, adipose capsule, renal capsule).
- Medial surface has a hilum (entry/exit for vessels, nerves, and ureter).
5. Protective structures of the kidneys:
- Renal fascia: Anchors kidneys to peritoneum.
- Adipose capsule: Cushions the kidneys.
- Renal capsule: Thin, dense irregular connective tissue directly covering the kidneys.
6. Internal anatomy of the kidneys:
- Cortex: Thin outer region.
- Medulla: Contains renal pyramids separated by renal columns.
- Renal pelvis: Funnel-shaped, collects urine from major and minor calyces.
7. Functional units of the kidneys:
- Nephrons.
8. Describe blood flow through the kidneys:
- Abdominal aorta → renal artery → segmental artery → interlobar artery → arcuate artery → cortical radiate artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries/vasa recta → cortical radiate vein → arcuate vein → interlobar vein → renal vein → inferior vena cava.
9. Components of a nephron:
- Renal corpuscle: Glomerular capsule and glomerulus.
- Renal tubules: Proximal tubule, nephron loop, distal tubule.
10. Structural features of the glomerular capsule:
- Thin-walled, with parietal and visceral layers. The visceral layer consists of podocytes with pedicels forming filtration slits.
11. Structural features of the glomerulus (glomerular capillaries):
- Fenestrated capillaries (highly permeable, allowing solute-rich fluid to pass).
12. What is filtrate?
- Fluid and dissolved solutes that pass through the filtration membrane into the capsular space.
13. Regions of the renal tubules:
- Proximal tubule, nephron loop (descending and ascending limbs), distal tubule.
14. Pathway of filtrate through a nephron:
- Capsular space → proximal tubule → descending limb → ascending limb → distal tubule → collecting duct.
15. Pathway of urine:
- Collecting duct → papillary duct → minor calyx → major calyx → renal pelvis → ureter → bladder → urethra.
16. Components of the juxtaglomerular apparatus (JGA):
- Juxtaglomerular cells (JG cells): Release renin, monitor blood pressure.
- Macula densa cells: Detect solute concentration and filtration rate.
17. Location of the JGA:
- At the point where the distal tubule meets the afferent arteriole of the same nephron.
18. Types of nephrons:
- Cortical nephrons (80%): Short loops, perform most reabsorption and secretion.
- Juxtamedullary nephrons (20%): Long loops, important for concentrated urine.
19. Processes in renal physiology:
- Glomerular filtration: Formation of filtrate by hydrostatic pressure.
- Tubular reabsorption: Return of solutes and water from filtrate to blood.
- Tubular secretion: Transfer of solutes from blood to filtrate.
20. Function of peritubular capillaries:
- Surround nephron tubules, facilitate reabsorption and secretion.
21. Structural features of the filtration membrane:
- Fenestrated capillary endothelium, podocytes with filtration slits, and basal lamina.
22. What is GFR?
- Glomerular Filtration Rate, the amount of filtrate formed per minute (~180 L/day for males, ~150 L/day for females).
23. Volume of filtrate vs urine:
- Filtrate: ~180 L/day, Urine: ~1.5-2 L/day.
24. Net Filtration Pressure (NFP):
- NFP = GHP - (GOP + CHP) = 10 mm Hg.
25. Factors increasing glomerular filtration rate:
- High glomerular hydrostatic pressure, high permeability of filtration membrane.
26. Autoregulation mechanisms:
- Myogenic mechanism: Adjusts afferent arteriole tone in response to BP changes.
- Tubuloglomerular feedback: Macula densa cells signal changes in GFR.
27. Renin-Angiotensin-Aldosterone System:
- Renin → Angiotensinogen → Angiotensin I → (via ACE) Angiotensin II → systemic vasoconstriction, aldosterone release, and increased BP.
28. Effect of ADH:
- Increases water reabsorption in collecting ducts, reduces urine volume, increases urine concentration.
Based on the information provided, here are detailed answers to the questions:
Here are the answers based on the information you provided:
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### 29. How do the macula densa cells help regulate GFR?
- Macula densa cells are located in the juxtaglomerular apparatus (JGA) and monitor the osmolarity (solute concentration) of the filtrate in the distal tubule. If the osmolarity is too high (indicating a high GFR), the macula densa cells induce constriction of the afferent arteriole, which reduces the glomerular hydrostatic pressure (HPG) and thus decreases the GFR. If the osmolarity is low (indicating a low GFR), the macula densa cells promote dilation of the afferent arteriole, increasing blood flow into the glomerulus and increasing GFR.
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### 30. Describe the importance of autoregulation.
- Autoregulation helps the kidneys maintain a constant GFR and renal blood flow despite fluctuations in systemic blood pressure. This prevents damage to the kidneys by ensuring stable filtration. The two mechanisms involved in autoregulation are:
1. Myogenic mechanism: Smooth muscle in the afferent arteriole contracts when stretched by increased blood pressure, reducing blood flow into the glomerulus, and relaxes when blood pressure decreases.
2. Tubuloglomerular feedback: The macula densa cells monitor filtrate osmolarity and adjust the afferent arteriole diameter to maintain a steady GFR.
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### 31. Describe the renin-angiotensin-aldosterone system.
- The RAAS is a hormonal system that regulates blood pressure and fluid balance:
1. Renin is released by juxtaglomerular cells when blood pressure is low.
2. Renin converts angiotensinogen (from the liver) to angiotensin I.
3. Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs.
4. Angiotensin II causes vasoconstriction (increasing blood pressure) and stimulates aldosterone release from the adrenal cortex.
5. Aldosterone increases Na+ and water reabsorption, which raises blood volume and pressure.
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### 32. What stimulates the release of renin?
- Renin is released by juxtaglomerular cells in response to:
- Low blood pressure (detected by baroreceptors in the afferent arteriole).
- Low Na+ concentration (detected by macula densa cells).
- Sympathetic nervous system activation (due to stress or low blood pressure).
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### 33. Describe the pathway of angiotensin II production.
1. Renin is released from juxtaglomerular cells and converts angiotensinogen (produced by the liver) into angiotensin I.
2. Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs.
3. Angiotensin II acts to constrict arterioles, increase aldosterone release, and raise blood pressure.
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### 34. What are the effects of angiotensin II?
- Angiotensin II has several effects to increase blood pressure:
- Vasoconstriction of efferent arterioles increases glomerular pressure and reduces GFR in response to low blood flow.
- Vasoconstriction of systemic arterioles increases blood pressure.
- Stimulates the release of aldosterone from the adrenal glands, leading to increased Na+ and water reabsorption.
- Stimulates Na+ and Cl- reabsorption in the proximal tubule.
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### 35. How does the renin-angiotensin system regulate GFR?
- The renin-angiotensin system regulates GFR by vasoconstricting efferent arterioles, which raises glomerular hydrostatic pressure (HPG) and helps maintain GFR despite reduced blood flow. This is particularly important during periods of low blood pressure or dehydration.
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### 36. How does atrial natriuretic peptide regulate GFR?
- Atrial natriuretic peptide (ANP) is released by atrial cells in response to increased blood volume. It causes:
- Vasodilation of afferent arterioles and vasoconstriction of efferent arterioles, which increases GFR and promotes fluid loss, helping reduce blood volume and pressure.
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### 37. What is the effect of low levels vs high levels of sympathetic stimulation on GFR?
- Low levels of sympathetic stimulation (e.g., light exercise):
- Increases renin release, resulting in mild vasoconstriction of afferent arterioles, helping maintain GFR.
- High levels of sympathetic stimulation (e.g., stress, severe exercise, blood loss):
- Increases renin release significantly, leading to high angiotensin II levels, which constrict both afferent and efferent arterioles, helping to maintain GFR under stress.
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### 38. What is the effect of aldosterone on the late distal tubule and cortical collecting duct?
- Aldosterone promotes Na+ reabsorption and K+ secretion in the late distal tubule and cortical collecting duct. This increases blood volume (since water follows Na+), raising blood pressure.
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### 39. What is the relative Na+ and K+ content of urine in the presence of aldosterone?
- Aldosterone increases Na+ reabsorption and K+ secretion. As a result:
- Urine contains low Na+ and high K+ levels when aldosterone is present.
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### 40. Describe the formation of a dilute urine.
- Dilute urine is formed when:
- The filtrate in the proximal tubule is isotonic.
- In the descending limb of the nephron loop, water is reabsorbed, and the filtrate becomes hypertonic.
- In the ascending limb and distal tubule, NaCl is reabsorbed, but the filtrate remains hypotonic.
- In the absence of ADH, the distal tubule and collecting duct remain impermeable to water, so urine is dilute.
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### 41. What is the function of ADH?
- Antidiuretic hormone (ADH) regulates water balance by increasing water reabsorption in the kidneys. It opens aquaporins in the distal tubule and collecting duct, allowing water to be reabsorbed and concentrating the urine.
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### 42. What is the mechanism of ADH release from the posterior pituitary?
- ADH is released from the posterior pituitary in response to:
- Increased blood osmolarity (detected by osmoreceptors in the hypothalamus).
- Decreased blood volume (detected by baroreceptors).
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### 43. How does ADH affect the volume and concentration of urine?
- ADH increases the reabsorption of water in the distal tubule and collecting duct. This:
- Reduces urine volume.
- Increases urine concentration, making it more concentrated.
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### 44. Describe the formation of a concentrated urine.
- Concentrated urine is formed when:
- ADH increases water reabsorption in the medullary collecting duct.
- The medullary osmotic gradient allows water to be reabsorbed by osmosis, resulting in a smaller volume of concentrated urine.
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### 45. What is the role of the kidneys in fluid balance?
- The kidneys regulate fluid balance by adjusting the volume and composition of urine. This involves:
- Reabsorbing water when necessary to maintain blood volume and prevent dehydration.
- Excreting excess water to reduce blood volume when fluid balance is disrupted.
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### 46. How do the kidneys help regulate the pH of body fluids?
- The kidneys help regulate blood pH by:
- Reabsorbing bicarbonate (HCO3-) to buffer the blood.
- Secreting hydrogen ions (H+) into the urine to decrease blood acidity.
### 1. What are the functions of the female reproductive system?
- Production of egg cells (ova).
- Production of sex hormones (estrogen and progesterone).
- Transport of the egg cell to the site of fertilization.
- Preparation of the uterus for implantation.
- Housing and nourishing the embryo during development.
- Delivering and nourishing the infant after birth.
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### 2. Describe the organs of the female reproductive system.
- Primary reproductive organ: Ovaries (produce gametes and hormones).
- Internal genitalia: Ovaries, uterine tubes, uterus, and vagina.
- External genitalia (vulva): Mons pubis, labia majora, labia minora, vestibule, and associated glands.
- Mammary glands: Responsible for lactation.
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### 3. What are the primary reproductive organs of the female?
- Ovaries.
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### 4. What are the functions of the ovaries?
- Produce egg cells (ova).
- Secrete sex hormones (estrogen and progesterone).
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### 5. Identify and describe the ligaments that secure the ovaries.
- Broad ligament: Secures the ovaries, uterine tubes, and uterus to the pelvis.
- Ovarian ligament: Connects the ovaries to the uterus.
- Suspensory ligament: Connects the ovaries to the pelvic wall and contains the ovarian artery and vein.
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### 6. What are ovarian follicles?
- Fluid-filled sacs in the ovarian cortex that contain developing egg cells (oocytes).
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### 7. Identify and describe the regions of the uterine tubes.
- Isthmus: Narrow region connecting the uterine tube to the uterus.
- Ampulla: Expanded region where fertilization typically occurs.
- Infundibulum: Funnel-shaped region near the ovary with finger-like fimbriae.
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### 8. What are the functions of the uterine tubes?
- Receive the ovulated oocyte.
- Serve as the site of fertilization (in the ampulla).
- Transport the fertilized egg to the uterus.
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### 9. What is the role of fimbriae?
- Fimbriae create currents that help move the ovulated oocyte into the uterine tube.
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### 10. What are the functions of the uterus?
- Site of implantation of the fertilized egg.
- Supports and nourishes the developing embryo/fetus.
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### 11. Identify the regions of the uterus.
- Fundus: Rounded upper region.
- Body: Main portion of the uterus.
- Cervix: Narrow lower portion that projects into the vagina.
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### 12. Identify the three layers of the uterine wall.
- Perimetrium: Outer layer.
- Myometrium: Middle layer of smooth muscle.
- Endometrium: Inner epithelial lining.
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### 13. What is the function of the myometrium?
- Facilitates uterine contractions during childbirth.
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### 14. What is the function of the endometrium?
- Prepares for implantation of the fertilized egg.
- Thickens, becomes vascular, and is shed during menstruation if no implantation occurs.
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### 15. Describe the location and structural features of the vagina.
- Muscular tube extending from the cervix to the exterior of the body.
- Positioned between the urethra and rectum.
- Lined with stratified squamous epithelium that provides physical and chemical protection.
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### 16. What is the function of the mammary glands?
- Lactation: production and secretion of milk.
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### 17. Describe the structure of the mammary glands.
- Composed of adipose tissue and 15-20 lobes of glandular tissue.
- Secretory cells in lobules produce milk that drains into lactiferous ducts.
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### 18. Define oogenesis.
- The process of producing female gametes (ova) via meiosis.
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### 19. When does oogenesis begin?
- Before birth, during embryonic development.
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### 20. What are oogonia?
- Diploid cells in ovarian follicles that serve as the initial stage in ovum development.
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### 21. Describe the stages of oogenesis.
1. Prior to birth: Oogonia divide, transform into primary oocytes, and become arrested in prophase I of meiosis.
2. Childhood to puberty: Primary oocytes remain dormant; many degenerate.
3. Puberty to menopause: Monthly cycles resume meiosis I, forming secondary oocytes arrested in metaphase II until fertilization.
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### 22. In what stage of meiosis are primary oocytes at birth?
- Arrested in prophase I.
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### 23. What hormone causes resumption of meiosis following onset of puberty?
- Follicle-stimulating hormone (FSH).
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### 24. Identify the daughter cells that are produced when meiosis I is complete.
- Secondary oocyte and the first polar body.
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### 25. What is ovulation?
- The release of a secondary oocyte from the follicle.
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### 26. What hormonal event triggers ovulation?
- Surge in luteinizing hormone (LH).
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### 27. What phase of meiosis is a secondary oocyte in when ovulated?
- Arrested in metaphase II.
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### 28. How many chromosomes are in a secondary oocyte?
- 23 chromosomes (haploid, with a copy).
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### 29. What is the role of sperm in the development of an ovum?
- Sperm penetration triggers completion of meiosis II, forming the ovum.
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### 30. What is the significance of the unequal distribution of cytoplasm during cell division in oogenesis?
- Provides the ovum with adequate nutrients for early development.
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### 31. What happens to the polar bodies?
- They degenerate and are reabsorbed.
Let me continue answering the remaining questions:
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### 32. Identify and describe the three phases of the ovarian cycle.
1. Follicular phase (Days 1–14): Follicles grow, and a primary oocyte completes meiosis I to form a secondary oocyte.
2. Ovulatory phase (Day 14): Secondary oocyte is released from the follicle in response to an LH surge.
3. Luteal phase (Days 14–28): Remaining follicular cells form the corpus luteum, which secretes estrogen and progesterone to prepare the uterus for implantation.
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### 33. Describe the corpus luteum.
- A temporary endocrine structure formed from the ruptured follicle after ovulation.
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### 34. What is the function of the corpus luteum?
- Secretes progesterone and estrogen to support the endometrium for implantation.
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### 35. Describe the hypothalamic-pituitary-gonadal (HPG) axis.
- The hypothalamus secretes GnRH, which stimulates the anterior pituitary to release FSH and LH. These hormones regulate ovarian function and estrogen/progesterone production.
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### 36. Describe the hormonal regulation of the ovarian cycle.
- FSH: Stimulates follicle growth and estrogen production.
- LH: Triggers ovulation and the formation of the corpus luteum.
- Estrogen and progesterone: Inhibit FSH and LH during the luteal phase and stimulate endometrial changes in the uterine cycle.
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### 37. Describe the fluctuations in estrogen and progesterone during the ovarian cycle.
- Estrogen rises during the follicular phase, peaking before ovulation.
- Progesterone rises during the luteal phase, secreted by the corpus luteum.
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### 38. What is the uterine cycle?
- A series of changes in the endometrium in response to fluctuating ovarian hormone levels during a 28-day cycle.
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### 39. Define menarche and menopause.
- Menarche: The first menstrual cycle following puberty.
- Menopause: The cessation of menstruation for 12 consecutive months, typically occurring between ages 45–52.
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### 40. What is the length of a typical uterine cycle in days?
- 28 days.
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### 41. Name and describe the three phases of the uterine cycle.
1. Menstrual phase (Days 1–5): The endometrium is shed.
2. Proliferative phase (Days 6–14): The endometrium regenerates and thickens.
3. Secretory phase (Days 15–28): Endometrial glands secrete nutrients, preparing for implantation.
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### 42. Describe how fluctuations in estrogen and progesterone during the ovarian cycle influence the phases of the uterine cycle.
- Rising estrogen levels in the follicular phase promote endometrial proliferation.
- Progesterone from the corpus luteum in the luteal phase supports the secretory phase.
- A drop in progesterone (if no fertilization occurs) leads to menstruation.
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### 43. What is fertilization?
- The union of a sperm cell and a secondary oocyte, resulting in the formation of a zygote.
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### 44. Where does fertilization occur?
- In the ampulla of the uterine tube.
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### 45. What hormone is used in pregnancy tests?
- Human chorionic gonadotropin (hCG).
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### 46. What is the role of human chorionic gonadotropin (hCG)?
- Maintains the corpus luteum to ensure continued progesterone production, sustaining the endometrium during early pregnancy.
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### 47. When do blood and urine levels of hCG increase following fertilization?
- Shortly after implantation, typically 6–10 days post-fertilization.
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### 48. Describe the events leading to fertilization.
1. Sperm undergo capacitation to become motile.
2. Acrosomal reaction releases enzymes to penetrate the egg's protective layers.
3. Sperm binds to the oocyte membrane, triggering the cortical reaction to block polyspermy.
4. The secondary oocyte completes meiosis II, forming an ovum.
5. Sperm and ovum