A&p2

What organs comprise the urinary system?

Kidneys, ureters, urinary bladder, and urethra.

How is the male urethra different from the female urethra?

The male urethra is about 20 cm long and has three parts: prostatic, membranous, and spongy. The female urethra is about 4 cm long and serves only urinary function.

What are the primary functions of the urinary system?

Elimination of metabolic wastes, regulation of blood ionic composition, pH, blood volume, blood pressure, and hormonal functions such as erythropoiesis.

What is the external structure of the kidneys?

Bean-shaped, covered by renal fascia, adipose capsule, and renal capsule with a hilum for vessels and nerves.

What structures protect the kidneys?

Renal fascia anchors the kidneys, adipose capsule cushions them, and renal capsule is the outer protective layer.

What are the parts of a nephron?

Renal corpuscle (glomerular capsule and glomerulus) and renal tubules (proximal tubule, nephron loop, distal tubule).

How does blood flow through the kidneys?

From 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.

What is glomerular filtration rate (GFR)?

The amount of filtrate formed per minute, approximately 180 L/day for males and 150 L/day for females.

What are the types of nephrons?

Cortical nephrons (80%) and juxtamedullary nephrons (20%).

How do the macula densa cells regulate GFR?

They monitor filtrate osmolarity, inducing constriction or dilation of the afferent arteriole to adjust GFR.

What is the renin-angiotensin-aldosterone system (RAAS)?

A hormone system that regulates blood pressure and fluid balance, triggered by low blood pressure or sodium concentration.

What are the main effects of angiotensin II?

Increases blood pressure through vasoconstriction, stimulates aldosterone release, and increases sodium and water reabsorption.

How does ADH affect urine concentration?

ADH increases water reabsorption in collecting ducts, reducing urine volume and increasing concentration.

What influences the secretion of atrial natriuretic peptide (ANP)?

Increased blood volume leads to ANP release, promoting vasodilation and increased GFR, which reduces blood volume.

What are the structural features of the glomerulus?

Fenestrated capillaries that are highly permeable to allow solute-rich fluid to pass.

What is the difference between filtrate and urine?

Filtrate is the fluid that spills into the capsular space (~180 L/day), whereas urine is what is actually excreted (~1.5-2 L/day).

What processes occur in renal physiology?

Glomerular filtration, tubular reabsorption, and tubular secretion.

What is the function of peritubular capillaries?

Surround nephron tubules to facilitate reabsorption and secretion.

What are the key components of the juxtaglomerular apparatus (JGA)?

Juxtaglomerular cells that release renin and macula densa cells that detect solute concentration.

What occurs during menstruation in the context of the reproductive system?

The shedding of the endometrium when implantation does not occur.

What hormonal changes trigger ovulation?

A surge in luteinizing hormone (LH) triggers the release of a secondary oocyte from the follicle.

What is the role of the corpus luteum after ovulation?

It secretes estrogen and progesterone to maintain the endometrium for potential embryo implantation.

What is the uterine cycle?

A series of changes in the endometrium occurring in response to ovarian hormone levels throughout a 28-day cycle.

What happens in the menstrual phase of the uterine cycle?

The endometrium is shed, marking the beginning of a new cycle.

What is oogenesis?

The process of producing female gametes (ova) through meiosis.

What hormone causes the resumption of oogenesis at puberty?

Follicle-stimulating hormone (FSH).

What is the significance of the unequal distribution of cytoplasm during oogenesis?

It ensures the ovum has adequate nutrients for early development after fertilization.

What triggers the release of human chorionic gonadotropin (hCG)?

It is released by the developing embryo after implantation.

Where does fertilization typically occur?

In the ampulla of the uterine tube.

What role do fimbriae play in the reproductive system?

They guide the ovulated oocyte into the uterine tube by creating currents.

What happens to the polar bodies during oogenesis?

They degenerate and are reabsorbed.

What are the phases of the ovarian cycle?

Follicular phase, ovulatory phase, and luteal phase.

What is the role of human chorionic gonadotropin (hCG)?

Maintains the corpus luteum to ensure continued progesterone production, sustaining the endometrium during early pregnancy.

When do blood and urine levels of hCG increase following fertilization?

Shortly after implantation, typically 6–10 days post-fertilization.

What are 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 fuse to form a zygote.

What are the 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.