Urinary System: Organs, Kidneys, Nephrons

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Questions and Answers

Match the urinary system organ with its primary function:

Kidney = Blood filtration Ureters = Connect the kidney to the bladder Bladder = Holds the urine before it's excreted Urethra = Where urine exits

Explain the structural organization of the kidney, mentioning its location and key regions.

The kidney is a 2-bean-shaped organ, about the size of a fist, located between vertebrae T12 and L3. The right kidney is typically lower due to the liver. Key regions include the renal cortex (outer layer for blood filtration), renal medulla (inner region for urine formation), renal papilla (tip of the medullary pyramids), renal columns (cortical tissue between pyramids), renal sinus (fat-filled central cavity), and hilum (entry/exit point for renal vein, artery, and ureter).

What is the renal cortex and its main function?

The renal cortex is the outer layer of the kidney, responsible for blood filtration.

What is the renal medulla and its main function?

<p>The renal medulla is the inner region of the kidney, primarily involved in urine formation and concentration.</p>
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What is a nephron?

<p>A nephron is the functional unit of the kidney.</p>
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Describe the main parts of a nephron and their basic functions.

<p>Key parts include: The glomerulus and glomerular capsule (blood filtration), PCT and descending tubule (absorb most water), Descending loop and DCT (absorb ions like Cl- and Na+), and the Collecting duct (receives urine from many nephrons for storage/further processing).</p>
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What is the glomerular filtration rate (GFR)?

<p>GFR is the amount of filtrate that passes through the glomerulus per minute.</p>
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How is hemodialysis used to treat kidney failure?

<p>Hemodialysis involves externally filtering the patient's blood to remove waste products and excess fluid, then returning the filtered blood to the body. This process substitutes the filtration function of failed kidneys.</p>
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Compare and contrast hemodialysis and kidney transplantation.

<p>Hemodialysis is easier to initiate but requires frequent sessions (takes a sling), involves dietary restrictions, and generally offers a shorter long-term life expectancy. Kidney transplantation is harder to get due to organ shortages and surgical risks, but it offers a better quality of life and longer life expectancy (average 5-9 years for a deceased donor kidney), although immunosuppression is required.</p>
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Describe the roles of the PCT, descending tubule, ascending tubule, and DCT in reabsorption and secretion.

<p>PCT: Secretes H+, creatine, drugs; Reabsorbs all glucose, amino acids, most salts. Descending Tubule: Reabsorbs most water. Ascending Tubule: Reabsorbs ions like Na+ and Cl-. DCT: Reabsorbs salts (Na+, Cl-, K+).</p>
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What is the micturition reflex?

<p>The micturition reflex is a neural reflex activated by the stretching of the bladder wall when it fills with urine, leading to the urge to urinate and contraction of the bladder muscle.</p>
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What is the effect of antidiuretic hormone (ADH) on urine output and blood volume?

<p>ADH reduces urine output by increasing water reabsorption in the kidneys, which in turn increases blood volume.</p>
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Compare diabetes insipidus and diabetes mellitus.

<p>Diabetes Insipidus involves problems with ADH production or the kidney's response to ADH, leading to excessive urination of dilute urine. Diabetes Mellitus involves problems with insulin production or action, leading to high blood sugar.</p>
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What are common causes and symptoms of urinary tract infections (UTIs)?

<p>UTIs are often caused by bacteria entering the urinary tract. They are more common in women due to a shorter urethra closer to the anus. Symptoms include painful urination, frequency, urgency, and sometimes fever or back pain. Prevention includes hydration, urinating after sex, and proper hygiene (wiping front to back).</p>
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Explain the bi-directional relationship between hypertension and kidney function.

<p>Hypertension (high BP) can damage nephrons (especially glomeruli) and blood vessels in the kidneys, leading to hardening (nephrosclerosis) and reduced GFR. Conversely, damaged kidneys fail to excrete enough sodium and waste, leading to fluid retention and waste buildup, which further raises blood pressure.</p>
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What is the role of the SRY gene in determining biological sex?

<p>The SRY gene, located on the Y chromosome, provides instructions for making the sex-determining region Y protein. This protein acts as a transcription factor that initiates the development of male sex organs (testes) by altering the expression of other genes.</p>
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Define homology in the context of reproductive structures.

<p>Homology refers to structures in different sexes that are derived from the same embryonic precursor tissue due to a common developmental origin.</p>
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Match the homologous reproductive organs:

<p>Clitoris = Glans (head) of penis Labia Minora = Shaft of penis Labia Majora = Scrotum Ovaries = Testes Uterine tubes/Fallopian tubes = Vas deferens</p>
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What are the primary functions of the male reproductive system?

<p>The primary functions include: 1. Producing androgens (male sex hormones, like testosterone) and gametes (sperm). 2. Facilitating the formation and maturation of sperm. 3. Delivering sperm into the female reproductive tract during intercourse.</p>
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Match the male reproductive structure with its function:

<p>Testes = Produce testosterone and sperm Epididymis = Store, mature, and transport sperm cells Ductus (vas) deferens = Transport sperm from the epididymis to the urethra during ejaculation Scrotum = Encloses and regulates temperature of the testes</p>
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Describe the secretions and role of the prostate gland.

<p>The prostate gland produces a milky, slightly acidic fluid containing citric acid, enzymes, and prostate-specific antigen (PSA). These secretions help activate sperm.</p>
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Describe the secretions and role of the seminal vesicles.

<p>The seminal vesicles secrete a thick, yellow, alkaline fluid containing fructose (energy for sperm), citric acid, and prostaglandins (enhance sperm motility). This secretion constitutes the largest contribution to semen volume.</p>
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Describe the secretions and role of the bulbourethral glands.

<p>The bulbourethral (Cowper's) glands secrete a clear, alkaline mucus prior to ejaculation. This mucus lubricates the tip of the penis and neutralizes any traces of acidic urine in the urethra.</p>
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Why is early screening for prostate cancer considered important?

<p>Early screening is crucial because prostate cancer is common, especially in men over 65, and claims many lives (over 30k men annually in some populations). Early detection through methods like PSA tests and digital rectal exams allows for earlier treatment and potentially better outcomes, although PSA reliability can fluctuate.</p>
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Describe the structure of the testes, including seminiferous tubules and their function.

<p>The testes contain coiled tubes called seminiferous tubules, which are the site of sperm cell development (spermatogenesis) and maturation. Immature sperm cells (spermatogonia) undergo meiosis and spermiogenesis within these tubules to become mature spermatozoa.</p>
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Within the seminiferous tubules, sperm develop _____.

<p>superficial to deep</p>
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What are Germ cells and Sertoli cells in the testes?

<p>Germ cells are the reproductive cells within the seminiferous tubules that develop into sperm. Sertoli cells (also called nursing cells) are supporting cells that protect and nourish developing germ cells and form the blood-testis barrier.</p>
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What are Leydig cells and what do they produce?

<p>Leydig cells are located in the connective tissue outside the seminiferous tubules. They are responsible for producing testosterone, the primary male hormone.</p>
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List the major functions of testosterone.

<p>Testosterone regulates sex differentiation during development, promotes the development of male secondary sex characteristics, drives spermatogenesis, influences fertility and libido, increases muscle mass, and affects body hair distribution.</p>
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Describe the steps in the hormonal regulation of testosterone production (negative feedback loop).

<ol> <li>Hypothalamus releases GnRH. 2. GnRH stimulates the anterior pituitary to release FSH and LH. 3. LH stimulates Leydig cells to produce testosterone. FSH stimulates Sertoli cells to release ABP (Androgen Binding Protein), which concentrates testosterone near developing sperm. 4. Rising testosterone levels inhibit GnRH release from the hypothalamus and LH/FSH release from the pituitary. 5. Inhibin, released by Sertoli cells in response to high sperm counts, specifically inhibits FSH release from the pituitary.</li> </ol>
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What are the primary functions of the female reproductive system?

<p>Functions include producing female sex hormones (like estrogen and progesterone), producing ova (eggs) through oogenesis, facilitating sexual activity, supporting the growth and survival of an embryo/fetus, and nourishing a newborn infant through breastfeeding.</p>
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Match the external female genitalia (vulva) component with its description/function:

<p>Prepuce = Hood covering the clitoris; Protects opening of urethra and vagina Clitoris = Highly sensitive erectile tissue involved in pleasurable stimulation Labia minora = Inner folds of skin protecting the openings of the urethra and vagina Labia Majora = Outer, larger folds of skin that protect and enclose other external reproductive organs Bartholin's Glands = Secrete mucus to lubricate the vagina during sexual arousal Vagina = Muscular tube connecting the vulva to the cervix; receives penis during intercourse, passage for fetus during delivery, and exit for menstrual flow</p>
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Match the internal female organ with its primary function:

<p>Ovaries = Produce oocytes (eggs) and female sex hormones (estrogen, progesterone) Fallopian Tubes = Transport oocytes towards the uterus; usual site of fertilization Uterus = Site of embryonic/fetal implantation, placental formation, and fetal development Cervix = Lower, narrow part of the uterus that acts as a barrier, allows menstrual flow, nourishes sperm, promotes fertility, and dilates during childbirth</p>
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Trace the typical path of an oocyte from the ovary to the site of implantation after fertilization.

<ol> <li>Ovulation: Oocyte is released from the ovary. 2. Fimbriae sweep the oocyte into the Fallopian tube. 3. Fertilization (if it occurs) usually happens in the ampulla of the Fallopian tube. 4. The fertilized egg (zygote) undergoes cleavage divisions as it travels down the Fallopian tube (takes several days). 5. It develops into a blastocyst. 6. The blastocyst reaches the uterus and implants into the uterine lining (endometrium).</li> </ol>
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What is the most common cause of cervical cancer, and how does it typically lead to cancer?

<p>The most common cause is infection with high-risk strains of the Human Papillomavirus (HPV), particularly types 16 and 18. HPV can block the host cell's ability to prevent mutated cells from dividing (e.g., by interfering with the p53 tumor suppressor protein), allowing mutated cells to grow uncontrollably, potentially leading to cancer.</p>
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Describe the basic structure of the female breast and its primary function.

<p>The breast is an accessory organ of the female reproductive system. Its primary function is lactation (producing and supplying milk to an infant). Structurally, it contains mammary glands (modified sweat glands), which consist of lobes containing alveoli (clusters of milk-secreting cells). Milk travels through lactiferous ducts that open onto the surface of the nipple. The nipple is surrounded by the areola.</p>
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Explain the lactation feedback loop (milk ejection reflex).

<p>Stimulus: Infant sucking on the nipple. Receptor: Sensory receptors in the skin of the nipple/areola detect sucking and send signals to the hypothalamus. Control Center: Hypothalamus signals the posterior pituitary to release oxytocin. Effector: Oxytocin travels through the bloodstream and stimulates myoepithelial cells surrounding the alveoli in the breast to contract, ejecting milk. This is a positive feedback loop, as continued sucking leads to continued oxytocin release and milk ejection.</p>
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Define 'development' in the context of organismal biology.

<p>Development refers to the progressive changes that occur during the lifespan of an organism, from fertilization to birth (and beyond). It includes changes in size, shape, function, genotype expression, and phenotype.</p>
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List the key genetic elements found within a human zygote.

<p>Key genetic elements include: 1. Chromosomes (46 total, 23 pairs: 23 from egg, 23 from sperm, including sex chromosomes XX or XY). 2. Genes (segments of DNA on chromosomes carrying instructions for specific traits). 3. DNA (Deoxyribonucleic Acid: the molecule making up chromosomes/genes, carrying the genetic code). 4. Mitochondrial DNA (mtDNA: inherited maternally, involved in energy production). 5. Regulatory Elements (DNA sequences like promoters, enhancers, introns, exons that control gene expression).</p>
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Describe the key steps in the process of fertilization.

<ol> <li>Sperm penetrates the corona radiata. 2. Sperm binds to the zona pellucida, triggering the acrosomal reaction (enzyme release to digest zona). 3. Sperm penetrates the zona pellucida (binding to ZP3 protein is key). 4. Sperm fuses with the egg's plasma membrane, causing depolarization and a calcium surge. 5. Calcium influx triggers the cortical reaction, inactivating ZP3 and blocking polyspermy (entry of more sperm). 6. Sperm entry stimulates the egg to complete meiosis II, forming the ovum and second polar body. 7. Male and female pronuclei form and fuse, creating a diploid zygote.</li> </ol>
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What is gastrulation and when does it occur?

<p>Gastrulation is the process during embryonic development where the single-layered blastula is reorganized into a trilaminar (three-layered) structure known as the gastrula. These three layers are the germ layers. It occurs around 13-14 days after fertilization.</p>
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Match the embryonic germ layer with the tissues/systems it primarily forms:

<p>Ectoderm = Outer layer; forms skin (epidermis) and the nervous system Mesoderm = Middle layer; forms muscle, bone, connective tissue, circulatory system, kidneys, gonads (internal organs) Endoderm = Inner layer; forms the lining of the digestive and respiratory tracts, liver, pancreas, bladder (lining of organs and glands)</p>
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Describe the formation of the neural tube.

<p>Neural tube formation (neurulation) begins around 18 days after fertilization. 1. The ectoderm overlying the notochord thickens to form the neural plate. 2. The edges of the neural plate elevate to form neural folds, with a neural groove in the center. 3. The neural folds meet and fuse in the midline, forming the hollow neural tube. Neural crest cells pinch off from the folds. 4. The neural tube develops into the brain and spinal cord (CNS), while neural crest cells form parts of the PNS, glia, and endocrine cells. It closes completely around day 26.</p>
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What are neural tube defects, and what nutrient is critical for their prevention?

<p>Neural tube defects are birth defects arising from the incomplete closure of the neural tube during early embryonic development. Examples include spina bifida (affecting the spinal cord/vertebrae) and anencephaly (affecting the brain). Folic acid (a B vitamin) taken before and during early pregnancy significantly reduces the risk of these defects.</p>
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Describe the formation and function of the fetal placental barrier.

<p>Formation: The blastocyst invades the uterine wall. Trophoblast cells differentiate and form the chorion. Embryonic cells invade maternal blood vessels, creating spaces called lacunae filled with maternal blood. Embryonic mesoderm forms blood vessels within chorionic villi that project into the lacunae. Function: The fetal placental barrier (formed by fetal capillary endothelium, connective tissue, and trophoblast layers) separates maternal and fetal blood but allows for the exchange of nutrients, oxygen, and waste products between mother and fetus. It also transfers maternal antibodies (IgG) and produces hormones essential for pregnancy.</p>
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What are the three stages of parturition (childbirth)?

<ol> <li>Dilation: Begins with uterine contractions, ends with full cervical dilation (around 10 cm). Involves amniotic sac rupture. Longest stage (8-24 hrs). 2. Expulsion: From full dilation until the baby is delivered. Involves strong contractions and maternal pushing (1 min to an hour). 3. Placental Stage: After birth, uterine contractions continue to expel the placenta from the uterus.</li> </ol>
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What is the APGAR score, and what does it assess?

<p>The APGAR score is a quick assessment of a newborn's health immediately after birth (at 1 and 5 minutes). It assesses five criteria: Appearance (skin color), Pulse (heart rate), Grimace (reflex irritability), Activity (muscle tone), and Respiratory Effort.</p>
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Differentiate between congenital disorders and genetic disorders.

<p>Congenital disorders are abnormalities present at birth. They can be caused by genetic factors, environmental factors (like infections or toxins during pregnancy), or unknown causes. Genetic disorders are specifically caused by abnormalities in genes or chromosomes. A genetic disorder can be congenital, but not all congenital disorders are genetic.</p>
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Define gene, wild type allele, and mutant allele.

<p>Gene: A segment of DNA that codes for a specific protein or functional RNA molecule, determining a trait. Wild Type Allele: The version of a gene that is considered the normal, typical, or most common sequence in a population. Mutant Allele: An altered version of a gene resulting from a mutation (a change in the DNA sequence), which may lead to a change in protein function.</p>
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Explain silent, nonsense, and missense mutations.

<p>Silent Mutation: A change in the DNA sequence that does not alter the resulting amino acid sequence of the protein (due to redundancy in the genetic code). It has no effect on protein function. Nonsense Mutation: A change in the DNA sequence that results in a premature stop codon, leading to a truncated and usually non-functional protein. Missense Mutation: A change in the DNA sequence that results in a different amino acid being incorporated into the protein. The effect on protein function can vary from minimal to severe.</p>
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Describe the functions of promoters, introns, and exons within a gene.

<p>Promoter: A region of DNA located upstream (before) the protein-coding sequence where RNA polymerase binds to initiate transcription. It controls when, where, and at what level a gene is expressed. Exons: Segments of a gene's DNA that code for amino acids and are spliced together to form the mature messenger RNA (mRNA). Introns: Segments of a gene's DNA located between exons that do not code for amino acids. They are transcribed into pre-mRNA but are removed during RNA splicing before translation.</p>
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What is alternative splicing, and why is it important?

<p>Alternative splicing is a process where different combinations of exons from the same gene are joined together during RNA processing. This allows a single gene to produce multiple different mRNA transcripts, which can then be translated into different protein variants (isoforms) with potentially different functions. It greatly increases the coding capacity of the genome and contributes to biological diversity and complexity.</p>
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What is the role of HOX genes in embryonic development?

<p>HOX genes (a type of homeobox gene) are master regulatory genes that control the body plan of an embryo along the head-to-tail axis. They act in hierarchies to specify the identity of different body segments and direct the formation of structures appropriate for each segment by activating or repressing specific target genes within those segments.</p>
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Define chemoattractant and chemorepellent in the context of chemotaxis.

<p>Chemotaxis is the directed movement of cells in response to chemical signals. A chemoattractant is a chemical signal that causes cells to move towards its source. A chemorepellent is a chemical signal that causes cells to move away from its source.</p>
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What is the role of Reelin in brain development?

<p>Reelin is a chemical signal (an extracellular matrix protein) primarily secreted by Cajal-Retzius (CJ) cells in the marginal zone of the developing cerebral cortex. It acts as a chemoattractant and guidance cue, directing newborn neurons to migrate superficially from deeper layers where they are born. This process helps establish the layered structure (lamination) of the cortex, with younger neurons migrating past older ones ('inside-out' development).</p>
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What is Lissencephaly, and what causes it?

<p>Lissencephaly ('smooth brain') is a rare brain malformation characterized by the absence or reduction of the normal folds (gyri) and valleys (sulci) in the cerebral cortex. It is often caused by mutations in genes involved in neuronal migration, including the gene for Reelin. Defective neural migration during development prevents the proper formation of cortical layers.</p>
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Briefly describe the key stages of heart development.

<p>Heart development begins around day 18-19 post-conception. Key stages include: Day 21: Two endothelial tubes fuse medially. Day 22: Rapid cell proliferation causes looping and formation of primitive chambers (atrium, ventricle, bulbus cordis). Day 33: Atrial and ventricular septa begin to grow, separating left and right sides. Weeks 5-7 (Day 35+): Septal formation continues, though some openings (like foramen ovale) remain until after birth.</p>
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What are atrial septal defects (ASD) and ventricular septal defects (VSD)?

<p>ASD and VSD are common congenital heart defects resulting from the incomplete closure of the septum (wall) separating the atria (ASD) or the ventricles (VSD). This allows blood to flow abnormally between the chambers.</p>
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What is amniocentesis and how is it used in fetal monitoring?

<p>Amniocentesis is a prenatal diagnostic test where a small sample of amniotic fluid is withdrawn from the uterus using a needle. This fluid contains fetal cells (shed from skin, urinary tract) and biochemical substances. The cells can be cultured and analyzed to check for chromosomal abnormalities (like Down syndrome) and specific genetic disorders. It can also be used to assess fetal lung maturity later in pregnancy.</p>
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Explain the role of the Renin-Angiotensin-Aldosterone System (RAAS) in regulating blood pressure and volume.

<ol> <li>Low blood pressure/volume causes kidneys to release Renin. 2. Renin converts Angiotensinogen (from liver) to Angiotensin I. 3. ACE (Angiotensin-Converting Enzyme, from lungs) converts Angiotensin I to Angiotensin II. 4. Angiotensin II causes vasoconstriction (raising BP) and stimulates the adrenal glands to release Aldosterone. 5. Aldosterone causes the kidneys to retain sodium and water, increasing blood volume and pressure.</li> </ol>
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Explain the feedback loop involving Atrial Natriuretic Peptide (ANP).

<ol> <li>High blood volume stretches the walls of the right atrium. 2. Atrial cells release ANP in response to stretch. 3. ANP acts on the kidneys, promoting sodium excretion (natriuresis) and consequently water excretion (diuresis). 4. ANP also inhibits the RAAS (renin, angiotensin II, aldosterone release), reducing sodium/water retention. 5. The resulting decrease in blood volume reduces atrial stretch, which inhibits further ANP release (negative feedback).</li> </ol>
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Identify the major fluid compartments of the body and their primary cation.

<p>The major fluid compartments are: 1. Intracellular Fluid (ICF): Fluid within cells (approx. 2/3 of total body water). Primary cation is Potassium (K+). 2. Extracellular Fluid (ECF): Fluid outside cells (approx. 1/3 of total body water). Includes interstitial fluid (fluid between cells) and plasma (fluid component of blood). Primary cation is Sodium (Na+). Chloride (Cl-) is the major ECF anion.</p>
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Describe the physiological consequences and symptoms of hyperhydration.

<p>Hyperhydration (overhydration or water intoxication) leads to dilution of solutes, particularly sodium, in the extracellular fluid (hyponatremia). This causes water to move into cells via osmosis, causing them to swell. Brain cell swelling is particularly dangerous. Symptoms include headache, nausea, vomiting, confusion, seizures, and potentially coma or death.</p>
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Describe the physiological consequences and symptoms of dehydration.

<p>Dehydration occurs when water loss exceeds intake, leading to increased solute concentration in the extracellular fluid (hypertonic solution). Water moves out of cells into the ECF, causing cells to shrink. This results in low blood volume (hypovolemia), leading to lower blood pressure. Blood becomes thicker (increased viscosity), making it harder for the heart to pump. Symptoms include dry mouth/skin, thirst, dizziness/lightheadedness, rapid heart rate, and dark urine.</p>
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Describe the main mechanisms involved in maintaining acid-base balance.

<p>Acid-base balance (maintaining stable pH) relies on: 1. Chemical Buffer Systems: Act instantly to resist pH changes by binding or releasing H+. Major systems include bicarbonate (ECF), phosphate (ICF, urine), and protein buffers (ICF, plasma). 2. Physiological Buffer Systems: Slower but more powerful. Includes the Respiratory System (regulates CO2 levels via breathing rate, acts in minutes) and the Renal System (excretes acids/bases and reabsorbs/generates bicarbonate, acts over hours/days).</p>
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A high concentration of H+ ions results in a high pH and basic conditions.

<p>False (B)</p>
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Compare the speed and capacity of chemical, respiratory, and renal buffering systems.

<p>Chemical buffers act almost instantly but have limited capacity. The respiratory system responds within minutes by adjusting ventilation to control CO2 levels, offering intermediate speed and capacity. The renal system takes hours to days to make significant adjustments but has the largest capacity to correct pH imbalances by excreting H+ and regulating bicarbonate.</p>
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Increasing CO2 levels in the blood leads to an increase in H+ concentration and a decrease in pH (more acidic).

<p>True (A)</p>
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Flashcards

Kidney

Blood filtration organ. Located between T12 and L3, right kidney is lower to make room for liver.

Ureters

Tubes that connect the kidney to the bladder, transporting urine.

Bladder

Organ that holds urine before it is excreted.

Urethra

Where urine exits the body.

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Renal cortex

Blood filtration occurs here

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Renal medulla

Urine formation occurs here.

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Hilium

Renal vein and ureter exit the kidney at this location

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Renal Papilla

Tip of the pyramid structure in the kidney.

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Nephron

Functional unit of the kidney; each kidney contains over 1 million.

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Glomerulus and Glomerular capsule

Where blood is filtered.

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PCT and descending tubule

Absorbs most of the water in the nephron

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Descending and DCT

Absorbs ions such as Chloride and Sodium

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Collecting duct

Many nephrons connect to this shared duct where urine is stored

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Hemodialysis

Externally filtering the blood when the kidney can't.

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Nephron

Functional unit of kidney

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PCT reabsorption

Reabsorption of all glucose, amino acids, and most salts.

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Ascending tubule

Reabsorption of ions such as Na+ and Cl-.

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Medulla

Most concentrated urine.

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Cortex

Less concentrated, more diluted urine.

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Micturition (urine) reflex

Reflex activated when your body needs to urinate, triggered by bladder wall stretching.

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ADH (Antidiuretic hormone)

Reduces urine output and increases blood volume.

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Diabetes Insipidus

Problem with ADH production or receptor, leading to excessive, dilute urine.

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Diabetes Mellitus

Problem of pancreas not producing enough insulin.

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UTI

More common in women due to shorter urethra

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Hemodialysis

Externally filtering the blood and returning it to the body.

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Study Notes

Urinary System Organs and Functions

  • Kidney function: blood filtration
  • Ureters function: connect the kidney to the bladder
  • Bladder function: holds urine before excretion
  • Urethra function: urine exits from here

Kidney Structural Organization

  • Kidneys are bean shaped and fist sized, located between T12 and L3
  • The right kidney is positioned lower to accommodate the liver
  • Renal cortex function: blood filtration
  • Renal medulla function: urine formation
  • Hilum description: where the renal vein and ureter exit the kidney
  • Renal papilla description: the tip of the pyramid structure
  • Renal sinus description: the fat-filled cavity in the middle of the kidney that cushions it
  • Renal columns description: cortical tissue between each pyramid

Nephron Anatomy and Function

  • Nephron definition: the functional unit of the kidney
  • Each kidney contains over 1 million nephrons
  • Glomerulus and glomerular capsule function: blood filtration occurs here
  • PCT and descending tubule function: primarily absorb water
  • Descending and DCT function: absorb ions (Cl- and Na+)
  • Collecting duct function: collects filtered urine from many nephrons

Glomerular Filtration Rate (GFR)

  • GFR definition: the amount of filtrate passing through the glomerulus per minute
  • Normal GFR: 120 mL/min
  • GFR of 90 mL/min: slightly concerning
  • GFR less than 15 mL/min: indicates kidney failure
  • High osmotic pressure and solute concentration allows water and solutes to leave the blood and enter the glomerular capsule

Hemodialysis in Kidney Failure

  • Hemodialysis filters blood externally and returns it to the body when the kidneys fail

Hemodialysis vs. Kidney Transplantation

  • Dialysis: easier to receive but requires dietary restrictions and has a lower life expectancy
  • Kidney transplant: more difficult to obtain due to organ shortages and involves surgical risks, but offers better life expectancy (5-9 years on average)

Kidney Tubule Regions

  • PCT Secretion: H+, creatine, and drugs are secreted
  • PCT Reabsorption: all glucose, amino acids, and most salts are reabsorbed
  • Descending Tubule: reabsorption of most water
  • Ascending Tubule: reabsorption of Na+ and Cl- ions
  • DCT reabsorption: Salts Na+, Cl-, K+ are reabsorbed
  • Collecting duct secretion: Blood vessel into tubule
  • Collecting duct reabsorption: Tubule into blood stream
  • Medulla concentration: most concentrated
  • Cortex concentration: less concentrated, more diluted

Micturition (Urine) Reflex

  • Micturition reflex definition: activated when the bladder wall stretches, indicating the need to urinate and is under parasympathetic control
  • Urine flow from kidney to bladder is continuous
  • Steps: Bladder filling stimulates stretch receptors, triggering action potentials, APs travel through pelvic nerves to the spinal cord, spinal cord APs activate parasympathetic neurons to contract the bladder's smooth muscle, somatic motor neurons are inhibited, relaxing the sphincter, sensory neuron APs reach the brain

Holding Urine

  • The brain controls urination: inhibits parasympathetic neurons and stimulates urethral sphincter contraction
  • Voluntary control: the brain controls the external sphincter via somatic neurons
  • Process: Constriction during holding, relaxation during urination

Antidiuretic Hormone (ADH)

  • ADH reduces urine output and increases blood volume

Diabetes Insipidus vs. Diabetes Mellitus

  • Diabetes Insipidus: ADH production or receptor problems causing excessive, diluted urine and is either synthetic ADH treatment or lifestyle changes for ADH receptor problem
  • Diabetes Mellitus: pancreas doesn't produce enough insulin

Urinary Tract Infections (UTIs)

  • More common in women due to shorter urethras and shorter distance between anus and external urethral orifice, and also more common in children under 5
  • Prevention: drink more water, urinate after sex, wipe front to back
  • Treatment: 2 weeks of antibiotics
  • Complications: pyelonephritis, involving kidney infections and spread to the bloodstream

Hypertension and Kidney Function

  • High BP damages nephrons and blood vessels, especially the glomerulus, leading to hardening
  • Damaged glomeruli cause high BP, reducing GFR, increasing waste and sodium in the blood and blood vessels in the nephron harden (nephrosclerosis), which reduces GFR
  • The kidneys can’t excrete sodium or uric acid, leading to more waste and blood vessel damage, increasing BP and reducing GFR

SRY Gene in Sex Determination

  • SRY is a transcription factor activating/deactivating genes
  • Function: SRY provides instructions for the sex-determining region Y protein, development of sex organs and SRY alters gene expression for MALE sex organs

Homology

  • Homology definition: structures/DNA from a common ancestor
  • Relevance: important for sex organ development
  • Origins: born with both Wolffian and Mullerian ducts
  • *In females Mullarian ducts form the uterine tubes and uterus and the wolffian degrades
  • *In males Wolffian Ducts form the epididymis and vas deferens and the mullerian ducts degrade
  • Homologous Organs:
    • Clitoris is homologous to the glans of the penis
    • Labia Minora is homologous to the shaft of the penis
    • Labia Majora is homologous to the scrotum
    • Ovaries are homologous to the testes
    • Uterine/fallopian tubes are homologous to the vas deferens

Male Reproductive System

  • Functions: produces androgens, sex hormones, and gametes, forms sperm, delivers sperm during intercourse

Male Anatomy - Structures

  • Scrotum
  • Testes: produce testosterone
  • Epididymis: stores, matures, and transports sperm
  • Ductus (vas) deferens: transports sperm from epididymis to urethra during ejaculation

Male Anatomy - Glands

  • Prostate secretions activate sperm, produce milky, slightly acidic fluid, and contains citric acid, enzymes, and prostate specific antigen (PSA)
  • Seminal glands secrete thick, yellow, alkaline fluid with fructose, prostaglandins, and citric acid for sperm nourishment/motility, largest contribution to semen volume
  • Bulbo-urethral glands secrete clear alkaline mucus lubricating penis tip during sex, neutralizing acidic urine traces in urethra

Prostate Cancer and Screening

  • Early screening is crucial
  • Over 30k men per year die
  • Men over 65 are most at risk
  • Men over 40 should get annual exams
  • PSA: blood test may not be reliable, high PSA means more testing, prostate exam, and biopsy needed

Testes Structure and Specialized Cells

  • Seminiferous Tubules: coiled tubes forming sperm and is the site of the sperm cell maturation
  • Seminiferous tubules Site: spermatogonia undergo meiosis/spermiogenesis, transforming into mature spermatozoa
  • Germ cells: become reproductive cells (sperm)
  • Sertoli cells (nursing cells): protect germ cells during development, form blood-testis barrier

Testosterone

  • Primary male sex hormone
  • Regulates sex differentiation, male sex characteristics, spermatogenesis, fertility, muscle mass, libido, phenotypic characteristics, body hair
  • Leydig cells: Located outside the seminiferous tubules, produces 6-7 mg testosterone/day
  • Females: The ovaries and adrenal glands also secrete small amounts.

Testosterone Control

  • Inhibin: Controls negative feedback to anterior pituitary
  • Testosterone: controls negative feedback to hypothalamus and anterior pituitary
  • Regulation steps:
    • Hypothalamus releases GnRH
    • GnRH tell anterior pituitary to release FSH and LH: FSH stimulates Sertoli cells to release ABP (androgen binding protein), LH stimulates Leydig cells to release testosterone
  • Negative feedback loop: -Increased blood testosterone inhibits hypothalamus/pituitary GnRH, LH, FSH -Inhibin inhibits anterior pituitary FSH release

Female Reproductive System

  • Functions: produces androgens/sex hormones (estrogen and progesterone), forms ovum during oogenesis, reproduction, supports embryo growth/survival, nourishes newborn infant through breastfeeding, located primarily in pelvic cavity
  • External organs (vulva):
    • Prepuce: protects urethra and vagina opening
    • Clitoris: provides stimulation
    • Labia minora: protects urethra and vagina opening
    • Labia majora: protects and encloses the external reproductive organs
    • Bartholin's glands: secrete mucus to lubricate when having sex
    • Vagina: facilitates uterine secretions, receives penis, assists delivery

Female Repro Internal Organs

  • Ovaries: produce oocytes and sex hormones
  • Fallopian tubes: transport oocytes to uterus for fertilization
  • Uterus: site of implantation and fetal development
  • Cervix: barrier to protect the uterus, allow menstrual fluids to exit, nourishes sperm, promotes fertility, and expands during childbirth
  • Fertilization: fusion of male and female gametes, membrane changes prevent further sperm fertilization, development along fallopian tubes until blastocysts implant in uterus

Cervical Cancer

  • HPV (human papillomavirus): Most common cause
  • Strains 16/18: account for 70%+ cervical cancers
  • HPV infection: often cleared by normal immune responses (2 years)
  • High-risk HPV: can result in cancer
  • Prevalence: females ages 20-24
    • HPV causes cancer: Blocks mutated cell prevention, P53 detects/prevents mutated cell growth, high-risk HPV inhibits P53, results in mutated cells growing
      • Prevention: vaccine, protection, screening and pap smear

Female Breasts

  • Accessory organ of female reproductive system
  • Lactation: to supply milk to infant
  • Organs:
    • Mammary glands: produce milk (modified sweat glands)
    • Alveoli: milk-secreting cell clusters
    • Milk ducts: milk exits through the nipple via 15-20 lactiferous ducts
    • Nipples
    • Lactiferous ducts lead to lactiferous sinuses, glandular lobe If pregnant: hormones develop mammary tissue and enlarge breasts

Lactation Feedback Loop

  • Stimulus: baby sucking
  • Receptor: sensory receptors in breast skin detect sucking sending signal to hypothalamus
  • Control: hypothalamus signals posterior pituitary and releases oxytocin
  • Effector: oxytocin stimulates breast to eject milk
  • Positive feedback loop: baby keeps sucking/stimulating loop

Development

  • Progressive changes during lifespan
  • Size
  • Shape
  • Function
  • Genotype
  • Phenotype

Genetic Elements of a Zygote

  • Chromosomes
    • Humans have 46 chromosomes (23 pairs).
    • 23 from egg, 23 from sperm -One pair determines sex (XX female, XY male)..
  • Genes -Segments of DNA located on chromosomes -Each gene carries instructions for characteristics (eye color, blood type).
  • DNA (Deoxyribonucleic Acid)
    • Molecule that makes chromosomes/genes -Carries entire genetic code for development
  • Mitochondria DNA (mtDNA) -Found in mitochondria, comes only from mother -Involved in energy production and passed down maternally
  • Regulatory Elements -DNA sequences control when/how genes are expressed

Fertilization and Blastocyst Implantation

  • Sperm pushes through corona radiata
  • Penetrates zona pellucida, activates ZP3 protein on egg
  • Triggers acrosomal reaction; sperm breaks through egg barrier
  • Sperm attaches to egg membrane and membrane triggers the following -electrical change (depolarization), calcium surge -Calcium stops sperm from entering and fertilizing egg (blocks polyspermy)
  • Entrance of sperm stimulates meiotic division forming second polar body, female/male genetic material (pronuclei) move/fuse
  • nuclei fuse into diploid cell called zygote

Germ Layers and Tissues

  • Gastrulation: formation of the 3 germ layers
    • 13-14 days after fertilization,embryonic flat disc forms 3 layers: ectoderm, mesoderm, endoderm

Neural Tube Formation/Defects

  • Neural tube: forms early brain/spine
  • Begins: 18 days post-fertilization Steps:
  1. Ectoderm near head thickens, forms neural plate
  2. Edges rise edges are neural folds, center is the groove
  3. Folds meet in midline- tops/crests Neuro crests-glia; PNS, endocrine cells
  4. beocms brain -Tube closes at day 26 Mnemoic = Please, Everyone, Find, Chloe, Today
  • Neural Tube defects (spinal bifida): -Spinal cord/vertebral column defects
    • Paralysis, bowels/bladder

Placental Barrier

  • blastocyte: diving cells Cluster made by a fertilized egg Cell types: -1)urteilinvades trophoblasts uteine call -2)Cells form embryo also invade mothers wall causing lacunae
  • Lacunae: crucial nutrients vessel for nutrition/waste
  • mesoderm forming in maternal arterial blood vessel Placenta is ONLY organ linking

Placental Functions

  • Transfer material between mother/fetus
  • Exchange wastes/nutrients
  • produce hormones/progesterone
  • Transfer immunity (IgG)
  • General protection membrane for embryo

Parturition (Childbirth)

  • Dilation :

  • Begins contractions uteine

  • Ruptures amniotic sac

  • Lasts 8-24 hrs

  • 95% head is inferior aiding out

  • Explusion:

  • Cervix dialution maxi when fetus exits

  • Contactions oxytocin is is generated positive loop; 1 minutes to an hour

  • Note- blood flow reduced when pushing

  • Placinetal

  • Expelled uterus

  • Contraction causes uterus most likely

Apgar score

  • Assessment criteria: skin color, pulse rate, response to stimuli, activity tone, respiratory effort. A low score indicates more need for for emerging support

Congenital Genetic Disorder

  • Congenital: At birth
  • Genetic: cause

Mutations

  • Silent dna but same amino no change to function
  • Nonsense- premature
  • Missense change affect function

Gene Components

  • Region protein control express

  • transcription function

  • transcribed levels expressed tissues location. segments-parkinsos with alzeheimers

  • proteins segments

  • Segments DNA function in splicing

  • exons DNA segments

Patterns

  • regulate
  • pattern in an and

compartments

  • compartments of the body and their subdivision
  • Intracellular, extracellular/ intersitial,

Hyperhdydration

  • high sodium called hyponatremia
  • cells swell(brain)

Dehydration:

Cells shrink Pumps harder

Acid bases

  • Acid-base affect

Concentration

  • -H+=pH and

  • -H+= pH and H+ions

  • Directy act

  • Shorter/minutes term

Buffer renal

Hates to bring H+=pH and

  • =H+=pHstarts to normal
  • =10th starts to normal
  • =

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