Renal Physiology Quiz

Urinary System Structures and Connections

• The urinary system consists of kidneys, ureters, urinary bladder, and urethra.
• Kidneys filter blood to produce urine.
• Urine travels from kidneys through ureters to bladder for storage.
• Urine is expelled from the body through the urethra.

Kidney Tissue Layers and Functions

• Tissues surrounding the kidneys include renal capsule (protective layer), adipose capsule (cushioning), and renal fascia (anchors).
• Renal capsule protects against infection and physical damage.
• Adipose capsule provides cushioning and insulation.
• Renal fascia anchors the kidneys to surrounding structures.

Kidney Regions and Renal Pyramids

• Kidney regions include cortex, medulla, and pelvis.
• Renal pyramids are cone-shaped structures in the medulla involved in urine processing.

Urine Pathway from Renal Papillae to Bladder

• Urine flows from renal papillae to minor calyx, then major calyx, renal pelvis, ureter, and finally to the urinary bladder.

Blood Flow Through Kidneys

• Blood flows from renal artery to afferent arterioles then glomerulus, efferent arterioles, peritubular capillaries, and finally renal vein.
• Afferent arterioles lack a direct vein counterpart.

Nephron Structure and Filtrate Pathway

• A nephron is the functional unit of the kidney involved in filtering blood and forming urine.
• Filtrate flows from glomerulus through Bowman's capsule, proximal convoluted tubule, nephron loop (loop of Henle), distal convoluted tubule, and collecting duct.

Renal Corpuscle Structure and Function

• A renal corpuscle is composed of Bowman's capsule and glomerulus.
• Filtration of blood to form filtrate is the first step in urine production.

Renal Tubule Structure and Microvilli

• Renal tubules become narrower and more convoluted from the proximal to distal end.
• Regions with more microvilli (proximal tubule) are involved in more reabsorption, increasing the surface area.

Renal Collecting Duct

• The collecting duct collects filtrate from multiple nephrons.
• It takes filtrate from the distal convoluted tubule to the renal pelvis.

Kidney Stones and Development

• Kidney stones are hard deposits of minerals and salts formed in the kidneys.
• They develop when urine becomes concentrated, causing crystals to form.

Cortical and Juxtamedullary Nephrons

• Cortical nephrons are primarily located in the cortex and involved in general filtration.
• Juxtamedullary nephrons have long loops of Henle and play a major role in urine concentration.
• Cortical nephrons are more numerous in a typical kidney.

Tubular Reabsorption and Tubular Secretion

• Reabsorption is the movement of substances from filtrate to blood.
• Secretion is the movement of substances from blood to filtrate.
• Proximal convoluted tubule is the primary site for reabsorption.

Glomerular Filtration Pressure

• Glomerular hydrostatic pressure (pressure exerted by blood in capillaries) drives filtration.
• Capsular hydrostatic pressure (resistance from fluid in Bowman's capsule)
• Glomerular colloid osmotic pressure (osmotic pressure from proteins in blood)
• Net glomerular filtration pressure is calculated by subtracting opposing forces from glomerular hydrostatic pressure.

Renin-Angiotensin Pathway and GFR

• Renin release from the kidneys increases blood pressure and reduces sodium loss, which can alter GFR and fluid balance.
• Higher pressure leads to higher glomerular filtration rate (GFR).

Water Reabsorption and Aquaporins

• Water reabsorption is primarily facilitated by aquaporin channels in the renal tubule, particularly in the proximal tubule and collecting ducts.

Obligatory and Facultative Water Reabsorption

• Obligatory water reabsorption happens in proximal tubule and descending loop, following osmotic gradients.
• Facultative water reabsorption is regulated by hormones (e.g., ADH), occurring in the distal tubule and collecting ducts.

Descending and Ascending Limbs of Loop of Henle

• Descending limb: Permeable to water, but not solutes.
• Ascending limb: Permeable to solutes (Na+, Cl-), but not water.

Countercurrent Multiplier Mechanism

• The nephron loop of juxtamedullary nephrons establishes a concentration gradient in the renal medulla by pumping solutes out of the ascending limb while water leaves the descending limb.
• Solute concentration is highest in the renal medulla and lowest in the renal cortex.

Urinary Tract in Males and Females

• The male urethra is longer and passes through the penis.
• The female urethra is shorter and leads directly to the external opening.

Electrolytes in the Human Body

• Electrolytes are charged particles (ions) that conduct electricity in water.
• Examples include sodium, potassium, chloride, calcium, bicarbonate, and phosphate.
• Most water is found in intracellular fluid (ICF).
• Sodium is the most abundant ion in extracellular fluid (ECF).
• Potassium is the most abundant ion in intracellular fluid (ICF).

Cell Environments (Hypertonic, Isotonic, Hypotonic)

• Hypertonic: Water moves out of the cell.
• Isotonic: No net movement of water.
• Hypotonic: Water moves into the cell.

Dehydration and Fluid Intake

• Dehydration causes cell shrinkage (crenation).
• Intake of water causes cells to rehydrate.

Principles of Mass Balance and Fluid Balance

• The body maintains a fluid balance by regulating intake, excretion, and storage of water
• Intake, output, and storage need to be equal

Brain Region and Thirst

• The hypothalamus initiates the thirst response.
• Person may experience thirst without dehydration.
• Salt intake, dry mouth, and psychological factors can also trigger thirst.

Hypernatremia, Hyponatremia, Hyperkalemia, Hypokalemia

• Hypernatremia: High sodium levels causing dehydration, confusion or seizures.

• Hyponatremia: Low sodium levels causing swelling of cells, headache, nausea, and potential coma.

• Hyperkalemia: High potassium levels leading to muscle weakness, cardiac arrhythmias, and potential heart failure.

• Hypokalemia: Low potassium levels causing muscle cramps, weakness, and arrhythmias.

Acids, Bases, and Buffers

• Acid: Substance that donates protons (H+) in solution.
• Base: Substance that accepts protons in solution.
• Buffers: Resist changes in pH by neutralizing excess acids or bases.
• Carbonic acid is the primary source of acid in the human body.

Regulation of Body pH

• Bicarbonate anion acts as a buffer by neutralizing excess hydrogen ions, preventing the blood from becoming too acidic.
• Kidneys secrete H+ and retain bicarbonate to help regulate blood pH.

Respiratory Rate and Blood pH

• Increased respiratory rate removes more CO2, thus decreasing acidity and raising pH (alkalosis).
• Decreased respiratory rate increases CO2, thus increasing acidity and lowering pH (acidosis).
• Changes in metabolism and respiration can result in metabolic or respiratory alkalosis or acidosis.
• The body compensates by adjusting respiratory rate and kidney function.

Chromosomes, Diploid, Haploid

• Chromosome: Thread-like structure made of DNA and proteins, carrying genetic information.
• Diploid cells have two sets of chromosomes.
• Haploid cells have one set of chromosomes.

Stages of Meiosis

• Meiosis I: Prophase I, Metaphase I, Anaphase I, Telophase I
• Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II.
• Meiosis involves two rounds of cell division and produces four genetically unique haploid cells.

Gametes and Genetic Uniqueness

• Gametes (sperm and egg cells) are haploid reproductive cells that fuse to form a zygote.
• Genetic uniqueness of gametes is achieved through independent assortment and crossing over during meiosis I.

Meiosis vs Mitosis

• Mitosis: One round, two identical diploid cells resulting.
• Meiosis: Two rounds, four non-identical haploid cells resulting.

Organs of the Male Reproductive System

• Testes, epididymis, vas deferens, seminal vesicles, prostate gland, and penis.
• Testies are the male gonads producing sperm and testosterone.
• Seminiferous tubules are part of the testes where sperm is produced.

Seminal Fluid and Glands

• Seminal fluid is a mixture of secretions from seminal vesicles, prostate gland, and bulbourethral glands which nourishes sperm.
• These glands are located around the base of the bladder and the urethra.

Spermatogenesis

• Spermatogenesis: The processes where spermatogonia (diploid germ cells), develop into sperm.
• Spermatogonia occurs in seminiferous tubules.

Blood-Testis Barrier Functions

• The blood-testis barrier, provided by Sertoli cells, protects developing sperm from the immune system attack.
• This ensures proper spermatogenesis.

Spermiogenesis

• Spermatogenesis has a final stage called spermiogenesis.
• During spermiogenesis, spermatids mature into sperm.
• Changes include developing a flagellum, condensing their nucleus, and forming an acrosome.

Functions of Hormones (LH, FSH & Testosterone)

• LH (Luteinizing Hormone): Stimulates testosterone production from Leydig cells.
• FSH (Follicle-Stimulating Hormone): Stimulates Sertoli cells to support sperm development.
• Testosterone: Promotes spermatogenesis, development of male secondary sex characteristics, and libido.

Female Reproductive System Organs

• Ovaries, fallopian tubes, uterus.
• Ovaries produce eggs (oocytes) & hormones (estrogen, progesterone).
• Fallopian tubes transport eggs to the uterus.
• Uterus is the site of embryo implantation and development.

External Genitalia of Female Reproductive System

• Vulva (Labia Majora/Minora, clitoris)
• Functions: Protection, sexual arousal, and passage for childbirth.

Breasts and Reproductive System Study

• Breasts, though part of the integumentary system, are also studied with the reproductive system due to their milk production function.
• These have glandular tissue and adipose tissue.

Oogenesis

• Oogenesis is the production of eggs from oogonia (female germ cells).
• Unlike spermatogenesis which produces many sperm per cycle, oogenesis produces one functional egg per cycle.

Phases of Ovarian Cycle

• Follicular phase: Development of follicles.
• Ovulation: Release of a mature egg.
• Luteal phase: Formation of the corpus luteum and progesterone release.
• Secondary oocyte is released during ovulation.

Uterine Cycle and Implantation

• During the uterine cycle, the endometrium (inner lining of the uterus) thickens during the proliferative phase if no pregnancy occurs.
• Implantation: Occurs in the endometrium.

Menses (Menstruation)

• Menses is the shedding of the uterine lining when pregnancy does not occur which leads to bleeding.
• It occurs during the menstrual phase of the uterine cycle.

Hormonal Signals and Phases of Uterine and Ovarian Cycles

• Estrogen and progesterone regulate ovarian cycles.
• LH surge triggers ovulation.
• These hormones regulate the uterine cycle phases.

Birth Control Methods

• Temporary methods: Condoms, birth control pills, IUDs.
• Permanent methods: Sterilization (vasectomy for men, tubal ligation for women).

Prenatal Period Phases

• Germinal phase: Fertilization to 2 weeks.
• Embryonic phase: Weeks 3-8.
• Fetal phase: Weeks 9-40.

Conceptus and Fetus

• Conceptus: Fertilized egg and subsequent development stages including embryo and fetus.
• Fetus: Stage from 9th week of development until birth when major organs are developed.

Sperm Fertilization

• Sperm undergoes capacitation process in female reproductive tract to begin fertilization process.
• Zones surrounding egg include zona pellucida and corona radiata.
• The acrosomal reaction involves enzyme release to break down the zona pellucida and allow sperm penetration.
• Cortical reaction prevents subsequent sperm entry.

Fertilization Post-Ovulation

• Fertilization can occur within 12-24 hours after ovulation.
• Result of fertilization is a single diploid zygote.

Egg Cell Meiosis

• The egg completes Meiosis II only after fertilization by a sperm.

Pre-Embryonic Period Stages

• Zygote, Morula, and Blastocyst stages.
• Cleavage: rapid cell divisions occurring from fertilization to the blastocyst stage.

Implantation

• Implantation occurs in the uterine wall, specifically the endometrium, 6-7 days after fertilization.

Extraembryonic Membranes

• Amnion (protective fluid-filled sac)
• Chorion (forms placenta)
• Yolk Sac (provides early nutrients and blood cell formation)
• Allantois (part of umbilical cord, early waste removal)

Gastrulation and Primary Germ Layers

• Gastrulation: Process during which ectoderm, mesoderm, and endoderm are formed.
• Ectoderm: Develops into skin and nervous system.
• Mesoderm: Develops into muscles, bones, and circulatory system.
• Endoderm: Develops into internal organs.

Placenta Functions

• Placenta connects the developing fetus to the uterine wall to provide nutrients, oxygen, and remove waste.
• Its functions include nutrient exchange, hormone production, and immune protection, and waste removal.

Placental Barrier

• The placental barrier consists of membranes separating maternal and fetal blood.
• Substances that can cross include oxygen, nutrients, waste, and hormones.
• Large molecules (e.g., red blood cells) and most drugs cannot cross this barrier.

Organogenesis

• Organogenesis is the development of organs during pregnancy, particularly from weeks 3-8.

Umbilical Cord and Blood Flow

• The umbilical cord contains two arteries (carry deoxygenated blood) and one vein (carry oxygenated blood).
• Blood in the umbilical vein is oxygen-rich, and blood in the arteries is oxygen-poor.
• The umbilical cord connects the fetus to the placenta.

Fetal Circulation Differences

• Foramen ovale: A hole between the right and left atria to bypass lungs.
• Ductus arteriosus: A vessel connecting pulmonary artery to aorta, bypassing lungs.
• Ductus venosus: A vessel shunting blood from umbilical vein to inferior vena cava, bypassing the liver.

Pregnancy Physiological Changes

• Increased blood volume, cardiac output, respiratory rate, hormonal changes, weight gain, and increased kidney function occur during pregnancy.

Uterine Contraction Feedback Loop

• Oxytocin stimulates uterine contractions.
• Prostaglandins enhance oxytocin's effect and promote cervical dilation.
• These hormones work together to increase the intensity and frequency of contractions, leading to labor.
• Hormonal changes happen in the positive feedback loop.

Stages of Labor

• Stage 1: Dilation of the cervix (10 cm).
• Stage 2: Expulsion of the fetus.
• Stage 3: Placental delivery.

Childbirth Position

• Cephalic (head-down) position is most conducive for vaginal childbirth.

Milk "Letdown" Reflex Hormones

• Prolactin stimulates milk production.
• Oxytocin stimulates milk ejection.

Genes, Alleles, Genotype, Phenotype

• Gene: Segment of DNA that encodes a trait or protein.
• Allele: Variations of a gene.
• Genotype: Genetic makeup (e.g., BB, Bb, bb).
• Phenotype: Physical expression (e.g., eye color).
• Complete dominance of an allele means it totally masks the other allele.

Polygenic Traits

• Polygenic traits are influenced by multiple genes such as skin color, height, and intelligence.
• Most complex human traits are polygenic traits.