Study Guide for the Final Exam-Spring Semester 2020

Study Guide for the

Overview of the Urinary System

  • Functions of the Urinary System

    • Regulation of blood volume and pressure.

    • Regulation of electrolyte levels.

    • Regulation of acid-base balance.

    • Removal of waste products from metabolism.

    • Regulation of fluid balance.

  • Anatomical Structure of the Kidneys

    • Each kidney is composed of an outer cortex and inner medulla.

    • Functional units called nephrons (approximately 1 million per kidney).

  • Blood Supply through the Kidney

    • Renal artery > segmental arteries > interlobar arteries > arcuate arteries > cortical radiate arteries > afferent arterioles > glomeruli.

Functional Unit of the Urinary System

  • Nephrons

    • Regions of the nephron:

    • Renal corpuscle: includes the glomerulus and Bowman’s capsule.

    • Renal tubule: includes proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT).

Renal Processes in Urine Formation

  • Three Basic Renal Processes:

    • Filtration: Movement of water and solutes from blood into the nephron.

    • Reabsorption: Movement of substances from nephron back into blood.

    • Secretion: Movement of substances from blood into nephron, which excretes them.

  • Filtering Plasma:

    • Approximately 180 liters of plasma are filtered daily, representing about 25% of cardiac output.

Glomerular Dynamics

  • Three Pressures at the Glomerulus:

    • Glomerular hydrostatic pressure (GHP): outward force.

    • Capsular hydrostatic pressure (CHP): inward force.

    • Blood colloid osmotic pressure (BCOP): inward force.

  • Glomerular Filtration Rate (GFR):

    • Amount of filtrate produced by the kidneys per minute (approximately 120 mL/min).

    • Maintaining GFR is crucial for homeostasis and kidney function management.

Juxtaglomerular Apparatus

  • Anatomy and Function:

    • Comprising macula densa, juxtaglomerular cells, and mesangial cells.

    • Regulates filtration through sensing sodium chloride concentration and secreting renin.

  • Myogenic Mechanism:

    • Smooth muscle cells contract in response to stretch, helping regulate blood flow in the glomerulus.

Reabsorption Processes

  • Glucose and Amino Acid Reabsorption:

    • Primarily occur in the proximal convoluted tubule (PCT).

    • Sodium ions (Na+) play a central role in this process.

  • Majority of Tubular Reabsorption:

    • Takes place in the proximal convoluted tubule (PCT).

Hormonal Regulation of Kidney Function

  • Effects of Angiotensin II:

    • Increases blood pressure and alters kidney function by vasoconstriction and stimulating aldosterone release.

    • Produced through the renin-angiotensin-aldosterone system (RAAS).

  • Atrial Natriuretic Peptide (ANP):

    • Secreted by the heart’s atria; acts on the kidneys to promote sodium excretion and reduce blood volume.

  • Kidneys in Urine Concentration/Dilution:

    • Versatile in regulating water reabsorption via the action of hormones like vasopressin (ADH).

Vasopressin (ADH)

  • Action and Effects:

    • Acts on the collecting ducts to increase water reabsorption.

    • Absence leads to dilute urine production (diabetes insipidus).

Urinary Tract Structure

  • Ureters and Urinary Bladder:

    • Ureters transport urine from kidneys to bladder; bladder stores urine.

Micturition Reflex

  • Process:

    • Reflexive control for urination involving detrusor muscle contraction and internal/external sphincter relaxation.

Homeostasis and Fluid/Electrolyte Balance

  • Fluid Balance:

    • Maintenance of appropriate body fluid levels.

  • Electrolyte Balance:

    • Regulation of ions across membranes essential for physiological functions.

  • Acid-Base Balance:

    • Regulation of pH in body fluids is vital for enzymatic and metabolic processes.

Hormonal Regulation of Fluid and Electrolytes

  • Hormones Involved:

    • Aldosterone: regulates sodium and potassium balance.

    • Antidiuretic hormone (ADH): regulates water reabsorption.

  • Mechanisms of Action:

    • Aldosterone promotes sodium reabsorption at the DCT and collecting ducts.

    • ADH promotes water reabsorption in kidneys.

  • Regulation Stimuli:

    • Changes in blood volume, osmolarity, and blood pressure promote secretion of these hormones.

Sources of Water and Loss

  • Sources of Water:

    • Ingested liquids, food, and metabolic processes.

  • Routes of Water Loss:

    • Urination, perspiration, respiration, and feces.

  • Regulation Mechanisms:

    • Thirst mechanism prompts water intake; kidneys adjust urine output according to hydration status.

Electrolyte Roles

  • Functions of Electrolytes:

    • Maintain osmotic balance and drive muscle and nerve functions; specific ions like Na+, K+, Ca2+, and Cl- are critical.

Buffer Systems

  • Three Major Buffer Systems:

    • Bicarbonate buffer system, phosphate buffer system, and protein buffer system.

    • Operate to maintain pH by neutralizing excess H+ or OH- ions.

Respiratory System and Acid-Base Balance

  • Influence on Acid-Base Homeostasis:

    • CO2 levels affect blood pH; increased CO2 (low pH) stimulates respiration to expel CO2, raising pH.

Kidney Contribution to pH Maintenance

  • Mechanisms:

    • Secrete hydrogen ions (H+) and reabsorb bicarbonate (HCO3-) to regulate blood pH balance.

Acidosis and Alkalosis

  • Definitions and Differences:

    • Acidosis: Condition of increased hydrogen ion (H+) concentration; can be respiratory (CO2 retainment) or metabolic.

    • Alkalosis: Condition of decreased H+ concentration; can be respiratory (hyperventilation) or metabolic.

Male and Female Reproductive Tracts

  • Anatomical Structures:

    • Male: testes, epididymis, vas deferens, prostate, penis.

    • Female: ovaries, fallopian tubes, uterus, vagina.

  • Functionality:

    • Testes produce sperm; ovaries produce ova (eggs).

Testes and Temperature Regulation

  • Testicular Location:

    • Located outside the body cavity to maintain cooler temperature necessary for spermatogenesis.

  • Regulatory Muscle:

    • Dartos muscle and cremaster muscle adjust position to regulate temperature.

Testicular Cells and Their Role in Reproduction

  • Cell Types in Testes:

    • Leydig cells: produce testosterone.

    • Sertoli cells: support spermatogenesis and nourish developing sperm.

Gametogenesis: Oogenesis and Spermatogenesis

  • Oogenesis:

    • The formation of ova in females; begins before birth and completes during ovulation.

  • Spermatogenesis:

    • The formation of sperm, continuous process initiated at puberty.

  • Differences in Gametogenesis:

    • Females have a fixed number of gametes (ovules); males continuously produce sperm after puberty.

Spermiogenesis and Spermiation

  • Spermiogenesis:

    • The maturation process of sperm cells into their functional form.

  • Spermiation:

    • The release of mature sperm from the Sertoli cells into the lumen of the seminiferous tubules.

  • Functional Morphology of Mature Sperm Cell:

    • Composed of the head (contains genetic material), midpiece (energy generation), and tail (motility).

Semen Components and Accessory Glands

  • Definition of Semen:

    • A fluid containing sperm and various secretions from accessory glands.

  • Major Accessory Sex Glands:

    • Seminal vesicles (provide fructose for energy), prostate gland (alkaline fluid), and bulbourethral glands (lubrication).

Autonomic Nervous System in Reproductive Function

  • Erection and Ejaculation:

    • Parasympathetic stimulation causes erection; sympathetic stimulation leads to ejaculation.

Regulation of Male Reproductive Hormones

  • Hypothalamic/Pituitary Regulation:

    • GnRH stimulates anterior pituitary to release LH and FSH.

  • Site of Action:

    • LH acts on Leydig cells to produce testosterone; FSH acts on Sertoli cells to stimulate spermatogenesis.

Meiosis in Females

  • Meiosis Timing:

    • Begins in fetal development; Meiosis I completed at ovulation.

    • Meiosis II completed upon fertilization.

Estrogen and Progesterone in Females

  • Actions of Estrogen:

    • Stimulates growth of uterine lining (endometrium).

  • Actions of Progesterone:

    • Prepares uterus for potential implantation and maintains pregnancy.

Ovulation and Menstrual Cycle Phases

  • Ovulation Trigger:

    • Surge in LH mid-cycle.

  • Phases:

    • Proliferative phase (building up the uterine lining), secretory phase (preparing for implantation), follicular phase (development of ovarian follicles), and luteal phase (after ovulation).

Luteinization and Hormonal Release

  • Luteinization:

    • Transformation of the ruptured follicle into the corpus luteum, which releases progesterone and estrogen.

  • Effect on Uterine Lining:

    • Thickening and maintenance for embryo implantation.

Corpus Luteum After Fertilization

  • If No Fertilization:

    • Corpus luteum degenerates (luteolysis).

  • If Fertilization Occurs:

    • Human chorionic gonadotropin (hCG) stimulates corpus luteum to continue hormone secretion.

Menses and Tissue Involvement

  • Definition of Menses:

    • Shedding of the uterine lining (endometrium); involves blood and tissue loss due to lack of pregnancy.

Prenatal Periods

  • Key Prenatal Stages:

    • Development phases: pre-embryonic (fertilization to week 2), embryonic (week 3 to 8), fetal (week 9 to birth).

Fertilization and Cleavage

  • Definition of Fertilization:

    • The union of sperm and egg resulting in a zygote.

  • Cleavage:

    • Rapid cell division of the zygote leading to the formation of the blastocyst.

Trophoblast and Inner Cell Mass

  • Trophoblast:

    • Outer cell layer of the blastocyst that develops into the placenta.

  • Inner Cell Mass:

    • Eventually forms the embryo.

Germ Layers and Adult Derivatives

  • Three Primary Germ Layers:

    • Ectoderm (nervous system, skin), mesoderm (muscles, bones, circulatory system), endoderm (gastrointestinal tract, lungs).

Role of the Placenta

  • Functions During Pregnancy:

    • Nutrient and gas exchange, hormone production, waste elimination.

Hormones in Parturition and Lactation

  • Parturition Hormone:

    • Oxytocin facilitates childbirth contractions.

  • Lactation Hormone:

    • Prolactin promotes milk production postpartum.

Genotype vs. Phenotype

  • Definitions:

    • Genotype: Genetic constitution of an individual.

    • Phenotype: Observable physical and physiological traits resulting from the genotype and environmental influences.