Lecture Test 3 (A&P) pt. 2

Urinary System

Plays a crucial role in maintaining homeostasis by producing and eliminating urine.

Kidneys

Organs primarily responsible for urine production and regulation of various bodily functions.

Homeostasis

The body's ability to maintain stable internal conditions despite external changes.

pH Regulation

The kidneys maintain blood pH by excreting bicarbonate (HCO₃⁻) and hydrogen ions (H⁺).

Acidosis

Condition where blood pH decreases, prompting kidneys to release hydrogen ions and retain bicarbonate.

Alkalosis

Condition where blood pH increases, prompting kidneys to excrete bicarbonate.

Blood Pressure Control

Kidneys manage blood volume and produce renin, influencing systemic blood pressure.

Renin

An enzyme produced by kidneys that converts angiotensinogen to angiotensin I, increasing blood pressure.

Erythropoietin

Hormone produced by kidneys that stimulates red blood cell production in response to low oxygen levels.

Vitamin D Activation

Kidneys convert inactive vitamin D into calcitriol, essential for calcium absorption.

Urine Composition Indicators

Urine can indicate health status based on the presence of certain substances, like proteins and glucose.

Filtration Process

The kidneys filter blood, producing approximately 200 liters of fluid daily, of which only about 2 liters becomes urine.

Hydration Levels

Urine color indicates hydration; darker urine suggests dehydration, while lighter suggests adequate hydration.

Urine Volume

Normal daily urine output ranges from 750 to 2000 milliliters.

Ureters

Tubes that transport urine from the kidneys to the bladder.

Bladder

Muscular storage organ for urine, lined with transitional epithelium.

Urethra

Tube through which urine is expelled from the body; shorter in females leads to higher UTI susceptibility.

Neural Control of Urination

Involves reflex mechanisms regulating involuntary and voluntary urination.

Stretch Receptors

Located in the bladder wall; they detect fullness and signal the spinal cord.

Detrusor Muscle

Muscle in the bladder that contracts to facilitate urination.

External Urethral Sphincter

Controlled by somatic motor neurons for voluntary regulation of urination.

Urine Detoxification

Urinary system detoxifies the body by eliminating waste and excess substances.

Transitional Epithelium

Lines the ureters and bladder, allowing stretching as they fill.

Muscular Layer of Ureters

Composed of smooth muscle that contracts rhythmically to move urine.

Kidney Location

Located posteriorly in the abdominal cavity, partly protected by ribs.

Kidney Size and Shape

Approximately the size of a large soap bar, around 10-12 cm long.

Blood Supply to Kidneys

Each kidney receives 20-25% of resting cardiac output from renal arteries.

Retroperitoneal Position

Kidneys sit outside the peritoneum, allowing for cushioning by fat.

Adrenal Glands

Located atop each kidney, secreting hormones like aldosterone.

Outer Cortex of Kidney

Contains renal corpuscles and renal tubules, involvement in filtration and reabsorption.

Inner Medulla of Kidney

Contains renal pyramids, loops of Henle, and collecting ducts, crucial for urine concentration.

Renal Columns

Extensions of the renal cortex providing structural support and blood vessel pathways.

Renal Pelvis

Funnel-shaped structure that collects urine from renal pyramids and channels into the ureter.

Glomerulus

Specialized capillary bed that filters blood to form urine.

Filtration Mechanism

Pressure-driven process where blood plasma is filtered to form tubular fluid.

Podocytes

Specialized cells in the glomerulus that facilitate filtration through slit-like openings.

Fenestrated Capillaries

Capillaries in the glomerulus that allow selective passage of small molecules.

Basement Membrane

Barrier that restricts passage of blood cells and large proteins during filtration.

Filtration Rate

The speed at which filtrate forms, impacting reabsorption and waste elimination.

Juxtaglomerular Apparatus

Structure that regulates GFR by monitoring sodium levels and fluid flow.

Angiotensin II

Vasoconstrictor that increases blood pressure and stimulates aldosterone secretion.

Aldosterone

Hormone that promotes sodium reabsorption in the kidneys.

Antidiuretic Hormone (ADH)

Hormone that increases water reabsorption in the kidneys.

Filtration Pressure

Combination of hydrostatic, osmotic, and capsular pressures affecting urine formation.

Proximal Convoluted Tubule (PCT)

Primary site for reabsorption of solutes and water in nephron.

Loop of Henle

Consists of descending and ascending limbs, crucial for urine concentration.

Countercurrent Multiplier System

Mechanism that enhances medullary concentration gradient for water recovery.

Distal Convoluted Tubule

Continues reabsorption of ions under hormonal regulation.

Collecting Ducts

Final site for hormone-regulated water reabsorption before urine is excreted.

Dehydration and ADH

Increased ADH release promotes water recovery; low ADH leads to more dilute urine.

Net Filtration Pressure

The pressure that drives fluid from blood into renal capsules.

Electrolyte Regulation

Management of sodium and calcium levels essential for bodily functions.

Acid-Base Balance

Kidneys maintain pH balance through bicarbonate and hydrogen ion regulation.

Nitrogen Waste Elimination

Kidneys eliminate nitrogenous wastes and excrete water-soluble drugs and toxins.

Baroreceptors

Sensory receptors that monitor blood pressure and volume changes.

GFR

Glomerular Filtration Rate; the volume of filtrate formed per minute.

RAAS

Renin-Angiotensin-Aldosterone System; regulates blood pressure and fluid balance.

Vasoconstriction

Narrowing of blood vessels to redirect blood flow, often due to sympathetic stimulation.

Myogenic Mechanism

Smooth muscle response in arterioles to maintain blood flow despite pressure changes.

Tubuloglomerular Feedback

Feedback mechanism where macula densa cells regulate GFR based on sodium levels.

Atrial Natriuretic Hormone (ANH)

Hormone that promotes vasodilation and sodium excretion to reduce blood pressure.

Glomerular Capsule

Structure in nephron where filtration of blood plasma occurs.

Filtrate

Fluid filtered from the blood, processed into urine.

Reabsorption and Secretion

Processes by which kidneys reclaim substances from filtrate and eliminate wastes.

Dilation and Constriction

Responses of arterioles that affect kidney blood flow and filtration rate.

Glucose Retention in Diabetes

Condition where glucose is not reabsorbed due to transporter saturation.

Hydrostatic Pressure

The pressure exerted by fluids, essential for driving filtration in the kidneys.

Osmotic Pressure

Pressure exerted by solutes, opposing filtration and affecting fluid movement.

Urine Concentration

Degree to which urine is concentrated, influenced by hydration and ADH levels.

Proximal Tubule Reabsorption

Major site for solute reabsorption and bicarbonate production.

Kidney Injury Risk

Kidneys are vulnerable to injury due to their posterior location and exposure.

Transitional Epithelium Function

Allows organs like the bladder to stretch while containing urine.

Micturition Reflex

Reflex that manages the involuntary and voluntary aspects of urination.

Collecting Duct Function

Regulates water retention in urine formation, influenced by ADH.

Blood Volume Impact

Fluid homeostasis directly relates to blood pressure and filtration mechanisms.

Kidney Disease Indicators

Presence of proteins, blood, or glucose in urine might indicate kidney dysfunction.

Glomerular Filtration Rate Regulation

Critical for maintaining kidney health and effective waste removal.

Potassium Regulation

Crucial balance maintained by kidneys through reabsorption and secretion.

Interstitial Fluid Role

Fluid in proximity to nephron aiding in reabsorption processes.

Renal Clearance

Rate at which specific substances are cleared from the plasma, indicating kidney function.

Detrusor Muscle Function

Facilitates urination by contracting during micturition.

Filtration Rate Importance

Maintaining a constant GFR is vital for kidney function and homeostasis.

Smooth Muscle Contraction

Rhythmic contractions in ureters that promote urine movement.

Calcium Homeostasis

Kidneys regulate calcium levels through hormone action and vitamin D activation.

Renal Capsule

Protective covering of the kidney providing support and structure.

Nephron Function

Each nephron filters blood, regulates urine formation, and participates in reabsorption.

Fluid Composition Regulation

Kidneys adjust fluid and electrolyte levels to maintain overall body equilibrium.

High Blood Pressure Effect

Increased pressure can cause damage to nephrons or lead to filtration issues.

Kidney Trauma Exposure

Kidneys are susceptible to injuries due to their anatomical position.

Kidney Disease Symptoms

Common indicators include changes in urine output and composition.

Volume Regulation Mechanism

Baroreceptors and hormones like ADH work to persistently regulate blood volume.

Hormonal Impacts on Kidneys

Hormones like renin and aldosterone influence kidney functions and blood balance.

Kidney Autoregulation

Process by which kidneys maintain GFR despite changes in systemic blood pressure.

Renal Blood Flow

The volume of blood delivered to the kidney for filtration and processing.

Fluid Reabsorption Mechanism

Essentials return to bloodstream through microvilli lining nephron tubules.

Bicarbonate Role

Buffers hydrogen ions, helping manage pH balance in the blood.

Sympathetic Nervous System Effects

Regulates kidney function via afferent and efferent arteriole adjustments.

Nephron Count

Each kidney contains about one million nephrons for filtration.

Collecting Duct Regulation

Influenced by hormones affecting the final volume and concentration of urine.

Intercalated Cells Function

Maintain acid-base balance by managing hydrogen and bicarbonate levels.