Urinary system part 1

Urinary system 6 organs

2-kidneys, 2-ureters, urinary bladder, urethra

Urinary system also known as

Renal system

Urinary primarily function

Removal of waste products from blood plasma

The urinary system also results

BP, blood volume, blood osmolarity, electrolytes, and acid base balance

Urinary system secretes and produces

EPO & calcitriol

Waste products

Any substance that cannot be utilized by the body or is produced in excess of the body needs

Metabolic waste

Waste products produced by the body

Nitrogen waste

One of the most toxic metabolic waste

Ammonia and urea

Byproduct of protein catabolism, converted by liver

Uric acid

Byproduct of nucleic acid catabolism

Creatinine

Byproduct of creatinine kinase catabolism- abundant in muscle tissue

Uremia

Syndrome produces by the accumulation of nitrogen waste products

Signs of uremia

N/V/D, dyspnea, arrhymia, coma and death

Kidney anatomy

Bean shaped organ and retroperitoneal

Renal fascia of the kidney

Binds kidney to abdominal wall

Perirenal fat capsule of the kidney

Cushions kidneys

Fibrous capsule of kidney

Encloses kidneys, defend VS. trauma and infection

Renal parenchyma

Functional tissue of the kidney that forms the urine

Cortex of the renal parenchyma

Has renal columns that divide medulla into renal pyramids

Nephron

Functional unit of kidney

Afferent arterials runs to an encapsulated ball of capillaries called the

Glomerulus

The glomerulus is

Primary site of blood filtration

Blood leaves the glomerulus by the

Afferent arteries and travels to the Peritubular capillaries

Peritubular capillaries

reabsorb most of H2O filtered out at the glomerulus.

Vasa Recta

Establishes osmotic gradient for water conservation and collects fluids and solutes absorbed by the medullary part of the renal tubule

Renal corpuscle is composed of

Glomerulus & Bowman’s capsule

Bowman’s capsule

Dual layered sac covering glomerulus

Renal Tubule

Duct made of simple cuboidal epithelium which leads away from renal corpuscle and divided into 4 regions.

What are the 4 regions of the renal tubule

• PCT

• Loop of henle

• DCT

• Collecting ducts

Cortical nephrons

85% of nephrons & located in cortex

Juxtamedullary nephrons

15% of nephrons, long loops of henle, maintains osmotic gradient

Urine formations step 1

Glomerular filtration: creates a plasma like filtrate of the blood

Urine formation step 2

Tubular reabsorption: removes useful solutes from the filtrate and returns them to blood

Urine formation step 3

Tubular secretion: removes useful solutes es additional waste from the blood adds then to the filtrate

Urine formation step 4

Water conservation: removes water from the urine and returns it to blood; concentrated waste

Glomerular filtration

Is a process in which water and some solitude and blood plasma, or pass from the glomerular capillaries into the calsular space

During the glomerular filtration, Must cross three barriers which form of filtration membrane

-fenestrated epithelium of capillary

-basement membrane

-filtration slits

Filtration pressure

Follows same principle as in other capillaries but the forces involved are different

Net filtration pressure

Difference between the net hydrostatic pressure and net, COP

NFP= BHP-CP-COP

Glomerular filtration rate (GFR)

The amount of filtrate formation by the kidneys per minute

Average adult has 105-125 ML/min

Average adult produces how much urine per day

1-2 L

Regulation of GFR

GFR must be precisely controlled

High = low filtrate reabsoption causing dehydration and electrolyte imbalance

Low = high filtrate, reabsorption causes reabsorption of waste product

Renal autoregulation

Nephrons can adjust own blood flow without external stimulation

Myogenic mechanisms

Vasoconstriction→ low GFR

VASODILATION→ higher GFR

Tubuloglomerular feedback

JGA monitors solutes in filtrate and adjust Afferent arteriole accordingly

Sympathetic control

Kidneys innervate by SNS

Produces vasoconstriction of Afferent arteriole→ lower GFR and urine volume

Potent systemic vasoconstrictor →

High systemic blood pressure

Vasoconstriction efferent arteriole→

High systemic BP and high GFR

Glomerular filtrate is converted to urine via

Addition/removal of chemicals

reabsorption

Reclaiming h2o and solutes from the tubules and returning them to blood

Secretion

Chemicals extracted from blood and secreted into tubular fluid