urinary system notes

list 3 primary functions of the urinary system.

filter blood to remove wastes,

produce urine, liquid waste, and eliminate it from the body,

maintain homeostasis of body fluids 

describe the location of the kidneys. (4)

high in the abdominal cavity,

against the dorsal body wall,

one on each side of the spine,

retroperitoneal

how is the location of the left kidney different than the right kidney?  

left kidney extends from T12 to L3,

right kidney is under the liver and, therefore, slightly lower

which internal region of the kidney is considered the “most superficial”?

cortex

which internal region of the kidney is deep to the cortex and deeper in color?

medulla

which internal region of the kidney is funnel-shaped tube that leads to the ureter?

pelvis

what do triangular renal pyramids in the medulla have a striped appearance?

bundles of urine-collecting tubules

describe a renal calyx.

cup-shaped area that collects urine from the base of the pyramids

how much blood passes through the kidneys each minute?  

between 20-25% of total blood volume 

how much urine is produced by the kidneys each day?  

1-2 liters

discuss the blood supply to the kidneys. 

blood enters the kidney through the renal artery,

the renal arteries branch into increasingly smaller arteries that carry blood to filtering units in the renal cortex 

describe the nephron.

the filtering units of the kidneys,

filter wastes from the blood,

produce urine,

each kidney contains over 1 million nephrons 

there are 2 main structures of the nephron. what is glomerulus?

ball of capillaries

there are 2 main structures of the nephron. what is a renal tubule?

cup-shaped capsule surrounds the glomerulus on one end,

then twists and coils for about 3 cm before leading to a collecting duct

describe the ureters. (3)

tubes of smooth muscle that propel urine from the kidneys to the urinary bladder,

extend from the renal pelvis to the posterior bladder,

about 25-30 cm long and 3-4 mm in diameter 

describe the urinary bladder. (3)

a hollow, muscular sac that stores urine before it is eliminated,

size and shape vary depending on the amount of urine it’s holding,

located posterior to the pubic symphysis 

describe the urethra (1)

thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis 

what is the internal urethral sphincter?

involuntary muscle that keeps the urethra closed most of the time

what is the urethral length in what is the urethral length in females? describe the opening as well.

3-4 cm; external opening lies anterior to the vagina

what is the urethral length in males? where does it pass through?

around 20 cm; penis

describe micturition. (also called voiding/urination)

flow of urine is controlled by 2 sphincters,

stretch receptors in the bladder wall will trigger bladder contractions,

urine is forced past the internal sphincter

what is the difference between the 2 sphincters that control the opening of the bladder?

internal sphincter is involuntary smooth muscle while external sphincter is voluntary skeletal muscle. 

what are some ways that the kidneys maintain blood composition? (5)

excrete nitrogen-containing wastes,

maintain water balance,

maintain electrolyte balance,

control blood pH,

control blood pressure 

list the locations in the body where most water is found. (2)

intracellular and extracellular fluid

name 3 examples of extracellular fluid.

interstitial fluid, blood plasma, lymph

what are some ways water enters the body?

ingestion of food and beverages, metabolism

what are some ways water leaves the body?

urine, sweat, exhaling, feces

how do the kidneys maintain water balance?

the kidneys control osmolarity or water concentration in blood plasma by controlling how much water is reabsorbed in the nephron or released from the body in urine 

what are the functions of antidiuretic hormone?

produced by the hypothalamus,

released in response to high solute concentration in the blood plasma,

causes kidneys to reabsorb more water and produce more concentrated urine 

what are some examples of electrolytes?

sodium, potassium, chloride, bicarbonate

describe electrolytes.

substances that form ions in solutions

kidneys control the excretion of?

several ions and electrolytes

correct amounts and proportions of electrolytes are important to proper body functions such as..

water balance, nerve signals, muscle contractions

what is normal blood pH?

7.35-7.45

how do the kidneys maintain it the blood’s pH? 

excreting H+ ions or conserving HCO3 ions 

how do the kidneys respond to high bp?

the kidneys reduce reabsorption of water to reduce blood volume and therefore, lowers blood pressure

how do the kidneys respond to low bp?

the kidneys produce the enzyme renin, which triggers a series of reactions that constrict blood vessels and raise blood pressure 

what effect does the hormone aldosterone have on homeostasis?  

a steroid hormone produced by the adrenal cortex, 

primary function is to regulate salt and water balance, 

presence of aldosterone increases the reabsorption of sodium which increases blood volume and, therefore, blood pressure increases

what are polycystic kidneys?

an inherited congenital defect in which the kidneys develop clusters of cysts

the kidneys lose function over time and kidney failure may as a result of?

polycystic kidneys

what are kidney stones?

hard mineral or salt deposits that form in the kidneys, passing them can be very painful

some stones can be broken up with sound waves, a procedure called?

lithotripsy

what is a urinary tract infection?

a bacterial infection in the urinary tract, usually the bladder and/or urethra 

what are the main symptoms of a UTI?

strong urges to urinate and a burning sensation during urination

what is incontinence?

inability to hold urine in the bladder

what are some common causes of incontinence?

common causes include pressure on the bladder from coughing, laughing, or lifting something heavy or urge incontinence, a sudden, intense urge to urinate followed by an involuntary loss of urine

how can UTIs be treated?

antibiotics

what is urinary retention?

inability to completely empty the bladder, can be acute or chronic

what is the more common cause of urinary retention in men?

enlarged prostate gland

what is dialysis and the life expectancy?

involves the use of a machine that filters the blood in patients that have lost most of their kidney function; 5-10 years

diabetes and high bp are leading causes of renal failure, leading to the need for a?

kidney transplant

when do kidneys begin to excrete urine in an embryo?

fetal kidneys begin excreting urine by the 10th week of 

pregnancy,

the urine is released into the amniotic fluid 

what are some facts about the function of the urinary system in infants?

filtration rate increases quickly during the first 2 weeks of life,

newborn babies have limited ability remove excess sodium and to concentrate and dilute urine 

when are the kidneys fully mature and functioning?

age 2

what are some facts about the function of the urinary system in the elderly? 

kidney mass and function begin to decline with age,

urinary tract infections and other diseases that affect the kidneys are more common in people over 60 

what are the 3 processes involved in urine production and where do they occur?

filtration in the glomerulus, 

reabsorption mostly in the proximal tubule, but also along the length of the renal tubule and collecting duct, 

secretion from the peritubular capillaries into the renal tubule 

describe the process of filtration.

blood pressure in glomerular capillaries pushes fluids and solutes smaller than proteins out of the blood and into the glomerular capsule; nonselective, passive process 

describe the process of reabsorption?

useful substances such as water, glucose, amino acids, and needed ions are transported from the filtrate to re-enter capillary blood, 

these substances are transported by diffusion and active transport 

describe the pressure of secretion?

additional substances that are not already in the filtrate are actively transported from the blood into the tubule to become part of urine; urea, uric acid, creatinine, drugs, and certain ions are secreted 

what are some characteristics of urine?

clear to deep yellow color,

pH is slightly acidic, 6 ,

turbidity should be clear or transparent, 

and specifically, gravity slightly higher than pure water; indicates concentration 

what are some substances that can be detected in a urinalysis?

drugs, protein, glucose, blood cells, and other substances