Biology Chapter 11

Urinary System

1. play a vital role in maintaining homeostasis

2. balance pH levels in blood

3. regulate blood pressure

4. vitamin d production

85% of EPO produced to stimulate RBC production is produced in the _____

kidney

Causes of urinary system failure

• weakness

• lethargy

• dyspnea

• anemia

• edema

• metabolic acidosis

• rising potassium levels

• heart arrhythmias

Excretion

process of removal of waste and excess material

Digestive System

excretes food residues and waste produced by liver

Respiratory System

excretes CO2

Integumentary System

excretes water and salt

Urinary System (Kidneys)

excretes nitrogenous wastes, excess solutes and water

The _____ regulate nitrogenous wastes and other solutes

kidneys

Protein metabolism produces _______

nitrogenous waste

Intially, NH3 (ammonia) is produced during breakdown of _____

amino acids

_____ detoxifies NH3 (ammonia), producing urea

liver

____ is transported from liver to kidneys for disposal

urea

Solutes regulated by kidneys

sodium, chloride, potassium, calcium, hydrogen ions and creatinine

____ does the maintenance of water levels

kidneys

Equation to maintain homeostasis

water input=water output

_____ adjust water output as necessary

kidneys

Water input

food, drinks and metabolism

Water output

lungs, skin, feces and kidneys

____ modify output based on intake and loss

kidneys

____ varies from ½ liter a day to 1 liter an hour

output

Majority of water intake is from variety of _______

foods and beverages

20-25% of recommended total fluid intake are from

food

On average, individuals consume ___ ounces of water daily

41

water intake from other beverages percentage

43.6%

water intake from pure water percentage

31.4%

____ is a diuretic

alcohol

Metabolic water

1. breakdown of macronutrient molecules in energy metabolism from carbon dioxide and water.

2. provides about 14% of daily water requirements for a sedentary person

Kidney/Urinary System

• Principal organ of the urinary system

• operate in kidney

Kidney

• lima bean-like structure

• located on either side of the vertebral column

• extend from the level of the last thoracic vertebra to above the third lumber vertebra

Primary function of Urinary system

process blood and form urine as a waste product

Three primary structures of kidneys

1. Cortex : outer portion of the kidney

2. Medulla : inner region of the kidney

3. Renal Pelvis : hollow space in center of kidney where urine collects

Additional organs of the Urinary System

• Ureters : Muscular tubes that transport urine from kidneys to bladder

• Urinary bladder : Three layers of smooth muscle, lined with epithelial cells. Stores urine (600-1,000 mL)

• Urethra : Carries urine from bladder to outside of body. Two sphincters control urination (one is controlled, one is not)

_____ have longer urethra

males

____ are a primary organ

kidneys

Urinary bladder contain

detrusor muscle

Detrusor muscle

• made mostly of smooth muscle

• network of crisscrossing bundles of muscle fibers

  • circular

  • oblique

  • lengthwise

Nephrons function

filter blood

Nephrons

functional unit of kidney

Two parts of Nephrons

• Renal Corpuscle :

  • glomerulus (capillaries) and bowman capsule (glomerular capsule)

• Renal Tubule :

  • proximal convoluted tubule

  • henle loop (nephron loop)

  • distal convoluted tubule

Special ________ supply the tubule

blood vessels

Renal artery supplies the

kidney

Blood vessels (arterioles and capillaries) are associated with

tubule

Renal vein collects filtered ____ from kidney

blood

Kidneys have three main processes

• Filtration

• Tubular Absorption

• Tubular Secretion

Filtration

movement of water and protein-free solutes from plasma in the glomerulus across the capsular space (takes everything out, filtering and then putting the good things back in)

Tubular Absorption

Tubes to Blood

Tubular Secretion

Blood to Tubes

We don’t want ___ in our urine

glucose

Filtration process

• as blood flow through glomerulus, water and small solutes filter out of blood into Bowman’s capsules

• 180 liters of glomerular filtrate being formed each day

• filtration occurs due to pressure gradients (high blood pressure in glomerular capillaries)

• rate of filtration is regulated in two ways

  • stress affect blood flow to kidney

Kidney Physiology

• 100% of filtered glucose, amino acids, bicarbonate and 50% of urea are reabsorbed

• most tubular reabsorption occurs in proximal tubule

• water reabsorption

  • 65-70% occur in proximal tubule

  • 25% occur in loop of henle

  • less than 10% occurs in distal tubule and collecting duct - this is where excretion is regulated

• brush border of microvilli on proximal tubule cells facilitate reabsorption

• reabsorption process starts in proximal tubule

Urine composition

• water intake

• exercise

• environmental temperature

• nutrient intake

• health and disease

Urinalysis

• the analysis of urine

• this often provides a number of dues to an individuals health and/or disease state

Normal urine characteristics

• odorless

• 750-2000mL/24hr in volume

• pH of 4.5-8.0

• normal range is 1-2L/day

• kidneys must produce minimum urine volume of 500mL/day to rid the body of waste products

Normal

1-2L/day

Polyuria

more than 2.5L/day

Oliguria

300-500mL/day

Anuria

less than 50mL/day

Ways kidneys maintain homeostasis

• contribute to maintenance of water balance

• contribute to maintenance of salt balance

• secrete an enzyme involved in the control of blood pressure

• maintain acid base balance and blood pH

• regulate RBC production via erythropoietin

• activate inactive form of vitamin d

ADH

regulates water balance

ADH stands for

antidiuretic hormone

ADH involves

1. Hypothalamus : synthesizes ADH

2. Posterior pituitary gland : releases ADH

3. Kidneys : respond to ADH

Negative feedback regulates solutes concentration of blood

• involves increasing or reducing ADH secretion

• involves increasing or decreasing thirst

__ regulates water balance

ADH

Blood solute concentration high

(Low water concentration) ADH released

Blood solute concentration low

(High water concentration) ADH inhibited

Diuresis

high urine flow rate

Diuretic

any substance that increases formation and excretion of urine

___ inhibits sodium reabsorpition

caffeine

__ inhibits ADH release

alcohol

_____ regulates salt balance

aldosterone

_________ is dependent on salt balance

blood volume control

Aldosterone

adrenal hormone that regulates sodium excretion

_____ is controlled by the renin - angiotensin system

aldosterone secretion

____ stimulates RBC production

erythropoietin

O2 sensitive cells in kidney secrete hormone (erythropoietin) in response to decrease in ____

oxygen

Erythropoietin triggers increase in ____ production in the bone marrow

RBC

Kidneys activate ____

vitamin d

Exposure of skin to sunlight cause production of ___ from a precursor found in skin

inactive form of vitamin d

Inactive form of vitamin d transported to ___, where it is modified

liver

Inactive form of vitamin d is influenced by actvity of ___

pth

PTH

parathyroid hormone

___ help maintain acid-base balance and blood pH

kidneys

Blood pH must stay between

7.35 and 7.45

__ regulated by kidneys, buffers and lungs

pH

Role of kidneys in pH maintenance

• reabsorption of filtered bicarbonate

• excretion of acid as ammonium (NH4+)

Acids and bases enter body through ____

foodstuffs and metabolism

Acids and bases are important in homeostasis, control of ___ is a large factor

hydrogen ions

Sources of hydrogen ions

• carbonic acid

• lactic acid

• sulfuric acid

• phosphoric acid

• acidic ketone bodies

Metabolism

• carbonic acid

• lactic acid

• ketone bodies

• sulfuric acid

• phosphoric acid

Foodstuffs

• acid-forming minerals

• basic-forming minerals

Carbonic acid

aerobic glucose catabolism

Lactic acid

anaeboric glucose catabolism

Ketone bodies

incomplete breakdown of fats

Sulfuric acid

oxidation of sulfur containing amino acids

Phosphoric acid

hydrolysis of nucleic acids and phosphoprotein

Acid-forming minerals

• chlorine, sulfur and phosphorus

• meat, fish poultry and eggs

  • high protein diets

• some grains (wheat, corn and oats)

Basic-forming minerals

• potassium, calcium, sodium and magnesium

• fruits and vegetables

Two main types of pH control mechanisms

• Chemical buffer - 1st line of defense

• Physiological buffer - 2nd line of defense

Chemical buffer (1st line of defense)

• rapid acting

• immediately combines with any added acid or alkali that enter body fluids