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The Excretory System

How Our Body Eliminates Cellular

Wastes

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Excretory Systemremoves excess water,H2O, urea, carbon dioxide, CO2, and otherwastes from our body or the blood.

Urinary tractfilter out excess water andurea

Lungsfilter out carbon dioxide, CO2,from the blood.

Skinexcretes water, as sweat, which

contains some trace chemical wastes,including urea.

Gastro-intestinal tracteliminates wasteproducts of digestion

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I. The Kidneys

Every drop of blood in your body is

filtered by your kidneys more than 300

times per day!filter blood- 2, 000 L/day (500 gal)

Kidneys eliminate urea, minerals and

excess water.

Kidneys regulate the amount of water we

need to maintain in our bodies.

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Kidneysfilter wastes and excess water

from the blood.

Ureterstubes that take urine from the

kidney to the urinary bladder.

Urinary Bladdera sack that stores urine.

Urethrasmall tube that leads urine out ofthe body.

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Urinary tract is the main system

of elimination

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Outer layer- Cortex

Inner layer- Medulla

Calyx- collects urine as

it is formed, join

together to form the

ureter

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Urine Formation:

Glomerular Filtration

First process occurs in renal

corpuscles

Fluid part of the blood isforced from glomerulous into

Bowmans capsule

Becomes glomerular filtrate

Glomerulus

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Factors affecting glomerular filtration

Filtration pressureamount of pressure that

forces filtrate from the glomerulus into

Bowmans capsule.

Determined by blood pressure

Rate of filtrationsympathetic nervous

system control

Constriction of afferent arterioles decreases

filtration pressure

Urine Formation:Glomerular Filtration (cont.)

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Second process in urine formation

Glomerular filtrateproximal convoluted tubule

Nutrients, water, and ions pass through the walls of therenal tubule into the peritubular capillaries

Water reabsorption depends on hormones

Antidiuretic hormone (ADH)

Aldosterone Both increase water reabsorption, which decreases urine

production

Urine Formation:Tubular Reabsorption

Tubular

Reabsorption

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Urine Formation: Tubular Secretion

Third process of

urine formation

Substances move

from blood in the

peritubularcapillaries into the

renal tubules

Secreted substances

Drugs

Hydrogen ions

Waste products

Tubular

Secretion

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Signs of Disease

Doctors analyze urine for disease;

Normal urine contains water, urea and trace

minerals.

Sugar in urine indicates Diabetes

Protein in urine indicates the kidneys are not

working and the person, or animal, is very sick.

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II. The Respiratory System

Eliminates carbon dioxide (CO2) in the

body

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The Lungs

Exchange of CO2and O2takes place at the

alveoli of the lungs

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The Bronchioles

Tiniest terminal segment that conducts

gases

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The Bronchi

Last segment that conducts gases

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The Trachea

Short tube that leads to the bronchi

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The Larynx

connects the pharynx and trachea

The vocal folds of the larynx control

airflow and allow the production of sound.

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The Pharynx

connects the nasal cavity with the larynx

A pair of tonsils are found here

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The Nasal Passages

Lined with hair to help filter the air weinhale

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III. The Integumentary System:

Skin

heaviest single organ of the body

Elastic

adults =1.22.3 m2of surface to theenvironment.

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Major Functions of the skin:

Protection

Sensation

Thermoregulation

Metabolic Functions

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Main Layers:

Epidermis

Dermis

Hypodermis/Subcutispanniculus adiposus

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EPIDERMIS

Consist mainly of stratif ied squamous

keratinized epithel ium, but also contain 4

less abundant cell types: Keratinocytes

Melanocytes

Langerhans cells

Merkels cells

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Layers of the Epidermis:

Stratum Basale

Stratum Spinosum

Stratum Granulosum

Stratum lucidum

Stratum corneum

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Thick skin 400X

thick layer of

stratum corneum

stratum lucidumstratum

granulosum

stratum spinosum

stratum basale

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Layers of the Dermis:

Papillary layer

Reticular layer

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Skin 400X

dermal

papilla

epidermis

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SUBCUTANEOUS TISSUE

consist of loose connective tissue that binds the

skin loosely to the subjacent organs, making it

possible for the skin to slide over them.

Often contain fats cells that vary in number

according to area and size according to nutritional

state.

Also referred to as the superficial fasciaand,where thick enough, the panniculus adiposus.

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IV. The Digestive Tract

A series of organs forming a long muscular

tube whose continuous lumen opens to the

exterior at both endsIt eliminates food debris and bacteria or

undigested food and bacteria

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