EXCRETORY SYSTEM

NOTES


RESPIRATORY
URINARY
RESPIRATORY NOTES--complete your outline using the information below.

The respiratory system consists of the nose, trachea, and lungs. Each has its own parts and functions. The nose consists of the nasal cavity which is the hollow space behind the nose. It is divided medially into right and left portions by the nasal septum. The nasal conchae are the bones inside the nose that curl out from the lateral walls and divide it into passageways. The nose is lined with a mucous membrane that contains a network of blood vessels. This membrane functions in heating and moistening the air as it enters the nose and in trapping dust and small particles that try to enter. The membrane is also ciliated and as the hairs move, mucus traps the particles and pushes them down the pharynx It is then swallowed and gastric juices dissolve the particles.

Sinuses are air-filled spaces located within four bones of the skull from which they are named. They open into the nasal cavity and are lined with mucus membranes. The sinuses function in reducing the weight of our skulls and in giving us a better voice quality.

The pharynx is the throat. It is located behind the mouth and between the nasal cavity and larynx. It functions as a passageway for food to the esophagus and for air to the trachea. In addition it helps create the sounds of speech. The pharynx is divided into three regions. The naso, oro and laryngopharnyx.

There are three different types of tonsils. The lingual tonsils are lymph tissue that lie at the base of the tongue. The pharyngeal tonsils, also known as adenoids, are found on the posterior wall of the mouth. The palatine tonsils are the ones we commonly call tonsils and may be removed if constantly infected.

The voice box is known as the larynx. It is the enlargement in the airway at the top of the trachea and below the pharynx. It serves as a passageway for air moving in and out of the trachea, it prevents foreign objects from entering the trachea and also houses the vocal cords. The false vocal cords are the two upper folds that do not function in production of sounds (thus false) but instead help to close the larynx during swallowing. True vocal cords contain elastic fibers and are responsible for vocal sounds created by forcing air between the cords. The glottis is the hole found between the true vocal cords and the epiglottis is a flap that closes the glottis when swallowing. This prevents food from going down the trachea. (This is why you should not talk while eating. Food could go "down the wrong" pipe.)

The windpipe is the trachea which is located in front of the esophagus. It is lined with a ciliated mucus membrane that contains many goblet cells. This membrane filters the incoming air. The trachea contains about 20 C-shaped pieces of hyaline cartilage, one above the other. This prevents the trachea from collapsing as food goes through the esophagus.

The bronchial tree consists of many airways leading from the trachea to microscopic air sacs. The first division of the bronchial tree are two bronchi. These branch into smaller bronchioles which branch into very thin tubes called alveolar ducts. Finally the alveoli are microscopic air sacs where gases are exchanged. Adults have over 300 million alveoli per lung. When you smoke, these alveoli clog with tar and nicotine, creating difficulty in breathing. If enough get "clogged", you can develop emphysema and other respiratory diseases.

The lungs are soft, spongy organs located in the thoracic cavity. There are two important membranes, the visceral pleura which is attached to the surface of each lung and the parietal pleura which is the outer membrane. The pleural cavity is the space between the two membranes. It contains a thin film of serous fluid for lubrication. The right lung is larger than the left lung and is divided into three lobes. (Can you think of a reason why the left is smaller?)

The process of breathing includes inhaling (inspiration) and exhaling (expiration). Atmospheric pressure causes the air to move into the lungs. The diaphragm is stimulated to contract by nerves. As it moves downward, the size of the thoracic cavity is enlarged and the pressure is reduced. As a result, air is forced into the lungs. A substance called surfactant is secreted by the cells of the lungs to reduce surface tension and to prevent the lungs from collapsing. (Can you determine under what circumstance a person's lungs would collapse?)

Other than normal breathing, our lungs move air during other nonrespiratory events. These include coughing, sneezing, laughing, crying, yawning and hiccuping.

VOLUME

"NORMAL" QUANTITY

DESCRIPTION
TIDAL Volume (TV)
500 cc
Volume moved in or out of the lungs during quiet breathing
INSPIRATORY RESERVE (IRV)
3000 cc
Volume that can be inhaled during forced breathing in addition to tidal volume
EXPIRATORY RESERVE (ERV)
1000 cc
Volume that can be exhaled during forced breathing in addition to tidal volume
VITAL CAPACITY (VC)
4500 cc
Maximum volume of air that can be exhaled after taking the deepest breath possible: VC = TV + IRV + ERV
RESIDUAL VOLUME (RV)
1500 cc
Volume that remains in the lungs at all times
TOTAL LUNG CAPACITY (TLC)
6000 cc
Total volume of air that the lungs can hold: TLC = VC + RV

 

The respiratory center of the body is found in the region of the brain stem. It is scattered throughout the pons and the upper two-thirds of the medulla. It initiates the impulse that travels from the cranial and spinal nerves to various breathing muscles. This region is also able to adjust the rate and depth of breathing. Several factors affect breathing. The inflation reflex helps us to maintain a respiratory rhythm and prevents overinflation of the lungs. Certain chemicals including the amount of carbon dioxide, oxygen, and hydrogen influence breathing.

Hyperventilation causes a lowering of the blood carbon dioxide levels; thus, dilating the blood vessels and decreasing the blood pressure. Oxygen supply to the brain may be inadequate and the person may faint. (What actions do you take to prevent this?)

In the alveoli gas are exchanged. Carbon dioxide is given up and oxygen is picked up by the hemoglobin of the RBC's. This exchange occurs within the capillaries of the alveoli. Carbon dioxide may be carried in solution, bonded to the hemoglobin and carried as a bicarbonate ion. Carbon monoxide, a third important gas, combines with hemoglobin more readily than hemoglobin does with oxygen. This, of course, is a problem because hemoglobin would then not be available for the oxygen. Since carbon monoxide is actually an odorless gas, fumes coming from a poorly functioning furnace can cause death for those breathing the air inside the house.

 

URINARY SYSTEM NOTES

I. Urinary System

A. Composition and Function

1. a pair of kidneys--remove substances from the blood and form urine

2. a pair of ureters--transports urine away from the kidneys to the bladder

3. one urinary bladder--serves as a urine reservoir

4. a urethra--leads urine to the outside of the body

B. Kidney

1. description--reddish brown, bean-shaped organ

2. location--on either side of the vertebral column in a depression high on the posterior wall of the abdominal cavity

3. retroperitoneally--behind the parietal perioneum

4. structure

a. renal sinus--cavity that into which the kidney fits

b. hilum--entrance to the sinus through which blood vessels, nerves, and lymphatic vessels pass

c. renal pelvis--funnel shaped part that leads to the ureter

d. major calyces--divisions of the renal pelvis

e. minor calyces--division of the major

f. renal papillae--elevations that project into the renal sinus

g. renal medulla--the inner body portion of the kidney

(1). pyramids--compose the medulla

h. renal cortex--forms a shell around the medulla

(1). nephrons--tubules that are the true functioning units of the kidney

5. renal blood vessels

a. renal artery--arises from the abdominal aorta

b. renal vein--returns blood to the inferior vena cava

6. nephrons--about 1 million in each kidney

a. renal corpuscle

(1). glomerulus--cluster of blood capillaries

(2). Bowman's capsule--saclike structure that surrounds the glomerulus

b. renal tubule--series of connecting tubes

(1). proximal convoluted tubule--first segment of a renal tubule

(2). Loop of Henle--the extension of the proximal tubule

(3). distal convoluted tubule--connects the Loop of Henle with the collecting tubule

(4). collecting tubule--straight part of a renal tubule

II. Urine Formation

A. urine--the end product of the kidneys

B. glomerular filtration

1. As the blood gets to these capillaries, water and wastes are filtered out.

2. Filtration enters the Bowman's capsule

3. Some is excreted and some is reabsorbed

C. rate--125 ml per minute or 180,000 ml (180 liters) in 24 hours; almost 45 gallons

D. tubular reabsorption--process by which substances reabsorbed into the blood stream

E. regulation--ADH from the posterior lob of the pituitary gland; inhibits the loss of body fluids

F. urea--a by-product of amino acid metabolism; directly related to the amount of protein in the diet

G. uric acid--results from the metabolism of certain organic bases in nucleic acids

H. urine

1. composition--95% water, urea, uric acid, amino acids, and electrolytes

2. amount--.6 to 2.5 liters per day

3. factors influencing amount--fluid intake, environmental temperature, relative humidity, emotional condition, respiratory rate, and body temperature

III. Elimination of Urine

A. ureter--tubular organ that extends from the kidneys to the bladder

1. wall layers

a. mucous coat--inner layer

b. muscular coat--middle layer, consisting of smooth muscle fibers

c. fibrous coat--outer layer, composed of connective tissue

2. peristaltic waves--move the urine from the kidneys to the bladder

3. mucous membrane--covers the opening through which the urine enters

B. urinary bladder

1. trigone--triangular are on the floor of the bladder

2. internal urethral orifice--opening into the urethra

3. wall layers

a. mucous coat--inner layer

b. submucous coat--second layer; consists of connective tissue and elastic fibers

c. muscular coat--composed of smooth muscle fibers

d. serous coat--consists of parietal peritoneum

C. micturition or urination--process by which urine is expelled from the urinary bladder

D. urethra--tube that moves urine from the urinary bladder to outside the body

Click to go back