Chapter 23Respiration and Excretion

When we exercise why do we breathe hard?

• Because your body needs more energy to sustain the activity that you are doing.

• The energy comes from the “burning” or breakdown of food in your cells, which is called Respiration.

What components make up the respiratory system?

• Nose and Mouth• Pharynx• Trachea• Lungs

Nose and Mouth• In most cases, air enters the respiratory

system through the nose.• The nose has 2 openings called the nostrils,

which are lined with short hairs.• What is the function of those hairs?– Filter or screen out particles of dirt and dust from

entering the nasal cavity

Nose and Mouth cont.• Air moving through the nasal cavity is filtered

and moistened done by 2 different types of cells.• 1st kind of cell secretes a sticky substance called

mucus, which traps particles in the air from entering the lungs.

• 2nd kind of cell is called cilia (tiny hair like structures), which move back and forth, pushing mucus back to the nostrils.

Nose and Mouth cont.• Mucus that collects in the nostrils can irritate

the nose which causes you to sneeze.• Sneezing is one way of blowing dirt and dust

from the nose.

Pharynx• Is the throat and the pathway for both food and

air.• At the end of the pharynx there is a fork in the

road (2 tubes)– Esophagus: tube for food to travel to the stomach– Windpipe: pathway of air to the lungs

Check for understanding

What is the function of the cilia in the nose?1)Oxygen absorption2)Movement of mucus to nostrils3)Secretes musus4)Kills bacteria5)Helps you breath

What is the function of the Epiglottis?

• Flap of tissue where the esophagus and windpipe meet which acts like a trap door.

• When you inhale, the epiglottis raises and air moves into the windpipe.

• When you swallow the epiglottis lowers and covers the windpipe.

Trachea (windpipe)• It is a 13 cm long tube located in front of the

esophagus.• At the top of the trachea is an organ called the

larynx, which is made of tough elastic tissue called cartilage.

• The larynx contains 2 thin folds of skin called the vocal cords.

• During normal, quiet breathing, the vocal cords are relaxed, but when you speak they tighten causing them to vibrate and produce sound.

Trachea cont.• The trachea is made up of rings of

cartilage and smooth muscle .• The cartilage keeps the trachea

open at all times so air can pass through.

• Like the nasal cavity there are two types of cells found in the trachea one for secreting mucus and the other cilia.

• Mucus in the trachea can cause irritation which causes coughing.

Bronchi and Bronchioles• The lower end of the trachea divides into 2

smaller tubes called the bronchi, which contain rings of cartilage and smooth muscle.

• Within the lungs, the bronchus branches into many smaller tubes called the bronchioles, which are made only of smooth muscle.

• They also both secrete mucus and have cilia that aid in trapping particles and transfer of mucus.

Check for understanding

• What is the function of mucus?1)Helps you breath2)Kills bacteria3)Traps dirt, dust, and bacteria4)Keeps respiratory system moist

Air sacs and Alveoli• Bronchioles end in structures called air sacs or

alveoli.• Each lung contains millions of alveoli.– A network of capillaries surround them– They are 1 cell thick– Thin walls allow oxygen and carbon dioxide to be

transported easily.

Chapter 23Respiration and Excretion

Gas exchange in the Alveoli• The most important part of the respiratory

process is the exchange of gases O2 and CO2.– Within the lungs these gases are exchanged between

the alveoli and the blood stream.– O2 moves in the bloodstream at the same time as CO2

moves into the alveoli.

• How does this exchange take place?– Diffusion

Gas exchange in the Alveoli cont.

Gas exchange in the Alveoli cont.• When air enters the lungs, the O2 from the air

dissolve within the alveoli.• The dissolved O2 then diffuses out of the alveoli

into the capillaries.• At the same time CO2 in the capillaries diffuse

into the alveoli.

Transport and Exchange of Blood • For Respiration to occur every

cell in your body must have O2.

• O2 from the lungs is carried by red blood cells to the heart and then is pumped to the rest of the body.

• What is the pathway called when blood is pumped between the heart and the lungs?– Pulmonary Circulation

Breathing• Breathing and respiration are related, but they are not the same process.

• Respiration is a chemical process.

• Breathing is a mechanical process that is a part of the Respiratory process.– Breathing: is the process by

which air enters and leaves the body.

– Your lungs can hold between 5-6 L of air.

How often do you breath?

• About 12 – 15 time per minute.• The organs that make breathing possible are

the ribs, the rib muscles, and the diaphragm.• Breathing is an involuntary action.• 24hrs a day your rib muscles and diaphragm

contract and relax.• However sometimes the diaphragm can have a

spasm, which causes you to have the hiccups.

Respiratory Diseases• Pneumonia• Bronchitis• Asthma

Pneumonia• Is one of the most common respiratory diseases.• It is the inflammation of the lungs that is usually

cause by bacteria.• Germs invade the lungs, as a result fluid fills the

lungs, which prevents the exchange of O2 and CO2 between the alveoli and the capillaries.

Bronchitis and Asthma• These are 2 diseases that are

caused by particles trapped in the bronchioles.

• Bronchitis is an inflammation of the bronchioles.– Symptoms: bad lasting cough

and difficulty breathing

• Asthma is when the muscular walls of the bronchioles contract, which causes them to become narrow and there is less room for air.