Respiration and the Respiratory System Notes

Respiration

Respiration is a chemical process involving the breakdown of nutrient molecules (specifically glucose) to release energy stored within their bonds.
It is enzyme-controlled.
Respiration can occur with oxygen (aerobically) or without oxygen (anaerobically).
Aerobic respiration releases significantly more energy per glucose molecule than anaerobic respiration.
Respiration occurs in all living cells, with most chemical reactions in aerobic respiration taking place in the mitochondria.

Humans require energy from respiration for:

Requires oxygen.
Defined as the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy.
It involves the complete breakdown of glucose, releasing a large amount of energy for cell processes.
Byproducts include carbon dioxide and water, along with useful cellular energy.

Does not require oxygen. It is the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen
Involves the incomplete breakdown of glucose, releasing a relatively small amount of energy compared to aerobic respiration.
Produces different breakdown products depending on the organism.
Important to know the equations for anaerobic respiration in humans (animals) and yeast.

Primarily occurs in muscle cells (and liver) during vigorous exercise.
During intense exercise, muscles demand more energy than when resting.
The body can only deliver a limited amount of oxygen to muscle cells for aerobic respiration.
In this situation, as much glucose as possible is broken down with oxygen, and some glucose is broken down without it, producing lactic acid instead
Energy remains stored in the bonds of lactic acid molecules; therefore, less energy is released during anaerobic glucose breakdown.

Utilized in bread making, where carbon dioxide causes dough to rise.
Also used in brewing, where ethanol gives beer its alcoholic content, and carbon dioxide provides fizz.

Trachea (Windpipe): Connects the mouth and nose to the lungs.
Larynx: Also known as the voice box; air passing across it enables sound production.
Clavicle (Collar Bone)
Ribs: Bone structures protecting internal organs such as the lungs.
Intercostal Muscles: Muscles between the ribs controlling their movement during inhalation and exhalation.
Bronchi: Large tubes branching off the trachea, with one bronchus for each lung.
Bronchioles: Smaller tubes formed by the branching of bronchi in the lungs, connected to alveoli.
Alveoli: Tiny air sacs where gas exchange occurs.
Diaphragm: Sheet of connective tissue and muscle at the bottom of the thorax, altering thorax volume for inhalation and exhalation.
Pleural Membranes
Pleural Cavity Fluid
External Intercostal Muscle
Internal Intercostal Muscles
Sternum

Cartilage is a soft, flexible bone arranged in rings on the trachea.
- Functions:
  - Keeps the air passage open.
  - Makes the trachea flexible.
  - Prevents the trachea from collapsing due to air pressure.

Muscles can only pull, not push, on bones.
Two sets of intercostal muscles are required: one to raise the rib cage and another to lower it.
- External intercostal muscles are located on the outside of the ribcage (pull up).
- Internal intercostal muscles are located on the inside of the rib cage (pull down).

The diaphragm is a thin sheet of muscle separating the chest cavity from the abdomen.
It controls the inflation and deflation of the lungs.

To move air inside, the pressure of the lungs should be less than the pressure of air in the environment.
Coordinated by controlling the state of the intercostal muscles and diaphragm.

Feature	Inhalation	Exhalation
Action of diaphragm	Contracts (flattens)	Relaxes
Action of intercostal muscles	External - contracts, Internal - relax	External - relax, Internal - contracts
Volume of thoracic cavity	Increases	Decreases
Air pressure in thoracic cavity	Decreases	Increases
Flow of air	Air is drawn into the thoracic cavity	Air is exhaled from the thoracic cavity

The passages down to the lungs are lined with ciliated epithelial cells.
Cilia (tiny hairs) beat and push mucus up the passages towards the nose and throat for removal.
Goblet cells produce mucus, trapping particles, pathogens, and dust, preventing them from entering the lungs and causing damage.

Gas exchange surfaces vary among organisms, with different mechanisms for transporting gases based on size and environment.
All gas exchange surfaces (e.g., alveoli in humans) share common features:
- Large surface area: enhances gas diffusion rates.
- Thin walls: minimize diffusion distances.
- Good ventilation: maintains diffusion gradients.
- Good blood supply: maintains high concentration gradient for faster diffusion.

As blood passes through capillaries surrounding the alveoli, oxygen diffuses from the lungs/alveoli into the blood.
Simultaneously, CO_2 diffuses from the blood down the concentration gradient.
Blood becomes oxygenated and returns to the heart through the pulmonary vein.

During exercise, the body produces energy anaerobically, leading to an oxygen debt.
Oxygen debt is the amount of oxygen needed after exercise to break down lactic acid into CO2 and H2O.
After exercise, breathing rate increases, and the extra oxygen is used to break down lactic acid into harmless products and supply energy.
This process is called clearing the oxygen debt.

Muscle cell respiration increases, leading to higher oxygen consumption and CO_2 levels.
The hypothalamus detects increased CO_2 levels and signals the lungs to increase breathing.
Breathing rate and volume increase, enhancing gaseous exchange.
The brain signals the heart to beat faster, pumping more blood to the lungs for gas exchange.
More oxygenated blood reaches muscles, and more CO_2 is removed.