Respiratory System Flashcards
Cellular Respiration
All animal and plant cells need oxygen to survive. The oxygen is used for aerobic cellular respiration- series of chemical reactions that provide energy and consume oxygen.
C6H12O6 + 6O2 🡺 6CO2 +6H2O + energy
Glucose + oxygen 🡺 carbon dioxide + water +energy
About 64% of the energy released during cellular respiration is thermal energy which aids in maintaining body temperature. 36% is stored in molecules called ATP (adenosine triphosphate).
ATP
Formed when energy from the breakdown of glucose is used to attach a phosphate group to adenosine diphosphate (ADP). This is know as phosphorylation.
Each molecule of glucose yields 36 ATP in cellular respiration.
ATP is used to power almost all energy requiring processes like growth, movement and building new molecules.
The energy for these processes comes when ATP reacts with other molecules reforming ADP and a phosphate group.
Cellular Respiration:
Gas Exchange
Gas Exchange- the process by which oxygen diffuses into the body cells and carbon dioxide out of the cells.
In simple organisms, gas exchange is simple. O2 diffuses directly from the environment through the cell membrane and carbon dioxide diffuses out.
In humans, fish and most other large multicellular animals they obtain oxygen and get rid of carbon dioxide via specialized organ systems.
The Respiratory System
Path of air: nasal passages, pharynx (crossroad for food and air), larynx (voice box), trachea (windpipe), bronchi, bronchioles, & alveoli.
Breathing vs Respiration- breathing is the physical movement of air (inhaling & exhaling). Respiration is the chemical exchange of oxygen and carbon dioxide.
Ventilation
In humans and other mammals gas exchange occurs at two sites: the lungs and body cells.
Lungs: oxygen diffuses from the air into the bloodstream. Oxygen is transported through the bloodstream and diffuses into cells.
Body cells: cells are surrounded by tissue fluid (aka interstitial fluid). Oxygen diffuses from the blood into the tissue fluid then into the cells. Carbon dioxide is transported through the bloodstream to the lungs where it diffuses into the air.
Ventilation- the process that ensures a flow of oxygen rich air into the lungs and carbon dioxide rich air away from the lungs
4 structural features of respiratory system
Thin permeable respiratory membrane through which diffusion can occur.
Large surface area for gas exchange.
Good supply of blood.
Breathing system for bringing in O2 rich air to the respiratory membrane.
Lungs
Each deep breath captures between 3-4L of air into your lungs.
The human respiratory system has 4 important structural features:
Thin permeable respiratory membrane through which diffusion can occur.
Large surface area for gas exchange.
Good supply of blood.
Breathing system for bringing in O2 rich air to the respiratory membrane.
lungs 2
Air then travels into the pharynx. The glottis remains open during breathing so air enters the windpipe.
Trachea- semi rigid tube of soft tissue wrapped around C shaped bands of cartilage which leads air from the mouth to the lungs.
The bands of cartilage are necessary to keep the trachea open.
The trachea is lined with mucus producing cells and cilia which trap foreign material.
Cilia sweep trapped material up the trachea where it is swallowed or expelled via a cough or sneeze.
Alveoli
When air reaches the alveoli its at normal body temperature (37°C) and is saturated with moisture.
The respiratory membrane of the alveoli is also moist which is critical for diffusion of dissolved oxygen.
The respiratory membrane is only one cell thick so oxygen can diffuse easily from air to capillaries and carbon dioxide the other way.
The alveoli are encapsulated by capillaries providing an adequate supply of blood.
Ventilation mechanism
The mechanism of ventilation fulfills the fourth structural feature of the respiratory system.
Ventilation or breathing is based on the principle of negative pressure. When air pressure inside the lungs is lower than atmospheric pressure air is forced into the lungs. When the air pressure inside the lungs is higher than atmospheric pressure than air is forced out.
The thoracic cavity is separated from the abdominal cavity by a large dome shaped sheet of muscle called the diaphragm.
Inhalation
Inhalation- the breathing control mechanism in the brain causes the diaphragm to contract. This shortens and flattens the diaphragm. The external intercostal muscles between the ribs contract and pull the ribs up and out.
This causes the thoracic cavity to increase in volume reducing the pressure in the lungs and so air rushes in. Filling and expanding the lungs
Exhalation
the diaphragm relaxes and returns to regular dome shape. This relaxation pushes up on the lungs.
External intercostal muscles relax and the ribs fall and return to resting position.
Air pressure in lungs is increased and the elasticity of the lungs forces the air out.
During strenuous exercise a second set of intercostal muscles (internal intercostal muscles) start contracting and relaxing. When they contract they pull the rib cage downward, increasing the pressure inside and forcing more air out.
Lung Movement
Movement of the lungs within the thoracic cavity would cause friction problems if not for the pleural membrane.
Pleural membrane- a thin layer of connective tissue that covers the outer surface of the lungs and lines the thoracic cavity.
The space between the pleural membrane is called the pleural cavity and is filled with fluid so they can slide past each other easily.
When air is introduced into the pleural cavity, the membrane separates which causes the lung to collapse (pneumothorax).
Respiratory Structures in Fish
Most aquatic organisms obtain oxygen from the water that surrounds them.
Their respiratory system involves gills.
Gills are folded and branched structures that provide max surface area through which O2 can be absorbed and CO2 removed.
Usually located on the side of the head.
Gills are made up of several gill arches, made up of rows of gill filaments which have capillaries in them. Blood flows in the opposite direction to the flow of oxygen rich water.
This is known as countercurrent exchange which maximizes the amount of oxygen that diffuses in the blood. Blood with lower oxygen concentration is always adjacent to water with higher oxygen concentration.
