Respiration Flashcards
Ventilation
The exchange of air between the lungs and the atmosphere; it is achieved by the physical act of breathing
Gas exchange:
The exchange of oxygen and carbon dioxide in the alveoli and the bloodstream; it occurs passively via diffusion
Cell Respiration
The release of ATP from organic molecules; it is greatly enhanced by the presence of oxygen (aerobic respiration)
Need for Ventilation System
- Oxygen is needed by cells to make ATP, carbon dioxide is a waste product of this process and must be removed ( aerobic respiration)
- oxygen must diffuse from the lungs into the blood, while carbon dioxide must diffuse from the blood into the lungs
- need low CO2 and high O2 in lungs
- ventilation system maintains this concentration gradient by continually cycling the air in the lungs with the atmosphere
Features of Alveoli
Thin Wall
Rich Capillary Network
Increases SA: Vol ratio
Moist
mechanism of ventilation of the lungs internal intercostal muscles, external intercostal muscles, diaphragm abdominal muscles. ) INSPIRATION
Inspiration
- Diaphragm muscles contract and flatten downwards
- External intercostal muscles contract, pulling ribs upwards and outwards
- This increases the volume of the thoracic cavity (and therefore lung volume)
- The pressure of air in the lungs is decreased below atmospheric pressure
- Air flows into the lungs to equalise the pressure
mechanism of ventilation of the lungs internal intercostal muscles, external intercostal muscles, diaphragm abdominal muscles. ) EXPIRATION
Diaphragm muscles relax and diphragm curves upwards
Abdominal muscles contract, pushing diaphragm upwards
External intercostal muscles relax, allowing the ribs to fall
Internal intercostal muscles contract, pulling ribs downwards
This decreases the volume of the thoracic cavity (and therefore lung volume)
The pressure of air in the lungs is increased above atmospheric pressure
Air flows out of the lungs to equalise the pressure
endocrine system consists of glands that release hormones that are transported in the blood.
endocrine gland is a ductless gland in the body that manufactures chemical messengers called hormones and secretes them directly into the blood
Hormones act on distant sites (target cells) and tend to control slow, long-term activities such as growth and sexual development
homeostasis
maintaining the internal environment of the body within safe limits
Internal equilibrium is maintained by adjusting physiological processes
Water balance CO2concentration blood glucose concentration blood Ph body temperature
homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms.
Most homeostatic control mechanisms operate through a negative feedback loop
When specialised receptors detect a change in an internal condition, the response generated will be the opposite of the change that occurred
When levels have returned to equilibrium, the effector ceases to generate a response
If levels go too far in the opposite direction, antagonistic pathways will be activated to restore the internal balance
body temperature, including the transfer of heat in blood, and the roles of the hypothalamus, sweat glands, skin arterioles,shivering.
hypothalamus in the brain monitors temperature of the blood, as heat is transferred in the blood, and compares it with a set point (close to 37 degrees celsius). If the blood temperature is lower or higher than the set point the hypothalamus signals parts of the body by neurones to bring the temperature back to the set point (negative feedback).
Responses to overheating:
- Skin arterioles become wider - more blood flows through the skin - this transfers the heat from the core of the body to the skin losing the heat to the environment.
- Skeletal muscles remain relaxed and resting so they do not generate heat.
- Sweat glands secrete sweat to make the surface of the skin damp - water evaporates which has a cooling effect.
Responses to chilling
- Skin arterioles become narrower - less blood is brought to the skin - the temperature of the skin falls and less heat is lost to the environment.
- Skeletal muscles do many rapid contractions to generate heat (shivering).
- Sweat glands do not secrete sweat - the skin remains dry.
Control of blood glucose concentration
Cells in the pancreas monitor the concentration of blood glucose. It send hormone messages to target organs when the level is low or high. The responses by target organs affect the rate at which glucose is loaded or unloaded to/from the blood. Mechanisms involved are examples of negative feedback.
Responses to high blood glucose levels:
- Beta cells in the pancreatic islets produce insulin.
- Insulin stimulates the liver and muscle cells to absorb glucose from the blood and convert it into glycogen.
- Other cells are stimulated to absorb glucose for the use in cell respiration instead of fat.
These processes reduces the blood glucose level.
