Biology
Feedback Loops
Systems
Negative Feedback Loops
Positive Feedback Loops
Homeostasis
Homeostasis refers to the body's tendency to achieve and maintain balance in the body. This is generally achieved through negative feedback loops.
Despite what the name might sound like, negative feedback loops have a set point of balance that they attempt to maintain or achieve under circumstances where there are external influences.
Positive feedback loops are not contrary to negative feedback loops in the way you'd likely imagine. Positive feedback loops exponentially amplify and enhance something further and further from the set point of equilibrium that negative feedback loops aim to maintain. This does not necessarily refer to something that is beneficial or detrimental to the body, it simply means that the difference between the point of equilibrium continues to grow.
Example: Contraction during the process of birth due to increased oxytocin levels.
Feedback systems generally have 3 key components. A receptor to detect change, an integrating center which processes information from the receptor, and an effector which attempts to act on an imbalance.
Example: Blood pressure regulation based on information received from baroreceptors.
Digestive System
Respiratory System
Gas Exchange; The exchange of oxygen and carbon dioxide between the alveoli and bloodstream (via passive diffusion)
Alimentary Canal; Food passes through
Accessory Organs; Aids in digestion
Pancreas
Stomach
Large & Small Intestine
Oesophagus
Liver
Salivary Glands
Gallbladder
Food and saliva is moved via peristalsis from the oral cavity to the stomach
Food is mixed through churning and begins the digestion process
Small Intestine
Large Intestine
Comprised of 3 parts: Duodenum, Jejunum, Ileum
Useful and usable nutrients are absorbed from digested food via microvilli
Consists of ascending, descending, transverse and sigmoid colon as well as the rectum
Microvilli are small hair-like projections which increase the surface are of the small intestine, thus allowing absorption of more nutrients.
Final organ of the alimentary canal, absorbs minerals and water
Moistens food and begins digestion process of starches through saliva
Produces a variety of enzymes that aid in digestion
Takes what was absorbed from small intestine to create key chemicals.
Produces the following enzymes: Pancreatic Protease (Aids digestion of proetin), Pancreatic Amylase (Aids digestion of carbohydrates), Pancreatic Lipase (Aids digestion of fats)
Purposes: Detoxification, Storage, Metabolism, Bile Production and Hemoglobin Breakdown
Stores bile produced by the liver which is used to emulsify fats. This bile from the gallbladder is released into the small intestine when needed.
Mechanical vs. Chemical Digestion
Mechanical digestion is physically breaking food down into smaller pieces.
Chemical digestion is breaking down food into simple nutrients which can actually be utilised by cells.
Components of the Respiratory System
Lung
Alveolus
Bronchiole
Diaphragm
Bronchus
Trachea
Ventilation;The exchange of air between the atmosphere and the lungs – achieved by the physical act of breathing
Cell Respiration; The release of energy (ATP) from organic molecules.
Body tissues require oxygen for aerobic respiration, producing carbon dioxide as a waste product. The respiratory system meets those needs by providing the oxygen by replacing the carbon dioxide.
Inspiration
Diaphragm Contracts → flatten → increase volume of
thoracic cavity
External Intercostals Contract → pulls rib
upwards and outwards (expand chest)
Expiration
Abdominal muscles Contracts → push diaphragm
upwards (force exhalation)
Internal intercostals Contract → pulls rib
inwards and downwards (reducing breadth of chest)
Diaphragm → relax
Cellular Respiration
Glycolysis; the breakdown of glucose by enzymes, releasing energy and pyruvate (oxygen not needed)
Input: Glucose
Output: 2 ATP + 2 pyruvate
Pyruvate; Broken down glucose
Anaerobic Respiration - no oxygen
Aerobic Respiration - Oxygen present
Anabolic
Catabolic
Photosynthesis
Carbon Dioxide + Water -> Glucose + Oxygen
Temperature
Photosynthesis is controlled by enzymes, which are sensitive to temperature fluctuations
As temperature increases reaction rate will increase, as reactants have greater kinetic energy and more collisions result
Above a certain temperature the rate of photosynthesis will decrease as essential enzymes begin to denature
Light Intensity
Light is absorbed by chlorophyll, which convert the radiant energy into chemical energy (ATP)
As light intensity increases reaction rate will increase, as more chlorophyll are being photo-activated
At a certain light intensity photosynthetic rate will plateau, as all available chlorophyll are saturated with light
Different wavelengths of light will have different effects on the rate of photosynthesis (e.g. green light is reflected)