biology ˚˖𓍢ִ໋🪷✧

• In order for any organism to survive it has to somehow be adapted to its environment
• Types of adaptations


  • Structural
  • Behavioral
  • Functional
• Structural adaptations


  • Physical features of the organism like shape or colour
• Structural adaptations


  • Thick fur of polar bears
  • Big eyes of owls
• Behavioral adaptations


  • The way an organism behaves or acts
• Behavioral adaptations


  • Elephants flapping their ears and spraying themselves with water
  • Swallows migrating to warmer countries in winter
• Functional adaptations


  • Processes going on inside an organism's body like metabolism or reproductive system
• Functional adaptations


  • Desert animals producing little sweat and concentrated urine
  • Camels accumulating fat in humps to release water
• The brown bear's diet is extremely diverse and variable including plants, fungi, fish, invertebrates and mammals
• The brown bear lives in a cold environment

  It has adaptations like thick fur to conserve body heat
• The brown bear eats fish and deer

  It has structural adaptations like sharp claws and strong muscles to catch and kill these prey
• Extremophiles are microorganisms like bacteria or archaea adapted to live in extreme environments
• Extreme environments extremophiles can live in

  • High temperatures in hot springs
  • High salt concentrations in salt lakes
  • High pressures in deep sea vents
• Homeostasis


  The regulation of conditions inside the body to maintain a stable internal environment in response to changes in both internal and external conditions
• Our body regulates everything and makes sure that everything is kept around the right levels
• Our temperature and glucose levels do fluctuate but only within small bounds
• Automatic control systems


  • Receptors which detect a change
  • Coordination centres such as the brain or spinal cord which interpret that change and decide what needs to be done about it
  • Effectors which are the things that carry out the change
• Nervous system


  Sends very fast and precise electrical impulses through nerves which allows us to respond to things very quickly
• Endocrine system


  Relies on hormones which are small chemicals released into the bloodstream and although they travel throughout the entire body they only affect certain cells that have the right receptors. It is generally slower, longer lasting and more generalized than the nervous system.
• Negative feedback mechanism


  1. If the level of something gets too high, negative feedback decreases it again to return it to normal

  2. If the level gets decreased too much and is now too low, negative feedback will increase it again
• Scenario of walking into a cold room

  • Receptors in skin detect low temperature
  • Nervous system sends impulses to brain and spinal cord
  • Brain and spinal cord interpret information and send signals to muscles to shiver
  • Shivering increases body temperature back to normal
  • If temperature gets too high, different receptors detect this and trigger sweating to cool down
• Overall, homeostasis is a loop where automatic control systems use negative feedback to bring levels back to normal if they get too high or too low
• This is done through two organ systems: the nervous system and the endocrine system
• Nerve cell (neuron)


  • Long
  • Thin
  • Lots of branch connections to either end
  • Adapted to carry electrical impulses from one point to another
• Synapse


  Connection between nerve cells where electrical impulses cause release of chemicals that diffuse across the gap to trigger another electrical impulse in the next nerve cell
• Parts of the nervous system

  • Central nervous system (brain and spinal cord)
  • Sensory neurons (carry information from receptors to central nervous system)
  • Motor neurons (carry impulses from central nervous system to effectors like muscles and glands)
• Reflex arc


  1. Receptor cells detect stimuli

  2. Sensory neuron carries impulse to spinal cord

  3. Relay neuron transfers impulse to motor neuron

  4. Motor neuron carries impulse back to effector (e.g. muscle) to respond
• Reflexes are rapid and automatic responses that help avoid getting hurt
• The central nervous system takes in sensory information, decides what to do, and sends out orders to the body
• Between neurons, electrical signals are temporarily converted to chemical signals at synapses to be passed between nerve cells
• The endocrine system allows different parts of our body to communicate with each other
• The endocrine system


  Is similar to the nervous system, but there are lots of differences between the two
• Endocrine system


  Consists of a series of glands that secrete hormones, which are small chemical molecules passed into the blood and spread throughout the body
• Hormones


  • Act as signals to trigger certain changes inside cells
  • Some tissues have receptors specific to certain hormones, while others do not
• Main glands in the endocrine system

  • Pituitary gland
  • Thyroid gland
  • Adrenal glands
  • Pancreas
  • Testes
  • Ovaries
• Pituitary gland


  Produces multiple hormones, some of which directly tell the body what to do and some which tell other glands to release their own hormones
• Thyroid gland


  Produces the hormone thyroxine, which regulates the rate of metabolism and plays an important role in growth and development
• Thyroid stimulating hormone (TSH)

  1. Pituitary gland detects low levels of thyroxine and releases TSH, which stimulates the thyroid to produce more thyroxine

  2. This is a negative feedback process to bring thyroxine levels back to normal
• Adrenal glands


  Produce the hormone adrenaline, which is released during the fight-or-flight response and increases heart rate and blood flow
• Pancreas


  Produces the hormone insulin, which helps regulate blood glucose concentrations