Bio lesson 2

• In animals, control and coordination are provided by nervous and muscular tissues
• Nervous tissue is made up of an organised network of nerve cells or neurons, specialised for conducting information via electrical impulses from one part of the body to another
• Information from the environment is detected by specialised tips of nerve cells, with receptors located in sense organs like the inner ear, nose, and tongue
• Nervous impulses travel from the dendrite to the cell body, then along the axon to its end, where chemicals are released to start a similar electrical impulse in the next neuron
• The thinking tissue in our body consists of dense networks of neurons, arranged intricately to receive signals from all over the body before responding to them
• Reflex arcs are formed in the spinal cord, allowing quick responses to stimuli without the need for conscious thought processes
• The brain and spinal cord make up the central nervous system, receiving and integrating information from all parts of the body
• The brain has three major regions: the fore-brain, mid-brain, and hind-brain, each responsible for different functions like sensory interpretation, decision-making, and motor control
• The brain is protected by sitting inside a bony box and contained in a fluid-filled balloon for shock absorption
• The vertebral column or backbone protects the spinal cord
• Nervous tissue collects information, sends it around the body, processes information, makes decisions based on information, and conveys decisions to muscles for action
• Muscle cells move by changing their shape so that they shorten in response to nervous electrical impulses
• Different kinds of muscles include voluntary muscles and involuntary muscles
• Voluntary muscles are under conscious control, while involuntary muscles are not
• Plants respond to stimuli through movements dependent on growth and movements independent of growth
• Plants use electrical-chemical means to convey information from cell to cell for movement
• Plant cells change shape by changing the amount of water in them, resulting in swelling or shrinking, and therefore changing shapes
• Plants show tropism in response to stimuli like light or gravity, with shoots bending towards light and roots bending away from it
• Geotropism refers to the upward and downward growth of shoots and roots, respectively, in response to the pull of earth or gravity
• Hydrotropism and chemotropism refer to directional growth movements in response to water and chemicals, respectively
• Information in multicellular organisms is communicated through electrical impulses and chemical communication using hormones
• Plants have hormones that control their directional growth, while animal hormones regulate growth and development of the body
• Iodine is necessary for the thyroid gland to make thyroxin hormone, which regulates carbohydrate, protein, and fat metabolism in the body for balanced growth
• Growth hormone, secreted by the pituitary gland, regulates growth and development of the body; deficiency in childhood leads to dwarfism
• Testosterone in males and estrogen in females are responsible for the dramatic changes associated with puberty
• Insulin, produced by the pancreas, regulates blood sugar levels; its deficiency leads to harmful effects like high blood sugar levels in diabetes
• Feedback mechanisms regulate the timing and amount of hormone released in the body