Overview

• Mitosis is the process of cell division, important for growth and repair.
• Before mitosis even starts, cells spend about 90 percent of their time in interphase, replicating their DNA and making more of their organelles like mitochondria and ribosomes.
• Mitosis begins with prophase, where the nucleus breaks down and spindle fibers appear.
• During metaphase, the spindle fibers pull the chromosomes to the middle of the cell.
• Anaphase is when the spindle fibers pull the chromatids away to each end of the cell, the chromatids are just one half of a chromosome.
• Telophase is the last stage of mitosis, where the nucleus reforms.
• Cytokinesis is the final stage of mitosis, where the cytoplasm finally splits creating two daughter cells.
• Mitosis always produces identical cells.
• Mutations in the DNA can cause mitosis to happen uncontrollably creating a tumor.
• Plant cells usually elongate and divide at the roots, while animal cells typically just divide.
• Stem cells are unspecialized cells that can differentiate into specialized cells.
• Embryonic stem cells are the ones found in the early embryo and can turn into any type of specialized cell in a human.
• Animal stem cells are already partially specialized and can only turn into certain types of cell.
• Plant stem cells can turn into any type of cells in a plant because plants continue to grow throughout their lives and always need new specialized cells.
• Stem cells can be used in medicine if we stimulate them to produce the cells we need, but there are a few problems, the cells could continue divide and create a tumor or the body's immune system could reject the cells killing it off.
• The nervous system is the way that the body sends and receives information, with the central nervous system made up of the brain and spinal cord, and the peripheral nervous system made up of all the other neurons.
• There are three different types of nerve cell: sensory neurons, motor neurons, and relay neurons.
• Sensory neurons have a dendron an axon as well as dendrites and axon terminals, and the middle part of the cell is the cell body which is where the nucleus and all the other organelles are found.
• Motor neurons have no dendron, instead the dendrites are directly on the cell body, and then they still have their axon terminals.
• Relay neurons are short neurons found in the brain and spinal cord, and they look exactly the same as motor neurons.
• Axon dendrites are located on the cell body and axon terminals are located at the end of the axon.
• A myelin sheath is a covers over neurons to insulate them and speed up impulses.
• An impulse begins with a stimulus and travels through all types of neurons and the brain before connecting to an effector, which could be a muscle or gland.
• Synapses are small gaps between neurons where neurotransmitters are released.
• The cerebrum, divided into two hemispheres, is the main bulk of the brain and is responsible for higher functions like thinking and reasoning.
• The cerebellum, located at the back of the brain, is responsible for motor functions like walking.
• The brain stem or medulla oblongata, located at the bottom of the brain, is responsible for unconscious processes like breathing and controlling heart rate.
• The brain is trapped inside of the skull, making it hard to access for scans or treatment.
• CT scans build up an image of the shapes and structures in the brain by detecting how much of an x-ray beam is absorbed by the brain.
• PET scans measure brain activity by injecting radioactive glucose into the patient and using a scanner to measure how much each part of the brain takes in.
• The eye is a receptor to help us see, with different parts to help us detect different types of light.
• The lens in the eye lets light into the eye and focuses it to control the lens and how much it bends.
• The iris is the colored part of the eye and the hole in the middle is the pupil which allows light in.
• The cornea helps focus light in the eye.
• The optic nerve sends vision information to the brain.
• The retina is the light sensitive part of the eye, filled with two types of cells, rods and cones.
• Rods are responsible for detecting differences in light intensity, so they work really well in dim light.
• Cones are responsible for detecting color, needing really bright light to work.
• Focus in an image is mainly done by the cornea, which refracts the light rays to bring them together at the back of the eye.
• The ciliary muscles help make the lens fatter or thinner to focus this light.