Lack of time, skipping meals, snacking on high calorie foods.
Answer:
When S mutans, lactobacilli, and other plaque species were compared in vitro for their ability to ferment sucrose at different pH values, S mutans was found to be more active than the other bacteria at pH 5.0, and thus, it is probably most active in vivo at the very pH at which the teeth begin to demineralize.
Answer:
There is no such thing as a skull bone. The skull is a flat bone that protects the brain.
Explanation:
The top part of the skull is made up of different pieces of bone that are fused together. You have the Frontal(1), Parietal(2), Temporal(2), Occipital(1), Sphenoid(1), and Ethmoid(1). Then you have the facial bones which make up the bottom part of the entire skull. The facial bones include Zygomatic(2), Maxilla(1), Nasal(1), Lacrimal(2), and Mandible(1).
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Axons are long nerve processes which carry nerve impulses from the Soma to other neurons, they vary in length but can become almost as long as half of the human body.
The soma (body) of the neuron contains the nucleus which acts as the cell's control centre, these contain many small neurofibrils which project from the nucleus into the dendrites.
Dendrites are short, thick processes which branch out of the soma in a tree like manor. They conduct nerve impulses to the soma.
The three categories of neurons:
Afferent (Sensory) Neurons have the dendrites connected to receptors such as the eyes, ears etc. These receptors change the information they receive into electrical impulses that are transmitted to other neurons. In sensory neurons the axons are connected to other neurons.
Efferent (Motor) Neurons have the dendrites connected to other neurons, the axons are connected to effectors. Effectors are either glands or a muscle cell that is the receiving end of the nerve impulse. The nerve, when excited will cause the effector to react (move, contract, or secrete etc).
Internuncial Neurons have both the dendrites and the axons are connected to other neurons. They are sometimes referred to as connector neurons.
Internuncial neurons are found throughout the body, but especially in the spinal cord and brain.
Properties and characteristics of Neurons:
Normally the electrical impulses (messages) travel through a neuron in only one direction.
The axon may be surrounded by a 'coat' of lipids (fats) and proteins known as the myelin sheath which acts as an insulator.
Neurons are specialist cells that have lost the ability to reproduce themselves. Once the soma of a neuron has died the entire neuron dies, and can never be replaced.
Repair of damaged neurons only occurs in myelinated neurons.
white matter are coloured by myelin, consisting of many neurons supported by neuroglia.
grey matter is soma and dendrites or bundles of unmyelinated axons and neuralgia.
