Health Study Notes
82,83,84,85,89,90
57,58,59.60,
The Central Nervous System
The central nervous system includes the brain and spinal cord. It processes and coordinates all information
picked up by the senses and motor commands telling various body parts what to do. It is also
the seat of brain functions such as memory, intelligence, learning, and emotion.
Neurons
Neurons are nerve cells. They collect sensory information or changes in the environment. Then they
activate muscles or glands to react.
Impulse Transmitters
Neurons transfer information to and from one another through electrical impulses. These impulses
pass from one neuron to another through connections called synapses.
The Brain
The brain is a complex control center for the body. It can be divided into sections in a number of
ways: into two hemispheres; into forebrain, midbrain, and hindbrain; and into lobes. However the
brain is viewed, it is made up of three main parts: the cerebrum, the cerebellum, and the medulla.
The Organ of Taste
Taste is the ability to sense dissolved chemicals in materials placed in the mouth. The tongue is the
organ that distinguishes taste. Its surface is covered with papillae, or projections.
Taste Buds
Within the papillae of the tongue are the taste buds. Taste buds are onion-shaped structures. Each
one contains between 50 and 100 taste cells. Chemicals from foods dissolve in the saliva and come in
contact with the taste cells. The types of chemicals the cells pick up determine the flavors we taste.
How Does That Taste?
Taste is described by four qualities: sweetness, saltiness, sourness, and bitterness. Some scientists also
think there is a fifth taste, umami. This describes the taste of amino acids present in the proteins of meat,
fish, legumes, and monosodium glutamate (MSG). While all taste cells can distinguish all tastes, some
seem more receptive to certain flavors than others.
The Nose and Smell
Smell is the sense by which odors are perceived. The nose is the special organ of smell, although it also
has a role in respiration and voice. The nose most often refers to the external portion, the part we see
that protrudes from our faces. However, the nose leads to internal portions that can be divided into
two main cavities separated by the septum.
Blemish, Pimple, Zit
Whether you call it a blemish, a pimple, or a zit, all three are caused by the same thing: acne. Acne is
an eruptive skin disorder of the sebaceous follicles of the skin. The sebum of the follicles accumulates
and mixes with dust and dirt. The follicles and surrounding tissue become inflamed and blackheads
appear. If the follicle opening closes, bacteria accumulate and a pimple forms. Use the terms in the
word box to label the three stages shown in the diagram.
Too Hot, Too Cold
The human body has its own way to cool off or retain warmth. When cold, the muscles around hair
follicles contract to form goose bumps. When warm, the skin perspires. The moisture then evaporates,
making us feel cooler.
