Study Guide for Biology

Skeletal system

bones, cartilage, ligaments, tendons... supports the body, protects internal organs, allows movement, stores mineral reserves, provides a site for blood cell formation.

Reproductive system

testes, epididymis, vas deferens, urethra, and penis- ovaries, fallopian tubes, uterus, vagina... produces reproductive cells, in females, nurtures and protects developing embryo.

Lymphatic/ Immune system

white blood cells, thymus, spleen, lymph nodes, lymph vessels... helps protect the body from disease, collects fluid lost from blood vessels and returns the fluid to the circulatory system.

Organ System

-An organ system is a group of organs that perform closely related functions. -The brain is on of the organs of the system, which gathers information about the outside world and coordinates the body's response.

Circulatory system

heart, blood vessels, blood... brings oxygen, nutrients, and hormones to cells, fights infection, removes cell wastes, helps to regulate body temperature.

Endocrine system

hypothalamus, pituitary, thyroid, parathyroid, adrenals, pancreas, ovaries, testes... controls growth, development and metabolism, maintains homeostasis.

Digestive system

mouth, pharynx, esophagus, stomach, small and large intestines, rectum... converts foods into simpler molecules that can be used by the cells of the body, absorbs food, eliminates wastes.

Respiratory system

nose, pharynx, larynx, trachea, bronchi, bronchioles, lungs... provides oxygen needed for cellular respiration and removes excess carbon dioxide from the body.

Nervous system

recognizes and coordinates the body's response to changes in its internal and external environments... brain, spinal cord, peripheral nerves.

Muscular system

skeletal muscle, smooth muscle, cardiac muscle... works with skeletal system to produce voluntary movement, helps to circulate blood and move food through the digestive system.

Integumentary system

skin, hair, nails, sweat, oil glands... serves as a barrier against infection and injury, helps to regulate body temperature, provides protection against ultraviolet radiation from the sun.

Excretory system

skin, lungs, kidneys, ureters, urinary bladder, urethra... eliminates waste products from the body in ways that maintain homeostasis.

Moving Impulse

-Action potential is the reversal of charges from negative to positive, AKA a nerve impulse. -A neuron remains in its resting state until it receives a stimulus large enough to start a nerve impulse. -An impulse begins when a neuron is stimulated by another neuron or by the environment. -At the leading edge of an action potential, gates in the sodium channels open, allowing Na+ ions to flow into the cell. -This flow of ions causes the action potential to move. At the trailing edge of an action potential, gates in the potassium channels open, allowing positive ions to flow out and restoring the resting potential of the neuron. -The cell membrane of a neuron contains thousands of protein channels that may allow ions to pass through, depending on the state of "gates" within the channels. Generally, the gates within these channels are closed. -As the impulse passes, gates within the potassium channels open, allowing K+ ions to flow out. This restores the resting potential so that the neuron is once again negatively charged on the inside of the cell membrane and positively charged on the outside.

Organs

-An organ is a group of tissues that work together to perform a complex function, such as sight. -A group of different types of tissues that work together to perform a single function is called an organ.

Tissues

-Epithelial tissue; includes glands and tissues that cover interior and exterior body surfaces. -Connective tissue provides support for the body and connects its parts. -Nervous tissue transmits nerve impulses throughout the body. -And muscle tissue, along with bones, enables the body to move. -A group of cells that perform a single function is called a tissue.

Nonliving Example of Homeostatsis

-Feedback inhibition or negative feedback; process by which a stimulus produces a response that opposes the original stimulus. -Systems controlled by feedback inhibition are generally fully automated and very stable.

Homeostatsis in the body

-Maintenance of homeostasis requires the integration of all organ systems at all times. -A part of the brain called the hypothalamus contains nerve cells that monitor both the temperature of the skin at the surface of the body and the temperature of organs in the body's core. -The temperature of the core is generally higher than the temperature of the skin. -if the nerve cells sense that the core temperature has dropped much below 37*C, the hypothalamus produces chemicals that signal cells throughout the body to speed up their activities. -If your body temperature drops well below its normal range, the hypothalamus releases chemicals that signal muscles just below the surface of the skin to contract involuntarily (to shiver). -If body temperature rises too far above 37*C, the hypothalamus slows down cellular activities, minimizing the production of heat. -Heat from the body's core is carried by the blood to the skin, so evaporation (of sweat) at the body surface also helps to lower the temperature of the core.

Neurons

-Neurons are the cells that transmit these impulses. -Cell body is the largest part of a typical neuron. -Dendrites are the branched extensions sprouting out from the cells body. -Axon is the long fiber that carries impulses away from the cell body. -Myelin Sheath is the insulating membrane surrounding the axon in some neurons. -The messages carried by the nervous system are electrical signals called impulses. -Neurons can be classified into three types according to the direction in which an impulse travels. -Sensory neurons carry impulses from the sense organs to the spinal cord and brain. Motor neurons carry impulses from the brain and spinal cord to muscles and glands. Interneurons connect sensory and motor neurons and carry impulses between them. -Most of the metabolic activity of the cell takes place in the cell body. -Dendrites carry impulses from the environment or from other neurons toward the cell body. -The axon ends in a series of small swellings called axon terminals, located some distance from the cell body. -Neurons may have dozens of dendrites but usually have only one axon. -In most animals, axons and dendrites are clustered into bundles of fibers called nerves. -Some nerves contain only a few neurons, but many others have hundreds or even thousands of neurons -The myelin sheath that surrounds a single long axon leaves many gaps, called nodes, where the axon membrane is exposed. As an impulse moves along the axon, it jumps from one node to the next, which increases the speed at which the impulse can travel.

Cells

-Specialized cells are uniquely suited to perform a particular function. -A cell is the basic unit of structure and function in living things. -Individual cells in multicellular organisms tend to be specialized

Resting Neuron

-The electrical charge across the cell membrane of a neuron in its resting state is known as the resting potential of the neuron. -When a neuron is resting, the outside of the cell has a net positive charge, and the inside of the cell has a net negative charge. -The cell membrane is said to be electrically charged because there is a difference in electrical charge between its outer and inner surfaces. -Some of the differences come from the selective permeability of the membrane. Most of the differences, however, are the result of active transport of ions across the cell membrane. -The sodium-potassium pump in the neuron cell membrane uses the energy of ATP to pump Na+ out of the cell and, at the same time, to pump K+ in. This ongoing process maintains resting potential.

Synapse

-The location at which a neuron can transfer an impulse to another cell is called a synapse. -Neurotransmitters are chemicals used by a neuron to transmit an impulse across a synapse to another cell. -When an impulse reaches the end of the axon of one neuron, neurotransmitters are released into the synaptic cleft. The neurotransmitters bind to receptors on the membrane of an adjacent. -This stimulus causes positive sodium ions to rush across the cell membrane, stimulating the second cell. If the stimulation exceeds the cells threshold, a new impulse begins.

Threshold

-The minimum level of a stimulus that is required to activate a neuron is called the threshold. -The strength of an impulse in response to a stimulus or there is not. -Any stimulus that is stronger than the threshold will produce an impulse. Any stimulus that is weaker than the threshold will produce no impulse. -Thus, a nerve impulse follows the all-or-nothing principle: either the stimulus will produce an impulse, or it will not produce an impulse.