Communication and Control

Communication and Control Chapter 11 – Section 1  Central nervous system (CNS): the brain and the spinal cord. It responds to all the messages coming from the peripheral nervous system.  Peripheral Nervous system (PNS): all of the parts of the nervous system except for the brain and the spinal cord. It connects all parts of the body to the CNS.  Neuron: a nerve cell that is specialized to receive and conduct electrical impulses. Impulses can travel as fast as 150 m/s or as slow as 0.2 m/s.  Axons: elongated extensions of a neuron. Has a tip called the axon terminal. Information is sent from here.  Dendrite: short branched extensions. This is where impulses are received.  Synapse: empty space between neurons where messages are sent.  Two types of Neurons:  Sensory Neuron: nerves that gather information about what is happening in and around your body. Have special endings called receptors. Ex. touching something hot or moving from a dark room to a lighted room. They send information to the CNS.

Communication and Control Chapter 11 – Section 1  Motor Neurons: Sends impulses from the brain and spinal cord to other systems. Muscle contract when touching something hot or squinting when seeing something bright.  Nerve: a collection of nerve fibers (axons) through which impulses travel between the central nervous system and other part of the body. Most contain a collection of both motor and sensory neurons.  PNS has two types of nerves:  Somatic nervous system: most of the neurons that are under your conscious control. They control voluntary movements such as writing, talking, smiling or jumping.  Autonomic Nervous System: nerves that do not need your conscious control. They control body functions such as digestion and heart rate. Has two divisions.  Sympathetic Nervous System:  Parasympathetic Nervous System

Communication and Control Chapter 11 – Section 1  Brain: the mass of nerve tissue that is the main control center of the nervous system. Largest organ in the nervous system. Is responsible for voluntary and involuntary control. Has three main parts:  Cerebrum: largest part of your brain, where you think and where most memories are stored, controls voluntary movements and allow you to sense touch, light, sound, odors, taste, pain, heat and cold. Has two hemispheres:  Left: speaking, reading, writing, and problem solving. Math and science. Directs right side of body.  Right: spatial thinking, processing music, interpreting emotions, arts, and acting. Directs left side of body.  Cerebellum: 2 nd largest part of your brain. Allows the brain to keep track of your body position. Helps you to stay balanced.  Medulla: controls involuntary processes such as blood pressure, body temperature, heart rate, and involuntary breathing. You cannot live without it.  Areas of the brain at work: pg  Spinal cord: Part of the CNS and is the size of your thumb and surrounded by vertebrae.

Communication and Control Chapter 11 – Section 2  Integumentary system: the organ system that forms a protective covering on the outside of the body  Reflex: an involuntary and almost immediate movement in response to a stimulus. Message does not go to the brain.  Feedback mechanism: a cycle of events in which information from one step controls or affects a previous step.  Ex: heat receptors detect high temperatures, body becomes hot, message is sent for blood vessels to dilate, sweating begins and temperature of body is lowered.  Retina: the light-sensitive inner layer of the eye: it receives images formed by the lens and transmits them through the optic nerve to the brain

Communication and Control Chapter 11 – Section 2  Cochlea: a coiled tube that is found in the inner ear and that is essential to hearing  Hearing Parts:  Ear Canal  Eardrum  Ear bones  Cochlea  Auditory nerve

Communication and Control Chapter 11 – Section 3  Endocrine system: a collection of glands and groups of cells that secrete hormones that regulate growth, development, and homeostasis. This system uses chemicals.  Gland: a group of cells that make special chemicals for the body. They make hormones.  Hormone: a substance that is made in one cell or tissue and that causes a change in another cell or tissue in a different part of the body. Basically, chemical messengers.  Endocrine glands can affect many organs at one time. Fight or flight---adrenal glands release adrenaline.

Section 3  Pituitary gland: stimulates skeleton growth and helps your thyroid gland function properly. It also regulates the amount of water in your blood. About the size of a marble and found at the base of the cerebrum. It also releases HGH—controls how fast everything grows. Releases hormones that control all other glands. Referred to as the “master gland”.  Thyroid: determines the rate at which you use energy. It controls metabolism. Located in the upper chest and is butterfly shaped.  Pancreas: regulates blood-glucose levels. Makes insulin and glucagon. Insulin regulates blood-glucose levels by telling the liver to convert glucose into glycogen. Glucagon has the opposite effect. Has liver convert into glucose and to release the glucose into the blood. Diabetes mellitus-person does not make enough insulin. Found behind the stomach.  Thymus: regulates the immune system. Killer T Cells mature in the thymus. These cells destroy foreign invaders in your body.  Parathyroid: regulates phosphate and calcium levels in the blood. It is behind the thyroid and is pea- sized  Adrenal glands: helps you respond to danger. Produces adrenaline and found right above the kidneys. Can make more than 30 hormones.