Chapter 7:6 The Nervous System

Key Terms Autonomic Nervous System Brain Central Nervous System Cerebellum Cerebrospinal Fluid Cerebrum Diencephalon Hypothalamus Medulla Oblongata Meninges Midbrain Nerves Nervous System Neuron Parasympathetic Peripheral Nervous System Pons Somatic Nervous System Spinal Cord Sympathetic Thalamus Ventricles

The Nervous System Neuron (nerve cell) – the basic structural unit of the nervous system Consists of: Cell body (soma) – contains the nucleus Dendrites – nerve fibers (carries impulses towards the cell body) Axon – single nerve fiber (carries impulses away from the cell body)

The Nervous System (Axons) Many axons have a lipid covering called a myelin sheath Increases the rate of impulse transmission Insulates and maintains the axon The axon of one neuron lies close to the dendrites of other neurons Synapses – the spaces between one neuron and the dendrites of another Impulses “jump” the synapses to reach the next dendrite Neurotransmitters (a special chemical) are located at the end of each axon

Draw and Label Your Own Neuron To Label: Axon Cell Body (Soma) Dendrites Myelin Sheath Terminal Branches

Central Nervous System (brain and spinal cord) Main Structures of the brain: Cerebrum – the largest and highest section of the brain Responsible for reasoning, thought, memory, judgment, speech, sensation, sight, smell, hearing, and voluntary body movements Cerebellum – section below the back of the cerebrum Responsible for muscle coordination, balance, posture, and muscle tone

Central Nervous System (brain and spinal cord) Main Structures of the brain: Diencephalon – section located between the cerebrum and midbrain, contains the thalamus and hypothalamus Thalamus – allows conscious recognition of pain and temperature Hypothalamus – regulates and controls the ANS, temperature, appetite, water balance, sleep, and blood vessel dilation and constriction. Also involved in emotions.

Central Nervous System (brain and spinal cord) Main parts of the brain: Midbrain – located below the cerebrum at the top of the brainstem Conducts impulses for certain eye and auditory reflexes Pons – located below the midbrain and in the brainstem Responsible for certain reflex actions such as chewing, tasting, and saliva production; also helps with respiration Medulla Oblongata – lowest part of the brainstem Responsible for regulating heartbeat, respiration, swallowing, coughing, and blood pressure

Draw and Label Your Own Brain To Label: Cerebellum Cerebrum Frontal Lobe Medulla Oblongata Midbrain Occipital Lobe Parietal Lobe Pons Temporal Lobe

Central Nervous System (brain and spinal cord) Continues down from the medulla oblongata and ends at the first or second lumbar vertebrae Meninges – cover and protect the brain and spinal cord Dura Mater – thick, tough, outer layer Arachnoid Membrane – middle layer that is delicate and weblike Subarachnoid Space – contains cerebrospinal fluid Pia Mater – innermost layer that is closely attached to the brain and spinal cord – provides nourishment to the nerve tissue

Peripheral Nervous System Consists of: Somatic Nervous System: 12 pairs of cranial nerves Some cranial nerves are responsible for special senses Other cranial nerves receive general sensations such as touch, pressure, pain, and temperature 31 pairs of spinal nerves Carry messages to and from the spinal cord Each nerve goes directly to a particular part of the body

Peripheral Nervous System Consists of: 2. Autonomic Nervous System Helps to maintain a balance in the involuntary functions of the body Allows the body to react in times of emergency 1. Sympathetic Nervous System Fight or flight response (increasing heart rate, respiration, and blood pressure, slow the digestive system 2. Parasympathetic Nervous System After the emergency, it returns the body to normal