The Nervous System Chapter 29.4

Key Vocabulary Cerebrum- the part of the brain that interprets signals from your body and forms responses, such as hunger, thirst, emotions, motion, and pain. Cerebral Cortex- Outer layer of the cerebrum that interprets information from your sensory organs and generates responses. Cerebellum- the part of the brain that coordinates your movements.

Key Vocabulary Brain Stem- connects the brain to the spinal cord and controls the most basic activities required for life, such as breathing, and heartbeat. Reflex Arc- nerve pathways that need to cross only 2 synapses before producing a response. Somatic Nervous System-the division of the PNS that regulates all of the movements over which you have voluntary control. Autonomic Nervous System- the division of the PNS that controls automatic functions that you do not have to think about.

Key Vocabulary Sympathetic Nervous System- the part of the autonomic nervous system that prepares the body for action and stress. Parasympathetic Nervous System- the division of the autonomic nervous system that calms the body and helps the body to conserve energy.

The Nervous System Divided into 2 parts: Central Nervous System (CNS) Peripheral Nervous System (PNS) CNS includes the brain and spinal cord Receives, interprets, and sends signals to the PNS Made up of interneurons

The Nervous System The PNS is the collection of nerves that connects the CNS to all of your organ systems. Uses sensory neurons and motor neurons

Central Nervous System Neurons are grouped a certain way. All of the neuron cell bodies are grouped together and called gray matter. The collection of axons is called white matter. In the brain the gray matter is on the outside and the white matter is on the inside. The spinal cord has this reversed.

Central Nervous System The brain has 3 layers of connective tissue called meninges. Between the meninges is fluid that helps to cushion the brain, cerebrospinal fluid (CSF)

Central Nervous System Brain has 3 main structures: Cerebrum Cerebellum Brainstem Cerebrum has right and left halves or hemispheres. Each hemisphere controls the opposite side of the body. Corpus Callosum is a thick band of nerves that connects the 2 hemispheres and allows for the crossing over.

Central Nervous System The outer layer of the cerebrum is the cerebral cortex. It’s not very thick but the folds give it an increased surface area. All stretched out it would cover your desk. Cerebral cortex is divided into lobes based on function.

Central Nervous System

Central Nervous System Under the cerebral cortex are many more important features: Limbic system: learning and emotions Thalamus: sorts signals from sensory organs Hypothalamus: gathers information about temperature, hunger, and thirst.

Central Nervous System Cerebellum coordinates your movements. Helps you maintain posture and balance Automatically adjusts body to help you move smoothly

Central Nervous System Brain stem controls basic activities for life. Has 3 major parts: Midbrain: controls reflexes Pons: regulates breathing and passes signals from brain to spinal cord Medulla Oblongata: connects brain to spinal cord and controls basic life-sustaining functions like heart function, vomiting, swallowing, and coughing.

Central Nervous System Spinal column contains vertebrae, CSF, meninges, and the spinal cord. Spinal cord is as wide as your thumb. Connects brain to nerves Delivers messages to the right muscles Damaged=paralysis

Central Nervous System Spinal Cord also controls involuntary movements called reflexes. Reflexes happen so fast because the signal never has to travel all the way up to the brain and back.

Peripheral Nervous System PNS has 12 pairs of nerves in the head and 31pairs of spinal nerves. PNS is made up of a sensory system and a motor system. Sensory system collects information about the body and it’s environment. System of motor nerves triggers voluntary and involuntary responses within the body.

Peripheral Nervous System The somatic nervous system is the reason why when you run, walk, and sit you can maintain your posture, balance, and movement. Connects the CNS to target organs.

Peripheral Nervous System Autonomic nervous system controls things that you don’t think about, like moving food along your intestines. It’s also key to maintaining homeostasis. It has 2 subdivisions: Sympathetic- fight or flight Parasympathetic- relaxation/ rest and digest