anatomy and physiology module 3

• central nervous system includes brain and spinal cord
• meninges is a 3-layered section of connective tissue, blood vessels, and spinal fluids
• cerebrospinal fluid is a fluid that circulated through spaces in the meninges. it spreads the force of an impact over large areas to protect the cns
• the 3 layers of the meninges are the dura mater, arachnoid mater, and pia mater
• dura mater is closest to the bone and made of tough connective tissue
• arachnoid mater is the middle layer and has a netlike membrane. it includes subarachnoid space that contains cerebrospinal fluid
• pia mater is attached to the surface of the cns. it supports and nourishes the underlying layers of brain and spinal cord.
• the spinal cord consists of white matter and grey matter
• white matter is made up of bundles of nerve fibers
• white matter covers the outside of the spinal cord and parts of the brain
• white matter is covered in a fatty protein called myelin
• grey matter is the inner material of the brain and spinal cord
• grey matter is made of cell bodies of neurons and interneurons
• grey matter is grey due to the absence of myelin coverings
• The nervous system, made up of the central nervous system and the peripheral nervous system, controls everything you do, including breathing, walking, thinking, and feeling.
• The peripheral nervous system is responsible for sending information to and from the brain and spinal cord.
• The sensory somatic nervous system, or SNS, is a voluntary system that interprets signals received from all your senses and responds to them.
• The autonomic nervous system, or ANS, is an involuntary system that acts without our conscious control and is responsible for making sure that all the things your body needs to do to keep you going, like breathing and digestion, continue to work without your having to think about them.
• The autonomic nervous system is also divided into two divisions: the sympathetic, “fight or flight,” and the parasympathetic, “rest and digest,” nervous systems.
• In situations like an angry bear popping out of the brush, the sympathetic nervous system is called into action, using energy and increasing blood pressure and heartbeat to prepare the body for emergencies or crises.
• The parasympathetic nervous system returns the body back to normal after a stressful situation, slowing the heart rate and digestion, and conserving energy.
• Without a nervous system to organize things like movement, body temperature, blood flow, learning, and memory, the body would be in chaos, with each organ system acting independently of the other.
• Sensory (afferent) nerves are fibers that convey messages toward the central nervous system.
• Motor (efferent) nerves carry impulses away from the CNS to effectors such as muscles and glands.
• Mixed nerves are fibers that can send and receive signals for the PNS
• The spinal cord is part of the central nervous system and has two important jobs: it coordinates our reflexes and it transfers messages between the brain and the body.
• When a quick reaction is necessary, the body may rely on reflexes.
• A reflex action of the spinal cord reduces the time it takes for a response.
• The "my hand is on fire" signal arrives at the spinal cord, is quickly processed, and the "get my hand out of the fire" response is sent to the muscles to remove the hand from the flame.
• The spinal cord starts at the base of the cranium, at the occipital bone, runs through the central canal of the vertebrae, and ends between the first and second lumbar vertebrae.
• There are thirty-one pairs of spinal nerves that leave the spinal cord and move out to the body.
• The spinal nerves are part of the peripheral nervous system and are divided into five regions: the cervical nerves, thoracic nerves, lumbar nerves, sacral nerves, and the coccygeal nerve.
• Spinal nerves are numbered from 1 to 31, with C1 being the first cervical nerve and C31 being the last cervical nerve.
• Spinal nerves are also referred to as cervical nerves.
• The spinal cord is divided into 31 sections, each corresponding to a specific spinal nerve.
• The spinal cord is also referred to as the central nervous system.
• The spinal cord is located in the midline of the back, between the top of the thoracic vertebrae and the bottom of the skull.
• The spinal cord is surrounded by three layers of meninges: the dura mater, the arachnoid, and the pia mater.
• The spinal cord is composed of structures such as interneurons, which can move signals in both directions and are only found in the central nervous system.
• The dura mater is the toughest layer of the meninges and is located closest to the spinal cord.