Nervous System Term 2 - 04 PDF

INTRODUCTION OF NERVOUS SYSTEM  NERVOUS SYSTEM The Nervous System has three important functions. It receives information from the environment and inside the body. It interprets the information it receives. It makes the body respond to the information.  NERVOUS SYSTEM CEN...

INTRODUCTION OF NERVOUS SYSTEM  NERVOUS SYSTEM The Nervous System has three important functions. It receives information from the environment and inside the body. It interprets the information it receives. It makes the body respond to the information.  NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM BRAIN SPINAL CORD PERIPHERAL NERVOUS SYSTEM NERVES CENTRAL NERVOUS SYSTEM BRAIN - SPINAL CORD  CENTRAL NERVOUS SYSTEM The Central Nervous System (CNS) – consists of the brain and the spinal cord. It receives and sorts out information coming from the environment and from inside the body and determines the appropriate action.  BRAIN FOREBRAIN - MIDBRAIN - HINDBRAIN  BRAIN It is one of the largest organs in the body, and coordinates most body activities. It is the center for all thought, memory, judgment, and emotion. Each part of the brain is responsible for controlling different body functions, such as temperature regulation and breathing.  SECTIONS OF THE BRAIN FOREBRAIN MIDBRAIN HINDBRAIN  BRAIN: FOREBRAIN CEREBRUM - CORTEX - THALAMUS - HYPOTHALAMUS  BRAIN: FOREBRAIN COMPOSED OF: CEREBRUM CORTEX THALAMUS HYPOTHALAMUS  BRAIN: FOREBRAIN - CEREBRUM It is the largest section of the brain It is located in the upper portion of the brain and is the area that processes thoughts, judgment, memory, problem solving, and language. The outer layer of the cerebrum is the cerebral cortex, which is composed of folds of gray matter.  BRAIN: FOREBRAIN - CEREBRUM The cerebrum is subdivided into the left and right halves called cerebral hemispheres. Each hemisphere has 4 lobes. The left hemisphere is considered the logical, analytical, and objective side. The right hemisphere is thought to be more intuitive, creative, and subjective. So when you are adding numbers you are using the left side, when you are listening to music, you are using the right side. LOBES OF CEREBRUM  LOBES OF CEREBRUM Frontal lobe: Most anterior portion of the cerebrum, controls motor function, personality, and speech Parietal lobe: The most superior portion of the cerebrum, receives and interprets nerve impulses from sensory receptors and interprets language.  LOBES OF CEREBRUM Occipital lobe: The most posterior portion of the cerebrum, controls vision. Temporal lobe: The left and right lateral portion of the cerebrum, controls hearing and smell  BRAIN: FOREBRAIN - CORTEX It is also known as “gray matter”. The outer layer of the cerebrum Information collected by the five senses comes into the brain from the spinal cord to the cortex. This information is then directed to other parts of the nervous system for further processing. For example, when you touch the hot stove, not only does a message go out to move your hand but one also goes to another part of the brain to help you remember what to avoid.  BRAIN: FOREBRAIN - THALAMUS The thalamus carries messages from the sensory organs like the eyes, ears, nose, and fingers to the cortex.  BRAIN: HYPOTHALAMUS The hypothalamus controls processes in our bodies that happen automatically, the pulse, thirst, appetite, sleep patterns, and others.  BRAIN: FOREBRAIN - HYPOTHALAMUS It also controls the pituitary gland, which produces the hormones that control metabolism, digestion, growth, sexual Pituitary Gland maturity, and response BRAIN: MIDBRAIN  BRAIN: MIDBRAIN The Midbrain – is located underneath the middle of the forebrain. It acts as coordinator for all the messages going in and out of the brain to the spinal cord.  BRAIN: HINDBRAIN CEREBELLUM - BRAIN STEM (MEDULLA OBLONGATA & PONS)  BRAIN: HINDBRAIN Located underneath the back end of the cerebrum Consists of the ○ cerebellum ○ pons ○ medulla oblongata  BRAIN: HINDBRAIN - CEREBELLUM Second largest portion of the brain Located beneath the posterior part of the cerebrum Aids in coordinating voluntary body movements and maintaining balance and equilibrium Refines the muscular movement that is initiated in the cerebrum  BRAIN: HINDBRAIN - BRAINSTEM The pons is the largest part of the brainstem, located above the medulla and below the midbrain. It is a group of nerves that function as a connection between the cerebrum and cerebellum (pons is Latin for bridge). The medulla oblongata plays a critical role in transmitting signals between the spinal cord and the higher parts of the brain and in Pons controlling autonomic activities, such as heartbeat and respiration. Medulla Oblongata  BRAIN: HINDBRAIN - BRAINSTEM It sends out and coordinates all of the brain’s messages. It also controls many of the body’s automatic functions like breathing, heart rate, blood pressure, swallowing, Pons digestion, and blinking. Medulla Oblongata  SPINAL CORD CERVICAL - THORACIC - LUMBAR - SACRAL - COCCYGEAL  SPINAL CORD Functions of the Spinal Cord: The spinal cord is the link between the peripheral nervous system and the brain. It serves as the pathway of information to and from the brain.  SPINAL CORD It handles some information coming from the senses and provides motor responses that do not come from the brain. This is called a reflex action.  SPINAL CORD Regions ○ Cervical (7) ○ Thoracic (12) ○ Lumbar (5) ○ Sacral (4) ○ Coccygeal (4) Gives rise to 31 pairs of spinal nerves - all are mixed nerves in 33 pieces of spinal column.  CENTRAL NERVOUS SYSTEM BRAIN SPINAL CORD CERVICAL THORACIC FOREBRAIN MIDBRAIN HINDBRAIN LUMBAR CEREBRUM CEREBELLUM SACRAL CORTEX BRAINSTEM COCCYGEAL THALAMUS PITUITARY PONS MEDULLA HYPOTHALAMUS GLAND MENINGES  MENINGES The meninges refer to the membranous coverings of the brain and spinal cord. There are three layers of meninges, known as the dura mater, arachnoid mater and pia mater. These coverings have two major functions: Provide a supportive framework for the cerebral and cranial vasculature.  MENINGES Dura mater: outermost layer; continuous with epineurium of the spinal nerves Arachnoid mater: thin and wispy Pia mater: bound tightly to surface SULCI & GYRI  SULCI & GYRI The grooves that make these wrinkles are called sulci and the ridges between them are called gyri. Gyri (Gyrus; singular) – elevated ridges of tissue that surround the entire cerebral hemisphere. Sulci (Sulcus; singular) – is a depression or groove in the cerebral cortex. FISSURE  FISSURE A fissure (Latin fissura, plural fissurae) is a groove, natural division, deep furrow, elongated cleft, or tear in various parts of the body also generally called a sulcus, or in the brain a sulcus.  FISSURE The sulci and fissures are both grooves in the cortex but they are differentiated by size. A sulcus is a shallower groove that surrounds a gyrus. A fissure is a large furrow that divides the brain into lobes, and also into the two hemispheres as the medial longitudinal fissure does. CEREBROSPINAL FLUID  CEREBROSPINAL FLUID Cebrospinal fluid (CSF), clear, colourless liquid that fills and surrounds the brain clear, colourless liquid that fills and surrounds the brain and the spinal cord and provides a mechanical barrier against shock. Formed primarily in the choroid plexus of the ventricles of the brain  CEREBROSPINAL FLUID CHOROID PLEXUS - network of blood vessels in each ventricle of the brain. It is derived from the pia mater and produces the cerebrospinal fluid. The term is derived from the Greek words “khorion” meaning “membrane enclosing the fetus” and “plexus” referring to “network”. PERIPHERAL NERVOUS SYSTEM SOMATIC NS - AUTONOMIC NS  PERIPHERAL NERVOUS SYSTEM The peripheral nervous system (PNS) is the division of the nervous system containing all the nerves that lie outside of the central nervous system (CNS). Primary role: to connect the CNS to the organs, limbs and skin. These nerves extend from the central nervous system to the outermost areas of the body.  PERIPHERAL NERVOUS SYSTEM The functional classification scheme is concerned only with PNS structures. It divides them into two principal subdivisions. ○ Sensory or afferent division ○ Motor or efferent division SENSORY /AFFERENT  SENSORY/AFFERENT Consists of nerve fibers that convey impulses to the central nervous system from sensory receptors located in various parts of the body. MOTOR/EFFERENT  MOTOR/EFFERENT Carries impulses from CNS to effector organs, the muscle and glands. These impulses activate muscles and glands that is they cause a motor response.  PERIPHERAL NERVOUS SYSTEM SOMATIC NERVOUS SYSTEM  SOMATIC NERVOUS SYSTEM The part of the peripheral nervous system responsible for carrying sensory and motor information to and from the central nervous system. derives its name from the Greek word soma, which means “body“  SOMATIC NERVOUS SYSTEM It contains two major neurons responsible for transmitting sensory information as well as for voluntary movement. Types of neurons: ○ sensory neurons (or afferent neurons) - carry information from the nerves to the central nervous system ○ motor neurons (or efferent neurons) - that carry information from the brain and spinal cord to muscle fibers throughout the body.  PERIPHERAL NERVOUS SYSTEM AUTONOMIC NERVOUS SYSTEM SYMPATHETIC - PARASYMPATHETIC  AUTONOMIC NERVOUS SYSTEM is the part of the peripheral nervous system responsible for regulating involuntary body functions, such as blood flow, heartbeat, digestion and breathing. further divided into two branches: ○ sympathetic system regulates the flight-or-fight responses ○ parasympathetic system helps maintain normal body functions and conserves physical resources. SYMPHATETIC  SYMPATHETIC The sympathetic nervous system is located to the sympathetic chain, which connects to skin, blood vessels and organs in the body cavity. The sympathetic chain is located on both sides of the spine and consists of ganglias.  SYMPATHETIC stimulates heartbeat raises blood pressure dilates the pupils dilates the trachea and bronchi stimulates glycogenolysis — the conversion of liver glycogen into glucose  SYMPATHETIC shunts blood away from the skin and viscera to the skeletal muscles, brain, and heart inhibits peristalsis in the gastrointestinal (GI) tract inhibits contraction of the bladder and rectum and, at least in rats and mice, increases the number of AMPA receptors in the hippocampus and thus increases long-term potentiation (LTP). PARASYMPHATETIC  PARASYMPATHETIC Parasympathetic system is the branch of the Autonomic Nervous System (ANS) responsible for the body’s ability to recuperate and return to a balanced state (known as "homeostasis") after experiencing pain or stress.  PARASYMPATHETIC Parasympathetic stimulation slowing down of the heartbeat (as Loewi demonstrated) lowering of blood pressure constriction of the pupils increased blood flow to the skin and viscera peristalsis of the GI tract  PERIPHERAL NERVOUS SYSTEM MOTOR NEURONS SENSORY NEURONS SOMATIC NERVOUS AUTONOMIC NERVOUS SOMATIC SENSORY VICERAL SENSORY SYSTEM SYSTEM SYMPATHETIC PARASYMPATHETIC DIVISION DIVISION SPINAL NERVES  SPINAL NERVES Spinal nerves or nerve roots, branch off the spinal cord and pass out through a hole in each of the vertebrae called the Foramen. These nerves carry information from the spinal cord to the rest of the body, and from the body back up to the brain. CRANIAL NERVES  CRANIAL NERVES Nerves that emerge directly from the brain, in contrast to spinal nerves, which emerge from segments of the spinal cord. In humans, there are traditionally twelve pairs of cranial nerves. Only the first and the second pair emerge from the cerebrum; the remaining ten pairs emerge from the brainstem.  CRANIAL NERVES SENSORY NERVES MOTOR NERVES MIXED NERVES CN I (olfactory) INNERVATES THE EYE CN V (trigeminal) MUSCLES CN II (optic) CN VII (facial) CN III (oculomotor) CN VIII CN IX CN IV (trochlear) (vestibulocochlear) (glossopharyngeal) CN VI (abducens) CN X (vagus) INNERVATES THE TONGUE CN XI (accessory) CN XII (hypoglossal) CRANIAL NERVES  CRANIAL NERVES Nerves Type Function I. Olfactory sensory olfaction (smell) II. Optic sensory vision (Contain 38% of all the axons connecting to the brain.) III. Oculomotor motor* eyelid and eyeball muscles IV. Trochlear motor* eyeball muscles Sensory: facial and mouth sensation V. Trigeminal mixed Motor: chewing VI. Abducens motor* eyeball movement Sensory: taste VII. Facial mixed Motor: facial muscles and salivary glands VIII. Auditory sensory hearing and balance Sensory: taste IX. Glossopharyngeal mixed Motor: swallowing X. Vagus mixed main nerve of the parasympathetic nervous system (PNS) XI. Accessory motor swallowing; moving head and shoulder XII. Hypoglossal motor* tongue muscles NERVE CELLS  NERVE CELLS Nerve cells also known as a neurons, are the active component of the nervous system. Neurons communicate with each other as well as with other cells through electric signals (nerve impulses), which in turn allows effector organs to respond to the appropriate stimuli.  NERVE CELLS Axon An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma. Take information away from the cell body Have a smooth surface Only one axon per cell No ribosome Have myelin  NERVE CELLS Dendrites These structures branch out in treelike fashion and serve as the main apparatus for receiving signals from other nerve cells. They function as an "antennae" of the neuron. Bring information to the cell body Have a rough surface Many dendrites per cell Have ribosome No myelin Branch near the cell body NERVE CELLS NERVE CELLS  SYNAPSES Synapse, also called neuronal junction, the site of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector). A synaptic connection between a neuron and a muscle cell is called a neuromuscular junction NEXT TOPIC: SKELETAL SYSTEM