Lesson 4: The Human Nervous System PDF

Lesson 4: The Human Nervous System The Nervous System  Question What is your idea about the nervous system? Nervous System Functions 1. controls all body functions 2. monitors internal and external stimuli 3. maintain homeostasis 4. mental activities  men...

Lesson 4: The Human Nervous System The Nervous System  Question What is your idea about the nervous system? Nervous System Functions 1. controls all body functions 2. monitors internal and external stimuli 3. maintain homeostasis 4. mental activities  mental activities Consciousness Memory Thinking  Nervous Response Stimulus: a thing or event that evokes a specific functional reaction in an organ. Response: any action resulting from a stimulus.  ANATOMY and PHYSIOLOGY of NERVES Neurons- conducting cells Neuroglia- supportive cells Parts of Neurons Cell body – the largest part containing nucleus and cytoplasm Dendrites - short, branched extensions spreading out from the cell body and they carry impulses from the environment or other neurons towards the cell body Axon - long fibers that carry impulses away from the cell body and end at the axon terminal Myelin sheath - It insulates the axons by surrounding it.  Dendrites Cell Body Axon Passes electrical Integrates incoming signals Collect electrical signals to dendrites of and generates outgoing signal signals to the axon another cell A synapse is a tiny gap across which a nerve cell, or neuron, can send an impulse to another neuron.  Classification of Neurons Neurons can be classified based on function or by structure. Structure: (1) Multipolar Many processes arising from cell body Brain or spinal cord (2) Bipolar 2 processes (1 from each end of cell body) Ear, eyes, nose (3) Unipolar Single process extends from cell body Outside of brain & spinal cord Affector A structure that sends or affects a signal. For example, a sensory cell in the skin or eye is an affector because it sends information to the central nervous system (CNS). Effector A structure that responds to or is affected by a signal. For example, a muscle or gland is an effector because it receives a signal from the CNS and responds by contracting or secreting a hormone  NEURON In the nervous system, afferent and efferent neurons work together to sense and respond to stimuli: Afferent neurons: Carry information from sensory receptors to the CNS. Efferent neurons: Carry motor information from the CNS to muscles and glands. Nervous System Central Peripheral Nervous Nervous System System Nervous System Central Nervous System  The central nervous system (CNS) is composed of the brain and spinal cord. The CNS is the control center of the body: –Relays messages –Processes information –Analyzes information  Brain and Spine Both are – protected by bone – wrapped in 3 layers of connective tissue = meninges – layers may have a space between them filled with cerebrospinal fluid which protects (shock absorber) Brain  Brain Major parts of the brain: Brainstem, Diancephalon, Cerebrum and Cerebellum  Brain Major parts of the brain: Brainstem, Diancephalon, Cerebrum and Cerebellum  Cerebrum- It is the largest part of the brain. It governs all the sensory and motor activities of the body. FOUR LOBES OF THE BRAIN  FOUR LOBES OF THE BRAIN The frontal lobe is located in the forward part of the brain, extending back to a fissure known as the central sulcus. The frontal lobe is involved in reasoning, motor control, emotion, language, and managing higher-level executive functions.  FOUR LOBES OF THE BRAIN The brain’s parietal lobe is located immediately behind the frontal lobe and is involved in processing information from the body’s senses. The temporal lobe is located on the side of the head and is associated with hearing, memory, emotion, and some aspects of language. The occipital lobe is located at the very back of the brain, and contains the primary visual cortex, which is responsible for interpreting incoming visual information.  Cerebellum- It is located beneath the back of part of the cerebrum. For voluntary movement and maintain balance Brainstem  Midbrain- controls the movement of the eye.  Medulla Oblongata- It controls breathing, heart rate and swallowing, temperature, and wake and sleep cycle. Cerebrum -The large upper region of the body. It consists of deep folds, which are divided into many ridges. Cerebellum -It is located beneath the back part of the cerebrum. It coordinates the muscle movement. - The master gland, It also releases growth hormones. Pituitary Glands Brain Stem -It is located below the cerebellum at the the base of the skull, which serves as the body`s life support system. Medulla -It controls breathing, heart rate and swallowing. Corpus Callosum - It is a broad band of nerve fibers joining the two hemispheres of the brain. Mid Brain -It is also linked to vision and controls the dilation of the pupil. Thalamus -It is responsible in processing the information from the sense organs. Hypothalamus -It links nervous system to endocrine system Review : Physiology of the Brain Brainstem 1. Medulla Oblongata 2. Pons Varolii 3. Midbrain Cerebellum Diencephalon 1. Hypothalamus 2. Thalamus Cerebrum Spinal Cord  Spinal Cord It carries information to and from the brain and to govern simple responses called reflexes. Peripheral Nervous System  Peripheral The peripheral nervous system (PNS) is made up of peripheral nerves that connect the CNS to the rest of the body. 12 pairs of cranial nerves- It carries impulses to and from the brain. 31 pairs of spinal nerves- It carries impulses to and from the spinal cord Peripheral-31 pairs of spinal nerves  Peripheral Nervous System Autonomic Somatic Nervous System Nervous System Sympathetic Parasympathetic Somatic It is responsible for actions that a person can control by the skeletal muscle. Examples: the blinking reflex, knee jerk reflex, gag reflex, and the startle reflex and rooting reflex in infants. Autonomic It controls autonomic functions which do not require a person to think. Ex: Involuntary muscles help to digest food, heartbeat and breathing  Autonomic division of the nervous system can be subdivided into 2 divisions: (1) Parasympathetic Is referred to as “rest and digest.” (2) Sympathetic Is referred to as “fight or flight”.  Autonomic division of the nervous system can be subdivided into 2 divisions: The division with opposing effects on most organs. (1) Parasympathetic – It helps the body to conserve energy (2) Sympathetic – Prepares the body for action and stress  Peripheral Nervous System Motor Sensory Somatic Autonomic Parasympathetic Sympathetic  General Functions of the Nervous System Sensory: gathers info about changes occurring within and around the body; sensory receptors, at ends of peripheral nerves, send signals to CNS examples – light, oxygen levels, body temperature Integrative: information is “brought together,” interpreted, to create sensations, create thoughts, add to memory, make decisions, etc. Motor: sending of signals to muscles and/or glands to elicit a response Bottom Line = Maintenance of Homeostasis  Keeping the Nervous System Healthy 1. Ensure adequate intake of healthy fats such as fish oil and vegetable oil. 2. Exercise the nervous system daily by stretching the arms and reading for the motor and sensory pathways used. 3. Spend a minimum of 15 minutes per day writing on paper legibly as you can. 4. Engage yourself in social activities to keep your brain active.