A Presentation by:Timothy Dominguez Nathan Maglasang Jose Mari Mendoza
What is the Nervous System? A very complex system Organ System that contain neurons Divided into two parts: Central Nervous System (CNS) Brain and Spinal Cord Peripheral Nervous System (PNS) Nerves and Ganglia
The CNS consists of the Brain and the Spinal Cord The brain plays a central role in the control of most bodily functions, that include: Awareness • Thoughts Movements • Speech Sensations • Memory Some reflex movements can occur via spinal cord pathways without the participation of brain structures.
Cerebrum - is the largest part of the brain and controls voluntary actions, speech, senses, thought, an d memory. Frontal Lobes - located in the front of the brain and are responsible for voluntary movement and, via their connections with other lobes, participate in the execution of sequential tasks; speech output; organizational skills; and certain aspects of behavior, mood, and memory. Parietal Lobes – processes sensory information such as temperature, pain, taste, and touch. Temporal Lobes - processes memory and auditory (hearing) information and speech and language functions. Occipital Lobes - receives and processes visual information.
The central structures of the brain include the thalamus, hypothalamus, and pituitary gland. Thalamus - integrates and relays sensory information to the cortex of the parietal, temporal, and occipital lobes. Hypothalamus - located below the thalamus, regulates automatic functions such as appetite, thirst, and body temperature. Pituitary Gland - regulates the production of many hormones that have a role in growth, metabolism, sexual response, fluid and mineral balance, and the stress response.
Midbrain - located below the hypothalamus. Some cranial nerves that are also responsible for eye muscle control exit the midbrain. Pons - serves as a bridge between the midbrain and the medulla oblongata. The pons also contains the nuclei and fibers of nerves that serve eye muscle control, facial muscle strength, and other functions. Medulla Oblongota - the lowest part of the brainstem and is interconnected with the cervical spinal cord. The medulla oblongata also helps control involuntary actions, including vital processes, such as heart rate, blood pressure, and respiration, and it carries the corticospinal (that is, motor function) tract toward the spinal cord.
Amygdala - The amygdala is an almond-shape set of neurons located deep in the brains medial temporal lobe.For processsing of emotions, the amygdala forms part of the limbic system.For fear responses and pleasure.Hippocampus - the part of the brain that is involved in memory forming, organizing, and storing. forming new memories and connecting emotions and senses, such as smell and sound, to memories. acts as a memory indexer for long-term storage and retrieving them when necessary.
Brocas area – For Language comprehension,action recognition and production, and speech-associated gesturesWernickes area - It is involved in the understanding of written and spoken language.
The spinal cord is an extension of the brain and is surrounded by the vertebral bodies that form the spinal column Within the spinal cord are 30 segments that belong to 4 sections (cervical, thoracic, lumbar, sacral), based on their location: Eight cervical segments: These transmit signals from or to areas of the head, neck, shoulders, arms, and hands. Twelve thoracic segments: These transmit signals from or to part of the arms and the anterior and posterior chest and abdominal areas. Five lumbar segments: These transmit signals from or to the legs and feet and some pelvic organs. Five sacral segments: These transmit signals from or to the lower back and buttocks, pelvic organs and genital areas, and some areas in the legs and feet. A coccygeal remnant is located at the bottom of the spinal cord.
Peripheral Nervous System DivisionsThe peripheral nervous system is divided into the following sections:Peripheral Nervous System Sensory Nervous System - sends information to the CNS from internal organs or from external stimuli. Motor Nervous System - carries information from the CNS to organs, muscles, and glands. Somatic Nervous System - controls skeletal muscle as well as external sensory organs. Autonomic Nervous System - controls involuntary muscles, such as smooth and cardiac muscle. Sympathetic - controls activities that increase energy expenditures. Parasympathetic - controls activities that conserve energy expenditures.
Peripheral Nervous System Connections Peripheral nervous system connections with various organs and structures of the body are established through cranial nerves and spinal nerves. There are 12 pairs of cranial nerves in the brain that establish connections in the head and upper body, while 31 pairs of spinal nerves do the same for the rest of the body.
Neurons are nerve cells that transmit nerve signals to and from the brain DIFFERENT TYPES OF NEURONS Sensory neurons or Bipolar neurons carry messages from the bodys sense receptors (eyes, ears, etc.) to the CNS. Motoneurons or Multipolar neurons carry signals from the CNS to the muscles and glands. Interneurons or Pseudopolare (Spelling) cells form all the neural wiring within the CNS. These have two axons (instead of an axon and a dendrite). One axon communicates with the spinal cord; one with either the skin or muscle.
Neurotransmitters are the chemicals which allow the transmission of signals from one neuron to the next across synapses.Acetylcholine: Associated with memory, muscle contractions, and learning.Endorphins: Associated with emotions and pain perception. The body releases endorphins in response to fear or traumaDopamine: Associated with thought and pleasurable feelings.
Glial cells make up 90 percent of the brains cells. Glial cells are nerve cells that dont carry nerve impulses. The various glial cells perform many important functions, including: digestion of parts of dead neurons, manufacturing myelin for neurons, providing physical and nutritional support for neurons, and more.
Microglia are special immune cells found only in the brain that can detect damaged or unhealthy neurons. Astrocytes are star-shaped glia that hold neurons in place, get nutrients to them, and digest parts of dead neurons. Oligodendrocytes are cells that coat axons in the central nervous system with their cell membrane forming a specialized membrane differentiation called myelin, producing the so-called myelin sheath. Schwann cells are involved in many important aspects of peripheral nerve biology - the conduction of nervous impulses along axons, nerve development and regeneration, trophic support for neurons, production of the nerve extracellular matrix,and modulation of neuromuscular synaptic activity
STEPS: a.) In order to transmit a signal between two neurons, an electrical impulse must be communicated over a synapse. b.) When an action potential begins in a neuron, it travels down the axon.
c.) When the action potential reaches the axonterminal, calcium channels open, and calcium ionsrush into neurons.d.) The neuron makes and stores neurotransmitter inventricles.e.) When calcium bind to ventricles, the vesicles carrytransmitter toward the presynaptic membrane.
f.) When the vesicles contact the axon terminalmembrane, the neurotransmitter is released into thesynaptic cleft.g.) Neurotransmitter diffuses across the synaptic cleftand binds to receptors on the postsynaptic neuron.h.) The postsynaptic neuron receptors are activated. Inthis case, these receptors allow Sodium in the neuronby facilitated diffusion, causing an action potential tostart in the postsynaptic membrane.
i.) Neurotransmitters are released from receptors anddiffuse back into the synaptic cleft.j.) Vesicles recycle some neurotransmitter to preparethe neuron for its next action potential.
Calcium Ions – a factor in the clotting of blood. Presynaptic membrane - The part of the cell membrane of an axon terminal that faces the cell membrane of the neuron or muscle fiber with which the axon terminal establishes a synapse. Postsynaptic membrane - The part of the cell membrane of a neuron or muscle fiber with which an axon terminal forms a synapse.
Synaptic cleft - a narrow extracellular cleft between the presynaptic and postsynaptic membranes. Axon - a process of a neuron that conducts impulses away from the cell body. Axons are usually long and straight.
During a thunderstorm, Luigi Galvani touched a frog’s leg with a metal instrument and noticed the muscles twitching. His conclusion was nerves do transmit impulses from one part of the body to another, but in a different way than in an ordinary conductor. The electrical properties are different in neural conduction because it is slower and does not vary in strength
There is an excess of negative ions inside the cell membrane and an excess of positive ions outside Potassium(K+) , sodium ions(Na+), chloride(Cl--) Nerve cells use both passive diffusion and active transport to maintain these differentials across their cell membranes. Specialized proteins embedded in the nerve cell membrane function as voltage-dependant channels, passing through Na+ and K+ during nerve impulse transmission.
If a physical or chemical stimulus is strong enough to cause depolarization from the resting potential of 70 mV to around 50 mV, the voltage-dependant Na+ transmembrane channels open. The influx of Na+ causes a local reversal of electric polarity of the membrane, changing the electric potential to about +40 mV
The sodium ions(Na+) channels then close again. The movement of K+ ions and slower action of the Na+- K+ pump soon restore concentration differentials and electric gradient to the resting state. The transient change in the electric potential across the membrane is the action potential. After depolarization, for a brief period (milliseconds), the Na+ channels cannot be stimulated. This is called the refractory period.
The local depolarization at the site of the original stimulus causes passive diffusion of ions into areas adjacent to the site of the stimulus. Because of the refractory period, the nerve impulse can only be propagated in one direction, away from the nerve cell body towards the terminal branches, to release neurotransmitter substances. The myelin sheath is a good insulator, so ions cannot flow through it.
*Arma TYG, Arma Nate, Arma Joey MARAMINGSALAMAT, SALAMAT, SALAMAT, SALAMAT, SALAMA T, SALAMATPhouewsszz… ARMA GOOD DAY!!!