THE NERVOUS SYSTEM A biological highway of information Can receive, send, and interpret information by electrical signals A complex network of nerve cells that regulates our bodily functions and permits us to reach to the external world It contains nerve cells or NEURONS
THE NERVOUS SYSTEM Neuron It is the base of the nervous system Its basic purpose is to receive information and send a signal to other neurons, muscles, or glands. It is a nerve cell It has a cell body, a very long axon sheathed in myelin, and dendrites.
THE NERVOUS SYSTEM Cell Body Also known as the Soma Is the bulbous end of the neuron It contains the cell nucleus It makes use of nutrients to supply energy for neuronal activity.
THE NERVOUS SYSTEM Axons These are long cytoplasmic tubes that carries electric impulses from one part of the body to another. They are insulated from each other by their myelin sheaths. May have branches called terminal buttons at its end.Myelin Sheath – the fatty insulating layer that surrounds many axons.
THE NERVOUS SYSTEM Dendrites These are tiny branches at the ends of all neurons Are organelles that sense the neurotransmitter secreted by the axon of another neuron Dendrites and axons do not directly touch each other; there is a gap, called a synapse.
THE NERVOUS SYSTEM 3 Types of Neurons Sensory Neurons (Afferent)– posses a long dendrite and short axon. They carry sensory receptors to the CNS. Motor Neurons (Efferent) – have long axon and short dendrites. They transmit messages to from the CNS to the muscles or the glands. Interneurons (Connector) – located only in the CNS where there is a neuron-to-neuron connection.
THE NERVOUS SYSTEM Neurotransmitters Chemicals, called neurotransmitters are released from one neuron at the presynaptic nerve terminal then they cross the synapse where they may be accepted by the next neuron at a specialized site called a receptor
THE NERVOUS SYSTEM Examples of Neurotransmitters Acetylcholine – fecilitates learning and memory Norepinephrine or Noradrenaline – too little may lead to depression; too much causes hyperactivity Dopamine – too much may lead to Schizophrenic Reaction; too little causes Parkinson’s Disease Epinephrine or Adrenaline – also called the fight- or-flight hormone Endorphins – natural pain-killers or “feel-good” drugs
CENTRAL NERVOUS SYSTEM Consists of the brain and the spinal cord It causes sensory information to the brain by the afferent and efferent nerves It plays a key role in various reflexes It integrates the information that it receives from, and coordinates the activity of, all parts of the bodiesAfferent – conveys impulse toward the CNSEfferent – conveys impulse to effectors
CENTRAL NERVOUS SYSTEM Spinal Cord It is a bundle of nerve fibers, no thicker than the human thumb, that links the brain with the rest of the body It is protected by the vertebral column Located at the dorsal side of the body and links the brain to the rest of the body.
CENTRAL NERVOUS SYSTEM Brain A mass of nerve tissue located in the head that controls the body’s function It is protected by the skull It weigh 3lbs and contains 90% of the body neurons It has two hemispheres: the left and right It has three major parts which consists of the forebrain, midbrain, and the hindbrain
CENTRAL NERVOUS SYSTEM 3 Major Parts of the Brain: 1. Forebrain Occupies the largest part and the entire upper portion of the skull It is composed of two major hemispheres:the left and right Important Parts are the: • Thalamus • Hypothalamus • Cerebrum
CENTRAL NERVOUS SYSTEMo Thalamus It may be thought of as a kind of switchboard of information Regulates the state of sleep and wakefulness A by-station from the sensory organs to the cerebral cortex sensory regions Has a somatosensory mapping of the body and has known integrative functions
CENTRAL NERVOUS SYSTEM Hypothalamus It collects and integrates a huge variety of information from the body and to organize neural and endocrine responses that maintain homeostasis It controls the autonomic functions, emotions, endocrine functions, homeostasis, motor functions, regulates food and water intake, regulates sleep-wake cycle, and sex drive and hormones
CENTRAL NERVOUS SYSTEM Cerebrum It is the main area of the forebrain It is the part of the brain that controls thought, memory and the senses It is divided into two parts - the right hemisphere, which controls the left side of the body; and the left hemisphere, which controls the right side of the body.
CENTRAL NERVOUS SYSTEM 3 Major Parts of the Brain: 2. Midbrain Tracts between the cerebrum and the spinal cord and functions as part of the overall impulse conduction system. It also controls some auditory and visual responses
CENTRAL NERVOUS SYSTEM 3 Major Parts of the Brain: 3. Hindbrain It is close to the spinal cord Includes the Medulla Oblongata, Pons, and Cerebellum • Medulla Oblongata - has an important role in heartbeat, breathing, and blood circulation • Pons - lies in the brainstem just above the medullaoblongata • Cerebellum - maintains posture, coordinates muscular activities; called organ of motor coordination
CENTRAL NERVOUS SYSTEM The brain also consists of 4 lobes namely the: 1. Frontal Lobe - is located at the front of the brain and is associated with reasoning, motor skills, higher level cognition, and expressive language 2. Parietal Lobe - is located in the middle section of the brain and is associated with processing tactile sensory information such as pressure, touch, and pain
CENTRAL NERVOUS SYSTEM The brain also consists of 4 lobes namely the 3. Temporal Lobe - is located on the bottom section of the brain. This lobe is also the location of the primary auditory cortex, which is important for interpreting sounds and the language we hear 4. Occipital Lobe - is located at the back portion of the brain and is associated with interpreting visual stimuli and information
PERIPHERAL NERVOUS SYSTEM It connects the CNS to sensory organs, other organs of the body, muscles, blood vessels, and glands This is divided into 2 major divisions namely the Somatic Nervous System and the Autonomic Nervous System
PERIPHERAL NERVOUS SYSTEM1. Somatic Nervous System Made up of sensory system and motor nerves that activate skeletal muscles responsible for movement Has 43 pairs of major nerves: 12 pairs of Cranial Nerves and 31 pairs of Spinal Nerves
PERIPHERAL NERVOUS SYSTEM2. Autonimic Nervous System Functions in an involuntary, reflexive manner Acts as a control system functioning largely below the level of consciousness, and controls visceral functions Has 2 subsystems namely the Sympathetic Nervous System and the Parasympathetic Nervous System Visceral – of relating to, or located on or among the viscera
PERIPHERAL NERVOUS SYSTEM1. Sympathetic Nervous System involved in the “fight or flight” response during emergency situation or in high emotion It increases alertness, stimulates tissue, and prepares the body for quick responses to unusual situations. causes activation & energy expenditure
PERIPHERAL NERVOUS SYSTEM2. Parasympathetic Nervous System involved in “rest or repose” system as it quiets the body and returns it to a lower intensity of arousal calms the body after the emergency situation is resolved involved in relaxation conserves energy and controls sedentary
ENDOCRINE SYSTEM is made up of glands that produce and secrete hormones hormones regulate the body’s growth, metabolism, and sexual development and function Hormones are directly released on the bloodstream because they have no ducts or structured passageways to the organs that they serve
ENDOCRINE SYSTEM Classification of Hormones 1. Steroids – lipids derived from cholesterol and it is secreted by the gonads, adrenal cortex, and placenta 2. Peptides – short chains of amino acids and it is secreted by the pituitary, parathyroid, heart, stomach, liver, and kidneys 3. Amines – derived from amino acid tyrosine and it is secreted by the adrenal medulla
ENDOCRINE SYSTEM Pituitary Gland is the master gland and influences growth, metabolism and regeneration It is divided into 2 parts: the anterior and posterior Growth Hormones (GH) is a peptide anterior pituitary hormone essential for growth. Too little GH may cause dwarfism and too much may cause gigantism. Gonadotropins affect the gonads by stimulating gamete formation and production of sex hormones
ENDOCRINE SYSTEM Prolactin is secreted near the end of pregnancy and prepares the breasts for milk production Antidiuretic Hormones (ADH) and oxytocin are produced in the hypothalamus and transported by axons to the posterior pituitary where they are dumped into the blood ADH controls water balance in the body and blood pressure Oxytocin is a small peptide hormone that stimulates uterine contractions during childbirth
ENDOCRINE SYSTEM Adrenal Glands enables us to cope with stress It is divided into an inner medulla and an outer cortex The medulla synthesizes amine hormones while the cortex secretes steroid hormones The adrenal medulla consists of modified neurons that secrete two hormones: epinephrine and norepinephrine The adrenal cortex produces several steroid hormones in three classes: mineralcorticoids, glucorticoids, and sex hormones
ENDOCRINE SYSTEM Thyroid Gland located in the neck and the follicles in the thyroid secrete thyroglobulin, a storage form of thyroid hormone Low production of thyroid hormones is called hypothyroidism High production of thyroid hormones is called hyperthyroidism
ENDOCRINE SYSTEM Pancreas contains exocrine cells that secrete digestive enzymes into the small intestine and clusters of endocrine cells (pancreatic islets)and it secretes the hormones insulin and glucagon, which regulate blood glucose levels Too high glucose level may result to hyperglycemia Too low glucose level may result to hypoglycemia