1. To be familiar with the different parts of a neuron, as well as it types and functions.2. To be able to trace how neurons communicate with one another.3. To be familiar with different parts of the nervous system and their functions4. To identify parts of the endocrine system and their influence in human behavior
Neurons are the information-processing and information- transmitting element of the nervous system They come in different shapes They may also be classified according to their major functions
Sensory neurons - They gather information from the environment and transmit them to the brain Motor neurons - Those that accomplish movement of the muscles Interneurons - Can be found in the central nervous system; responsible for perceiving, learning, remembering, planning, and deciding among other important neural activities
Soma- Contains the nucleus and other parts that are responsible proving the life processes of the cell. Dendrites- Tree-like structures that serve as the recipient of messages coming from the neighboring neurons. Axon- The axon is a long slender tube, covered by a fatty insulator called the myelin sheath, that carries information from the cell body to the terminal button. Bundles of axons constitute nerves
Terminal Buttons - Knob-like structures at the end of the axon’s twigs. Action potential- brief electrical/ chemical event. The transmission of the messages occurs in the synapse, a junction between the terminal buttons of the sending cell and a portion of the somatic or dendritic membrane of the receiving cell.
Terminal Buttons release chemicals known as neurotransmitters or transmitter substances Neurotransmitters may be classified into two: excitatory or inhibitory
A neuron fires an impulse when it receives signals from sense receptors that are stimulated by pressure, heat or light, or when it is simulated by chemical messages from adjacent neurons If these signals exceed a minimum intensity, called the threshold, they trigger an impulse. The impulse, called the action potential, is a brief electrical charge the travels down to the axon.
The neuron’s reaction is an all-or-none response, meaning they either fire or not. A stronger stimulus cannot trigger a stronger or faster impulse, but they can trigger more neuron to fire. When the Action potential reaches the terminals at an axons end, it triggers the release of chemical messengers, called neurotransmitters , onto the synapse – a gap between axons and dendrites of adjacent neurons.
These neurotransmitter molecules cross the synaptic gap and bind to the receptor site on the dendrites of the receiving neuron. This allows electrically charged atoms to enter the receiving neuron and excite or inhibit a new action potential.
Dopamine influences movement, learning, attention, and emotion. Serotonin affects mood, hunger, sleep, and arousal. Norepinephrine helps control alertness and arousal. Gamma-aminobyutric acid (GABA) inhibitory functions and is sometime implicated in eating and sleep disorders. Acetylcholine works on neurons in muscle action, learning and memory. Endorphins are released in response to pain and vigorous exercise.
The nerve impulse can be excitatory; It prompts the adjacent neuron to fire. An impulse can also be inhibitory; it prevents the adjacent neuron to fire
All-or-non law - An action potential either occurs or does not occurs, and is always in constant strength. Rate law - A high rate of firing causes a strong muscular contraction and an intense odor causes a high rate of firing in the axon the serves the nose. Saltatory conduction - action potentials are only conducted in a hopping fashion in the nodes of Ronvier
Reuptake - a rapid removal of neurotransmitter from the synaptic cleft by the terminal buttons Enzymatic deactivation - enzymes destroy some neurotransmitter molecules into its constituents
The rate an axon fires is determined by the relative activity of the excitatory and inhibitory synapses on the soma and dendrites of that cell The interaction of these activities is referred to as neural integration If the activity of the excitatory synapses goes up, the rate of firing will go up. If the activity of inhibitory synapses goes up, the rate of firing will go down
Neuromodulators - chemicals released by neurons in larger amounts and diffused for the longer distances, modulating the activity of many neurons in a particular part of the brain Hormones secreted by endocrine glands Hormones affect the activity of the cells that contain specialized receptors, called target cells Many neurons contain hormone receptors, thus influencing their activity
Anterior or Rostral- front end Posterior or Caudal – the tail Dorsal- the back surface Ventral- front surface Lateral-toward the side Medial- toward the midline Ipsilateral – same side of the body Contralateral- opposite sides of the body Cross section- slice transversely Horizontal section-slice parallel to the ground (the brain) Sagittal section- slice perpendicular to the ground and parallel to the neuroaxis
The brain is encased in a skull Floats in a pool of cerebrospinal fluid (CSF) Chemically protected by the blood brain barrier
Dura mater (the hard mother) Archnoid membrane – not found in PNS Pia mater ( pious mother) - contains surface blood vessels and follows the surface convolution of the brain Subarachnoid space - gap filled with cerebrospinal fluid
MAJOR DIVISION SUBDIVISION PRINCIPAL STRUCTUREForebrain Telencephalon Cerebrum/ Cerebral cortex Basal ganglia Limbic System Diencephalon Thalamus HypothalamusMidbrain Mesencephalon Tectum/TegmentumHindbrain Metencephalon Cerebellum Pons Myelencephalon Medulla Oblangata
Cerebrum, covered by the cerebral cortex Limbic system Basal ganglia
Two cerebral hemispheres Glia, cell bodies, dendrite, and interconnecting axons of neurons Called the “gray matter” The cerebral hemisphere can be divided into four areas
Lobes Regions / AreasFrontal Lobe Primary motor cortex, Motor association cortexParietal Lobe Primary somatosensory cortex, somatosensory association cortexOccipital Lobe Primary visual cortex, Visual association cortexTemporal Lobe Primary auditory cortex, Auditory association cortex
With the exemption for the olfactory sense, all information from the body or the environment is sent to the primary sensory cortex of the contralateral (opposite) hemisphere.
Controls the automatic nervous system and the endocrine system Behaviors related to survival of the species, such as fighting, feeding and mating
Inferior colliculi - part of the auditory system Superior colliculi - part of the visual system; involved in visual reflexes and reaction to moving objects
Reticular formation - plays role in sleep and arousal, attention, muscle tonus, movement and various vital reflexes Periaqueductal gray matter - contains neural circuits that control sequences of movements such as fighting and mating.
From the red nucleus emerges one of two major fiber systems that bring motor information from the cerebral cortex and cerebellum to the spinal cord The degeneration of neuron in the substantia nigra is responsible for Parkinson’s disease
The “little brain” Attached to the dorsal surface of the pons by bundles of axons Facilitates standing, walking or performance of coordinated movement, such as playing a musical instrument Receives and integrates visual, auditory, vestibular and somatosensory information about individual muscle movements and modifies the motor outflow by exerting a coordinating and smoothing effect on the movements.
Contains portion of the reticular formation - important in sleep and arousal Also contains a large nucleus that relays information from the cerebral cortex to the cerebellum
Medulla oblongata Contains part of the reticular formation As well as nuclei that controls vital function such as regulation of cardiovascular system, respiration, and skeletal muscle tonus
A long, conical structure, approximately as thick as our little finger Distributes motor axons Collects somatosensory information Functions independently - reflexive control circuits
Housed by the vertebral column 24 individual vertebrae cervical (neck) thoracic (chest) lumbar (lower back) sacral and coccygeal portions
Spinal Nerves Cranial Nerves - serve sensory and motor functions of the head and the neck region
Somatic nervous system - control movements of the muscles and to send sensory information from the sensory organs to the brain Autonomic nervous system - control of smooth muscles, cardiac muscles and glands
Sympathetic nervous system – expenditure of energy from the reserves that are stored in the body Thoracolumbar system Parasympathetic nervous system - activities that are involved with the increase in the body’s supply of stored energy Craniosacral system
Endocrine glands Processes that happen slowly, such as cell growth, regulation of mood Produces and secretes or give off chemicals - hormones Communicates messages, information and instructions to other group of cells
Travel through the bloodstream to target cells (of body organs) Target cells have receptors that latch only onto specific hormones When hormone level reach a certain normal or necessary amount, further secretion is controlled by important body mechanisms - negative feedback system
The primary link between the endocrine and nervous systems Controls the pituitary gland Releasing hormones - signal the pituitary gland to secrete stimulating hormones Somatostatin - causes the pituitary gland to stop the release of growth hormone
“Master gland” because it makes hormones that control several other endocrine glands Can be influenced by factors such as emotions and seasonal changes Hypothalamus relays these information anterior lobe , posterior lobe
Regulates the activity of the thyroid, adrenals, and reproductive glands Growth hormone Prolactin Thyrotropin Corticotrophin Follicle-stimulating hormone Leutinizing hormone Endorphins Gonadotropic hormones
Shaped like a bowtie or butterfly Thyroxine , triiodothyronine - regulate metabolism; body temperature and weight Iodine If iodine lacks in his/her diet, the thyroid cannot make the hormones – Goiter Calcitonin - regulation (reduction) of calcium level in the blood
Secrete parathyroid hormone, or parathormone Parathormone - regulation (increase) of calcium level in the blood Hypoparathyroidism - insufficient secretion of parathyroid hormone leading to increased nerve excitability.
corticosteroids such as cortisone - influences or regulates salt and water balance in the body; body’s response to stress, metabolism, the immune system and sexual development
Steroid hormones in three classes: Mineralocorticoids maintain electrolyte balance Glucocorticoids produce a long-term, slow response to stress by raising blood glucose level through the breakdown of fats and proteins Sex hormones
Catecholamines, such as epinephrine - increases blood pressure and heart rate when the body experiences stress
Stimulated by the nerves from the eye Melatonin - a hormone that may help regulate the wake-sleep cycle (circadian rhythm) Secreted at night, when it is dark Depressing the activity of the gonads Affects thyroid and adrenal cortex functions Seasonal affective disorder
Main source of sex hormones Testes located in the scrotum Ovaries, are located in the pelvis
Androgens most important of which is testosterone regulate body changes associated with sexual development supports the production of sperm
Produce eggs Estrogen - involved in the development of female sexual features Progesterone - causes the uterine lining to thicken in preparation for pregnancy Estrogen and progesterone - pregnancy and the regulation of the menstrual cycle
Islets of Langerhans Glucagon - tells the liver to take carbohydrate out of storage to raise a low blood sugar level Insulin - tells the liver to take excess glucose out of circulation to lower a blood’s sugar level that’s too high Diabetes mellitus