Francis Miguel P. Perito General Psychology I Ms. Ella Roque BS Forestry I-A (Assign #2) July 8, 2014

Typical Structure of a Neuron

Parts and Meaning of a Neuron

1) Dendrite - are tiny branches on the ends of neurons that are responsible for passing information that is gathered from other neurons to the cell nucleus. It receives and conduct signals toward the cell body.

2) Axon - It conducts impulses away from cell body.

3) Neurofibrils - one of the delicate threads running in every direction through the cytoplasm of a nerve cell and extending into the axon and dendrites in a silver-stained preparation; believed to be neurofilament bundles, and perhaps neurotubules, coated with silver. It gives the neuron support and shape.

4) Neurotransmitter - is a chemical messenger that carries, boosts and modulates signals between neurons and other cells in the body. In most cases, a neurotransmitter is released from the axon terminal after an action potential has reached the synapse. Their function is to transmit a signal between neurons.

5) Microtubule – It serve as the major railways for organelle and other cargo transport, in both directions. Especially critical to their role in transport, the organization of microtubules in axons and dendrites is tightly regulated.

6) Receptor – their function is to receive data from nerves and other neurons in electrical form, and to process or send out information.

7) Synapse - is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another cell (neural or otherwise).

8) Synapse (axosomatic) - synapses, probably the most prominent kind of synapses, are synapses that one neuron makes onto the dendrite of another neuron.

9) Synapse (axoaxonic) - are synapses made by one neuron onto the synapse of another neuron. Axoaxonic synapses mediate presynaptic inhibition and presynaptic facilitation.

10)Axon Hillock - This is the region where the plasma membrane generates nerve impulses; the axon conducts these impulses away from the soma or dendrites toward other neurons. It is where the axon is joined to the cell. It is from here that the electrical firing known as an action potential usually occurs. 

11)Synaptic vesicles - a small secretory vesicle that contains a neurotransmitter, is found inside an axon near the presynaptic membrane, and releases its contents into the synaptic cleft after fusing with the membrane.

12)Node of Ranvier - periodic gap in the insulating sheath (myelin) on the axon of certain neurons that serves to facilitate the rapid conduction of nerve impulses. It speeds the transmission of signals by allowing it to jump from one node to the next.

13)Microfilament - are thin fibers that function as cooperative members of the cytoskeleton. Single fibers usually group together to perform various functions. They form a thin skeleton just inside plasma membranes called the cortical cytoskeleton to provide stiffness, structure, and shape to the membrane. Actin-mediated protrusion is the means by which neurons extend their axons toward target muscles and organs. In mitosis, cytokinesis is the result of contractile actin-myosin II fibers.

14)Axon terminal - are distal terminations of the branches of an axon. An axon nerve fiber is a long, slender projection of a nerve cell, or neuron that conducts electrical impulses (called "action potentials") away from the neuron's cell body, or soma, in order to transmit those impulses to other neurons.

15)Myelin Sheath - is an insulating layer, or sheath, that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty substances. The purpose of the myelin sheath is to allow electrical impulses to transmit quickly and efficiently along the nerve cells. If myelin is damaged, the impulses slow down. This can cause diseases such as multiple sclerosis. It prevents leakage of electrical current from axon; increases speed of conduction; makes impulse propagation more efficient.

16)Schwann cell - any of the cells in the peripheral nervous system that produce the myelin sheath around neuronal axons.

17)Rough Endoplasmic Reticulum (Nissl Body) - also known as Nissl or tigroid substance, is a large granular body found in neurons. These granules are rough endoplasmic reticulum (RER) with rosettes of free ribosomes, and are the site of protein synthesis.

18) Polyribosomes - any structure consisting of two or more ribosomes attached to different points on the same strand of messenger RNA. Hence, Polysomes is a complex involved in the cellular synthesis of the polypeptide specified in the message. Polysomes affect the synthesis of all proteins, but in the case of secretory proteins they become attached to the rough endoplasmic reticulum.

19) Synaptic cleft – the space between neurons at a nerve synapse across which a nerve impulse is transmitted by a neurotransmitter also called as synaptic gap. It is the space between the presynaptic and postsynaptic endings. It is about 20nm wide. It is the small gap, measured in nanometers, between an axon terminal and any of the cell membranes in the immediate vicinity.

20) Smooth Endoplasmic Reticulum - has a wide range of functions including carbohydrate and lipid synthesis. It serves as a transitional area for vesicles that transport ER products to various destinations. In liver cells the smooth ER produces enzymes that help to detoxify certain compounds. In muscles the smooth ER assists in the contraction of muscle cells, and in brain cells it synthesizes male and female hormones.

21) Ribosomes – It plays a very important role in protein synthesis, which is the process by which proteins are made from individual amino acids. Without the ribosomes the message would not be read, thus proteins could not be produced.

22) Golgi apparatus - It is membrane-bound structure that plays a role in packaging peptides and proteins (including neurotransmitters) into vesicles.

23) Mitochondrion - this is the part of the cell responsible for the supply of energy in the form of ATP (adenosine triphosphate). Neurons need an enormous amount of energy. The brain is one of the most metabolically active tissues in the body. In man, for example, the brain uses 40 ml of oxygen per minute. Mitochondria use oxygen and glucose to produce most of the cell's energy.

24) Nucleus - It is derived from the Latin word for "nux", nut, the nucleus is the archivist and the architect of the cell. As archivist it contains the genes, consisting of DNA which contains the cell history, the basic information to manufacture all the proteins characteristic of that cell. As architect, it synthesizes RNA from DNA and ships it through its pores to the cytoplasm for use in protein synthesis. 

25) Nucleolus - It is an organelle within the nucleus which is involved actively in ribosome synthesis and in the transfer of RNA to the cytosol. 

General Parts of the Human Brain(Mid-line incision view)

Parts with meaning of the Human Brain

1) Splenium of corpus callosum - connects the posterior cortices with fibers varying in size from thin late-myelinating axons in the anterior part, predominantly connecting parietal and temporal areas, to thick early-myelinating fibers in the posterior part, linking primary and secondary visual areas.

2) Sulcus of corpus callosum - the fissure between the corpus callosum and the cingulate gyrus.

3) Marginal portion of sulcus cinguli - is the portion of the cingulate sulcus adjacent to the paracentral lobule and the precuneus.

4) Central sulcus – it separates frontal from parietal lobe.

5) Paracentral lobule - refers to the junction of the precentral gyrus and postcentral gyrus on the medial surface of the cerebral cortex. It lies across the boundary between the frontal lobe and the parietal lobe.

6) Pineal body (Pineal Gland) - is an important endocrine gland. It is a small, oval structure descending from the roof of the diencephalon, a section of the brain that relays sensory information between the brain's different regions. It produces and secretes melatonin (induces sleep).

7) Pineal recess - a diverticulum from the posterior part of the third ventricle extending back between the posterior commissure and the habenular commissure; sometimes extending into the stalk of the pineal.

8) Posterior commissure - is a rounded bundle of white nerve fibers that crosses the midline immediately dorsal to the cerebral aqueduct, where the aqueduct becomes continuous with the third ventricle. The precise functions served by the various fibers that cross in the posterior commissure are not well understood.

9) Tela choroidea of third ventricle - The part of the choroid plexus in relation to the body of the ventricle forms the vascular fringed margin of a triangular process of pia mater and projects from under cover of the lateral edge of the fornix.

10) Intermediate mass of thalamus – It joins right and left sides of thalamus and is therefore also called the 'interthalamic adhesion'.

11)Gyrus cinguli - a long curved structure on the medial surface of the cerebral hemispheres; the cortical part of the limbic system.

12)Thalamus – It is a midline symmetrical structure of two halves, within the vertebrate brain, situated between the cerebral cortex and the midbrain that relays sensory and motor signals to the cerebral cortex, along with the regulation of consciousness, sleep, and alertness.

13) Body of Corpus callosum – the main arched portion of the corpus callosum. It interconnects areas of the premotor and supplementary motor regions and motor cortex, with proportionally more corpus dedicated to supplementary motor regions like Broca's area.

14)Body of fornix - is a constituent of the hippocampus of the cerebrum and serves an integral part in its limbic system.

15)Lamb of septum pellucidum - is a thin, triangular, vertical membrane separating the anterior horns of the left and right lateral ventricles of the brain. It runs as a sheet from the corpus callosum down to the fornix. It is a thin membrane of nervous tissue that forms the medial wall of the lateral ventricles in the brain.

16)Subfrontal portion of sulcus cinguli – It begins below the rostrum of the corpus callosum and curves forwards and upwards around the genu, and then turns backwards above the body of the corpus callosum. Before it reaches the level of the Splenium, it turns upwards and cuts and terminates in the supero-mesial border of the hemisphere, as the next sulcus behind the upper termination of the central sulcus.

17) Interventricular foramen - are channels that connect the paired lateral ventricles with the third ventricle at the midline of the brain. As channels, they allow cerebrospinal fluid (CSF) produced in the lateral ventricles to reach the third ventricle and then the rest of the brain's ventricular system.

18)Column of fornix - are known as anterior pillars and fornicolumns. These are found in the brain. In the brain, the columns of fornix travel downward in an arch, falling in front of the interventricular foramen and going behind the anterior commissure.

19)Anterior commissure - is a bundle of nerve fibers (white matter), connecting the two cerebral hemispheres across the midline, and placed in front of the columns of the fornix.

20)Superior Frontal Gyrus - is located on top of the brain, running down toward the front and adjacent to the fold that divides the right and left hemispheres of the brain. This massive gyrus comprises about a third of the lobe's area, and it plays a role in several higher-level cognitive processes.

21)Frontal pole – It is the most anterior promontory of each cerebral hemisphere.

22) Genu of the corpus callosum - is bent downward and backward in front of the septum pellucidum; diminishing rapidly in thickness, it is prolonged backward under the name of the rostrum, which is connected below with the lamina terminalis.

23) Rostrum of the corpus callosum - It is connected below with the lamina terminalis, which stretches from the interventricular foramen to the recess at the base of the optic stalk.

24) Parolfactory area - a small region of cerebral cortex on the medial surface of the frontal lobe, formed by the junction of the straight gyrus with the cingulate gyrus, demarcated from the subcallosal gyrus by the posterior parolfactory sulcus.

25) Anterior Parolfactory Sulcus - a fissure marking the anterior border of the parolfactory area.

26) Posterior Parolfactory Sulcus - a shallow groove on the medial surface of the hemisphere demarcating the subcallosal gyrus or precommissural septum from the parolfactory area.

27) Subcallosal gyrus - a shallow groove on the medial surface of the hemisphere demarcating the subcallosal gyrus or precommissural septum from the parolfactory area.

28) Hypothalamic sulcus - is a groove in lateral wall of third ventricle, marking the boundary between the thalamus and hypothalamus.

29) Lamina Terminalis – It stretches from the Interventricular foramen (Foramen of Monro) to the recess at the base of the optic stalk and contains the organum vasculosum of the lamina terminalis, which regulates the osmolarity of the blood.

30) Optic recess – It is a diverticulum extending forward from the anterior part of the third ventricle above the optic chiasm.

31) Optic nerve – It connects the eye to the brain. The optic nerve carries the impulses formed by the retina, the nerve layer that lines the back of the eye and senses light and creates impulses. These impulses are dispatched through the optic nerve to the brain, which interprets them as images.

32) Optic chiasma – It is an X-shaped space just in front of the pituitary gland where optic nerve fibers pass through to the brain. The fibers from the nasal half of each retina cross over, but those from the temporal sides do not.

33) Infundibulum – It is the hollow conical process of gray matter that is borne on the tuber cinereum and constitutes the stalk of the neurohypophysis by which the pituitary gland is continuous with the brain—called also neural stalk.

34) Anterior lobe body - is mainly involved in development of the body, sexual maturation and reproduction. Hormones produced by the anterior lobe regulate growth and stimulate the adrenal and thyroid glands as well as the ovaries and testes. It also generates prolactin, which enables new mothers to produce milk.

35) Hypophysis (Pituitary gland) - is an endocrine gland about the size of a pea and weighing 0.5 grams (0.018 oz.) in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragma sellae).

36)Posterior lobe - is the portion of the cerebellum caudal to the primary fissure. It is sometimes equated to the "neocerebellum", since phylogenetically it is the newest part of the cerebellum. It plays an important role in fine motor coordination, specifically in the inhibition of involuntary movement via inhibitory neurotransmitters, especially gamma-Aminobutyric acid.

37)Mammillary body - are a pair of small round bodies, located on the undersurface of the brain, that, as part of the diencephalon form part of the limbic system. Mammillary bodies, and their projections to the anterior thalamus via the mammillothalamic tract, are important for recollective memory.

38)Oculomotor nerve - is the third cranial nerve. It enters the orbit via the superior orbital fissure and controls most of the eye's movements, including constriction of the pupil and maintaining an open eyelid by innervating the levator palpebrae superioris muscle.

39)Posterior perforated substance - is a layer of gray matter that is located in the interpeduncular fossa. It is triangular. Its base corresponds to the corpus albicans, its apex to the pons, and its sides to the crus cerebri. It gives passage to the posteromedian ganglionic branches of the posterior cerebral and posterior communicating arteries.

40)Pons - is a portion of the hindbrain that connects the cerebral cortex with the medulla oblongata. It also serves as a communications and coordination center between the two hemispheres of the brain. As a part of the brainstem, the pons helps in the transferring of messages between various parts of the brain and the spinal cord.

41)Cerebral aqueduct - is the structure within the brainstem that connects the third ventricle to the fourth. It is located within the midbrain, surrounded by periacqueductal grey matter (PAG) with the tectum of midbrain located posteriorly and the tegmentum anteriorly.

42)Anterior medullary velum –It is the thin layer of white matter stretching between the two superior cerebellar peduncles, forming part of the roof of the fourth ventricle.

43)Medulla Oblongata – It is where the spinal cord connects to the brain stem. It is the bottom portion of the brain stem. It separates the hemispheres of the cerebellum. It regulates autonomic functions including: blood pressure, heart rate, digestion, and breathing. It also relays sensory information to the brain stem centers. It is the communication center between the brain and spinal cord.

44)Fourth Ventricle - is located in the brain stem, just in front of the cerebellum. It is connected to the third ventricle by a narrow canal, the cerebral aqueduct (aqueduct of Sylvius), which passes lengthwise through the brain stem.

45)Tela chorioidea of fourth ventricle - is the name applied to the triangular fold of pia mater which is carried upward between the cerebellum and the medulla oblongata.

46)Spinal cord - It is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain (the medulla oblongata specifically). It is the main pathway for information connecting the brain and peripheral nervous system.

47)Central Canal –It is a small canal that runs through the center of the spinal cord and is filled with cerebrospinal fluid. It represents the remainder of the neural canal in adults. The neural tube develops to become the brain stem and, expands dorsally and laterally to create the fourth ventricle.

48)Calamus scriptorius – It is continuous with the central canal of the closed part of the medulla oblongata. It is the lowest portion of the floor of the fourth ventricle, situated between the restiform bodies.

49)Vermis of cerebellum – It is located in the medial, cortico-nuclear zone of the cerebellum, residing in the posterior fossa of the cranium. The primary fissure in the vermis curves ventrolaterally to the superior surface of the cerebellum, dividing it into anterior and posterior lobes. Functionally, the vermis is associated with bodily posture and locomotion. The vermis is included within the spinocerebellum and receives somatic sensory input from the head and proximal body parts via ascending spinal pathways.

50)Vermis of cerebellum (inferior portion) – It is the bottom portion of the cerebellar vermis.

51)Medullary substance of vermis – It is the lipid material present in the myelin sheath of nerve fibers.

52)Cerebellar hemisphere - are located to either side of a small area called the vermis that separates the two hemispheres down the middle. Each of the cerebellar hemispheres is further divided into five lobes. Deep folds in the cerebellum separate the ten lobes. Positioned at the lower rear of the brain, the cerebellum sits below the cerebrum and behind the pons.

53)Occipital lobe - are one of the four main lobes or regions of the cerebral cortex. They are positioned at the back region of the cerebral cortex and are the main centers for visual processing. The occipital lobes are involved in several functions of the body including visual perception and color recognition.

54)Lingual gyrus – It is a brain structure that is linked to processing vision, especially related to letters. It is thought to also play a role in analysis of logical conditions (ie logical order of events) and encoding visual memories. The lingual gyrus is named after the shape it most closely resembles - the tongue. Contrary to the name, the region has little to do with speech.

55) Occipital pole – It is the most posterior part of the brain's occipital lobe, where visual information at the center of the visual field is processed. Strokes affecting the occipital pole cause a visual deficit called a central visual defect.

56) Calcarine fissure - is located on the medial surface of the occipital lobe and divides the visual cortex (aka calcarine cortex) into two. It is where the primary visual cortex (V1) is concentrated. The central visual field is located in the posterior portion of the calcarine sulcus and the peripheral visual field in the anterior portion.

57) Vermis of cerebellum (superior portion) – It is the top portion of the cerebellar vermis.

58) Cuneus - is a smaller lobe in the occipital lobe of the brain. The cuneus is bounded anteriorly by the parieto-occipital sulcus, inferiorly by the calcarine sulcus. It receives visual information from the contralateral superior retina representing the inferior visual field. It is most known for its involvement in basic visual processing.

59) Lamina quadrigemina – It is the roofplate of the mesencephalon (midbrain) formed by the quadrigeminal bodies.

60) Parieto-occipital fissure - a sulcus near the posterior end of each hemisphere that separates the parietal lobes and the occipital lobes in both hemispheres.

61) Subparietal sulcus - a sulcus continuing the direction of the cingulate sulcus from where the marginal part of that fissure bends upward; it forms the upper boundary of the posterior portion of the cingulate gyrus.

62) Precuneus (praecuneus in Latin) – It is a square-shaped coil in the parietal lobe of the brain, near the juncture between the two hemispheres; it is sometimes called the quadrate lobe. It gets its name from its location just above the cuneate lobe. The precuneus is involved in episodic memory, visual-spatial abilities, and motor activity coordination strategies. Additionally, functions of the precuneus include self perception, consciousness, and the executive and working memory.

63) Cerebrum – It is also known as the telencephalon, is the largest and most highly developed part of the human brain. It is involved in several functions of the body including: determining intelligence, determining personality, thinking, perceiving, producing and understanding language, interpretation of sensory impulses, motor function, planning and organization and touch sensation.

64) Brain stem –It is the region of the brain that connects the cerebrum with the spinal cord. It consists of the midbrain, medulla oblongata, and the pons. The brainstem controls several important functions of the body including: alertness, arousal, breathing, blood pressure , digestion , heart rate, other autonomic functions and relays Information between the peripheral nerves and spinal cord to the upper parts of the brain.

65) Hypothalamus - It is a section of the brain responsible for hormone production. The hormones produced by this area of the brain govern body temperature, thirst, hunger, sleep, circadian rhythm, moods, sex drive, and the release of other hormones in the body. Its primary function is homeostasis, which is to maintain the body's status quo system-wide.