Intro to Nervous system + brain Flashcards
which cranial nerves are part of the CNS
cranial nerve I + II only the rest of cranial nerves are part of PNS
explain simply function of
1) Central Nervous system (CNS)
2) Peripheral Nervous System (PNS)
1)CNS= processes, interprets, stores info; issues orders to muscles, glands + organs
2)PNS= transmits info to + from CNS
The peripheral nervous system is further subdivided into the somatic + autonomic nervous system; explain simply these groupings
PNS is subdivided into
SOMATIC NERVOUS SYSTEM = controls skeletal muscles
AUTONOMIC NERVOUS SYSTEM= regulates, glands, blood vessels, internal organs
what is the autonomic nervous system and what is it subdivided into
autonomic nervous system is a component of the peripheral nervous system that regulates involuntary physiologic processes including heart rate, blood pressure, respiration, digestion, and sexual arousal. It contains three anatomically distinct divisions: sympathetic, parasympathetic, and enteric.
SYMPATHETIC NERVOUS SYSTEM= mobilises body for action, energy output
PARASYMPATHETIC NERVOUS SYSTEM= conserves energy, maintains quiet state
ENTERIC NERVOUS SYSTEM = or intrinsic nervous system is one of the main divisions of the peripheral nervous system and consists of a mesh-like system of neurons that governs the function of the gastrointestinal tract
Activation of sacral ______ pathways elicits penile erection through the release of vasorelaxant neurotransmitters that increase blood flow to the penis and relax the penile erectile tissue. Sympathetic pathways are antierectile.
Activation of sacral PARASYMPATHETIC pathways elicits penile erection through the release of vasorelaxant neurotransmitters that increase blood flow to the penis and relax the penile erectile tissue. Sympathetic pathways are antierectile.
explain what grey matter is
(40%) Grey matter is a type of tissue in your brain and spinal cord (central nervous system). It consists of high concentrations of neuronal bodies, axon terminals (endings) and dendrites.
(NON-MYELINATED)
* fully developed once a person reaches their 20s
* contains most of the brain’s neuronal cell bodies
* processes and sends info to various parts of the body
explain what white matter is
(60%) White matter is found in the deeper tissues of the brain (subcortical). It contains nerve fibers (axons), which are extensions of nerve cells (neurons). Many of these nerve fibers are surrounded by a type of sheath or covering called myelin. Myelin gives the white matter its color.
* develops throughout 20s + peaks in middle age
* made up of bundles of axons that connect various grey areas
* interprets sensory info from body
* decision-making, selection, initiation, + control of motor responses
what is the function of myelin sheath
Myelin sheath is a fatty product formed from specific neuroglial cells that increases the rate of conduction of action potentials as it insulates them
This insulation is key as our action potential travels down the membrane, sometimes ions are lost as they cross the membrane and exit the cell. The presence of myelin makes this escape pretty much impossible, and so helps to preserve the action potential.
A myelin sheath also decreases the capacitance of the neuron in the area it covers. Since the neuron is at a negative membrane potential, it’s got a lot of agitated negative ions that don’t have a positive ion nearby to balance them out. Like charges repel, so the negative ions spread out as far from each other as they can, to the very outer edges of the axon, near the membrane. This then attracts positive ions outside the cell to the membrane as well, and helps the ions in a way, calm down. We then end up with thin layers of negative ions inside of the cell membrane and positive ions outside the cell membrane. However, where myelin wraps around the cell, it provides a thick layer between the inside and the outside of the cell. Fewer negative ions gather at those points because it is further away from the positive charges. Now there are parts of the axon that are still negative, but contain proportionally far fewer negative ions. This means that as the action potential comes rushing by, it is easier to depolarize the areas that are sheathed, because there are fewer negative ions to counteract.
what is an oligodendrocyte (CNS only) + its function
- myelin forming cells in CNS
- derived from neuroectoderm
- damaged in leukodystrophies
- ‘fried-egg- appearance
remebere it as ‘ol-EGG-odendrocytes’
what is a schwann cell (PNS only) + its function
Schwann cells serve as the myelinating cell of the PNS and support cells of peripheral neurons. A Schwann cell forms a myelin sheath by wrapping its plasma membrane concentrically around the inner axon.
- derived from NEURAL CREST
remember it as ‘Schwann’s crest’
glia vs microglia
Satellite glia provide nutrients and structural support for neurons in the PNS. Microglia scavenge and degrade dead cells and protect the brain from invading microorganisms i.e. mciroglia are resident immune cells w the astrocytes that can phagocyte during disease
what is an astrocyte + its function
‘star-like’ cells responsible for the chemical environment for signalling. Primary function is to maintain proper extracellular environment so other cells in CNS can function.
maintain blood brain barrier + reactive gliosis (changes in brain after traumatic injury)
presence of GFAP (if u see this mentioned answer is astrocyte lol)
communicate via gap junctions
extra stuff: Astrocytes are specialized glial cells, there ratio to neurons in CNS is 1;1, but in PNS there’s more glial cells than neurons . They contiguously tile the entire central nervous system (CNS) and exert many essential complex functions in the healthy CNS.
function: regulation of blood flow, homeostasis of extracellular fluid, ions and transmitters, energy provision, and regulation of synapse function, and synaptic remodeling
what is an ependymal cell + its function
- simple columnar or simple cuboidal cells that line the ventricles
- involved in CSF regulation (ependymal cells line the ventricles)
- ependymal cell’s apical surfaces contain cilia + microvilli.. move CSF along
Ependymal cells are glial cells in the CNS, accumulating evidence demonstrates that ependymal cells play key roles in mammalian CNS development and normal physiological processes by controlling the production and flow of cerebrospinal fluid (CSF), brain metabolism, and waste clearance
what are glial cells
Glial cells are a type of cell that provides physical and chemical support to neurons and maintain their environment. Located in the central nervous system and peripheral nervous system, glial cells are sometimes called the “glue” of the nervous system, as well as neuroglia or just glia.
what is the forebrain made up of
forebrain made up of: telencephalon + diencephalon
it consists of:
1) cerebral cortex
* grey matter
2) subcortical white matter
* commisural fibres (corpus callosum)
* association fibres
* projection fibres
3) subcortical structures
* dorsal + ventral striatum (basal ganglia)
* limbic system
The structures in the forebrain include the cerebrum, thalamus, hypothalamus, pituitary gland, limbic system, and the olfactory bulb.
