Module 1-class1 Flashcards
Afferent
Relating to nerves that run from periphery into the CNS. All afferent nerves have sensory function
Autonomic (aka Visceral)
The autonomic/visceral portion of the NS is the part of that innervates viscera (abdominal and thoracic organs) and other non-somatic organs.
Blood Brain Barrier (BBB)
-A physiological concept that describes the way that many substances circulating within blood are unable to diffuse or filter into CNS tissue (in contrast to most tissues in the body), protecting the CNS from potential pathogens and neurotoxic substances. The blood brain barrier is formed by the presence of extensive tight junctions between endothelial cells lining capillaries within CNS tissue.
-The BBB is maintained by astrocytes, which have cellular processes that associate with endothelial cells, and is incomplete in some parts of the brain (most of these regions are in the hypothalamus, and are important for sensing blood osmolarity, or for responding to or secreting neurohormones into the blood)
Central Nervous System (CNS)
-The division of the nervous system that is encased within the bony structures of the skull and vertebral column (i.e. the brain and the spinal cord).
-Excludes the peripheral nervous system (PNS) - i.e. spinal nerves and cranial nerves, but does include the retina.
Cerebrospinal Fluid (CSF)
-An aqueous fluid containing ions and secreted proteins which is generated in the ventricles in the brain. It percolates through CNS tissue via the glymphatic system, forming the ECF for CNS cells and reaches the subaracnoid space through the fourth ventricle.
-CSF provides a cushion for the brain to prevent the brain from hitting the skull upon impact, and carries waste materials out of the brain.
-CSF is secreted by cells in the choroid plexus within the brain’s ventricular system. It flows within the subarachnoid space and drains back into the bloodstream at the sagittal sinus.
- ependymal cells of the choroid plexus secrete most of the fluid that becomes CSF.
Efferent
-Relating to nerves that run from the CNS to peripheral structures, including (but not only) muscles.
-Some other examples of structures innervated by efferent neurons are glands, smooth muscles, and adipocytes (fat cells)
Facilitated Diffusion
-Movement of molecules down their concentration gradients (i.e. according to diffusive forces) when that molecule crosses a membrane using specific transmembrane proteins.
-Facilitated’ because the molecule requires the assistance of a membrane protein, diffusion because this does not require input of energy.
Free Diffusion
-The movement of molecules down their concentration gradient (i.e. according to diffusive forces), through a membrane that is completely permeable to them
-Free’ because there is no assistance needed from other molecules, such as membrane proteins
Glymphatic System
-Cerebrospinal fluid circulatory system in the CNS. Comprised of interconnected astroglia and the spaces around brain arteries, this system is primarily responsible for waste removal in the brain
-This system has similarities to the lymphatic system in the rest of the body, but instead of lymph, the fluid is CSF. The ‘gl’ in the name name refers to the role of glial cells in creating the flow of the fluid.
Meninges (singular: meninx)
-Three layers of membranes beneath the bony skull and the vertebrae (dura mater, arachnoid mater, and pia mater) that help protect the CNS by anchoring it in place and containing the cerebrospinal fluid that cushions the CNS.
-the meninges also allow CSF to flow bacj into the bloodstream, specifically via structures called arachnoid granulations.
Skull (and Vertebral Column)
The bony structures surrounding the CNS that offer protection from external trauma.
Somatic
The somatic portion of the NS is the part that innervates muscles and integument (skin, tendons, etc).
Soma = ‘body’
Includes afferent and efferent components.
Transporter Proteins
-Transmembrane proteins that allow molecules, such as ions or polar organic molecules like glucose to cross a cell membrane - i.e. proteins that perform facilitated diffusion). These proteins can either be channels (i.e. pores which allow many molecules to cross at once) carrier proteins, which allow one or a few molecules to cross in each cycle of activity, or pumps (which allow molecules to move against their concentration gradients using ATP hydrolysis).
-Proteins with the term ‘transporter’ in their name are almost always carrier proteins, NOT channels, so the term is often used specifically to mean carrier proteins.
