Slide set 4: Nervous system Flashcards
What is the general function of nervous system?
Along with the endocrine system, is to control and communicate
What are the 3 components pf nervous system?
brain, spinal chord, peripheral nerves
What are the 2 smaller “system” of nervous system?
- Central nervous system
- Peripheral nervous system
What are the parts, role of central nervous system? (CNS)
- Structural and functional center of entire nervous system
- Brain + spinal cord
- Integrates sensory information, evaluates it, and initiates an outgoing response
What are the parts/role of peripheral nervous system?
- Nerves that lie in “outer region” of nervous system
- Cranial nerves=> originate from brain
- Spinal nerves => originate from spinal cord
How is the nervous system also divided? What are the “categories” called?
According to types of organs they innervate.
Somatic vs Autonomic nervous system
How is the somatic nervous system divided?
- Somatic motor division: Carries information to the somatic effectors (skeletal muscles)
- Somatic sensory division: Carries feedback information to somatic integration centers in CNS from PNS
What is the difference between autonomic and somatic nervous system?
Autonomic=> without voluntary control
What is the afferent division and the efferent division
Afferent=> incoming message from visceral receptors
Efferent=> outgoing of ANS => carries information to the visceral effectors ( smooth and cardiac muscles and glands)
What are the 2 autonomic categories?
Sympathetic division
Parasympathetic division
What is the sympathetic division of the ANS efferent pathway?
it prepares the body to deal with immediate threats to the internal environment: produces fight-or-flight response
What is the parasympathetic division of the ANS efferent pathway?
Coordinates the body’s normal resting activities : something called the rest-and-repair division
What are some effect of the sympathetic control on the heart rate?
- Sympathetic branch of the ANS controls heart rate in emergency response-has and overall stimulatory effect
- When there is a need for greater blood flow
- Blood beats more forcefully and squeezes out more blood
- Has a vasoconstriction effect on blood vessels
What are some effect of parasympathetic control over the stomach?
- Distention of the stomach caused by the presence of food triggers parasympathetic reflexes
- increase secretion of gastric juice
- In response to presence of amino acids, Parasympathetic innervation causes gastrin (digestive hormone) secreted by mucosa in presence of food causes increased secretion of gastric juice
What are the 2 major cells of the nervous system?
- Neurons
- Glial cells
What are characteristics of neurons?
Are EXCITABLE cells that CONDUCT IMPULSES (functional cells) and are required for all nervous system activities
What are characteristics of Glial cells?
DO NOT conduct information, but support the functions of the neurons
What type of structure in neurons help transport small organelles? In what part of the cell is the transport more important?
Cytoskeleton :
- Microtubules and microfilaments as well as neurofibrils
They are a shuttle for small molecules and organelles
Axon transport
-motor molecules, move proteins on cytoskeleton. Highway for release at the synaptic knobs
What are the 4 types of glial cells of the central nervous system?
- Oligodendrocytes
- Microglia (modified immune cells)
- Astrocytes
- Ependymal cells
What are some characteristics of Astrocytes?
- Star-shaped
- Largest
- Most numerous
Cell extensions connect to both neurons and capillaries
Transfer nutrients from the blood to the neurons
Form tight sheats around brain capillaires, which with tight junctions between capilarru endothelial cells constitute the BLOOD-BRAIN-BARRIER (BBB)
What is the role of the blood-brain-barrier?
The BBB is the specialized system of capillary endothelial cells that protects the brain from harmful substances in the blood stream AND allow supply of the brain with required nutrients for proper function
How does BBB protect the brain?
BBB strictly limits transport into the brain through both physical (tight junctions) and metabolic (enzymes ) barriers
What are the 2 specialization that allows the BBB to function?
- Capillaries are specialized as they are held together by tight junctions => this acts as a barrier against molecules
- Second specialization involves the feet of the astrocytes
What is a tight junction?
- Occur in cells that are joined by “collars” of tightly fused material
- Molecules cannot permeate the cracks of tight junctions
- Important in the blood brain barrier in connecting endothelial cells
What is the role of astrocyte in BBB?
- Webs of astrocytes forms tight sheets around the brain’s capillaries => restrict the entrance of potentially harmful chemicals from the blood, while allowing entrance of essential nutrients
- This is a double barrier made up of astrocyte feet and the endothelial cells that make up the walls of the capillaries
What molecules can penetrate through the BBB?
- Lipid soluble molecules (ethanol, caffeine…)
- Glucose
- Liposomes (Liposome-A => spherical vesicle with a membrane composed of PHOSPHOLIPID BILAYER
What is a microglia?
- Macrophage of the brain
- Small, usually stationary cells
- Exception is in INFLAMED BRAIN TISSUE, where they ENLARGE , MOVE, and CARRY on phagocytosis to remove microorganisms and cellular debris
What are ependymal cells?
- RESEMBLE EPITHELIAL CELLS and form thin sheets that line fluid-filled cavities (cerbral-spinal fluid) in the CNS
- Have cilia
- Some produce fluid , others aid in circulation of fluid (reason why cilia)
What are oligodendrocytes?
- Smaller than astrocytes with fewer processes
- Hold nerve fibers together and produce MYELIN SHEATH in CNS
What is multiple sclerosis?
- Disorder of oligodendrocytes
- Auto-immune disease
- Most common disease in CNS
- Characterized by myelin loss and destruction
- Failure in nerve conduction
- Communication interupted
- Treatment, immune modulating , inflammation reducing
What is a Schwann cell?
- Glial cell
- Found only in PNS
- Functional equivalent of oligodendrocyte
- Support nerve fibers in some cases form MYELIN SHEATS. Gaps in the myelin sheats are called NODES OF RANVIER
- The myelin sheats and nodes of Ranvier are important for the CONDUCTION OF IMPULSES along nerve fibers