Nervous System Flashcards
Central nervous system (CNS)
Is the control center for the entire nervous system and consists of the brain and spinal cord.
The nervous system
One of the body’s principal control and integrating centers. The other is the endocrine system. In humans, the nervous system serves three broad functions: sensory, integrative and motor.
Peripheral nervous system (PNS)
All nerve tissue outside of those structures.
Cells
Two types of cells found in the nervous system Neurons neuroglia.
Neurons
Highly specialized cells for nerve impulse condition.
Afferent (sensory)
Neurons carry impulses from peripheral sense receptors to the CNS.
Efferent (motor)
Neurons carry impulses from CNS effector organs such as muscles and glands.
Interneurons
Located entirely within the CNS, in which they form the connecting link between the afferent and efferent neurons.
Types of neurons
Afferent, efferent, and interneurons
Myelin
Sheath formed from the plasma membranes or specialized glial cells known as Schwann cells.
Schwann cells
Serve a supportive and nutritive role.
Node of Ranvier
Gaps between Schwann cells.
Neuroglia (glial cells)
Connective tissue cells that do not conduct nerve impulses, but instead, they support, nourish, and protect the neurons.
Nerve
A cordlike structure consisting of a collection of nerve fibers (neurons) that convey impulses.
Spinal cord
A cylindrical bundle of nerves that is slightly flattened anteriorly and posteriorly.
Meninges
The three layers are the pia matar, arachnid matar, and the dura matar.
Pia matar
The innermost layer.
Arachnoid layer
A spider web like appearance.
Dura matar
The thicker, tougher outermost layer of the meninges
Afferent system
Consists of nerve cells that covey information from receptors in the periphery of the body to the central nervous system (CNS).
Afferent (sensory) neurons
Are the first cells to pick up incoming information.
Efferent system
Consists of nerve cells that convey information from the central nervous system to the muscles and glands.
Efferent (motor) neurons
Nerve cells within the efferent system.
Somatic nervous system
Consists of efferent neurons that conduct impulses from the central nervous system to skeletal muscle tissue. It is under conscious control and is therefore considered voluntary.
Autonomic nervous system
Contains efferent neurons that convey impulses from the central nervous system to smooth muscle tissue, cardiac muscle tissue and glands.
Sympathetic nervous system (fight & flight)
- Stimulates heartbeat
- Dilates the pupils
- Dilates the trachea and bronchi (breathing tube)
- Stimulates the conversion of liver glycogen into glucose
- Shunts blood away from the skin and viscera to the skeletal muscles, brain, and heart
- Inhabits peristalsis in the gastrointestinal (GI) tract
- Inhabits contraction of the bladder and rectum
Parasympathetic nervous system (rest & digest)
- Slowing down of the heartbeat
- Lowering of blood pressure
- Constriction of the pupils
- Increase blood flow to the skin and viscera
- Peristalsis of the GI tract
Cranial nerves
There are 12 pairs
Spinal nerves
There are 31 pairs of spinal nerves
Plexus
Network on either side of the body created by the grouping of adjacent nerves.
Cervical plexus
First four cervical nerves (C1-C4) with contributions from C5.
Brachial plexus
Formed by spinal nerves C1-C8 and T1.
Lumbar plexus
Spinal nerves L1-L4.
Sacral plexus
Spinal nerves L4,L5, and S1-S4
Sciatic nerve
The largest nerve arising from the sacral plexus and the largest nerve in the body.
Thoracic nevers
Spinal nerve T2-T11.
Amines
Derived from one or two amino acids
Ex: epinephrine, norepinephrine, thyroid hormone.
Proteins and peptides
Consists of three or more amino acids.
Ex: all pituitary hormones and insulin.
Steroids
Derived from cholesterol.
Ex: estrogen and testosterone.
Exocrine glands
Secrete their products through ducts.
Endocrine glands
Ductless glands that secrete hormones.
Pituitary glands (master glands)
Releases several hormones, some which control the release of other hormones.
Epinephrine (adrenaline)
Stimulates the sympathetic nervous system producing the fight or flight response.
Norepinephrine
Along with epinephrine it stimulates the fight or flight response; plays a role in attention and focus; also serves as a neurotransmitter.
Cardiovascular system
Made up of the blood, heart, and blood vessels.
The heart
An efficient pump, responsible for circulating blood throughout the body.
Pericardium
A sac which serves to protect the heart and anchor it to the surrounding tissue.
Blood
Highly specialized connective tissue consisting of cells in a fluid medium.
Blood is composed of two portions
Formed elements (cells and cell-like structures) Plasma (liquid containing dissolved substances)
Erythrocytes (red blood cells)
Transport oxygen from the lungs to the cells and carbon dioxide from the cells to the lungs.
Leukocyte (white blood cells)
They fight infection.
Thrombocytes (cell fragments)
Play a role in clotting.
Plasma
The straw colored liquid portion of the blood.
Interstitial fluid
When certain constituents of plasma move out of the blood through the capillary walls; it bathes the cells.