SubstanceAbuse; Exam1, Module1

Exam #1; Module 1

Central Nervous System (7 parts)

• spinal cord

• medulla oblongata

• pons

• midbrain

• cerebellum

• diencephalon

• cerebrum

spinal cord

• and processes sensory info from the skin, joints, and muscle of the limbs/trunk

• controls movement of the limbs/trunk

• subdivided into cervical, thoracic, lumbar, and sacral regions

medulla ablongata (brainstem)

• receives sensory info from the skin and muscles of the head

• provides motor control for the musculature

• coveys info from the spinal cord to the brain and from the brain the the spinal cord

• regulates levels of arousal and awareness

• also vital for autonomic functions (e.g. digestion, breathing, control of heart rate)

pons (brainstem)

conveys info about movement from the cerebral hemispheres to the cerebellum

midbrain (brainstem)

controls many of the sensory and motor functions, including eye movement and the coordination of visual and auditory reflexes

cerebellum

• connected to the brain stem via several major fiber tracts called penduncles

• modulates the force and range of movement and is involved in the learning of motor skills

diencephalon

has 2 structures:

• thalamus= processes most of the info reaching the cerebral cortex

• hypothalamus= regulates autonomic, endocrine, and visceral functions

autonomic NS

heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal

endocrine system

• similar to the nervous system

• yet its effects and mechanism are classifiably different

• is the collection of glands of an organism that secrete hormones directly into the circulatory system

• hormones carries towards distant target organs

visceral system

part of the nervous system that represents the motor innervation of smooth muscle, cardiac muscle, and gland cells

cerebrum

has two cerebral hemispheres:

• each hemisphere consisting of heavily wrinkled outer later (cerebral cortex) and 3 deep-lying structures:

  • basal ganglia

  • hippocampus

  • amygdaloid nuclei (amygdala)

Computerized Axial Tomography (CAT) scan

• x-ray procedure that combines many x-ray images with the aid of a computer to generate cross-sectional views

functional magnetic resonance imaging (fMRI)

is a procedure that measures brain activity by detecting changes associated with blood flow

mental processes

are the end product of the interactions between elementary processing units in the brain

• specific brain regions are not responsible for specific mental faculties; instead are elementary processing units

Meningitis

acute inflammation of the protective membranes covering the brain and spinal cord; inflammation may be caused by infection with viruses, bacteria, or other microorganisms

can be life-threatening because of the inflammations proximity to the brain and spinal cord

Blood Brain Barrier

endothelial cells form from the blood-brain barrier

• exclude toxic substances

• filter out large molecules and bacteria

• protect neurons from circulating neurotransmitters

• allow CO2, O2, hormones; supported by astrocytes

• tight junction

Nerve cells

2 classes of cells:

1. neurons- sensory (vision, touch, hearing), motor, interneurons

2. glia- oligodendrocytes (CNS), Schwann cells (PNS), astrocytes (BBB< neuron support)

Neurons

morphologically defined regions: cell body, dendrites, axon, presynaptic terminals

soma (cell body) - metabolic center containing nucleus (genes) and endoplasmic reticulum (protein synthesis factory)

Endoplasmic Reticulum (ER)

folding proteins transporting to Golgi apparatus

Golgi Apparatus

labeling and shipping to destination

Neurons (continued)

• axon coveys electrical signals (conveys electrical signals (action potentials) over distances of 0.1mm to 2m

• AP initiated at initial segment or axon hillock

• AP propagate down the axon without failure or distortion

• the amplitude of action potential remains constant because the AP is all-or-none impulse

• inside: electrical signal

• outside: chemical signal

• AP- signals by which the brain receives analyzes, and conveys info

• AP signals about vision are identical to those about odors 

key principle of brain function:

the info conveyed by the action potential is determined not by the form of the signals but by the pathway the signal travels in the brain

Ramon y Cajal

• examined structure of neurons in many animals including humans

• described classes of and mapped the precise connections between many of them

• through his observations, in addition to neuron doctrine, two other principles of neural organization were added

  • 1. principle of dynamic polarization: electrical signals within a nerve cell flow only in one direction

  • 2. connectional specificity: nerve cells do not connect randomly with one another in the formation of networks

    • each cell makes specific connections - at particular contact points

  • Cajal noted distinguishing features of various neurons -  form (bipolar (interneuron), unipolar (sensory neuron), multipolar (motorneuron))

3 categories of nerve cells

1. sensory or afferent neurons: carry information from body’s peripheral system into the nervous system (perception, motor coordination)

2. motor neurons: carry commands from the brain or spinal cord to muscles and glands (efferent info)

3. interneurons: most numerous and subdivided into relay and local. relay have long axons and relay information over the long distances; local have short axons and form connections with nearby neurons in local circuits

Neurons: Myelin

• increase the speed of transmission

• wrap axons in a lipid substance

• interrupted at regular intervals at the nodes of Ranvier

• uninsulated spots is where the AP is regenerated

glial cells- support nerve cells

• oligodendrocytes (CNS)

• Schwann cells (PNS)

• astrocytes (BBB, neuron support)

  • astrocytes can be identified in culture because unlike other mature glia, they express glial fibrillary acidic protein (GFAP)

• greatly outnumbered neurons (2-10 times more)

• name derived from the Greek for glue

• they dont commonly hold cells together

• rather they surround the cell bodies, axons, and dendrites of neurons

• glia do not form dendrites or axons

• glia are not electrically excitable and not directly involved in electrical signaling

glia cells divided into two major classes: microglia and macroglia

microglia

immune system cells that immobilized to present antigens and  become phagocytes during injury, infection, or degenerative diseases

macroglia

the main types:

• oligodendrocytes

• Schwann cells

• astrocytes

Galen

• prominent greek physician, surgeon, and philosopher of the roman empire

• proposed that nerves convey fluid secreted by the brain and spinal cord to the bodys periphery

• gallens views dominated until late 1800s

Luigi Galvani

• recognized as the main pioneer of the bioelectromagnetic

• he discovered the muscles of dead frogs legs twitched when struck by electrical spark

Frantz Joseph Gall

proposed 2 radically new ideas:

1. brain is the origin of the mind; all mental functions emanate from the brain

2. argued: a) cerebral cortex did not function as a single organ, b) rather, particulate regions of the cerebral cortex control specific regions

mental faculties of the mind

• literary, observing, and knowing

• intuitive, reasoning, and reflection

• moral and religious sentiments

• perfecting

• selfishness

• domestic

Marie Jean Pierre Flourens

• french physiologist

• founder of experiment brain science and a pioneer in anesthesia

• used ablations in animals ton prove that the mind was located in the brain, not the heart

Camillo Golgi & Santiago Ramon Cajal

Golgi = staining with silver salts

Cajal = used Golgi stain to produce very first drawings of neurons; developed key concepts

• Cajal Neuron Doctrine = the principle that individual neurons are the elementary building blocks and signaling elements of the nervous system

Cell Theory

a scientific theory which describes the properties of cells; a combined effort

• all living organisms are composed of one or more cells

• the cell is the basic unit of life

Ross Harrison

showed that dendrites and the axon grow from the cell body even in tissue culture

Sanford Palay

unambiguously demonstrated the existence of synapses (regions that permit chemical or electrical signaling)