Sensory Neuron

[image]

[image]an afferent (approaching) neuron that carries information from sesory receptors in the skin to the brain

Motor Neuron

an efferent (exiting) nerve that carries information from the brain to the neurons controlling muscles--> causing a response

[image]

Local Interneuron

• form circuits within the striatum only

Relay Interneurons

• connect local interneurons

Multipolar Neuron

• has one axon, many dendrites
• sends signals from brain and spinal chord to muscles
• is the most common cell type in the brain
• is a motor neuron

• [image]

Bipolar Neuron

• has two axons attached to the soma
• is used mostly for vision and hearing
• is a sensory neuron

[image]

Unipolar Neuron

• has a divided axon--> one branch recieves, the other sends information to the CNS
• is important in the somatosensory system
• is located in the dorsal root ganglion

[image]

Exocytosis

• when a vessicle is made to transport hormones released by nerosecretory cells
• it is the process by which neurtransmitters are secreted

Axoplasmic Transport

• an active process where substances are propelled along microtubules down an axon
• there are two types of transport

1. antereograde
2. retrograde

Antereograde Transport

• axoplasmic transport that goes from the cell body-->to the terminal buttons

Retrograde Transport

• axoplasmic transport that goes from the terminal buttons-->to the cell body

Glia Cells

"neuroglia"

• supporting cells
• surround neurons and hold them in place
• control their supply of nutrients
• insulate neurons
• act as housekeepers

Microglia

• glial cells that perform phagocytosis
• are the main immune defense system of the CNS
• attack microorganisms
• are very small

[image]

Macroglia

• glial cells that are larger than microglia
• have different jobs depending on the type of macroglia cell

1. astrocytes
2. oligodendrocytes
3. schwann cells

Astrocytes

"star cell"

• glial cells that are macroglia
• perform phagocytosis
• supply nutrients from capillaries

[image]

Oligodendrocyte

• a glial cell that is a macroglia
• form the myelin around the axons in the CNS

[image]

Schwann Cells

• a glial cell that is a macroglia
• forms the myelin around the axons in the PNS

[image]

Blood Brain Barrier

"BBB"

• a semi-permeable membrane
• regulates chemicals that can enter the CNS from the blood
• helps the CNS maintain the proper composition of fluids inside and outside
• has the area postrema where the BBB is weakest

Area Postrema

• the portion of the BBB where it is the weakest
• poisons can be dected by neurons there and can initiate vomiting reflexes
• located on the medulla

Microelectrode

• device thatcan record electricity charge from a channel

Oscilloscope

• a device that can measure the membrane potential changes over time

Resting Membrane Potential

• -70mV
• the normal electrical charge of a neuron

[image]

• the Na+ outside the cell has both electrostatic and diffusion pressure pushing it into the cell, it is the only one that is imbalanced

Depolarization

• when the charge of the neuron becomes more positive
• ex. -70mV--> -40mV
• does cause an action potential at -60mVs

Hyperpolarization

• when the charge of the neuron becomes more negative than normal
• ex. -70mV--> -100mV
• does not cause an action potential

Threshold of Excitation

• the point where the depolarization of the electrical activity gets to the point where it triggers an excitation response
• when the neuron reaches a -60mVs or more positivity[image]

Diffusion

• one of two forces that factors into maintaining membrane potential
• the pressure goes with the concentration gradient

Electrostatic Pressure

• one of two forces that factors into maintaining membrane potential
• the pressure is caused by the force between charged particles

1. opposites attract
2. alike charges repel

Sodium Potassium Pump

• required to maintain the resting membrane potential
• driven by ATP

exchanges 3NA+ ions inside the cell-->
for 2K+ ions outside the cell

[image]

Principals of Action Potential

1. All or None Law
2. Rate Law
3. Saltatory Conduction

1. All-or-None--once an action potential is triggered it is propagated without decrement to the terminal buttons
2. Rate Law--variations in the intensity of a stimulus are represented by variations in the rate at which the axon fires
3. Saltatory Conduction--the current of the signal decreases if it is not an action potential (so, it is usually a hyperpolerization)

Action Potential

(the six steps)

1. Na+ channels open-->Na+ enters cell
2. K+ channels open-->K+ begins to leave cell
3. Na+ channels close
4. K+ continues to leave cell
5. K+ channels finnally close
6. the excess K+ outside diffuses away

[image]

Sagittal Slice of Brain

Horizontal Slice of Brain

Frontal (Coronal) Slice of Brain

Meninges

• the protective sheath around the brain
• the CNS has 3, the PNS has only 2
  
  1. dura mater
  2. arachnoid membrane and subarachnoid space
  3. pia mater

[image]

Cerebrospinal Fluid

• a clear fluid that is similar to blood fluid that fills the ventricular system of the brain
• has a continuous circulation of 125ml
• half-life is only 3 hours, so the choroid plexus must continually make more

Ventricles

1. Lateral--two largest chambers, telencephalon
2. Third--pierced by the massa intermedia, diencephalon
3. Cerebral Aqueduct--connecting tube between third and fourth ventricle, mesencephalon
4. Fourth--lowest chamber, metencephalon

Telencephalon

1. cerebral cortex
2. basal ganglia
3. limbic system

• located in the forebrain
• surrounds the lateral ventricle

Cerebral Cortex

• the outermost layer of gray matter
• is 3mm thick, 6 layers
• located in the telencephalon

Basal Ganglia

• a collection of subcortical nuclei beneath the lateral ventricles

1. caudate nucleus/putamen
2. globus pallidus

[image]

Limbic System

1. limbic cortex
2. hippocampus
3. amygdala
4. fornix
5. mamillary bodies

• primary function is motivation and emotion

[image]

Hippocampus

• part of the limbic system
• funtion is to lay down new memories

[image]

Amygdala

• an almond shaped structure
• responsible for feelings and emotional memories
• located in the limbic system, connected to hippocampus

[image]

Diencephalon

1. thalamus
2. hypothalamus

• the region surrounding the third ventricle
• located in the forebrain

Thalamus

• is the relay station of the brain
• has two lobes connected by the massa intermedia
• divided into several portions that connect to different cortexes of brain

1. lateral geniculate nucleus-->1°visual
2. medial geniculate nucleus-->1°auditory
3. ventrolateral nucleus--from cerebellum-->1°motor

[image]

Hypothalamus

1. anterior pituitary gland-->indirect control
2. posterior pituitary gland-->direct control

• controls autonomic nervous systems and endocrine system, organizes behavior related to survival (4 F's--fucking, fleeing, feeding, fighting)

[image]

Mesencephalon

1. tectum
2. tegementum

• surrounds the cerebral aqueduct
• makes up the entirety of the midbrain

Tectum

1. superior colliculi--part of visual system
2. inferior colliculi--part of auditory system

[image]

Tegmentum

• the portion of the mesencephalon beneath the tectum

1. periaqueductal gray matter
2. red matter
3. substancia nigra
4. reticular formation

[image]

Posterior Pituitary Gland

• directly controlled by the hypothalamus
• secretes oxytocin- stimulates lactation
• secretes vasopressin- urine output

Anterior Pituitary Gland

• indirectly controlled by the hypothalamus
• can stimulate gonads

Periaqueductal Gray Matter

• a part of the tegmentum
• consists mostly of gray matter surrounding the cerebral aqueduct
• controls sequences of movement for species-typical behaviors like fighting and mating
• opiates stimulate receptors related to pain in this region

Red Nucleus

• a part of the tegmentum
• recieves input from the cerebellum and motor cortex and sends information to axons of motor neurons in the spinal chord

Substantia Nigra

• a dark region of the tegmentum
• contains neurons that communicate with the caudate nucleus and putamen in the basal ganglia
• degeneration of these dopamine pathways causes Parkinsons Disease-->this area becomes lighter

Reticular Formation

• a large structure consisting of many nuclei in the core of the tegmentum and brain stem
• plays a role in sleep, arousal, attention, muscle tone, movement, and reflexes
• projects axons to the cerebral cortex, thalamus, and spinal chord

Metencephalon

• composed of the :

1. cerebellum
2. pons

[image]

Pons

• part of the metencephalon
• a large bulge in the brain stem
• contains part of the reicular formation
• plays a role in sleep and arousal

Cerebellum

• part of the metencephalon
• a "little brain" within the brain
• coordinates movement by integrating visual, auditory, balance, and somatosensory information and modifying accordingly

Myencephalon

• composed solely of the medulla
• regulates the cardiovascular system, respiration, skeletal muscles

The Spinal Chord

• composed on 31 paired sets of spinal roots
• surrounded by 24 vertabrae
• dorsal roots-->afferent and sensory
• ventral roots-->efferent and motor

[image]

Dorsal Root Ganglion

Cingulate Gyrus

Fissure

• a major groove in the surface of the brain
• large, deeper than a sulcus

Primary Motor Cortex

Prefrontal Cortex

Central Sulcus

Calcarine Fissure

The Lobes of the Brain

F-POT

[image]

Primary Auditory Cortex

Primary Somatosensory Cortex

CNS Development Steps

1. Induction of the Neural Plate
2. Neural Proliferation
3. Migration and Aggregation
4. Axon Growth and Synapse Formation
5. Neuronal Death and Synapse Rearrangement

1. Induction of the Neural Plate (E0-E28)

1. E18--> neural plate forms from embyonic disk
2. E21--> neural groove forms
3. E8--> neural tube closes completely, neural crest is formed

2. Neural Proliferation (E28/week 4--week 30)

1. Symmertrical Division (week 4-7)--cells proliferate as stem cells into more identical stem cells
2. Asymmetrical Division (week 7-30)--cells begin to reproduce into differentiated  cells

3. Migration and Aggregation

• radial glial cells form fibers extended radially from the ventricular zone to provide pahtways for neurons
• 1 billion migrate per day

[image]

4. Axon Growth and Synapse Formation

• once migrated, neurons grwon dendrites and axons
• they form a growth cone that helps to reach the target destination of the appropriate post-synaptic cell

5. Neuronal Death

• apoptosis occurs, which is the death of unnecessary nerve cells

Some Say Marry Money, But My  Brother Says Better Brains Matter More

S= Sensory

M=Motor

B=Both Sensory and Motor

Often Old Opticians Try To Abduct Fair And Glamorous Virgins Sipping Highballs

1. ---

   Often                                     Olfactory

2. ---

   Old                                              Optic

3. ---

   Opticians                          Oculomotor

4. ---

   Try                                         Trochlear

5. ---

   To                                         Trigeminal

6. ---

   Abduct                                    Abducens

7. ---

   Fair                                              Facial

8. ---

   And                                          Auditory

9. ---

   Glamorous                  Glossopharyngeal

10. ---

    Virgins                                          Vagus

11. ---

    Sipping                         Spinal Accessory

12. ---

    Highballs                             Hypoglossal