NEURAL TISSUE AND BRAIN- JONES

The nervous system is divided into what 2 systems/categories?

CNS and PNS

What 2 components made up the CNS?

brain and spinal cord

What 2 types of neurons made up the PNS?

Which sends afferent signals and where?

Which receives efferent signals from the CNS?

1. motor neurons —> receives efferent signals from CNS

2. sensory neurons —> sends afferent signals to CNS

What are the 2 categories of motor neurons?

Which controls voluntary movement?

Which controls involuntary movement?

• somatic and autonomic nervous system

• voluntary movements—> somatic

• involuntary responses —> autonomic

What division of the autonomic nervous system deals with “fight or flight”?

sympathetic division

What division of the autonomic nervous system deals with “rest or digest”?

parasympathetic

What is the functional unit of the nervous system?

neuron

What part of the neuron receives signals?

dendrites

What part of the neuron is also known as the cell body and where the organelles are?

soma

What part of the neuron is a long projection that conducts signals from the dendrites to terminal buttons?

axon

What part of the neuron releases NTs?

terminal buttons

What acts as an insulator around axons and allows signals to be sent quickly?

myelin

Most neurons are _________________.

a. unipolar

b. bipolar

c. pseudounipolar

d. multipolar

d.

Bipolar and pseudounipolar cells deal with what process?

a. motor

b. transport

c. senses

d. structure

c.

What’s the function of the glial cells in the PNS?

• satellite cells

• Schwann cells

• satellite cells—> support cell bodies

• Schwann cells—> form the myelin sheath

What’s the function of the glial cells in the CNS?

• oligodendrocytes

• astrocytes

• microglia

• ependymal cells

• oligodendrocytes- form the myelin sheath

• astrocytes- support CNS, FORM BBB, secrete neurotropic factors, take up K+ and NTs

• microglia- act as scavengers, immune cells that destroy invading pathogens

• ependymal cells- create barriers between compartments… lines the SPACES in the brain w/CSF not blood

Gray matter in the CNS is the _______________.

a. axon

b. cell body

b.

White matter in the CNS is what? why is it white?

• is the axon

• white bc it doesn’t stain bc axon is fatty

PRACTICE: Which region of a neuron contains the highest concentrations of ligand-gated channels which are activated by neurotransmitters?

a. axon

b. axon hillock

c. myelin

d. terminal button

e. dendrites

e.

What are some things that protect the brain and spinal cord?

• skull/ vertebrae

• meninges

• CSF

• BBB

What are the meninges?

What are the names of the layers? innermost? outermost?

• tissue layers that surround CNS

• always 3 layers

  • pia mater (innermost)

  • arachnoid mater

  • dura mater (outermost)

Arachnoid mater is made of what components?

• subarachnoid space—> filled with CSF, contains major blood vessels

• arachnoid villus—> cushion, DRAINAGE point

A lumbar puncture samples CSF from which space?

subarachnoid space

What is the function of ventricles (in the brain)?

Which ventricles are the largest?

What does each ventricle contain? fxn?

• function: store CSF

• lateral ventricles the largest

• each ventricle contains a CHOROID plexus (mass of capillaries)—> what MAKES the CSF

Explain how CSF is made, flows through CNS, and is reabsorbed.

• choroid plexus secretes CSF in lateral ventricles

• flow of CSF:

  • lateral ventricle—> interventricular foramina—> 3rd ventricle—> cerebral aqueduct—> 4th ventricle—> median and lateral apertures —> subarachnoid space

• reabsorbed at arachnoid villi

What happens if there is a blockage in the apertures of the brain?

hydrocephaly—> swelling in brain

What is the difference between communicating and noncommunicating hydrocephalus?

• Communicating: CSF flow blocked after ventricles

• Noncommunicating: Blockage within ventricles.

What is called the barrier between the brain circulation and tissue fluid of the brain?

blood-brain barrier

What forms tight junctions to limit movement out of capillaries aka allows endothelial cells to be VERY VERY tight?

astrocytes

The brainstem is composed of what 3 main structures?

• midbrain

• pons

• medulla oblongata

What is the function of the medulla oblongata in general?

• CONNECTS spinal cord to brain

• involuntary/autonomic controls

  • vomiting

  • respiration

  • speech

  • sweating

  • CV, GI

Name 2 important structures within the anterior and posterior medulla:

• anterior

  • pyramids/ white matter

  • olives (olivary nucleus)

• posterior

  • nucleus cuneatus and gracilis

What is the function of each of the following:

• olives

• pyramids/white matter

• nucleus cuneatus and gracilis

• olives- relaying SOUND/auditory

• pyramids/white matter- axons run up medulla

• nucleus cuneatus and gracilis- sensory perception

What is the primary function of the pons?

• Relay station between cerebrum/cerebellum

• coordinates breathing and urination

What connects the cerebellum to the pons?

cerebellar peduncles (bundles of nerves)

What are pontine fibers?

Transverse white matter tracts connecting the cerebrum to the cerebellum

(part of the pons)

Describe EACH of the following components of the MIDBRAIN:

• tegmentum

• substantia nigra

• cerebral crus

• superior colliculi

• inferior colliculi

• tegmentum: fine motor movement

• substantia nigra: relays inhibitory signals to thalamus and basal nuclei to control unwanted movement

• cerebral crus: white matter of corticospinal tract

• superior colliculi: visual movements and tracking of head (visual reflexes)

• inferior colliculi: receives info from inner ear (auditory relay)

What is the reticular formation?

nerve cell bodies forming gray matter which runs vertically throughout the brainstem

What does the reticular formation of the brainstem regulate?

• arousal

• sleep

• somatic muscle tone

• breathing

• blood pressure

• pain modulation

What is the function of the cerebellum?

controls coordinated movements, posture, balance

There are 2 ways to classify the cerebellum…by lobe or based on input.

• what are the 3 lobes?

• what are the 3 cortex divisions (based on input)?

(idk how important)

Function of each of the following in the cerebellum:

• peduncles

• arbor vitae

• deep nuclei

• Peduncles (connect cerebellum to other regions)

• Arbor vitae (white matter within each hemisphere)

• Deep nuclei (gray matter within each arbor vitae)

What is the function of granule neurons in the cerebellum?

What is the role of Purkinje neurons in the cerebellum?

• They are located in the cortex layer and modify Purkinje cells.

• They project from the cortex to the deep nuclei.

The Thalamus and Hypothalamus make up the ____________________.

Diencephalon

Function of the thalamus?

• integration center/relay for sensory and motor info

• (chat: Acts as the brain’s "relay station," processing and transmitting sensory and motor signals to the cerebral cortex)

Function of the hypothalamus?

nuclei which regulate homeostasis and behavioral drive

• endocrine/hormone

• autonomic nervous system

• pituitary gland

Function of the cerebrum? (overview)

• cerebral cortex

• basal ganglia

• limbic system

• cerebral cortex

  • sensory fields

  • motor fields

  • association area

• basal ganglia

  • movement control

• limbic system

  • emotions

  • learning

  • memories

Be able to identify visually the lobes of the brain:

1. frontal lobe

2. parietal lobe

3. occipital lobe

4. temporal lobe

The cerebrum is divided into white matter and grey matter.

Describe the WHITE matter of the cerebrum:

• what does it includes?

• what are projection tracts?

• what are commissural tracts?

• what are association tracts?

• includes myelinated AXONS and glial cells

• projection tracts- vertical connections between cerebrum and lower areas (ex: spinal cord, brainstem, etc.)

• commissural tracts- connections from one hemisphere to another

• association tracts- connections within same hemisphere

The cerebrum is divided into white matter and grey matter.

Describe the GRAY matter of the cerebrum:

• grey matter also called what?

• what cells?

• layered structure is called what?

• all inputs go into what layer?

• grey matter of cerebrum: cerebral cortex

• cells: stellate cells and pyramidal cells

• layered structure called neocortex

• all inputs go into the IV layer of the neocortex

We know the basal nuclei play a role in movement… but more specifically its function is what 3 things?

1. integrated motor movement

2. motivation

3. addiction

What are the 3 main basal nuclei and what do they combine to form?

• 3 main nuclei:

  • caudate

  • putamen

  • globus pallidus

• combine to form the CORPUS STRIATUM

Which two major structures send inputs to the basal nuclei?

Where do the basal nuclei send their final output signals?

• inputs: cerebral cortex, substania nigra

• outputs: internal, thalamus to cortex

How does Huntington’s disease affect the basal nuclei? Results?

• corpus striatum degenerates/missing

• results in uncontrollable jerky movements

What are the 3 core structures of the limbic system?

• amygdala

• cingulate gyrus

• hippocampus

What part of the limbic system serves as nerve bundles from the hippocampus to the hypothalamus?

fornix

What part of the limbic system is responsible for MEMORY?

hippocampus

What part of the limbic system is responsible for pleasure, reward, FEAR, aggression and motivation?

AMYGDALA

Which of the following is a function of the limbic system:

a. eyesight

b. olfaction

c. hearing

d. taste

b.

The cerebral cortex (grey matter of the cerebrum) can be split into 4 lobes.

What’s the function of each:

• occipital

• temporal

• parietal

• frontal

• occipital- VISION

• temporal- auditory, olfaction, language

• parietal- taste, somatosensory area

• frontal- olfactory, motor skills, language

IDK HOW IMP:

Explain the step-by-step process of voluntary movement:

• Which brain region initiates voluntary movement planning, and where does it send signals?

• What is the role of the corticospinal tract in motor control?

• How do the basal nuclei contribute to movement?

• What two roles does the cerebellum play in motor control?

• Where are lower motor neurons located, and what do they activate?

• premotor cortex sends signal to motor cortex

• through the corticospinal tract carries signals from motor cortex to spinal cord/lower brain regions (basal nuclei/cerebellum)

• basal nuclei regulate movement and tell when to start/stop

• cerebellum deals with coordination/posture and ADDITIONALLY involved in error correction

• ventral horn of spinal cord → directly stimulate muscle groups.

Language is an integrated function and deals with reading, writing, speaking, and speech comprehension.

What are the 2 main areas associated with language and where are they located?

• Wernicke area- left hemisphere, temporal lobe

• Broca area- left hemisphere, frontal cortex

Function of Wernicke’s area?

recognition of spoken/written language

How does Broca’s area interact with Wernicke’s area and the motor cortex?

Receives interpreted language from Wernicke’s → sends speech/writing commands to motor cortex.

What is a language deficit due to lesion in the left hemisphere called?

aphasia

What are the 2 types of aphasia?

Where is the location of damage?

What are the symptoms?

2 types:

• Receptive

  • Damage to Wernicke’s area

  • cannot understand spoken or visual information

  • fluent gibberish

• Expressive

  • Damage to Broca’s area

  • understands, but cannot chose words properly, slow speech, or write clearly

PRACTICE:

A patient speaks fluently but uses incorrect words (e.g., "fork" for "pen"). Where’s the lesion?

Wernicke’s area