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Figure 3.1

Figure 3.1 The Diversity of Cells in the Human Body

The Anatomy of a Representative Cell

Figure 3.2

Label:1. Cilia2. Centriole3. Mitochondrion4. Rough ER5. Smooth ER6. Cytosol7. Ribosomes8. Golgi9. Chromatin10. Lysosome

• A cell is surrounded by extracellular fluid. This fluid is called interstitial fluid.

• A cell contains intracellular fluid. This fluid is called cytosol (not cytoplasm; cytoplasm = cytosol + organelles).

• The solute contents and concentrations of interstitial fluids differ from those of cytosol.

• The concentration differences are due primarily to the cell membrane, which acts as a barrier and transporter.

• Name three molecules or atoms that you think would differ between the cytosol and interstitial fluid. In which solution do you think they would be more concentrated? Why?

Inside and Outside are not the same

The Cell Membrane

• Physical isolation• Regulation of exchange with the

environment• Structural support

Cell membrane functions include:

• The cell membrane is a phospholipid bilayer with proteins, lipids and carbohydrates.

Figure 3.3 The Cell Membrane

Figure 3.3

• Integral proteins• Peripheral proteins• Anchoring proteins• Recognition proteins• Receptor proteins• Carrier proteins• Channels

Membrane proteins include:

Figure 3.2 The Anatomy of a Representative Cell

Figure 3.2

• Microfilaments• Intermediate filaments• Microtubules • Thick filaments

Microvilli increase surface area

Cytoskeleton provides strength and flexibility

Figure 3.5 The Cytoskeleton

Figure 3.5

• Direct the movement of chromosomes during cell division

• Organize the cytoskeleton• Cytoplasm surrounding the centrioles is

the centrosome

Centrioles

• Is anchored by a basal body• Beats rhythmically to move fluids across

cell surface

Cilia

Figure 3.6 Centrioles and Cilia

Figure 3.6

Figure 3.7 Ribosomes

Figure 3.7

• Are responsible for manufacturing proteins

• Are composed of a large and a small ribosomal subunit

• Contain ribosomal RNA (rRNA)• Can be free or fixed ribosomes

Ribosomes

Figure 3.8 The Endoplasmic Reticulum

Figure 3.8

• Intracellular membranes involved in synthesis, storage, transportation and detoxification

• Forms cisternae• Rough ER (RER) contains ribosomes

• Forms transport vesicles• Smooth ER (SER)

• Involved in lipid synthesis

Endoplasmic reticulum

Figure 3.9 The Golgi Apparatus

Figure 3.9

• Forms secretory vesicles• Discharged by exocytosis

• Forms new membrane components• Packages lysosomes

Golgi Apparatus

Figure 3.10 Functions of the Golgi Apparatus

Figure 3.10

• Lysosomes are• Filled with digestive enzymes• Responsible for autolysis of injured

cells• Peroxisomes

• Carry enzymes that neutralize toxins

Lysosomes and Peroxisomes

Figure 3.11 Lysosome Functions

Figure 3.11

• Continuous movement and recycling of membranes • ER• Vesicles• Golgi apparatus• Cell membrane

Membrane flow

• Responsible for ATP production through aerobic respiration

• Matrix = fluid contents of mitochondria• Cristae = folds in inner membrane

Mitochondria

Figure 3.13 The Nucleus

Figure 3.13

Neuroscience: Exploring the Brain, 3rd Ed,ear, Connors, and Paradiso

Copyright © 2007 Lippincott Williams & Wilkins

Slide 26

• Chapter 02: Neurons and Glia

Slide 27 Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso


Introduction

• “Neurophilosophy”• Brain is the origin of mental abilities

• Glia and Neurons• Glia: Insulates, supports, and nourishes

neurons• Neurons

• Process information• Sense environmental changes • Communicate changes to other neurons

• Command body response



The Neuron Doctrine

• Histology• Study of tissue

structure• The Nissl Stain

• Facilitates the study of cytoarchitecture in the CNS





The Neuron Doctrine

• Golgi-stain shows two parts of neurons:• Soma and perikaryon• Neurites: Axons and dendrites







The Neuron Doctrine

• Cajal’s Contribution• Neural circuitry• Neurons

communicate by contact, not continuity

• Neuron doctrine• Neurons adhere to cell theory



The Prototypical Neuron

• Neuronal membrane• The Soma

• Cytosol: Watery fluid inside the cell• Organelles: Membrane-enclosed structures within the soma

• Cytoplasm: Contents within a cell membrane (e.g., organelles, excluding the nucleus)




• The Soma• Gene expression• Protein synthesis• RNA splicing• Molecular biology




• The Soma• Rough Endoplasmic

Reticulum (ER)• Major site for protein synthesis

• Free ribosomes• Polyribosomes






• The Soma• Rough ER

• Protein synthesis in neurons




• The Soma• Smooth ER and Golgi Apparatus

• Sites for preparing/sorting proteins for delivery to different cell regions (trafficking) and regulating substances








• The Soma• Mitochondrion

• Site of cellular respiration (inhale and exhale)

• Krebs cycle• ATP- cell’s energy source




• The Neuronal Membrane• Barrier that encloses cytoplasm• ~5 nm thick• Protein concentration in membrane

varies• Structure of discrete membrane regions

influences neuronal function












• The Cytoskeleton• Not static• Internal scaffolding

of neuronal membrane

• Three “bones”• Microtubules• Microfilaments• Neurofilaments






• The Axon• Axon hillock

(beginning)• Axon proper (middle)• Axon terminal (end)

• Differences between axon and soma• ER does not extend

into axon• Protein composition:

Unique




• The Axon• The Axon Terminal

• Differences between the cytoplasm of axon terminal and axon

• No microtubules in terminal• Presence of synaptic vesicles• Abundance of membrane proteins• Large number of mitochondria




• The Axon• Synapse

• Synaptic transmission

• Electrical-to-chemical-to-electrical transformation

• Synaptic transmission dysfunction

• Mental disorders




• The Axon• Axoplasmic transport• Anterograde (soma to terminal) vs.

Retrograde (terminal to soma) transport




• Dendrites• “Antennae” of

neurons• Dendritic tree• Synapse -

receptors• Dendritic spines

• Postsynaptic (receives signals from axon terminal)



Classifying Neurons

• Classification Based on the Number of Neurites • Single neurite

• Unipolar• Two or more

neurites • Bipolar- two• Multipolar- more than two



Classifying Neurons

• Classification Based on Dendritic and Somatic Morphologies • Stellate cells (star-

shaped) and pyramidal cells (pyramid-shaped)

• Spiny or aspinous



Classifying Neurons

• Further Classification• By connections within the CNS

• Primary sensory neurons, motor neurons, interneurons

• Based on axonal length• Golgi Type I• Golgi Type II

• Based on neurotransmitter type• e.g., – Cholinergic = Acetycholine at synapses



Glia

• Function of Glia • Supports neuronal

functions • Astrocytes

• Most numerous glia in the brain

• Fill spaces between neurons

• Influence neurite growth



Glia

• Myelinating Glia• Oligodendroglia (in

CNS) and Schwann cells (in PNS)• Insulate axons

• Node of Ranvier• Region where the axonal membrane is exposed



Glia

• Myelinating Glia (Cont’d)• Oligodendrog

lial cells• Node of

Ranvier• Other Non-

Neuronal Cells• Microglia as

phagocytes (immune)



Concluding Remarks

Structural characteristics of a neuron tell us

about its function

NEURONSSomaAxons

DendritesSynapse

Elaborate structure of

dendritic tree = receiver

e.g., Dense Nissl stain = protein;

suggests specialization

Structure Correlates with Function

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