1. Pima Medical Institute
Introduction to Human Anatomy & Physiology
Cell Types, Structure & Function
Cell Types, Structure & Function

2. Composite Cell Cells vary in size, shape, content, and function
A composite cell includes many known cell structures
Specialized cells differ in the numbers and types of organelles
Nerve Cell
Epithelial Cell
Tissue Cell
Cell membrane
Nucleus
Controls cellular activities
Organelles
Divide the labor of the cell
Describing a typical cell is impossible because cells vary in size, shape, content, and function.
A composite cell includes many known cell structures.
Under a light microscope, a properly applied stain reveals three basic cell parts: the cell membrane that encloses the cell, the nucleus that houses the genetic material and controls cellular activities, and the cytoplasm that fills out the cell. Within the cytoplasm are specialized structures called organelles, which are suspended in a liquid called cytosol. These organelles perform specific functions, which divides the labor of the cell.
Specialized cells differ in the numbers and types of organelles, reflecting their functions.
Cytoplasm
Generally includes organelles and cytosol

3. Cell Membrane
ACTIVE
Cell membrane
(plasma membrane)
Regulates movement of substances in and out of the cell
Is thin, flexible, and elastic
Maintains cell integrity
Selectively permeable
Complex surface features
Nucleus
The cell membrane (also called the plasma membrane) is more than a simple boundary surrounding the cellular contents. It is an actively functioning part of the living material. The cell membrane regulates movement of substances in and out of the cell and is the site of much biological activity.
The cell membrane is extremely thin, flexible, and somewhat elastic. In addition to maintaining cell integrity , the cell membrane is selectively permeable, which means that only certain substances can enter or leave the cell. The cell membrane has complex surface features with many outpouchings and infoldings that increase surface area.

4. Signal Transduction
A series of molecules detect signals from outside the cell and transmit them inward
Other molecules orchestrate the cell’s response
Signal transduction is a molecular communication process through which the cell can interact with other cells. A series of molecules that are part of the cell membrane form pathways that detect signals from outside the cell and transmit them inward, where yet other molecules orchestrate the cell’s response. The cell membrane also helps cells adhere to certain other cells, which is important in forming tissues.
Signal transduction enables cell interaction
The cell membrane helps cells adhere to other cells

5. OILY Double layer (bilayer) of phospholipid molecules C O O
Amino acids
Sugars
Proteins
Nucleic Acids
Various ions
Double layer (bilayer) of phospholipid molecules
The cell membrane is composed mainly of lipids and proteins, with few carbohydrates. Its basic framework is a double layer, or bilayer, of phospholipid molecules.
The membrane’s interior is oily because it consists largely of the fatty acid portions of the phospholipid molecules. Molecules such as oxygen and carbon dioxide, which are soluble in lipids, can easily pass through this bilayer.
However, the bilayer is impermeable to water-soluble molecules, such as amino acids, sugars, proteins, nucleic acids, and various ions.
OILY O C O

6. Cholesterol & Membrane Proteins
A cell membrane includes many kinds of proteins that are classified according to their positions
Cholesterol
Makes membrane less permeable to water-soluble substances
Cholesterol molecules embedded in the cell membrane’s interior help make the membrane less permeable to water-soluble substances, while stabilizing the membrane with their rigid structure.
A cell membrane includes a few types of lipid molecules, but many kinds of proteins which provide special functions.
Membrane proteins are classified according to their positions. Membrane-spanning (transmembrane) proteins extend through the lipid bilayer and may protrude from one or both faces. Peripheral membrane proteins associate mostly with only one side of the bilayer.
Peripheral protein
Associate with one side of the bilayer
Transmembrane protein
Extends through the lipid bilayer

7. Cell Membrane Proteins
Some form receptors that start signal transduction
Receptor
Membrane proteins have a variety of functions
Membrane proteins have a variety of functions, some form receptors on the cell surface that bind incoming hormones or growth factors, starting signal transduction.
Other proteins transport ions or molecules across the cell membrane. Membrane proteins form selective channels that allow only particular ions to enter or leave. In nerve cells, for example, such selective channels control movement of sodium and potassium ions.
Cell membrane
Ion
Some transport ions or molecules across the cell membrane

8. Cell Membrane Proteins
Another type of cell membrane protein is a cellular adhesion molecule (CAM) which guides a cell’s interactions with other cells
Glycoprotein
Attached to a carbohydrate
Identify the cell
Proteins that extend inward from the inner face of the cell membrane anchor it to the protein rods and tubules that support the cell from within. Proteins that extend from the outer surface of the cell membrane mark the cell as part of a particular tissue or organ in a particular person. This identification as self is important for the functioning of the immune system. Many of these proteins are attached to carbohydrates, forming glycoproteins.
Another type of protein on a cell’s surface is a cellular adhesion molecule (CAM), which guides a cell’s interactions with other cells. For example, a series of CAMs helps a white blood cell move to the site of an injury, such as a splinter in the skin.
Filaments anchored to the protein
CAMs help a white blood cell move to the site of an injury

9. Cytoplasm Gel-like material in which organelles are suspended
Gel-like material in which organelles are suspended
Makes up most of a cell’s volume
Contains networks of membranes and organelles suspended in the clear liquid cytosol
Includes abundant protein rods and tubules that form a cytoskeleton
Place where nutrients are received, processed, and used
The cytoplasm is the gel-like material in which organelles are suspended—it makes up most of a cell’s volume. Through a light microscope, cytoplasm usually appears as a clear jelly with specks scattered throughout. Through an electr5on microscope, with its greater magnification, the cytoplasm contains networks of membranes and organelles suspended in the clear liquid cytosol. Cystoplasm also includes abundant protein rods and tubules that form a framework, or cytoskeleton, meaning “cell skeleton”.
Cell activities occur mainly in the cytoplasm where nutrients are received, processed, and used.

10. ENDOPLASMIC RETICULUM
ER & Ribosomes
RIBOSOMES
ENDOPLASMIC RETICULUM
Protein
RNA
Are composed of protein and RNA molecules
The following organelles have specific functions in carrying out certain cellular activities
Provides a vast tubular network that transports molecules
Is the site of protein and lipid synthesis
May leave the cell as secretions or be used within the cell
Provide enzymatic activity and structural support to form proteins
Polysomes help a cell to manufacture proteins in large amounts
The following organelles have specific functions in carrying out certain cellular activities.
The endoplasmic reticulum (ER) provides a vast tubular network that transports molecules from one cell part to another. The ER is the site of protein and lipid synthesis. These molecules may leave the cell as secretions or be used within the cell for such functions as producing new ER or cell membrane as the cell grows. The ER’s outer membrane can be studded with many tiny, spherical structures called ribosomes, which give the ER a textured appearance when viewed with an electron microscope.
Ribosomes are composed of protein and RNA molecules. They provide enzymatic activity as well as a structural support on which amino acids are strung together to form proteins. Clusters of ribosomes in the cytopasm, called polysomes, enable a cell to quickly manufacture proteins required in large amounts.
Ribosomes

11. Golgi Apparatus GOLGI APPARATUS
refines and packages the proteins synthesized by ribosomes
consists of a stack of about six flattened, membranous sacs whose membranes are continuous with the ER
The Golgi (gohl’-jee) apparatus consists of a stack of about six flattened, membranous sacs whose membranes are continuous with the endoplasmic reticulum. This functions to refine and "package" the proteins synthesized by the ribosomes associated with the endoplasmic reticulum.
These membranous sacs continually receive vesicles from the endoplasmic reticulum (ER) and produce vesicles that enclose secretions.
A transmission electron micrograph of a Golgi apparatus (48,500x)
The sacs receive vesicles from the ER and produce vesicles that enclose secretions

12. Mitochondrion Cristae: Contain enzymes that control chemical reactions
Mitochondrion are elongated fluid-filled sacs
Mitochondrion are elongated fluid-filled sacs. The membrane surrounding a mitochondrion has an inner and outer layer. The inner layer is folded extensively to form partitions called cristae.
In the cristae, are enzymes that control some of the chemical reactions by which energy is released from organic substances. The cristae function in transforming this energy into a chemical form that is usable by various cell parts. Mitochondria are the major sites of chemical reactions that capture and store this energy within the chemical bonds of adenosine triphosphate (ATP), a chemical form that the cell can easily use.
A transmission electron micrograph of a mitochondrion (28,000x)
Cristae:
Contain enzymes that control chemical reactions
Function in transforming energy into a form that cell parts can use
Mitochondria:
Are major sites of chemical reactions that capture and store this energy

13. Lysosome & Peroxisomes
Lysome
LYSOSOME
Are sacs that contain powerful enzymes that break down nutrients or foreign particles
Help destroy worn cellular parts or substances that enter cells
PEROXISOMES
Lysosome are tiny, membranous sacs that contain powerful enzymes that are capable of breaking down molecules of nutrients or foreign particles that enter cells. Also, lysosomes digest worn cellular parts or substances that enter cells.
Peroxisomes are these membranous sacs that are abundant in liver and kidney cells. They house enzymes that catalyze (or speed up) a variety of biochemical reactions, including synthesis of bile acid (used to digest fats); detoxify alcohol and hydrogen peroxide, a by-product of metabolism; and breakdown certain lipids and rate biochemicals.
Are sacs that are abundant in the liver and kidney cells
House enzymes that catalyze biochemical reactions
Synthesis of bile acid
Detoxify alcohol and hydrogen peroxide
Break down certain lipids and rate biochemicals

14. Microfilaments & Microtubules
A cell’s shape is critical to its function
Microfilaments and microtubules help maintain the shape of a cell by forming a cytoskeleton within the cytoplasm. A cell’s shape is critical to its function.
Microfilaments are tiny rods of protein arranged in meshworks or bundles that function to cause various kinds of cellular motility (movement). In the muscle cells, for example, microfilaments aggregate (mass in a dense cluster) to form myofibrils, which help these cells contract.
Microtubules are long, slender tubes that have a diameter two or three times greater than microfilaments. Microtubules are composed of molecules of a globular protein called tubulin, attached in a spiral to form a long tube.
MICROFILAMENTS
MICROTUBULES
Microfilaments (built of actin) and microtubules (built of tubulin)
help maintain the shape of a cell by forming
a cytoskeleton within the cytoplasm
Cause various kinds of cellular motility
Form myofibrils to help cells contract
Have a diameter 2 or 3 times greater than microfilaments
Composed of tubulin attached in a spiral

15. Two centrioles distribute chromosomes to new cells
Centrosome & Vesicles
CENTROSOME
VESICLES
Located near the Golgi apparatus and nucleus
Two centrioles distribute chromosomes to new cells
during mitosis
Created when the cell membrane folds and pinches off
Is a bubble containing liquid or solid material formerly outside the cell
The Golgi apparatus and ER also form vesicles
The centrosome is located in the cytoplasm near the Golgi apparatus and nucleus. It is nonmembranous and consists of two hollow cylinders called centrioles that function in cell reproduction by distributing chromosomes to new cells during cell division (mitosis).
Vesicles are membranous sacs formed by part of the cell membrane folding inward and pinching off. As a result, a tiny, bubblelike vesicle, containing some liquid or solid material formerly outside the cell, appears in the cytoplasm. The Golgi apparatus and the endoplasmic reticulum also form vesicles that play a role in secretion.
scienceblogs.com

16. Cilia & Flagella CILIA FLAGELLA Cilia Flagella
Cilia and flagella are motile (moht-l) extensions from the surfaces of cells. Cilia are short, motile extensions. There are many of these and they have a wave-like motion. This action serves to move fluids, such as mucus, over the surface of certain tissues, including those that form the inner linings of the respiratory tubes.
Flagella are long, motile extensions. These have a whip-like motion that generally is used for movement, like the tail of a sperm cell. The tail of a sperm cell is a flagellum that enables this motile cell to “swim” and is the only example of a flagellum in humans.
Are short, motile extensions
Have a wave-like motion
Serve to move fluids over the surface of certain tissues
Are long, motile extensions
Have a whip-like motion used for movement
Like the tail of a sperm cell
Including inner linings of the respiratory tubes

17. Transmission electron micrograph of a nucleus (7,500x)
The nucleus houses the genetic material (DNA), which direct all cell activities
Nuclear envelope
consists of inner and outer lipid bilayer membranes
Nucleolus
is composed of RNA and protein; synthesizes ribosomes
Chromatin
is composed of DNA and protein; become chromosomes
Nuclear pores
are selectively permeable channels formed from 100+ proteins
When the cells divide, chromatin fibers coil tightly and become chromosomes
commons.wikimedia.org
The nucleus houses the genetic material (DNA), which direct all cell activities. It is a large, roughly spherical structure enclosed in a double-layered nuclear envelope, which consists of inner and outer lipid bilayer membranes. The nuclear envelope has protein-lined channels called nuclear pores that allow only certain molecules to exit the nucleus. A nuclear pore is not just a hole, but a complex opening formed from 100 or so types of proteins.
The nucleolus (“little nucleus”) is a small, dense body composed largely of RNA and protein. Ribosomes form in the nucleolus, and then migrate through nuclear pores to the cytoplasm.
Chromatin consists of loosely coiled fibers composed of DNA molecules and protein that contain information for synthesizing proteins. These become chromosomes during cell division (mitosis). When the cell begins to divide, chromatin fibers coil tightly, and individual chromosomes become visible when stained and viewed under a light microscope.
Transmission electron micrograph of a nucleus (7,500x)

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