Chapter 003

The Human Body in Health and Illness, 4th edition

Barbara Herlihy

Chapter 3: Cells

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Lesson 3-1 Objectives

• Label a diagram of the main parts of atypical cell.

• Identify the structure of the cell membrane.• Explain the role of the nucleus.• Describe the functions of the main organelles

of the cell.

Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights

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Cells Are Specialized

• Cells are basic units of allliving matter.

• Cell structures reflect their specialized functions.


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A Typical Cell


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Cell Membrane


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• Cell membrane– Encases cell– Regulates what

enters and leaves the cell

– Semipermeable

• Cell membrane– Encases cell– Regulates what

enters and leaves the cell

– Semipermeable

Inside the Cell

• Nucleus– Controls the workings of the entire cell– Is surrounded by double-layered nuclear

membrane– Found inside the nucleus• Nucleoplasm: Gel-like substance• Nucleolus: Involved in synthesis of ribosomes• Chromatin: Threadlike structure that contains genes


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Inside the Cell (cont’d.)

• Cytoplasm: A gel-like substance found inside the cell but outside the nucleus

• Composed of – Cytosol (gel-like)– Organelles (“little organs”)


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Cytoplasmic Organelles


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• Mitochondria– Slipper-shaped

power plants of cell

– Two layers• Smooth outer

layer• Folds (cristae) in

inner layer

• Mitochondria– Slipper-shaped

power plants of cell

– Two layers• Smooth outer

layer• Folds (cristae) in

inner layer

Cytoplasmic Organelles (cont’d.)

• Ribosomes– Sites of protein synthesis– Fixed and free

• Endoplasmic reticulum (ER)– Network of membranes in cytosol– Rough endoplasmic reticulum (RER): Fixed

ribosomes on surface– Smooth endoplasmic reticulum (SER): No

ribosomes; site of lipid and steroid synthesis


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• Golgi apparatus– Puts finishing

touches on protein after synthesis on RER

– Packages protein in Golgi membrane


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• Lysosomes– Break down waste for “housekeeping” within the

cell• Cytoskeleton

– Composed of microfilaments and microtubules– Provides for intracellular shape and support

• Centrioles– Are rod-shaped structures– Help separate chromosomes during mitosis

• Lysosomes– Break down waste for “housekeeping” within the

cell• Cytoskeleton

– Composed of microfilaments and microtubules– Provides for intracellular shape and support

• Centrioles– Are rod-shaped structures– Help separate chromosomes during mitosis

On the Cell Membrane• Cilia– Short, hairlike projections– Wavelike motions move substances across cell’s

surface

• Flagella– Whiplike: thicker, longer, and fewer in number

than cilia– Enable sperm to swim

• Microvilli– Help move water across cell membrane


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Cell Structure andFunction Summary


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Cell Structure

Function

Cell membrane

Contains cellular contents; regulates what enters and leaves the cell

Cytosol Surrounds and supports organelles; medium through which nutrients and waste move

Nucleus Contains genetic information; control center of the cell

Cell Structure andFunction Summary (cont’d.)


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Cell Structure

Function

Endoplasmic reticulum (ER)

Transports material through the cytoplasm

Rough (RER)

Contains the ribosomes, where proteins are synthesized

Smooth (SER)

Site of lipid and steroid synthesis

Mitochondria Produce ATP

Golgi apparatus

Packages protein in membrane; puts finishing touches on protein

Cell Structure andFunction Summary (cont’d.)


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Cell Structure

Function

Ribosomes Sites of protein synthesis

Lysosomes “Housekeeping” within cell; conduct phagocytosis using powerful enzymes

Cytoskeleton Provides for intracellular shape and support

Centrioles Separate chromosomes during mitosis

Cilia Create movement over cell surface

Flagella Enables the sperm to swim

Microvilli Water transport

Lesson 3-2 Objectives• Describe the active and passive movement of

substances across a cell membrane.• Define tonicity and compare isotonic,

hypotonic, and hypertonic solutions.• Describe the active and passive movement of

substances across a cell membrane.• Describe the phases of the cell cycle.• Explain what is meant by cell differentiation.


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Passive and Active Transport


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Transport Mechanisms

• Passive mechanisms– Diffusion– Facilitated diffusion– Osmosis– Filtration

• Active mechanisms– Active transport pumps– Endocytosis– Exocytosis


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Passive Transport: Diffusion• Movement of a substance from an area of

higher concentration to one of lower concentration

• Equilibrium: Point at which concentration is equal and no further net diffusion occurs


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Passive Transport: Diffusion (cont’d.)


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Passive Transport: Facilitated Diffusion

• A helper molecule within the membrane assists with the movement of substances from higher to lower concentration.


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Passive Transport: Osmosis

• Movement of water (solvent) from area with more water to area with less water


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Passive Transport: Osmosis (cont’d.)

• Tonicity: Ability of a solution to affect the volume and pressure within a cell


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Passive Transport: Filtration

• Movement of water and dissolved substances from an area of higher pressure to an area of lower pressure

• Water and dissolved substances are pushed.


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Active Transport: Pumps• Active transport

pumps– Move substance

from area of lower concentration to area of higher concentration

– Require input of energy (ATP)


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Active Transport: Endocytosis

• Ingestion of substances by the cell membrane– Phagocytosis– Pinocytosis


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Active Transport: Exocytosis

• Secretion of cellular products out of the cell


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Cell Division

• Types of cell reproduction (division)– Mitosis: Bodily growth and repair– Meiosis: Sex cells only

• Cell cycle: The sequence of events that a cell goes through from one mitotic division to the next


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Cell Cycle

• Two phases of cell cycle– Interphase– Mitosis

• Interphase– First gap phase (G1)– Phase (S)– Second gap phase (G2)


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Cell Division (cont’d.)

• Mitosis (M)– Four phases: Prophase,

metaphase, anaphase, telophase

– Chromosomes line up and split into two identical sets.

– Ends with cytokinesis: Cell membrane pinches to create two identical cells


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Cell Differentiation


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Disorders of Cellular Growth

• Atrophy– Decrease in size of cells; leads to a wasting away

of tissues and organs• Dysplasia– Change in shape, size, organization; can become

cancerous• Hyperplasia– Overgrowth or increase in number of cells; results

in increase in size of tissues and organs


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Disorders of Cellular Growth (cont’d.)

• Metaplasia– Transformation of one cell type into another

• Necrosis– Death of cells or groups of cells

• Neoplasm– Abnormal new growth, also called a tumor– Malignant neoplasms (cancerous tumors) are

invasive and tend to metastasize from original (primary) site to another (secondary) site.


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Technology

Chapter 003