Transcript The Human Body in Health and Illness

The Human Body in Health and
Illness, 4th edition
Barbara Herlihy
Chapter 3:
Cells
1
Lesson 3-1 Objectives
• Label a diagram of the main parts of a
typical cell.
• Identify the structure of the cell membrane.
• Explain the role of the nucleus.
• Describe the functions of the main organelles
of the cell.
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2
Cells Are Specialized
• Cells are basic units of all
living matter.
• Cell structures reflect their
specialized functions.
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3
A Typical Cell
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4
Cell Membrane
• Cell membrane
– Encases cell
– Regulates what
enters and
leaves the cell
– Semipermeable
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5
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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6
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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7
Cytoplasmic Organelles
• Mitochondria
– Slipper-shaped
power plants of
cell
– Two layers
• Smooth outer
layer
• Folds (cristae) in
inner layer
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8
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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9
Cytoplasmic Organelles (cont’d.)
• Golgi apparatus
– Puts finishing
touches on protein
after synthesis on
RER
– Packages protein in
Golgi membrane
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Cytoplasmic Organelles (cont’d.)
• 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
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11
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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12
Cell Structure and
Function Summary
Cell Structure
Cell membrane
Cytosol
Nucleus
Function
Contains cellular contents; regulates
what enters and leaves the cell
Surrounds and supports organelles;
medium through which nutrients and
waste move
Contains genetic information; control
center of the cell
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13
Cell Structure and
Function Summary (cont’d.)
Cell Structure
Endoplasmic
reticulum (ER)
Function
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
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Cell Structure and
Function Summary (cont’d.)
Cell Structure Function
Ribosomes
Sites of protein synthesis
Lysosomes
Cytoskeleton
“Housekeeping” within cell; conduct
phagocytosis using powerful enzymes
Provides for intracellular shape and support
Centrioles
Separate chromosomes during mitosis
Cilia
Flagella
Create movement over cell surface
Enables the sperm to swim
Microvilli
Water transport
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15
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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16
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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21
Passive Transport: Osmosis
• Movement of
water (solvent)
from area with
more water to
area with less
water
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22
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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25
Active Transport: Endocytosis
• Ingestion of
substances by
the cell
membrane
– Phagocytosis
– Pinocytosis
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26
Active Transport: Exocytosis
• Secretion of
cellular
products out of
the cell
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27
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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30
Cell Differentiation
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31
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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33