Unit 2 Cells, Tissues & Membranes

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2/18/2014

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1

Unit 2
Cells, Tissues and Membranes
[
2]
Hilario Cruzada Noveno Jr.
Lecturer [

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]

2

Cells & Tissues
• Carry out all chemical activities needed to
sustain life
• Cells are the building blocks of all living things
• Tissues are groups of cells that are similar in
structure and function

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3

Figure 1.1

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4

• Cells are organized into three main regions
– Nucleus
– Cytoplasm
– Plasma membrane

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5

The Cell
The functional unit of the human body.
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6

The Cell and its parts [

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]

7

The Nucleus [
• Control center of the
cell
– Contains genetic
material (DNA)
• Three regions
– Nuclear membrane
– Nucleolus
– Chromatin

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]

(DNA)

8

Nuclear Membrane [
• Barrier of nucleus
• Consists of a double
phospholipid
membrane
• Contain nuclear pores
that allow for exchange
of material with the rest
of the cell

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]
•

9

Nucleoli [
• Nucleus contains one or
more nucleoli
• Sites of ribosome
production

]
•

– Ribosomes then migrate
to the cytoplasm
through nuclear pores

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10

Chromatin [

]

• Composed of DNA and
protein
• Scattered throughout
the nucleus
• Chromatin condenses
to form chromosomes
when the cell divides

•

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11


Chromatin [

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]

12

Plasma Membrane [
• Barrier for cell contents
• Double phospholipid
layer

]
•

– Hydrophilic heads
– Hydrophobic tails

• Also contains
protein, cholesterol, an
d glycoproteins

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13

Plasma Membrane Specialization
[
]
• Microvilli
– Finger-like projections
that increase surface
area for absorption

•

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14

Plasma Membrane Specialization
[
]
• Membrane junctions
– Tight junctions
– Desmosomes
– Gap junctions

•
Desmosomes

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15

Cytoplasm [
• Material outside the
nucleus and inside the
plasma membrane

]
•

– Cytosol
• Fluid that suspends other
elements

– Organelles
• Metabolic machinery of
the cell

– Inclusions
• Non-functioning units
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16

Cytoplasmic Organelles
[
]

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17

[
]
• Ribosomes

•

– Made of protein and
RNA
– Sites of protein synthesis
– Found at two locations
• Free in the cytoplasm
• Attached to rough
endoplasmic reticulum

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18

[
]
• Endoplasmic reticulum (ER)
– Fluid-filled tubules for
carrying substances
– Two types of ER

•

ER)

ER

• Rough Endoplasmic
Reticulum
– Studded with
ribosomes
– Site where building
materials of cellular
membrane are formed
• Smooth Endoplasmic
Reticulum
– Functions in
cholesterol synthesis
and breakdown, fat
metabolism, and
detoxification of drugs

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19

[
]
• Golgi apparatus
– Modifies and packages
proteins
– Produces different types
of packages
• Secretory vesicles
• Cell membrane
components
• Lysosomes

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Lysosomes


20

Golgi apparatus [

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]

21

[
]
• Lysosomes
– Contain enzymes that
digest nonusable
materials within the cell

• Peroxisomes

nonusable
Peroxisomes

– Membranous sacs of
oxidase enzymes
• Detoxify harmful
substances
• Break down free radicals
(highly reactive
chemicals)

– Replicate by pinching in
half
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22

[
]
• Mitochondria

•

– “Powerhouses” of the
cell
– Change shape
continuously
– Carry out reactions
where oxygen is used to
break down food
– Provides ATP for cellular
energy

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23

[
]
• Cytoskeleton

•

– Network of protein
structures that extend
throughout the
cytoplasm
– Provides the cell with an
internal framework

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24

[
]
• Cytoskeleton

•

– Three different types
• Microfilaments
• Intermediate filaments
• Microtubules

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25

[
]

Cytoskeleton
Three different types
Microfilaments
Intermediate filaments
Microtubules

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26

[
]
• Centrioles

Centrioles •

– Rod-shaped bodies
made of microtubules
– Direct formation of
mitotic spindle during
cell division

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27

Cellular Projections
[
]
• Not found in all cells
• Used for movement

•

– Cilia moves materials
across the cell surface
– Flagellum propels the
cell

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28

Cell Diversity
[
]

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29

Cell Diversity
[
]

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30

Types of Cells

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31

Tissues

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32

Body Tissues
[
]
• Cells are specialized for
particular functions
• Tissues

•

– Groups of cells with
similar structure and
function
– Four primary types
•
•
•
•

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Epithelium
Connective tissue
Nervous tissue
Muscle


33

Epithelial Tissues
[
]
• Found in different areas
– Body coverings
– Body linings
– Glandular tissue
• Functions
– Protection
– Absorption
– Filtration
– Secretion
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34

Epithelium Characteristics
[
]
• Cells fit closely together
• Tissue layer always has
one free surface
• The lower surface is
bound by a basement
membrane
• Avascular (have no
blood supply)
• Regenerate easily if well
nourished

•

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35


Classification of Epithelium
[
]
• Number of cell layers
– Simple – one layer
– Stratified – more than
one layer

•
---

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36

Classification of Epithelium
[
]
• Shape of cells
– Squamous – flattened
– Cuboidal – cube-shaped
– Columnar – column-like

–
--

---

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37

Simple Epithelium
[
]
• Simple squamous
– Single layer of flat cells
– Usually forms membranes
• Lines body cavities
• Lines lungs and capillaries

•

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38

Simple Epithelium
[
]
• Simple cuboidal

– Single layer of cube-like
cells
– Common in glands and
their ducts
– Forms walls
of kidney tubules
– Covers the ovaries

•

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39

Simple Epithelium
[
]
• Simple columnar
– Single layer of tall cells
– Often includes goblet
cells, which produce mucus
– Lines digestive tract

•

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40

Simple Epithelium
[
]
• Pseudostratified
– Single layer, but some
cells are shorter than
others
– Often looks like a
double cell layer
– Sometimes
ciliated, such as in the
respiratory tract
– May function in
absorption or
secretion

•

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41


Simple Epithelium
[
]

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42

Stratified Epithelium
[
]
• Stratified squamous
– Cells at the free edge
are flattened
– Found as a protective
covering where
friction is common
– Locations

•

• Skin
• Mouth
• Esophagus
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43

[
]

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44

[
]
• Stratified cuboidal

•

– Two layers of cuboidal cells

• Stratified columnar
– Surface cells are
columnar, cells underneath
vary in size and shape

• Stratified cuboidal and
columnar
– Rare in human body
– Found mainly in ducts of
large glands
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45

[
]
• Transitional epithelium

•

– Shape of cells depends
upon the amount of
stretching
– Lines organs of the
urinary system

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46

[
]

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47

Glandular Epithelium
[
]
• Gland – one or more
cells that secretes a
particular product
• Two major gland types

--

•

– Endocrine gland
• Ductless
• Secretes hormones

– Exocrine gland
• Empty through ducts to
the epithelial surface
• Example: sweat and oil
glands

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48

Connective Tissue
[
]
• Found everywhere in
the body
• Includes the most
abundant and widely
distributed tissues
• Functions

•

– Binds body tissues
together
– Supports the body
– Provides protection
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49

Connective Tissue Characteristics
[
]
• Variations in blood
supply

•

– Vascular (with blood
vessel)
– Avascular (without blood
vessel)

• Extracellular matrix
– Non-living material that
surrounds living cells

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50

Extracellular Matrix
[
]
• Two main elements
– Ground substance –
mostly water along
with adhesion proteins
and polysaccharide
molecules
– Fibers

--

•

• Produced by the cells
• Three types
– Collagen fibers
– Elastic fibers
– Reticular fibers

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51

•
Connective Tissues
•
•
•
•

Osseus (bone)
Hyaline cartilage
Elastic cartialge
Fibrocartilage
Dense connective tissue
– Tendons
– Ligaments

•
•
•
•
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Areolar connective tissue
Adipose tissue
Reticular connective tissue
Blood


52

Connective Tissue Types
[
]
• Bone (osseous tissue)
– Composed of:

•

• Bone cells in lacunae
(cavities)
• Hard matrix of
calcium salts
• Large numbers of
collagen fibers

– Used to protect and
support the body
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53

[
]

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54

[
]
• Hyaline cartilage

•

– Most common cartilage
– Composed of:
• Abundant collagen fibers
• Rubbery matrix

– Entire fetal skeleton is
hyaline cartilage

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55

[
]

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56

[
]
• Elastic cartilage

•

– Provides elasticity
– Example: supports the
external ear

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57

[
]
• Fibrocartilage

•

– Highly compressible
– Example: forms cushionlike discs between
vertebrae

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58

[
]

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59

[
]
• Dense connective tissue
– Main matrix element
is collagen fibers
– Cells are fibroblasts
– Examples
• Tendon – attach
muscle to bone
• Ligaments – attach
bone to bone

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•

---

60

[
]

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61

[
]
• Areolar connective
tissue

•

– Most widely distributed
connective tissue
– Soft, pliable tissue
– Contains all fiber types
– Can soak up excess fluid
– Lines many organs of the
body

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62

[
]

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63

[
]
• Adipose tissue
– Matrix is an areolar
tissue in which fat
globules
predominate
– Many cells contain
large lipid deposits
– Functions

•

• Insulates the body
• Protects some organs
• Serves as a site of
fuel storage
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64

[
]

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65

[
]
• Reticular connective
tissue
– Delicate network of
interwoven fibers
– Forms stroma
(internal supporting
network) of
lymphoid organs
• Lymph nodes
• Spleen
• Bone marrow

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•

•


66

[
]

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67

[
]
• Blood

•

– Blood cells surrounded
by fluid matrix
– Fibers are visible during
clotting
– Functions as the
transport vehicle for
materials

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68

[
]

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69

•
Connective Tissues
•
•
•
•

Osseus (bone)
Hyaline cartilage
Elastic cartialge
Fibrocartilage
Dense connective tissue
– Tendons
– Ligaments

•
•
•
•
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Areolar connective tissue
Adipose tissue
Reticular connective tissue
Blood


70

Muscle Tissue
[
]
• Function is to produce
movement
• Three types

•

– Skeletal muscle
– Cardiac muscle
– Smooth muscle

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71

Muscle Tissue Types
[
]
• Skeletal muscle

•

– Voluntary control
– Cells attached to
connective tissue
– Striated cells
– Cells have more than
one nucleus

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72

Muscle Tissue Types
[
]

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73

Muscle Tissue Types
[
]
• Cardiac muscle
– Found only in the
heart
– Involuntary control
– Cells attached to
other cardiac muscle
cells at intercalated
disks
– Striated cells
– One nucleus per cell
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•

74

Muscle Tissue Types
[
]

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75

Muscle Tissue Types
[
]
• Smooth muscle
– Involuntary muscle
– Surrounds hollow
organs
– Attached to other
smooth muscle cells
– No visible striations
– One nucleus per cell

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•

76

Muscle Tissue Types
[
]

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77

Characteristics

Skeletal muscle

Cardiac muscle

Smooth muscle

Striated

Yes

Yes

Not visible

Control

Voluntary

Involuntary

Cells

Multinucleated

Mononucleated

Attachment

Organs

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Attached to other
Attached to other
cardiac muscles
Connective tissue
smooth muscle
at intercalated
cells
discs

Skeletal muscles

Heart


Bronchus
Lungs
Diaphragm
Blood vessels
Bladder
GIT
78

Muscle Tissue Types
[
]
• Neurons and nerve
support cells
• Function is to send
impulses to other areas
of the body

•

– Irritability
– Conductivity

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79

Muscle Tissue Types
[
]

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80

Tissue Repair
[
]
• Regeneration
– Replacement of
destroyed tissue by the
same kind of cells

•

• Fibrosis
– Repair by dense fibrous
connective tissue (scar
tissue)

• Determination of
method
– Type of tissue damaged
– Severity of the injury
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81

Events Tissue Repair
[
]
• Capillaries become very
permeable

•

– Introduce clotting
proteins
– Wall off injured area

• Formation of
granulation tissue
• Regeneration of surface
epithelium
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82

Regeneration of Tissues
[
]
• Tissues that regenerate
easily
– Epithelial tissue
– Fibrous connective
tissue and bone
• Tissues that regenerate
poorly
– Skeletal muscle
• Tissues that are replaced
largely with scar tissue
– Cardiac muscle
– Nervous tissue (brain
and spinal cord)
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•

83

Developmental Aspects of Tissue
[
]
• Epithelial tissue arises
from all three primary
germ layers
• Muscle and connective
tissue arise from the
mesoderm
• Nervous tissue arises
from the ectoderm
• With old age there is a
decrease in mass and
viability in most tissues
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•

viabililty

84

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