CHAPTER 3: Anatomy and Physiology- Cells and Tissue

Chapter 3
Cells and Tissues
Lecture Presentation by
Patty Bostwick-Taylor
Florence-Darlington Technical College
© 2018 Pearson Education, Inc.

 Matthias Schleiden
– German Botanist
Matthias Schleiden
– 1838
– ALL PLANTS "ARE
COMPOSED OF
CELLS".
 Theodor Schwann
– Also in 1838,
– discovered that
animals were made
of cells
 Rudolf Virchow
– 1855, German
Pathologists
– discovered that
humans are made up
of cells
Discovery of Cells

1. All living things are composed of a
cell or cells.
2. Cells are the basic unit of life.
3. All cells come from preexisting
cells.
The Cell Theory states that:

Concepts of the Cell Theory
•A cell is the basic structural and functional unit
of living organisms.
•The activity of an organism depends on the
collective activities of its cells.
•According to the principle of complementarity,
the biochemical activities of cells are dictated
by the relative number of their specific
subcellular structures.
•Continuity of life has a cellular basis.

CELL Size
•Limits in Cellular and Multicellularity
- Cells will only grow so big; after that, they
either remain the same size, or they divide
into two smaller cells

Part I: Cells
 Cells are the structural units of all living things
 The human body has 50 to 100 trillion cells

Overview of the Cellular Basis of Life
 Most cells are composed of four elements:
1. Carbon
2. Hydrogen
3. Oxygen
4. Nitrogen
 Cells are about 60-80% water

Anatomy of a Generalized Cell
 In general, a cell has three main regions or parts:
1. Nucleus
2. Cytoplasm
3. Plasma membrane
Nucleus
Cytoplasm
Plasma
membrane
(a) Generalized animal cell

The Nucleus
 Control center of the cell
 Contains genetic material
known as deoxyribonucleic
acid, or DNA
 DNA is needed for building
proteins
 DNA is necessary for cell
reproduction
 Three regions:
1. Nuclear envelope
(membrane)
2. Nucleolus
3. Chromatin

The Nucleus
 Nuclear envelope (membrane)
 Consists of a double membrane that bounds the
nucleus
 Contains nuclear pores that allow for exchange of
material with the rest of the cell
 Encloses the jellylike fluid called the nucleoplasm

The Nucleus
 Nucleolus
 Nucleus contains one or more dark-staining nucleoli
 Sites of ribosome assembly
 Ribosomes migrate into the cytoplasm through nuclear
pores to serve as the site of protein synthesis

The Nucleus
 Chromatin
 Composed of DNA wound around histones (proteins)
 Scattered throughout the nucleus and present when
the cell is not dividing
 Condenses to form dense, rodlike bodies called
chromosomes when the cell divides

The Plasma Membrane
 Transparent barrier for cell contents
 Contains cell contents
 Separates cell contents from surrounding
environment

The Plasma Membrane
 Fluid mosaic model is constructed of:
 Two layers of phospholipids arranged ―tail to tail‖
 Cholesterol and proteins scattered among the
phospholipids
 Sugar groups may be attached to the phospholipids,
forming glycolipids

Figure 3.2 Structure of the plasma membrane.
Extracellular fluid
(watery environment)
Glycoprotein Glycolipid
Cholesterol
Sugar group
Polar heads of
phospholipid
molecules
Bimolecular
lipid layer
containing
proteins
Nonpolar tails of
phospholipid
molecules
Channel
Proteins Filaments of
cytoskeleton Cytoplasm
(watery environment)

The Plasma Membrane
 Phospholipid arrangement in the plasma
membrane
 Hydrophilic (―water loving‖) polar ―heads‖ are oriented
on the inner and outer surfaces of the membrane
 Hydrophobic (―water fearing‖) nonpolar ―tails‖ form the
center (interior) of the membrane
 This interior makes the plasma membrane relatively
impermeable to most water-soluble molecules

The Plasma Membrane
 Role of proteins
 Responsible for specialized membrane functions:
 Ion Channels (Na+, K+, Ca+2, Cl-)
 Enzymes
 Receptors for hormones or other chemical messengers
 Transport as channels or carriers
 Recognition site

The Plasma Membrane
 Role of sugars
 Glycoproteins are branched sugars attached to
proteins that abut the extracellular space
 Glycocalyx is the fuzzy, sticky, sugar-rich area on the
cell’s surface

The Plasma Membrane
 Cell membrane junctions
 Cells are bound together in three ways:
1. Glycoproteins in the glycocalyx act as an adhesive or
cellular glue
2. Wavy contours of the membranes of adjacent cells fit
together in a tongue-and-groove fashion
3. Special cell membrane junctions are formed, which
vary structurally depending on their roles

The Plasma Membrane
 Main types of cell junctions
 Tight junctions
 Impermeable junctions
 Bind cells together into leakproof sheets
 Plasma membranes fuse like a zipper to prevent
substances from passing through extracellular space
between cells

The Plasma Membrane
 Main types of cell junctions (continued)
 Desmosomes
 Anchoring junctions, like rivets, that prevent cells from
being pulled apart as a result of mechanical stress
 Created by buttonlike thickenings of adjacent plasma
membranes

The Plasma Membrane
 Main types of cell junctions (continued)
 Gap junctions (communicating junctions)
 Allow communication between cells
 Hollow cylinders of proteins (connexons) span the width
of the abutting membranes
 Molecules can travel directly from one cell to the next
through these channels

Figure 3.3 Cell junctions.
Microvilli Tight
(impermeable)
junction
Desmosome
(anchoring
junction)
Plasma
membranes of
adjacent cells
Connexon
Gap
(communicating)
junction
Underlying
basement
membrane
Extracellular
space between
cells

The Cytoplasm
 The cellular material outside the nucleus and
inside the plasma membrane
 Site of most cellular activities
 Includes cytosol, inclusions, and organelles

The Cytoplasm
 Three major component of the cytoplasm
1. Cytosol: Fluid that suspends other elements and
contains nutrients and electrolytes
2. Inclusions: Chemical substances, such as stored
nutrients or cell products, that float in the cytosol
3. Organelles: Metabolic machinery of the cell that
perform functions for the cell
 Many are membrane-bound, allowing for
compartmentalization of their functions

Figure 3.4 Structure of the generalized cell.
Chromatin
Nucleolus
Smooth endoplasmic
reticulum
Cytosol
Lysosome
Mitochondrion
Nuclear envelope
Nucleus
Plasma
membrane
Centrioles
Rough
endoplasmic
reticulum
Ribosomes
Golgi apparatus
Microtubule
Intermediate
filaments
Secretion being released
from cell by exocytosis
Peroxisome

The Cytoplasm
 Mitochondria
 ―Powerhouses‖ of the cell
 Mitochondrial wall consists of a double membrane with
cristae on the inner membrane
 Carry out reactions in which oxygen is used to break
down food into ATP molecules

The Cytoplasm
 Ribosomes
 Made of protein and ribosomal RNA
 Sites of protein synthesis in the cell
 Found at two locations:
 Free in the cytoplasm
 As part of the rough endoplasmic reticulum

The Cytoplasm
 Endoplasmic reticulum (ER)
 Fluid-filled tunnels (or canals) that carry substances
within the cell
 Continuous with the nuclear membrane
 Two types:
 Rough ER
 Smooth ER

The Cytoplasm
 Endoplasmic reticulum (ER) (continued)
 Rough endoplasmic reticulum
 Studded with ribosomes
 Synthesizes proteins
 Transport vesicles move proteins within cell
 Abundant in cells that make and export proteins

Figure 3.5 Synthesis and export of a protein by the rough ER.
Ribosome
mRNA
Rough ER
As the protein is synthesized on the ribosome,
it migrates into the rough ER tunnel system.
In the tunnel, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a glycoprotein).
The protein is packaged in a tiny
membranous sac called a transport vesicle.
The transport vesicle buds from the rough ER
and travels to the Golgi apparatus for further
processing.
Protein
Transport
vesicle buds off
Protein inside
transport vesicle
1
2
3
4
1
2
3
4
Slide 1

The Cytoplasm
 Endoplasmic reticulum (ER) (continued)
 Smooth endoplasmic reticulum
 Lacks ribosomes
 Functions in lipid metabolism
 Detoxification of drugs and pesticides

The Cytoplasm
 Golgi apparatus
 Appears as a stack of flattened membranes
associated with tiny vesicles
 Modifies and packages proteins arriving from the
rough ER via transport vesicles
 Produces different types of packages
 Secretory vesicles (pathway 1)
 In-house proteins and lipids (pathway 2)
 Lysosomes (pathway 3)

Figure 3.6 Role of the Golgi apparatus in packaging the products of the rough ER.
Rough ER Tunnels Proteins in tunnels
Membrane
Transport
vesicle
Lysosome fuses with
ingested substances.
Golgi vesicle containing
digestive enzymes
becomes a lysosome.
Pathway 3
Golgi
apparatus
Pathway 1
proteins to be secreted
becomes a secretory
vesicle.
Pathway 2
Secretory vesicles
Proteins
Secretion by
exocytosis
membrane components
fuses with the plasma
membrane and is
incorporated into it.
Plasma membrane
Extracellular fluid

The Cytoplasm
 Lysosomes
 Membranous ―bags‖ that contain digestive enzymes
 Enzymes can digest worn-out or nonusable cell
structures
 House phagocytes that dispose of bacteria and cell
debris

The Cytoplasm
 Peroxisomes
 Membranous sacs of oxidase enzymes
 Detoxify harmful substances such as alcohol and
formaldehyde
 Break down free radicals (highly reactive chemicals)
 Free radicals are converted to hydrogen peroxide and
then to water
 Replicate by pinching in half or budding from the ER

The Cytoplasm
 Cytoskeleton
 Network of protein structures that extend throughout
the cytoplasm
 Provides the cell with an internal framework that
determines cell shape, supports organelles, and
provides the machinery for intracellular transport
 Three different types of elements form the
cytoskeleton:
1. Microfilaments (largest)
2. Intermediate filaments
3. Microtubules (smallest)

Figure 3.7 Cytoskeletal elements support the cell and help to generate movement.
(a) Microfilaments
Actin subunit
7 nm
(b) Intermediate filaments
Fibrous subunits
10 nm
(c) Microtubules
Tubulin subunits
25 nm
Microfilaments form the blue
batlike network.
Intermediate filaments form
the purple network surrounding
the pink nucleus.
Microtubules appear as gold
networks surrounding the cells’
pink nuclei.

The Cytoplasm
 Centrioles
 Rod-shaped bodies made of nine triplets of
microtubules
 Generate microtubules
 Direct the formation of mitotic spindle during cell
division

Table 3.1 Parts of the Cell: Structure and Function (1 of 5)

Cell Extensions
 Surface extensions found in some cells
 Cilia move materials across the cell surface
 Located in the respiratory system to move mucus
 Flagella propel the cell
 The only flagellated cell in the human body is sperm
 Microvilli are tiny, fingerlike extensions of the plasma
membrane
 Increase surface area for absorption

Figure 3.8g Cell diversity.
Nucleus
Sperm
(g) Cell of reproduction
Flagellum

Cell Diversity
 The human body houses over 200 different cell
types
 Cells vary in size, shape, and function
 Cells vary in length from 1/12,000 of an inch to over
1 yard (nerve cells)
 Cell shape reflects its specialized function

Cell Diversity
 Cells that connect body parts
 Fibroblast
 Secretes cable-like fibers
 Erythrocyte (red blood cell)
 Carries oxygen in the bloodstream

Figure 3.8a Cell diversity.
Fibroblasts
Secreted
fibers
Rough ER and
Golgi apparatus
No organelles
Nucleus
Erythrocytes
(a) Cells that connect body parts

Cell Diversity
 Cells that cover and line body organs
 Epithelial cell
 Packs together in sheets
 Intermediate fibers resist tearing during rubbing or
pulling

Figure 3.8b Cell diversity.
Epithelial
cells
Nucleus
Intermediate
filaments
(b) Cells that cover and line body organs

Cell Diversity
 Cells that move organs and body parts
 Skeletal muscle and smooth muscle cells
 Contractile filaments allow cells to shorten forcefully

Figure 3.8c Cell diversity.
Skeletal
muscle cell
Contractile
filaments
Nuclei
Smooth
muscle cells
(c) Cells that move organs and body parts

Cell Diversity
 Cell that stores nutrients
 Fat cells
 Lipid droplets stored in cytoplasm

Figure 3.8d Cell diversity.
Fat cell Lipid droplet
Nucleus
(d) Cell that stores nutrients

Cell Diversity
 Cell that fights disease
 White blood cells, such as the macrophage (a
phagocytic cell)
 Digests infectious microorganisms

Figure 3.8e Cell diversity.
Lysosomes
Macrophage
Pseudopods
(e) Cell that fights disease

Cell Diversity
 Cell that gathers information and controls body
functions
 Nerve cell (neuron)
 Receives and transmits messages to other body
structures

Figure 3.8f Cell diversity.
Processes
Rough ER
Nerve cell
Nucleus
(f) Cell that gathers information and
controls body functions

Cell Diversity
 Cells of reproduction
 Oocyte (female)
 Largest cell in the body
 Divides to become an embryo upon fertilization
 Sperm (male)
 Built for swimming to the egg for fertilization
 Flagellum acts as a motile whip

Figure 3.8g Cell diversity.
Nucleus
Sperm
(g) Cell of reproduction
Flagellum

FUNCTION of the cell
•Ability to metabolize (use nutrients to build
new cell material, break down substances &
make ATP)
•Digest foods
•Dispose wastes
•Reproduce
•Grow
•Move
•Respond to stimulus

Plasma Membrane
 Barrier for cell contents and
separates them from the
surrounding environment.
 Double phospholipid layer
– Hydrophilic heads
– Hydrophobic tails
 A phospholipid has a
backbone derived in
carbon molecule called
GLYCEROL, with long
carbon called fatty acid.

Membrane Transport
•Protein synthesis
•Cell reproduction
- The means by which substances get through
plasma membranes.
FUNCTION:

TERMS:
•Solution
•Solvent
•Solutes
•Intracellular fluid
•Interstitial fluid
•Selective Permeability

Solutions and Transport
•Solution —homogeneous mixture of two or
more components (ex. Air that we breath, fluid
of plasma membrane, seawater, rubbing
alcohol)
•Solvent— largest amount in the solution
dissolving medium; typically water in the
body
•Solutes—components in smaller quantities
within a solution

Solutions and Transport
•Intracellular fluid—nucleoplasm and cytosol
- solution containing small amounts of
gases (O 2 and CO2). Nutrients in salts
dissolved in water.
•Interstitial fluid—fluid on the exterior of the cell
- continuously bathes the exterior of our
cell
- contains thousands of nutrients (amino
acids, sugars, fatty acids, vitamins),
regulatory subs. (hormones,
neurotransmitters, salts & waste
products)

Membrane Transport
•The plasma membrane is a selectively
permeable barrier
•Some materials can pass through, while
others are excluded
•For example:
•Nutrients can enter the cell
•Undesirable substances are kept out

A&P FlixTM: Membrane Transport

Cell Physiology: Membrane Transport
•Two basic methods of transport
•Passive processes
•No energy is required
•Active processes
•Cell must provide metabolic energy (ATP)

Cell Physiology: Membrane Transport
•Two types of Passive processes
•Diffusion
•Simple diffusion
•Osmosis
•Facilitated diffusion
•Filtration

Membrane Transport
•Diffusion
•Molecule movement is from high
concentration to low concentration, down
a concentration gradient
•Particles tend to distribute themselves
evenly within a solution
•Kinetic energy (energy of motion) causes
the molecules to move about randomly
•Size of the molecule and temperature
affect the speed of diffusion

Passive Processes
•Diffusion
•Molecules will diffuse only if:
(1) The molecules are small enough to pass through
the membrane’s pores.
(2) The molecule are lipid soluble
(3) The molecules are assisted by a membrane carrier

Passive Processes
•Types of diffusion
•Simple diffusion
•An unassisted process
•Solutes are lipid-soluble (fats, fat-soluble
vitamins, oxygen, carbon dioxide)
materials or small enough to pass through
membrane pores

© 2012 Pearson Education, Inc. Figure 3.10a
Cytoplasm
(a) Simple diffusion
of fat-soluble
molecules
directly through
the phospholipid
bilayer
Extracellular fluid
Lipid-
soluble
solutes

Passive Processes
•Types of diffusion (continued)
•Osmosis—simple diffusion of water
- is the net movement of solvent
molecules from a region of high solvent
potential to a region of lower solvent.
•Highly polar water molecules easily cross
the plasma membrane through aquaporins
(water pores) created by proteins in the
membrane.

© 2012 Pearson Education, Inc. Figure 3.10d
(d) Osmosis, diffusion
of water through a
specific channel
protein (aquaporin)
or through the lipid
bilayer
Water
molecules
Lipid
bilayer

• Isotonic – same solute & water concentration
- No changes in cells, RBCs retain their normal size & disc
like shape.
• Hypertonic – contains more solutes or dissolved subs, than there
inside the cells
- cell begin to shrink
- given to patients with edema (swelling of the feet and
hands due to fluid retention)
• Hypotonic – solution contains fewer solutes (ex. Distilled water)

Passive Processes
•Facilitated diffusion
•Transports lipid-insoluble and large
substances (glucose)
•Substances require a protein carrier for
passive transport (use a protein
membrane protein channel) to move
glucose & certain other solutes

(b) Carrier-mediated facilitated
diffusion via protein carrier
specific for one chemical;
binding of substrate causes
shape change in transport
protein
Lipid-
insoluble
solutes
(c) Channel-mediated
facilitated diffusion
through a channel
protein; mostly ions
selected on basis
of size and charge
Small lipid-
insoluble
solutes
Figure 3.10b–c

Passive Processes
•Filtration
• Water and solutes are forced through a
membrane by fluid, or hydrostatic pressure
• A pressure gradient must exist
• Solute-containing fluid is pushed from a
high-pressure area to a lower pressure
area

Active Processes
•Substances are transported that are unable to
pass by diffusion
•Substances may be too large
•Substances may not be able to dissolve in
the fat core of the membrane
•Substances may have to move against a
concentration gradient
•ATP is used for transport

Active Processes
•Two common forms of active transport
•Active transport (solute pumping)
•Vesicular transport
•Exocytosis
•Endocytosis
•Phagocytosis
•Pinocytosis

Active Processes
•Active transport (solute pumping)
•Amino acids, some sugars, and ions are
transported by protein carriers called solute
pumps
•ATP energizes protein carriers
•In most cases, substances are moved
against concentration gradients

© 2012 Pearson Education, Inc. Figure 3.11
Extracellular fluid
ADP
ATP
Binding of cytoplasmic
Na+ to the pump protein
stimulates phosphorylation
by ATP, which causes the
pump protein to change its
shape.
The shape change expels
Na+ to the outside.
Extracellular K+ binds,
causing release of the
phosphate group.
Loss of phosphate
restores the original
conformation of the pump
protein. K+ is released to the
cytoplasm and Na+ sites are
ready to bind Na+ again; the
cycle repeats.
Na+
Na+
Na+
Na+
Na+
Na+
K+
K+
P
P K+
K+
3
3
2
1
2
1
Cytoplasm

Active Processes
•Vesicular transport (bulk)
•Exocytosis
•Moves materials out of the cell

Extracellular
fluid
Molecule
to be
secreted
Secretory
vesicle Cytoplasm
Fusion pore formed
Fused
SNAREs
(a) The process of exocytosis
The membrane-
bound vesicle
migrates to the
plasma membrane.
There,
v-SNAREs bind
with t-SNAREs, the
vesicle and plasma
membrane fuse,
and a pore opens
up.
Vesicle
contents are
released to the
cell exterior.
3
2
1
Vesicle
SNARE
(v-SNARE)
Plasma
membrane
SNARE
(t-SNARE)
Figure 3.12a
• Material is carried
in a membranous
vesicle
• Vesicle
combines with
plasma
membrane
• Material is
emptied to the
outside
• Vesicle
migrates to
plasma
membrane

Active Processes
•Vesicular transport (continued)
•Endocytosis
•Extracellular substances are engulfed by
being enclosed in a membranous vesicle
•Types of endocytosis
•Phagocytosis—―cell eating‖
•Pinocytosis—―cell drinking‖

Extracellular
fluid
Vesicle
fusing with
lysosome
for digestion
Ingested
substance
Pit
Membranes and
receptors (if present)
recycled to plasma
membrane
Detached vesicle
containing ingested
material
Transport to plasma
membrane and exocytosis
of vesicle contents
Release of
contents to
cytosol
Cytosol Plasma
membrane
Lysosome
2
1
3
Vesicle
Figure 3.13a

(b)
Pseudopod
Bacterium
or other
particle
Cytoplasm
Extracellular
fluid
Figure 3.13b

(c)
Membrane
receptor
Figure 3.13c

Cell Cycle – series of changes a cell goes
through from the time it is formed
until it divides.
 Cells have two major periods
– Interphase (longer phase of cell cycle)
• Cell grows
• Cell carries on metabolic processes
– Cell division
• Cell replicates itself
• Function is to produce more cells for growth
and repair processes

Cell Division
 Preparations: DNA Replication
– Genetic material is duplicated and
readies a cell for division into two cells
– Occurs toward the end of interphase

Cell Division
 Process of DNA replication
– DNA uncoils into two nucleotide chains,
and each side serves as a template
– Nucleotides are complementary
• Adenine (A) always bonds with thymine (T)
• Guanine (G) always bonds with cytosine (C)
– For example, TACTGC bonds with new
nucleotides in the order ATGACG

Figure 3.14 Replication of the DNA molecule at the end of interphase.
KEY:
Adenine
Thymine
Cytosine
Guanine
Old
(template)
strand
Newly
synthesized
strand
New
strand
forming
DNA of one sister chromatid
Old (template)
strand

Cell Division
 Events of cell division
– Mitosis—division of the nucleus
• Results in the formation of two daughter
nuclei
– Cytokinesis—division of the cytoplasm
• Begins when mitosis is near completion
• Results in the formation of two daughter
cells

A&P Flix™: Mitosis

Stages of Mitosis
 Prophase (Prepares)
– First part of cell division
– Centrioles migrate to the poles to direct assembly of
mitotic spindle fibers
– DNA appears as double-stranded chromosomes
– Nuclear envelope breaks down and disappears

Stages of Mitosis
 Metaphase
– Chromosomes
are aligned in the
middle of the cell
on the metaphase
plate

Stages of Mitosis
 Anaphase
– Chromosomes are
pulled apart and
toward the
opposite ends of
the cell
– Cell begins to
elongate

Stages of Mitosis
 Telophase (terminate)
– Chromosomes uncoil
to become chromatin
– Nuclear envelope
reforms around
chromatin
– Spindles break down
and disappear

Stages of Mitosis
 Cytokinesis
– Begins during late anaphase and
completes during telophase
– A cleavage furrow forms to pinch the cells
into two parts
– Division of cytoplasm

Centrioles Chromatin
Forming
mitotic
spindle
Centrioles
Chromosome,
consisting of two
sister chromatids
Nuclear
envelope
Plasma
membrane
Interphase
Metaphase
plate
Nucleolus
Early prophase
Fragments of
nuclear envelope
Late prophase
Nucleolus
forming
Spindle
pole
Cleavage
furrow
Nuclear
envelope
forming
Telophase and cytokinesis
Daughter
chromosomes
Anaphase
Sister
chromatids
Spindle
Metaphase
Spindle
microtubules
Centromere
Centromere
Figure 3.15

Importance of Mitosis:
 Increasing the number of cells in a
particular tissue.
 Protection from harmful microorganism
in case of a cut or wound.
 Replacement of dead or inefficient cells
in a tissue.
 To maintain the cytoplasm to
nucleoplasm as well as surface area to
volume ratio.

What Happens When Mitosis Goes Wrong?
 Deletion – ex. Cri du chat and Prader-
Willi Syndrome
 Inversion
 Translocation
lymphomas, Down Syndrome,
leukemias and some psychiatric
disorders

 Changes in Chromosome Number
(Nondisjunction)
aneuploidy - new cells with either extra
or missing chromosomes
ex. Down Syndrome
Turner syndrome
Edward’s Syndrome
Patau Syndrome ; and
Kleinfelter’s Syndrome

 Mitotic Errors and Cancer
* cancer is some form of uncontrolled
cell growth; a result of deletions,
Inversions and translocations
*Such changes can alter control of the cell
cycle. They can also activate genes known
to be cancerous -- oncogenes. Changes may
also inactivate tumor-suppressing genes.

Protein Synthesis
 DNA serves as a blueprint for making proteins
 Gene: DNA segment that carries a blueprint for
building one protein or polypeptide chain
 Proteins have many functions
 Fibrous (structural) proteins are the building materials
for cells
 Globular (functional) proteins can act as enzymes
(biological catalysts)

Protein Synthesis
 DNA information is coded into a sequence of
bases
 A sequence of three bases (triplet) codes for an
amino acid
 For example, a DNA sequence of AAA specifies
the amino acid phenylalanine

Protein Synthesis
 The role of DNA
 Most ribosomes, the manufacturing sites of proteins,
are located in the cytoplasm
 DNA never leaves the nucleus in interphase cells
 DNA requires a decoder and a messenger to carry
instructions to build proteins to ribosomes
 Both the decoder and messenger functions are carried
out by RNA (ribonucleic acid)

Protein Synthesis
 How does RNA differ from DNA?
 RNA is single-stranded
 RNA contains ribose sugar instead of deoxyribose
 RNA contains uracil (U) base instead of thymine (T)

Protein Synthesis
 Three varieties of RNA
 Transfer RNA (tRNA): Transfers appropriate amino
acids to the ribosome for building the protein
 Ribosomal RNA (rRNA): Helps form the ribosomes
where proteins are built
 Messenger RNA (mRNA): Carries the instructions for
building a protein from the nucleus to the ribosome

Protein Synthesis
 Protein synthesis involves two major phases:
 Transcription
 Translation
 We will detail these two phases next

Protein Synthesis
 Transcription
 Transfer of information from DNA’s base sequence to
the complementary base sequence of mRNA
 DNA is the template for transcription; mRNA is the
product
 Each DNA triplet corresponds to an mRNA codon
 If DNA sequence is AAT-CGT-TCG, then the mRNA
corresponding codons are UUA-GCA-AGC

Figure 3.16a Protein synthesis (1 of 2).
Nucleus
(site of transcription)
DNA
gene
Cytoplasm
(site of translation)
mRNA specifying
one polypeptide is
made from a gene on
the DNA template by an
enzyme (not shown).
mRNA
Nuclear pore
Nuclear membrane Correct amino
acid attached to
each type of
tRNA by an
enzyme
Amino
acids
mRNA leaves nucleus
and attaches to ribosome,
and translation begins.
Synthetase
enzyme
1
2

Protein Synthesis
 Translation
 Base sequence of nucleic acid is translated to an
amino acid sequence; amino acids are the building
blocks of proteins
 Occurs in the cytoplasm and involves three major
varieties of RNA

Protein Synthesis
 Translation (continued)
 Steps correspond to Figure 3.16 (step 1 covers
transcription)
 Step 2: mRNA leaves nucleus and attaches to
ribosome, and translation begins
 Step 3: incoming tRNA recognizes a complementary
mRNA codon calling for its amino acid by temporarily
binding its anticodon to the codon

Figure 3.16 Protein synthesis.
Nucleus
DNA
gene
Cytoplasm
mRNA specifying
one polypeptide is
made from a gene on
enzyme (not shown).
mRNA
Nuclear pore
acid attached to
each type of
tRNA by an
enzyme
Amino
acids
mRNA leaves nucleus
Synthetase
enzyme
As the ribosome moves
along the mRNA, a new amino
acid is added to the growing
protein chain.
Growing
polypeptide
chain
tRNA ―head‖
bearing anticodon
Incoming tRNA
recognizes a complementary
mRNA codon calling for its
amino acid by temporarily
binding its anticodon to the
codon.
Peptide bond
Released tRNA
reenters the cytoplasmic
pool, ready to be recharged
with a new amino acid.
Large ribosomal subunit
Codon
Portion of
mRNA already
translated
Direction of ribosome
reading; ribosome
moves the mRNA strand
along sequentially
as each codon is read.
Small ribosomal subunit
IIe
Met
Gly
Ser
Ala
Phe
1
2
4
5
Slide 1
3

Figure 3.16 Protein synthesis (1 of 2).
Nucleus
DNA
gene
Cytoplasm
mRNA specifying
one polypeptide is
made from a gene on
enzyme (not shown).
mRNA
Nuclear pore
acid attached to
each type of
tRNA by an
enzyme
Amino
acids
Synthetase
enzyme
1
Slide 2

mRNA leaves
nucleus and attaches to
ribosome, and
translation begins.
2
Nucleus
DNA
gene
Cytoplasm
mRNA specifying
one polypeptide is
made from a gene on
enzyme (not shown).
mRNA
Nuclear pore
acid attached to
each type of
tRNA by an
enzyme
Amino
acids
Synthetase
enzyme
Slide 3
1

Incoming tRNA
codon.
tRNA ―head‖
bearing anticodon
Codon
Portion of
mRNA already
translated
reading; ribosome
along sequentially
IIe 3
Slide 4

Protein Synthesis
 Translation (continued)
 Steps correspond to Figure 3.16
 Step 4: as the ribosome moves along the mRNA, a new
amino acid is added to the growing protein chain
 Step 5: released tRNA reenters the cytoplasmic pool,
ready to be recharged with a new amino acid

Growing
polypeptide
chain
Incoming tRNA
codon.
tRNA ―head‖
bearing anticodon
Peptide bond
Codon
Portion of
mRNA already
translated
reading; ribosome
along sequentially
IIe
Met
Gly
Ser
Ala
Phe
Slide 5
As the ribosome moves along
the mRNA, a new amino acid is
added to the growing protein
chain.
3
4

As the ribosome moves along
the mRNA, a new amino acid is
added to the growing protein
chain.
Growing
polypeptide
chain
Incoming tRNA
codon.
tRNA ―head‖
bearing anticodon
Peptide bond
Released tRNA
Codon
Portion of
mRNA already
translated
reading; ribosome
along sequentially
IIe
Met
Gly
Ser
Ala
Phe
5
Slide 6
3
4

Figure 3.16 Protein synthesis. Slide 7
Nucleus
DNA
gene
Cytoplasm
mRNA specifying
one polypeptide is
made from a gene on
enzyme (not shown).
mRNA
Nuclear pore
acid attached to
each type of
tRNA by an
enzyme
Amino
acids
mRNA leaves nucleus
Synthetase
enzyme
As the ribosome moves
along the mRNA, a new amino
acid is added to the growing
protein chain.
Growing
polypeptide
chain
tRNA ―head‖
bearing anticodon
Incoming tRNA
codon.
Peptide bond
Released tRNA
Codon
Portion of
mRNA already
translated
reading; ribosome
along sequentially
IIe
Met
Gly
Ser
Ala
Phe
1
2
4
5
3

Part II: Body Tissues
 Tissues
 Groups of cells with similar structure and function
 Four primary types:
1. Epithelial tissue (epithelium)
2. Connective tissue
3. Muscle tissue
4. Nervous tissue

Epithelial Tissue
 Locations:
 Body coverings
 Body linings
 Glandular tissue
 Functions:
 Protection
 Absorption
 Filtration
 Secretion

Epithelial Tissue
 Hallmarks of epithelial tissues:
 Cover and line body surfaces
 Often form sheets with one free surface, the apical
surface, and an anchored surface, the basement
membrane
 Avascular (no blood supply)
 Regenerate easily if well nourished

Epithelial Tissue
 Classification of epithelia
 Number of cell layers
 Simple—one layer
 Stratified—more than one layer
 Shape of cells
 Squamous—flattened, like fish scales
 Cuboidal—cube-shaped, like dice
 Columnar—shaped like columns

Figure 3.17a Classification and functions of epithelia.
Apical surface
Basal
surface
Simple
Apical surface
Basal
surface Stratified
(a) Classification based on number
of cell layers

Figure 3.17b Classification and functions of epithelia.
Squamous
Cuboidal
Columnar
(b) Classification based on
cell shape

Figure 3.17c Classification and functions of epithelia.
Number of layers
Cell shape
Squamous
One layer: simple epithelial
tissues
Diffusion and filtration Secretion in
serous membranes
Secretion and absorption; ciliated types
propel mucus or reproductive cells
Secretion and absorption; ciliated types
More than one layer: stratified
epithelial tissues
Protection
Cuboidal
Columnar
Protection; these tissue types are rare
in humans
Transitional
(c) Function of epithelial tissue related to tissue type
Protection; stretching to accommodate
distension of urinary structures
No simple transitional epithelium exists

Epithelial Tissue
 Simple epithelia
 Functions in absorption, secretion, and filtration
 Very thin (so not suited for protection)

Epithelial Tissue
 Simple squamous epithelium
 Single layer of flat cells
 Locations—usually forms membranes
 Lines air sacs of the lungs
 Forms walls of capillaries
 Forms serous membranes (serosae) that line and cover
organs in ventral cavity
 Functions in diffusion, filtration, or secretion in
membranes

Figure 3.18a Types of epithelia and examples of common locations in the body.
Air sacs of
lungs
Nucleus of
squamous
epithelial cell
Nuclei of
squamous
epithelial
cells
Basement
membrane
(a) Diagram: Simple squamous
Photomicrograph: Simple squamous
epithelium forming part of the alveolar
(air sac) walls (275×).

Epithelial Tissue
 Simple cuboidal epithelium
 Single layer of cubelike cells
 Locations
 Common in glands and their ducts
 Forms walls of kidney tubules
 Covers the surface of ovaries
 Functions in secretion and absorption; ciliated types

Figure 3.18b Types of epithelia and examples of common locations in the body.
Nucleus of
simple
cuboidal
epithelial
cell
Basement
membrane
Simple
cuboidal
epithelial
cells
Basement
membrane
Connective
tissue
Photomicrograph: Simple cuboidal
epithelium in kidney tubules (250×).
(b) Diagram: Simple cuboidal

Epithelial Tissue
 Simple columnar epithelium
 Single layer of tall cells
 Goblet cells secrete mucus
 Locations
 Lining of the digestive tract from stomach to anus
 Mucous membranes (mucosae) line body cavities
opening to the exterior
 Functions in secretion and absorption; ciliated types

Figure 3.18c Types of epithelia and examples of common locations in the body.
Nuclei of simple
columnar epithelial cells
tend to line up
Mucus of a
goblet cell
Simple columnar
epithelial cell
Basement
membrane
Basement
membrane
(c) Diagram: Simple columnar
Photomicrograph: Simple columnar
epithelium of the small intestine (575×).

Epithelial Tissue
 Pseudostratified columnar epithelium
 All cells rest on a basement membrane
 Single layer, but some cells are shorter than others
giving a false (pseudo) impression of stratification
 Location: respiratory tract, where it is ciliated and
known as pseudostratified ciliated columnar epithelium
 Functions in absorption or secretion

Figure 3.18d Types of epithelia and examples of common locations in the body.
Pseudo-
stratified
epithelial
layer
Basement
membrane
Nuclei of
pseudostratified
cells do not line up
(d) Diagram: Pseudostratified (ciliated)
columnar
Cilia
Pseudostratified
epithelial layer
Basement
membrane
Connective tissue
Photomicrograph: Pseudostratified
ciliated columnar epithelium lining
the human trachea (560×).

Epithelial Tissue
 Stratified epithelia
 Consist of two or more cell layers
 Function primarily in protection

Epithelial Tissue
 Stratified squamous epithelium
 Most common stratified epithelium
 Named for cells present at the free (apical) surface,
which are squamous
 Functions as a protective covering where friction is
common
 Locations—lining of the:
 Skin (outer portion)
 Mouth
 Esophagus

Figure 3.18e Types of epithelia and examples of common locations in the body.
Nuclei
Stratified
squamous
epithelium Stratified
squamous
epithelium
Basement
membrane
Connective
tissue
Basement
membrane
Photomicrograph: Stratified
squamous epithelium lining of
the esophagus (140×).
(e) Diagram: Stratified squamous

Epithelial Tissue
 Stratified cuboidal epithelium—two layers of
cuboidal cells; functions in protection
 Stratified columnar epithelium—surface cells are
columnar, and cells underneath vary in size and
shape; functions in protection
 Stratified cuboidal and columnar
 Rare in human body
 Found mainly in ducts of large glands

Epithelial Tissue
 Transitional epithelium
 Composed of modified stratified squamous epithelium
 Shape of cells depends upon the amount of stretching
 Functions in stretching and the ability to return to
normal shape
 Location: lining of urinary system organs

Figure 3.18f Types of epithelia and examples of common locations in the body.
Basement
membrane
Transi-
tional
epithelium
Basement
membrane
Transitional
epithelium
Connective
tissue
Photomicrograph: Transitional epithelium lining of
the bladder, relaxed state (270×); surface rounded cells
flatten and elongate when the bladder fills with urine.
(f) Diagram: Transitional

Epithelial Tissue
 Glandular epithelia
 One or more cells responsible for secreting a particular
product
 Secretions contain protein molecules in an aqueous
(water-based) fluid
 Secretion is an active process

Epithelial Tissue
 Two major gland types develop from epithelial
sheets
 Endocrine glands
 Ductless; secretions (hormones) diffuse into blood
vessels
 Examples include thyroid, adrenals, and pituitary
 Exocrine glands
 Secretions empty through ducts to the epithelial surface
 Include sweat and oil glands, liver, and pancreas (both
internal and external)

Connective Tissue
 Found everywhere in the body to connect body
parts
 Includes the most abundant and widely
distributed tissues
 Functions
 Protection
 Support
 Binding

Connective Tissue
 Characteristics of connective tissue
 Variations in blood supply
 Some tissue types are well vascularized
 Some have a poor blood supply or are avascular
 Extracellular matrix
 Nonliving material that surrounds living cells

Connective Tissue
 Two main elements of the extracellular matrix
1. Ground substance—mostly water, along with
adhesion proteins and polysaccharide molecules
2. Fibers
 Collagen (white) fibers
 Elastic (yellow) fibers
 Reticular fibers (a type of collagen)

Connective Tissue
 Types of connective tissue from most rigid to
softest, or most fluid:
 Bone
 Cartilage
 Dense connective tissue
 Loose connective tissue
 Blood

Connective Tissue
 Bone (osseous tissue)
 Composed of:
 Osteocytes (bone cells) sitting in lacunae (cavities)
 Hard matrix of calcium salts
 Large numbers of collagen fibers
 Functions to protect and support the body

Figure 3.19a Connective tissues and their common body locations.
Osteocytes
(bone cells)
in lacunae Central canal
Lacunae
(a) Diagram: Bone Photomicrograph: Cross-sectional view
of bone (165×).

Connective Tissue
 Cartilage
 Less hard and more flexible than bone
 Found in only a few places in the body
 Chondrocyte (cartilage cell) is the major cell type
 Types
 Hyaline cartilage
 Fibrocartilage
 Elastic cartilage

Connective Tissue
 Hyaline cartilage
 Most widespread type of cartilage
 Abundant collagen fibers hidden by a glassy, rubbery
matrix
 Locations
 Trachea
 Attaches ribs to the breastbone
 Covers ends of long bones
 Entire fetal skeleton prior to birth
 Epiphyseal (growth) plates in long bones

Figure 3.19b Connective tissues and their common body locations.
Chondrocyte
(cartilage cell)
Chondrocyte
in lacuna
Lacunae
(b) Diagram: Hyaline cartilage
Matrix
Photomicrograph: Hyaline cartilage
from the trachea (400×).

Connective Tissue
 Elastic cartilage (not pictured)
 Provides elasticity
 Location: supports the external ear
 Fibrocartilage
 Highly compressible
 Location: forms cushionlike discs between vertebrae of
the spinal column

Figure 3.19c Connective tissues and their common body locations.
Chondrocytes
in lacunae
Chondro-
cytes in
lacunae
Collagen
fibers
(c) Diagram: Fibrocartilage
Collagen fiber
Photomicrograph: Fibrocartilage of an
intervertebral disc (150×).

Connective Tissue
 Dense connective tissue (dense fibrous tissue)
 Main matrix element is collagen fiber
 Fibroblasts are cells that make fibers
 Locations
 Tendons—attach skeletal muscle to bone
 Ligaments—attach bone to bone at joints and are more
elastic than tendons
 Dermis—lower layers of the skin

Figure 3.19d Connective tissues and their common body locations.
Ligament
Tendon
Collagen
fibers
Collagen
fibers
Nuclei of
fibroblasts
Nuclei of
fibroblasts
(d) Diagram: Dense fibrous Photomicrograph: Dense fibrous connective
tissue from a tendon (475×).

Connective Tissue
 Loose connective tissue
 Softer, have more cells and fewer fibers than other
connective tissues (except blood)
 Types
 Areolar
 Adipose
 Reticular

Connective Tissue
 Areolar connective tissue
 Most widely distributed connective tissue
 Soft, pliable tissue like ―cobwebs‖
 Functions as a universal packing tissue and ―glue‖ to
hold organs in place
 Layer of areolar tissue called lamina propria underlies
all membranes
 All fiber types form a loose network
 Can soak up excess fluid (causes edema)

Figure 3.19e Connective tissues and their common body locations.
Mucosal
epithelium
Lamina
propria
Elastic
fibers
Collagen
fibers
Elastic
fibers of
matrix
Fibroblast
nuclei
Nuclei of
fibroblasts
Collagen
fibers
(e) Diagram: Areolar Photomicrograph: Areolar connective tissue, a
soft packaging tissue of the body (270×).

Connective Tissue
 Adipose connective tissue
 An areolar tissue in which adipose (fat) cells dominate
 Functions
 Insulates the body
 Protects some organs
 Serves as a site of fuel storage
 Locations
 Subcutaneous tissue beneath the skin
 Protects organs, such as the kidneys
 Fat ―depots‖ include hips, breasts, and belly

Figure 3.19f Connective tissues and their common body locations.
Nuclei of
fat cells
Vacuole
containing
fat droplet
Nuclei of
fat cells
Vacuole
containing
fat droplet
(f) Diagram: Adipose Photomicrograph: Adipose tissue from the
subcutaneous layer beneath the skin (570×).

Connective Tissue
 Reticular connective tissue
 Delicate network of interwoven fibers with reticular
cells (like fibroblasts)
 Forms stroma (internal framework) of organs
 Locations
 Lymph nodes
 Spleen
 Bone marrow

Figure 3.19g Connective tissues and their common body locations.
Spleen
Reticular
cell
Blood
cell
Reticular
fibers
(g) Diagram: Reticular
White blood cell
(lymphocyte)
Reticular fibers
Photomicrograph: Dark-staining network
of reticular connective tissue (400×).

Connective Tissue
 Blood (vascular tissue)
 Blood cells surrounded by fluid matrix known as blood
plasma
 Soluble fibers are visible only during clotting
 Functions as the transport vehicle for the
cardiovascular system, carrying:
 Nutrients
 Wastes
 Respiratory gases

Figure 3.19h Connective tissues and their common body locations.
Blood cells
in capillary Plasma (fluid
matrix)
Neutrophil
(white blood
cell)
White
blood cell
Red
blood cells
Red blood
cells
Monocyte
(white blood
cell)
(h) Diagram: Blood Photomicrograph: Smear of human blood (1290×)

Muscle Tissue
 Function is to contract, or shorten, to produce
movement
 Three types of muscle tissue
1. Skeletal
2. Cardiac
3. Smooth

Muscle Tissue
 Skeletal muscle tissue
 Packaged by connective tissue sheets into skeletal
muscles, which are attached to the skeleton and pull
on bones or skin
 Voluntarily (consciously) controlled
 Produces gross body movements or facial expressions
 Characteristics of skeletal muscle cells
 Striations (stripes)
 Multinucleate (more than one nucleus)
 Long, cylindrical shape

Figure 3.20a Types of muscle tissue and their common locations in the body.
(a) Diagram: Skeletal muscle Photomicrograph: Skeletal muscle (195×).
Striations
Multiple nuclei
per fiber
Part of muscle
fiber

Muscle Tissue
 Cardiac muscle tissue
 Involuntarily controlled
 Found only in the heart
 Pumps blood through blood vessels
 Characteristics of cardiac muscle cells
 Striations
 One nucleus per cell
 Short, branching cells
 Intercalated discs contain gap junctions to connect cells
together

Figure 3.20b Types of muscle tissue and their common locations in the body.
Intercalated
discs
Nucleus
(b) Diagram: Cardiac muscle Photomicrograph: Cardiac muscle (475×).

Muscle Tissue
 Smooth (visceral) muscle tissue
 Involuntarily controlled
 Found in walls of hollow organs such as stomach,
uterus, and blood vessels
 Peristalsis, a wavelike activity, is a typical activity
 Characteristics of smooth muscle cells
 No visible striations
 One nucleus per cell
 Spindle-shaped cells

Figure 3.20c Types of muscle tissue and their common locations in the body.
Nuclei
Smooth
muscle cell
(c) Diagram: Smooth muscle Photomicrograph: Sheet of smooth muscle (360×).

Nervous Tissue
 Function is to receive and conduct
electrochemical impulses to and from body parts
 Irritability
 Conductivity
 Composed of neurons and nerve support cells
 Support cells called neuroglia insulate, protect, and
support neurons

Figure 3.21 Nervous tissue.
Brain
Spinal
cord
Nuclei of
neuroglia
(supporting
cells)
Cell body
of neuron
Neuron
processes
Diagram: Nervous tissue
Nuclei of
neuroglia
(supporting
cells)
Cell body
of neuron
Neuron
processes
Photomicrograph: Neurons (320×)

Summary of Tissues
 Figure 3.22 summarizes the tissue types and
functions in the body

Figure 3.22 Summary of the major functions, characteristics, and body locations of the four tissue types: epithelial, connective, muscle, and
nervous tissues.
Nervous tissue: Internal communication and control
Hallmarks: irritable, conductive
• Brain, spinal cord, and nerves
Muscle tissue: Contracts to cause movement
Hallmarks: irritable, contractile
• Muscles attached to bones (skeletal)
• Muscles of heart wall (cardiac)
• Muscles of walls of hollow organs (smooth)
Epithelial tissue: Forms boundaries between different
environments, protects, secretes, absorbs, filters
Hallmarks: one free (apical) surface, avascular
• Lining of GI tract and other hollow organs
• Skin surface (epidermis)
Connective tissue: Supports, protects, binds
other tissues together
Hallmarks: extracellular matrix, varying vascularity
• Cartilage
• Bones
• Tendons
• Fat and other soft padding tissue

Tissue Repair (Wound Healing)
 Tissue repair (wound healing) occurs in two ways:
1. Regeneration
 Replacement of destroyed tissue by the same kind of
cells
2. Fibrosis
 Repair by dense (fibrous) connective tissue (scar
tissue)

 Whether regeneration or fibrosis occurs depends
on:
1. Type of tissue damaged
2. Severity of the injury
 Clean cuts (incisions) heal more successfully
than ragged tears of the tissue

 Events of tissue repair
 Inflammation sets the stage
 Capillaries become very permeable
 Clotting proteins migrate into the area from the
bloodstream
 A clot walls off the injured area
 Granulation tissue forms
 Growth of new capillaries
 Phagocytes dispose of blood clot and fibroblasts
 Rebuild collagen fibers

 Events of tissue repair (continued)
 Regeneration and fibrosis effect permanent repair
 Scab detaches
 Whether scar is visible or invisible depends on severity
of wound

 Tissues that regenerate easily
 Epithelial tissue (skin and mucous membranes)
 Fibrous connective tissues and bone
 Tissues that regenerate poorly
 Skeletal muscle
 Tissues that are replaced largely with scar tissue
 Cardiac muscle
 Nervous tissue within the brain and spinal cord

Developmental Aspects of Cells and Tissues
 Growth through cell division continues through
puberty
 Cell populations exposed to friction (such as
epithelium) replace lost cells throughout life
 Connective tissue remains mitotic and forms
repair (scar) tissue
 With some exceptions, muscle tissue becomes
amitotic by the end of puberty
 Nervous tissue becomes amitotic shortly after
birth

 Injury can severely handicap amitotic tissues
 The cause of aging is unknown, but chemical and
physical insults, as well as genetic programming,
have been proposed as possible causes

 Neoplasms, both benign and cancerous,
represent abnormal cell masses in which normal
controls on cell division are not working
 Hyperplasia (increase in size) of a tissue or organ
may occur when tissue is strongly stimulated or
irritated
 Atrophy (decrease in size) of a tissue or organ
occurs when the organ is no longer stimulated
normally

CHAPTER 3: Anatomy and Physiology- Cells and Tissue

Recommended

Recommended

More Related Content

Similar to CHAPTER 3: Anatomy and Physiology- Cells and Tissue

Similar to CHAPTER 3: Anatomy and Physiology- Cells and Tissue (20)

More from ImmanuelCapurcosDuab

More from ImmanuelCapurcosDuab (13)

Recently uploaded

Recently uploaded (20)

CHAPTER 3: Anatomy and Physiology- Cells and Tissue