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CELLS AND TISSUES
Cells – Cell Theory
 In 1665, and English scientist named
Robert Hooke looked at empty cork cells
and identified the firs...
Cells – Cell Theory
 Robert Brown was the first
person to discover the nucleus:
the cell part that controls most
of the c...
Cells – Cell Theory
 All these ideas combined into the
modern Cell Theory:
 1. All living things are made of one or
more...
Cells – The basics
 All cells are primarily made of four
elements: Carbon, Oxygen, Hydrogen,
Nitrogen
 Living cells are ...
Cells – Interstitial Fluid
 In addition to large amounts of water,
the body cells are constantly covered in
a dilute salt...
Two main types of cells
Prokaryotic Cells Eukaryotic Cells
 “pro” means before
 More primitive
 Lack a nucleus
 DNA is...
What type of cell is this?
What about this one?
Cells – The generalized cell
 No one cell type is exactly like another
 Most do have the same parts
 Let’s talk about a...
Cells – The generalized cell
Cells – The generalized cell
The cell – The nucleus
 Nucleus: controls all of the cell’s
activities
 Contains DNA
 The “boss” of the cell
 Determin...
The cell – the nucleus
 Is enclosed by a nuclear membrane (or
nuclear envelope)
 Nuclear membrane: structure that
surrou...
The cell – the nucleus
 Nucleolus: the center of the nucleus
 Some cells contain multiple nucleoli
 Contains the DNA
 ...
The cell – the nucleus
 Chromatin: a loose network of DNA combined
with protein scattered throughout the nucleus
 When a...
The cell – the nucleus
The cell – the plasma
membrane
The cell – the plasma
membrane
 Plasma membrane: a fragile, transparent
barrier that contains the cell contents and
separ...
The cell – the plasma
membrane
 The plasma
membrane is a
phospholipid bilayer
 This means it has
two layers of fats
that...
The cell – the plasma
membrane
 The phospholipids each
have a hydrophilic and a
hydrophobic end
 This allows the
membran...
The cell – the plasma
membrane
 The proteins scattered in the lipid bilayer
are responsible for most of the
membrane’s sp...
The cell – Specializations of the
plasma membrane
 Let’s talk about microvilli
and membrane junctions
 Microvilli: tiny ...
The cell – specializations of the
plasma membrane
 Membrane junctions: specialized
connections between plasma
membranes
...
The cell – membrane junctions
 1. Tight junctions: impermeable
junctions that bind cells together into
leakproof sheets t...
The cell – membrane junctions
 Tight Junction
The cell – membrane junctions
 2. Desmosomes: anchoring junctions that
prevent cells subjected to mechanical
stress from ...
The cell – membrane junctions
 Desmosomes
The cell – membrane junctions
 3. Gap junctions: common to heart cells
and embryonic cells, these junctions
function main...
The cell – membrane junctions
 Gap junctions
The cell – the cytoplasm
 Cytoplasm: the cellular material outside
the nucleus and inside the plasma
membrane
 It is whe...
The cell – the cytoplasm
 The cytosol is the semitransparent fluid
that suspends the other elements
 The organelles or “...
The cell – the cytoplasm
Organelles - Mitochondria
 Mitochondria: energy-producing
organelle in animal cells
 Consists of two membranes
 The out...
Organelles – Mitochondria
 Break down food through the
process of cellular respiration
to form ATP molecules
 ATP molecu...
Organelles - Ribosomes
 Ribosomes: tiny, bilobed, dark bodies
made of proteins and RNA
 Site of protein synthesis in the...
Organelles - Ribosomes
 Ribosomes: tiny particles of RNA and
protein
 The sight of protein synthesis
 Two types:
 1. F...
Organelles – Endoplasmic
Reticulum
 Endoplasmic Reticulum: a system of
fluid-filled sacs and membranes located
near the n...
Organelles – Endoplasmic
Reticulum
 Endoplasmic Reticulum: a system of
fluid-filled canals (cisterns) that coil and
twist...
Organelles – Endoplasmic
Reticulum
 Two forms of the ER:
 1. Rough ER: studded with ribosomes
 All of the building mate...
Organelles – Endoplasmic
Reticulum
 2. Smooth ER: plays no role in protein
synthesis
 Functions in lipid metabolism and
...
Organelles – Endoplasmic
Reticulum
Organelles – Golgi
Apparatus
 Golgi Apparatus: flattened stack of
membranous sacs that modifies and
packages proteins and...
Organelles - Lysosomes
 Lysosomes: small, enzyme-filled
organelles
 Digest worn-out cell structures, foreign
substances,...
Organelles - Peroxisomes
 Peroxisomes: mebranous sacs
containing powerful oxidase enzymes
that use molecular oxygen to de...
Organelles - Peroxisomes
 Free radicals: highly reactive chemicals
with unpaired electrons that can
scramble the structur...
Organelles - Peroxisomes
 Peroxisomes convert free radicals to
hydrogen peroxide
 Are created by budding from the Golgi
...
Organelles - Cytoskeleton
 Cytoskeleton: an elaborate network of
protein
 the cell’s “bones and muscles”
 Determine:
 ...
Organelles - Cytoskeleton
 3 types of cytoskeleton:
 1. Microfilaments
 Involved in cell motility and changes in cell
s...
Organelles - Cytoskeleton
Organelles - Cytoskeleton
 Centrioles: rod-shaped bodies that lie at
right angles to each other
 Made up of fine microtu...
Organelles - Cytoskeleton
 Some cells have projections known as
cilia and flagella
 Cilia: whiplike cellular extensions ...
Organelles - Cytoskeleton
Cell Diversity
 1. Cells that connect body parts
 2. Cell that covers and lines body organs
 3. Cells that move organs ...
1. Cells that connect body parts
 Fibroblast: most common connective
cells in animals
 Elongated shape
 Secretes cable-...
1. Cells that connect body parts
 Erthrocyte: red blood cell
 Carries oxygen in the bloodstream
 Concave disk shape
 E...
2. Cells that cover and line
body organs
 Epithelial cell
 Hexagonal shape
 Allows cells to pack
together
 Many interm...
3. Cells that move organs and
body parts
 Skeletal muscle and smooth muscle
cells
 Elongated
 Filled with many contract...
4. Cells that store nutrients
 Fat cell (adipose cell)
 Large and spherical
 Produced by large lipid droplets in the
cy...
5. Cells that fight disease
 Macrophage (phagocytic cell)
 Long, extendable pseudopods (“false
feet”)
 Crawl through ti...
6. Cells that gather information
and control body functions
 Nerve cell (neuron)
 Has long processes for receiving and
t...
7. Cells of reproduction
 Oocyte (female): egg cell
 Largest cell in the body
 Contains several copies of all organelles
7. Cells of reproduction
 Sperm (male)
 Long and streamlined (built for
swimming)
 Flagellum acts as a motile whip to
p...
Membrane Transport
 The fluid environment on both sides of
the plasma membrane is an example of
a solution.
 Solution: a...
Membrane Transport - solutions
 Every solution is made of two major
components – a solvent and solutes
 Solvent: the sub...
Membrane Transport
 Intracellular Fluid: a solution containing small
amounts of gases, nutrients, and salts dissolved in
...
Membrane Transport
 Quick reminder!
 Plasma membranes are selectively or
semi-permeable
 This means they let some thing...
Membrane Transport
 Movement of substances through the
plasma membrane happens two ways
 1. Passive Transport
 2. Activ...
Passive Transport
 Passive Transport: movement in which
substances are transported across the
membrane without energy inp...
Passive Transport
 Diffusion: the
movement of
particles from an
area of high
concentration to an
area of low
concentratio...
Passive Transport
 The particles are said to
move down their
concentration gradient:
the gradual change in
the concentrat...
Passive Transport
 The hydrophobic core of the plasma
membrane makes it a physical barrier to
diffusion
 Particles will ...
Passive Transport
 Simple diffusion:
unassisted diffusion
of solutes through
the plasma
membrane
 Facilitated diffusion:...
Passive Transport
 Although facilitated diffusion follows the
laws of diffusion, a protein membrane
channel is used
 Thi...
Passive Transport
 Substances that
pass into and out
of cells by diffusion
save energy
 Includes the
movement of key
mol...
Passive Transport
 Osmosis: the diffusion of water
across a selectively permeable
membrane
 Remember water is highly pol...
Passive Transport
 Filtration: the process by which water
and solutes are forced through a
membrane by fluid, or hydrosta...
Passive Transport
 This is a passive process
 The gradient however, is the pressure
gradient that pushes solute-containi...
Active Transport
 Whenever a cell uses some of its ATP
supply to move substances across the
membrane, the process is cons...
Active Transport
 The ATP-energized protein carriers used
in active transport are called solute
pumps
 Amino acids, some...
Active Transport
 Movement against the concentration
gradient requires energy (ATP)
 Ex. Sodium-Potassium Pump
 Simulta...
Active Transport
Vesicular Transport
 Vesicular transport: moves substances
in or out of cells without their actually
crossing the plasma ...
Vesicular Transport
 Two main types:
 1. Endocytosis
 2. Exocytosis
Vesicular Transport
Endocytosis Exocytosis
 Endocytosis take up, or
engulf, extracellular
substances by enclosing
them in...
Vesicular Transport
 Three types of endocytosis:
 1. phagocytosis: “cell eating”
 Ingestion of solid substances
 2. pi...
Vesicular Transport
MITOSIS
Cell Division
 The cell life cycle is the series of
changes a cell goes through from the
time it is formed until it divid...
Cell Division – Cell Cycle
Cell Division - Interphase
 Interphase has three major stages
 1. G1 – Growth 1
 Cell increases in size
 2. S – Synthe...
Cell Division - Interphase
Cell Division
 Mitosis: division of the nucleus
 Cytokinesis: division of the cytoplasm
Cell Division
 Mitosis is divided into
four major phases:
 1. Prophase
 2. Metaphase
 3. Anaphase
 4. Telophase
 And...
1. Prophase
 As cell division begins, the chromatin
threads condense to form barlike bodies
called chromosomes (“colored ...
1. Prophase
 The centrioles separate from each other
and begin to move to opposite sides
(“poles”) of the cell
 The dire...
1. Prophase
 The nuclear envelope and nucleoli break
down and disappear
 Chromosome attach randomly to spindle
fibers at...
2. Metaphase
 The chromosome cluster and align
along the metaphase plate (center of the
spindle midway)
 Creates a strai...
3. Anaphase
 The centromeres split
 The sister chromatids split (now called
chromosomes again)
 Chromatids move to oppo...
4. Telophase
 Essentially prophase in reverse
 Chromosomes uncoil and become
chromatin again
 Spindle fibers break down...
4. Telophase
Cytokinesis
 Cytokinesis usually begins during late
anaphase and finishes in telophase
 A contractile ring of microfilam...
Cytokinesis
Mitosis and Cytokinesis
 Mitosis and Cytokinesis usually go
together, but sometimes the cytoplasm
does not divide
 This ...
Transcription and Translation
Protein Synthesis
 DNA is the blueprint for protein
synthesis
 A gene is defined as the DNA segment
that carries the inf...
Protein Synthesis - RNA
 DNA requires a messenger and a
decoder to complete the building of
proteins
 These jobs are car...
Protein Synthesis
 Protein Synthesis occurs in two major
phases:
 1. Transcription – when complementary
mRNA is made at ...
Protein Synthesis -
Transcription
 Transcription involves the
transfer of information from
DNA’s base sequence into
the c...
Protein Synthesis -
Transcription
 So if the DNA sequence is:
 ATG – TCT – GAA
 (triplets)
 The transcribed mRNA seque...
Protein Synthesis - Translation
 In translation the language
of nucleic acids (the base
sequence) is “translated”
into th...
Protein Synthesis - Translation
 Once the mRNA attaches to the
ribosome, tRNA comes into the picture
 Each tRNA carries ...
Protein Synthesis - Translation
Protein Synthesis - Translation
 Once the first tRNA has moved itself into
the correct position, the ribosome moves
the m...
Protein Synthesis
Body Tissues
 Tissues: groups of cells that are similar
in structure and function
 Four primary tissue types:
 1. Epith...
Epithelial Tissues
 Epithelial Tissue (epithelium): the lining,
covering and glandular tissue of the
body
 Helps form bo...
Epithelial Tissues
 Functions of the epithelium:
 Protection
 Absorption
 Filtration
 Secretion
Epithelial Tissues -
Characteristics
 1. Fit closely together (except glandular cells)
 Bound together by many desmosome...
Epithelial Tissues -
Classification
 Each epithelium is given two names
 The first indicates the relative number of
cell...
Epithelial Tissues -
Classification
 The classifications by cell arrangement are:
 Simple epithelium – one layer
 Strat...
Epithelial Tissues -
Classification
 The second indicates the shape of the
cell.
 There are:
 Squamous – flattened like...
Epithelial Tissues -
Classification
Epithelial Function
 Simple Epithelia are concerned mainly
with absorption, secretion and filtration
 Stratified epithel...
Glandular Epithelium
 A gland consists of one or more cells
that make and secrete a particular
product
 This product is ...
Glandular Epithelium
 Two major types of glands develop from
epithelial sheets:
 1. Endocrine glands
 2. Exocrine glands
Endocrine Glands
 Endocrine glands:
glands that lose their
connection to the
surface or duct (also
called ductless glands...
Exocrine Glands
 Exocrine glands:
gland that retain
their ducts
 Secretions empty
through the ducts to
the epithelial
su...
Glandular Epithelium
 The term secretion
also indicates an
active process in
which the glandular
cells obtain needed
mate...
Connective Tissue
 Connective Tissue: connects body parts
 Found everywhere in the body
 Most abundant and widely distr...
Connective Tissue
 The characteristics of connective tissue
include:
 1. Variations in blood supply
 Most connective ti...
Connective Tissue
 The extracellular matrix distinguishes
connective tissue from other cell types
 Has two main elements...
Connective Tissue
 The ground substance of the matrix is
composed largely of water plus some
adhesion proteins and large,...
Connective Tissue
 Various types and amounts of fibers are
in the matrix and form parts of the matrix
itself
 Including ...
Connective Tissues
 Because of the extracellular matrix,
connective tissue can form soft packing
tissue around organs, be...
Connective Tissue
 There is great variation in connective
tissue
 The major classes are:
 Bone
 Cartilage
 Dense Conn...
Connective Tissue - Bone
 Bone (osseous tissue)
 Composed on bone cells sitting in
cavities called lacunae (pits) and
su...
Connective Tissue - Bone
Connective Tissue -
Cartilage
 Less hard and more flexible than bone
 Found a few places in the body
 Most widespread i...
Connective Tissue -
Cartilage
 Forms supporting structures in the
larynx, attaches ribs to the breastbone,
covers ends of...
Connective Tissue
 There are other types of cartilage:
 Fibrocartilage: highly compressible that
forms the cushionlike d...
Connective Tissue
 Dense Connective Tissue:
collagen fibers as its main
matrix element
 Crowded between the collagen
fib...
Connective Tissue
 Tendons: attach skeletal muscles to
bones
 Ligaments: connect bones to bones at
joints
 Ligaments ar...
Connective Tissue
 Loose Connective Tissue: softer, have
more cells and fewer fibers
 Areolar Tissue: most widely distri...
Connective Tissue
 When a body region is inflamed, the
areolar tissue in the area soaks up the
excess fluid like a sponge...
Connective Tissue
 Adipose Tissue:
commonly called
fat, areolar tissue in
which fat cells
predominate
 Forms
subcutaneou...
Connective Tissue
 Reticular connective tissue: a delicate
network of interwoven reticular fibers
associated with reticul...
Connective Tissue
 Blood: (vascular tissue)
is considered connective
tissue because it
consists of blood cells
surrounded...
Muscle Tissue
 Muscle tissue: highly specialized to
contract, or shorten, to produce
movement
Muscle Tissue
 Three main types:
 1. skeletal muscle
 2. cardiac muscle
 3. smooth muscle
Muscle Tissue
 Skeletal Muscle
 attached to the skeleton
 can be controlled voluntarily
 when contracted they pull on
...
Muscle Tissue
 Cardiac Muscle
 Found only in the heart
 As it contracts, the heart acts as a pump
and propels blood thr...
Muscle Tissue
Muscle Tissue
 Smooth Muscle (visceral muscle)
 No visible striations
 Single nucleus, spindle-shaped
 Found in the wa...
Nervous Tissue
 Think neurons
 All neurons receive and conduct
electrochemical impulses from one part
of the body to ano...
Nervous Tissue
 Drawn out cytoplasm, allow for long
signal transmission
 With supporting cells, neurons make up
the stru...
Tissue Repair
 Tissue repair occurs in two major ways:
 Regeneration – replacement of
destroyed tissue by the same kind ...
Tissue Repair
 Tissue injury sets the following steps in
motion:
 1. capillaries become permeable
 Fluid rich in clotti...
Tissue Repair
Three other important
terms:
 Neoplasm: an abnormal mass of
proliferating cells
 Benign or malignant
 Hyperplasia: when...
Chapter 3   cells and tissues
Chapter 3   cells and tissues
Chapter 3   cells and tissues
Chapter 3   cells and tissues
Chapter 3   cells and tissues
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Chapter 3 cells and tissues

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Chapter 3 Cells and Tissues

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Chapter 3 cells and tissues

  1. 1. CELLS AND TISSUES
  2. 2. Cells – Cell Theory  In 1665, and English scientist named Robert Hooke looked at empty cork cells and identified the first cells  he used the word cell to describe the empty spaces in the cork
  3. 3. Cells – Cell Theory  Robert Brown was the first person to discover the nucleus: the cell part that controls most of the cell’s activities  Two German biologists Mathias Schleiden and Theodor Schwann formed the theory that all plants and animals are made up of cells
  4. 4. Cells – Cell Theory  All these ideas combined into the modern Cell Theory:  1. All living things are made of one or more cells  2. Cells are the basic units of structure and function  3. All cells come from existing cells
  5. 5. Cells – The basics  All cells are primarily made of four elements: Carbon, Oxygen, Hydrogen, Nitrogen  Living cells are about 60% water
  6. 6. Cells – Interstitial Fluid  In addition to large amounts of water, the body cells are constantly covered in a dilute saltwater solution called interstitial fluid  This fluid is derived from blood
  7. 7. Two main types of cells Prokaryotic Cells Eukaryotic Cells  “pro” means before  More primitive  Lack a nucleus  DNA is free floating  “eu” means true  More complex  Have a nucleus that contain DNA  Have organelles (“tiny organs”)
  8. 8. What type of cell is this?
  9. 9. What about this one?
  10. 10. Cells – The generalized cell  No one cell type is exactly like another  Most do have the same parts  Let’s talk about a generalized cell: a basic cell used to demonstrate most cell features
  11. 11. Cells – The generalized cell
  12. 12. Cells – The generalized cell
  13. 13. The cell – The nucleus  Nucleus: controls all of the cell’s activities  Contains DNA  The “boss” of the cell  Determines how and when proteins are made  Controls cell reproduction  The nucleus usually conforms to the shape of the cell
  14. 14. The cell – the nucleus  Is enclosed by a nuclear membrane (or nuclear envelope)  Nuclear membrane: structure that surrounds the nucleus and separates it from the rest of the cell  Nuclear pores: openings in the nuclear membrane that allows molecules to pass  Nucleoplasm: the jelly-like fluid between the two layers of the nuclear membrane
  15. 15. The cell – the nucleus  Nucleolus: the center of the nucleus  Some cells contain multiple nucleoli  Contains the DNA  Helps makes ribosomes  Contains chromatin
  16. 16. The cell – the nucleus  Chromatin: a loose network of DNA combined with protein scattered throughout the nucleus  When a cell is dividing, the Chromatin condenses and coils to form chromosomes  Chromosomes: threadlike structures with information that determines traits a living thing will have
  17. 17. The cell – the nucleus
  18. 18. The cell – the plasma membrane
  19. 19. The cell – the plasma membrane  Plasma membrane: a fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment  It is semi-permeable or selectively permeable which means it allows some things to pass while blocking others
  20. 20. The cell – the plasma membrane  The plasma membrane is a phospholipid bilayer  This means it has two layers of fats that line up tail to tail
  21. 21. The cell – the plasma membrane  The phospholipids each have a hydrophilic and a hydrophobic end  This allows the membrane to reseal itself quickly when damage occurs  A substantial amount of cholesterol is also found in the plasma membrane
  22. 22. The cell – the plasma membrane  The proteins scattered in the lipid bilayer are responsible for most of the membrane’s specialized functions  Ex. enzymes, hormone receptors, binding sites, protein channels, etc
  23. 23. The cell – Specializations of the plasma membrane  Let’s talk about microvilli and membrane junctions  Microvilli: tiny fingerlike projections that greatly increase the cell’s surface area to increase the rate of absorption
  24. 24. The cell – specializations of the plasma membrane  Membrane junctions: specialized connections between plasma membranes  Three main types are:  1. Tight junctions  2. Desmosomes  3. Gap junctions
  25. 25. The cell – membrane junctions  1. Tight junctions: impermeable junctions that bind cells together into leakproof sheets that prevent substances from passing through the extracellular space between cells  Plasma membranes fuse together like a zipper  Ex. in the small intestine, these junctions prevent digestive enzymes from seeping into the bloodstream
  26. 26. The cell – membrane junctions  Tight Junction
  27. 27. The cell – membrane junctions  2. Desmosomes: anchoring junctions that prevent cells subjected to mechanical stress from being pulled apart  Structurally these junctions are buttonlike thickenings of adjacent plasma membranes (plaques), connected by fine protein filaments  Thicker protein filaments extend from the plaques inside the cells to the plaques on the cells’ opposite side, forming an internal system of strong wires  Ex. skin cells
  28. 28. The cell – membrane junctions  Desmosomes
  29. 29. The cell – membrane junctions  3. Gap junctions: common to heart cells and embryonic cells, these junctions function mainly to allow communication  Chemical molecules (nutrients, ions, etc) pass directly from one cell to another through the gap  In gap junctions, the neighboring cells are connected by connexons: hollow cylinders composed of proteins that span the entire width of the adjoining membranes
  30. 30. The cell – membrane junctions  Gap junctions
  31. 31. The cell – the cytoplasm  Cytoplasm: the cellular material outside the nucleus and inside the plasma membrane  It is where most chemical reactions occur inside the cell  Made of three major elements:  1. the cytosol  2. the organelles  3. inclusions
  32. 32. The cell – the cytoplasm  The cytosol is the semitransparent fluid that suspends the other elements  The organelles or “tiny organs” are the machinery of the cell  Inclusions are chemical substances that may or may not be present, depend on the cell type  Include stored nutrient, lipids, glycogen, mucus, various crystallized products, etc
  33. 33. The cell – the cytoplasm
  34. 34. Organelles - Mitochondria  Mitochondria: energy-producing organelle in animal cells  Consists of two membranes  The outer is smooth and featureless  The inner contains shelflike protrusions called cristae
  35. 35. Organelles – Mitochondria  Break down food through the process of cellular respiration to form ATP molecules  ATP molecules provide the energy for all cellular work  “Busy” cells such as liver and muscles cells have larger amounts of mitochondria
  36. 36. Organelles - Ribosomes  Ribosomes: tiny, bilobed, dark bodies made of proteins and RNA  Site of protein synthesis in the cell  Two types:  Free – free floating in the cell  Bound/Attached – attached to the Endoplasmic Reticulum
  37. 37. Organelles - Ribosomes  Ribosomes: tiny particles of RNA and protein  The sight of protein synthesis  Two types:  1. Free – free-floating in the cytoplasm  2. Bound/Attached – found on the rough Endoplasmic Reticulum
  38. 38. Organelles – Endoplasmic Reticulum  Endoplasmic Reticulum: a system of fluid-filled sacs and membranes located near the nucleus that packages and exports protein, lipids and other small molecules.  Accounts for about half of a cell’s membrane
  39. 39. Organelles – Endoplasmic Reticulum  Endoplasmic Reticulum: a system of fluid-filled canals (cisterns) that coil and twist through the cytoplasm  Accounts for about half the cell’s membranes  Provides a network of channels for carrying substances
  40. 40. Organelles – Endoplasmic Reticulum  Two forms of the ER:  1. Rough ER: studded with ribosomes  All of the building materials of cellular membranes are formed either in or on it:  Proteins are packaged and sent out in transport vesicles  Greater number in organs that require more proteins, ○ Ex. pancreas
  41. 41. Organelles – Endoplasmic Reticulum  2. Smooth ER: plays no role in protein synthesis  Functions in lipid metabolism and detoxification  Therefore there are many smooth ER in liver cells
  42. 42. Organelles – Endoplasmic Reticulum
  43. 43. Organelles – Golgi Apparatus  Golgi Apparatus: flattened stack of membranous sacs that modifies and packages proteins and lipids  Forms secretory vesicles including lysosomes
  44. 44. Organelles - Lysosomes  Lysosomes: small, enzyme-filled organelles  Digest worn-out cell structures, foreign substances, etc  Many in phagocytes, cells that dispose of bacteria and debris
  45. 45. Organelles - Peroxisomes  Peroxisomes: mebranous sacs containing powerful oxidase enzymes that use molecular oxygen to detoxify a number of harmful or poisonous substances  Most important function is to “disarm” free radicals
  46. 46. Organelles - Peroxisomes  Free radicals: highly reactive chemicals with unpaired electrons that can scramble the structure of proteins and nucleic acids  Free radicals are usually produced by cellular respiration but if they accumulate they have devastating effects on the cell
  47. 47. Organelles - Peroxisomes  Peroxisomes convert free radicals to hydrogen peroxide  Are created by budding from the Golgi apparatus
  48. 48. Organelles - Cytoskeleton  Cytoskeleton: an elaborate network of protein  the cell’s “bones and muscles”  Determine:  Cell shape  Supports the organelles  Provides the machinery needed for intracellular transport and various types of cellular movement
  49. 49. Organelles - Cytoskeleton  3 types of cytoskeleton:  1. Microfilaments  Involved in cell motility and changes in cell shape  2. Microtubules  Determine the overall shape of a cell and the distribution of organelles  3. Intermediate Filaments  Help form desmosomes, resist pulling forces on the cell
  50. 50. Organelles - Cytoskeleton
  51. 51. Organelles - Cytoskeleton  Centrioles: rod-shaped bodies that lie at right angles to each other  Made up of fine microtubules  Best known for their role in cell division  (direct the formation of the mitotic spindle)
  52. 52. Organelles - Cytoskeleton  Some cells have projections known as cilia and flagella  Cilia: whiplike cellular extensions that move substances along the cell surface  Ex. ciliated respiratory cells moving mucus  Flagella: substantialy longer projections formed by the centrioles  only flagellated human cell is a sperm cell
  53. 53. Organelles - Cytoskeleton
  54. 54. Cell Diversity  1. Cells that connect body parts  2. Cell that covers and lines body organs  3. Cells that move organs and body parts  4. Cells that stores nutrients  5. Cells that fight disease  6. Cells that gather information and controls body functions  7. Cells of reproduction
  55. 55. 1. Cells that connect body parts  Fibroblast: most common connective cells in animals  Elongated shape  Secretes cable-like fibers  Produce large amounts of collagen  Abundant rough ER and large Golgi Apparatus (make and secrete necessary proteins  Important in wound healing
  56. 56. 1. Cells that connect body parts  Erthrocyte: red blood cell  Carries oxygen in the bloodstream  Concave disk shape  Extra surface area  So much oxygen-carrying pigment (hemoglobin) is packed in that other organelles have been excluded to make room
  57. 57. 2. Cells that cover and line body organs  Epithelial cell  Hexagonal shape  Allows cells to pack together  Many intermediate filaments that resist tearing
  58. 58. 3. Cells that move organs and body parts  Skeletal muscle and smooth muscle cells  Elongated  Filled with many contractile filaments  Can shorten with great force ○ Moves bone ○ Change size of internal organs
  59. 59. 4. Cells that store nutrients  Fat cell (adipose cell)  Large and spherical  Produced by large lipid droplets in the cytoplasm
  60. 60. 5. Cells that fight disease  Macrophage (phagocytic cell)  Long, extendable pseudopods (“false feet”)  Crawl through tissue to reach infection sites  Lysosomes within the cell digest the infectious microorganisms
  61. 61. 6. Cells that gather information and control body functions  Nerve cell (neuron)  Has long processes for receiving and transmitting messages  Processes are covered with an extensive plasma membrane  Large rough ER to synthesize membrane components
  62. 62. 7. Cells of reproduction  Oocyte (female): egg cell  Largest cell in the body  Contains several copies of all organelles
  63. 63. 7. Cells of reproduction  Sperm (male)  Long and streamlined (built for swimming)  Flagellum acts as a motile whip to propel the sperm
  64. 64. Membrane Transport  The fluid environment on both sides of the plasma membrane is an example of a solution.  Solution: a homogeneous mixture of two or more components
  65. 65. Membrane Transport - solutions  Every solution is made of two major components – a solvent and solutes  Solvent: the substance present in the largest amount that does the dissolving  Usually a fluid (liquid or gas)  Solute(s): the substance(s) present in smaller amount that get dissolved
  66. 66. Membrane Transport  Intracellular Fluid: a solution containing small amounts of gases, nutrients, and salts dissolved in water  Interstitial Fluid: the fluid that continuously bathes the exterior of our cells  A rich, nutritious “soup”  Contains amino acids, sugars, fatty acids, vitamins, etc
  67. 67. Membrane Transport  Quick reminder!  Plasma membranes are selectively or semi-permeable  This means they let some things pass while blocking others
  68. 68. Membrane Transport  Movement of substances through the plasma membrane happens two ways  1. Passive Transport  2. Active Transport
  69. 69. Passive Transport  Passive Transport: movement in which substances are transported across the membrane without energy input from the cell
  70. 70. Passive Transport  Diffusion: the movement of particles from an area of high concentration to an area of low concentration  High to Low, Go with the Flow!
  71. 71. Passive Transport  The particles are said to move down their concentration gradient: the gradual change in the concentration of solutes in a solution  Speed of diffusion is affected by the size of the molecules (smaller = faster) and temperature (warmer = faster)
  72. 72. Passive Transport  The hydrophobic core of the plasma membrane makes it a physical barrier to diffusion  Particles will still diffuse if:  1. they are small enough to pass through the membrane pores  2. they can dissolve in the fatty portion of the membrane  3. they are assisted by a membrane carrier
  73. 73. Passive Transport  Simple diffusion: unassisted diffusion of solutes through the plasma membrane  Facilitated diffusion: provides passage for certain needed substances that are both lipid-insoluble and too large to pass through the pores
  74. 74. Passive Transport  Although facilitated diffusion follows the laws of diffusion, a protein membrane channel is used  This acts as a transport vehicle
  75. 75. Passive Transport  Substances that pass into and out of cells by diffusion save energy  Includes the movement of key molecules like water, glucose, oxygen and carbon dioxide
  76. 76. Passive Transport  Osmosis: the diffusion of water across a selectively permeable membrane  Remember water is highly polar and is repelled by the non-polar core of the membrane, so it must pass through aquaporins  aquaporins: special pores created by membrane proteins that allow osmosis to occur
  77. 77. Passive Transport  Filtration: the process by which water and solutes are forced through a membrane by fluid, or hydrostatic pressure  In the body, this is usually seen in blood
  78. 78. Passive Transport  This is a passive process  The gradient however, is the pressure gradient that pushes solute-containing fluid (the filtrate) from high-pressure areas to low pressure areas  Important to kidneys
  79. 79. Active Transport  Whenever a cell uses some of its ATP supply to move substances across the membrane, the process is considered active  Active Transport: also called solute pumping, requires ATP –energized protein carriers to transport substances across the membrane
  80. 80. Active Transport  The ATP-energized protein carriers used in active transport are called solute pumps  Amino acids, some sugars, and most ions are transported across the membrane in this way  And in most cases, they travel against the concentration gradient  This is opposite to the direction in which substances would normally flow
  81. 81. Active Transport  Movement against the concentration gradient requires energy (ATP)  Ex. Sodium-Potassium Pump  Simultaneously carries Sodium (Na+) ions out of the cell and Potassium (K+) ions into the cell  The Na-K Pump is essential for normal nerve cell transmissions
  82. 82. Active Transport
  83. 83. Vesicular Transport  Vesicular transport: moves substances in or out of cells without their actually crossing the plasma membrane  Requires ATP
  84. 84. Vesicular Transport  Two main types:  1. Endocytosis  2. Exocytosis
  85. 85. Vesicular Transport Endocytosis Exocytosis  Endocytosis take up, or engulf, extracellular substances by enclosing them in a small membrane vesicle  Once the vesicle, or sac, is formed, it detaches from the plasma membrane and moves into the cytoplasm, where it fuses with a lysosome and its contents are digested  Exocytosis moves substances out of cells  Is how cells actively secrete hormones, mucus and other products  Products are packed in small vesicles or sac  The sac migrates to the plasma membrane and fuses  The contents are then spilled outwards
  86. 86. Vesicular Transport  Three types of endocytosis:  1. phagocytosis: “cell eating”  Ingestion of solid substances  2. pinocytosis: “cell drinking”  Ingestion of liquid substances  3. Receptor-mediated endocytosis: main cellular mechanism for taking up specific target molecules  Both receptor and the target molecule are taken into the vesicle
  87. 87. Vesicular Transport
  88. 88. MITOSIS
  89. 89. Cell Division  The cell life cycle is the series of changes a cell goes through from the time it is formed until it divides  The cycle has two major periods:  1. Interphase, in which the cell grows and carries on it usual metabolic activities  2. Cell Division, time when the cell reproduces itself
  90. 90. Cell Division – Cell Cycle
  91. 91. Cell Division - Interphase  Interphase has three major stages  1. G1 – Growth 1  Cell increases in size  2. S – Synthesis  DNA and organelles are replicated  3. G2 – Growth 2  Continued cell growth before division
  92. 92. Cell Division - Interphase
  93. 93. Cell Division  Mitosis: division of the nucleus  Cytokinesis: division of the cytoplasm
  94. 94. Cell Division  Mitosis is divided into four major phases:  1. Prophase  2. Metaphase  3. Anaphase  4. Telophase  And results in two identical daughter cells
  95. 95. 1. Prophase  As cell division begins, the chromatin threads condense to form barlike bodies called chromosomes (“colored bodies”)
  96. 96. 1. Prophase  The centrioles separate from each other and begin to move to opposite sides (“poles”) of the cell  The direct the assembly of the mitotic spindle  The mitotic spindle provides the structure for attachment and movement of the chromosomes for the duration of mitosis
  97. 97. 1. Prophase  The nuclear envelope and nucleoli break down and disappear  Chromosome attach randomly to spindle fibers at the centromere
  98. 98. 2. Metaphase  The chromosome cluster and align along the metaphase plate (center of the spindle midway)  Creates a straight line of chromosomes
  99. 99. 3. Anaphase  The centromeres split  The sister chromatids split (now called chromosomes again)  Chromatids move to opposite poles of the cell  When chromosome movement ends
  100. 100. 4. Telophase  Essentially prophase in reverse  Chromosomes uncoil and become chromatin again  Spindle fibers break down and disappear  Nuclear envelopes reform and nucleoli reappear around each group of chromatin
  101. 101. 4. Telophase
  102. 102. Cytokinesis  Cytokinesis usually begins during late anaphase and finishes in telophase  A contractile ring of microfilaments forms a cleavage furrow over the midline of the spindle  This squeezes the original cytoplasmic mass into two parts  Each daughter cell is smaller, but genetically identical
  103. 103. Cytokinesis
  104. 104. Mitosis and Cytokinesis  Mitosis and Cytokinesis usually go together, but sometimes the cytoplasm does not divide  This creates binucleated or multinucleated cells  This is common in liver cells
  105. 105. Transcription and Translation
  106. 106. Protein Synthesis  DNA is the blueprint for protein synthesis  A gene is defined as the DNA segment that carries the information for building one protein of a poly peptide chain
  107. 107. Protein Synthesis - RNA  DNA requires a messenger and a decoder to complete the building of proteins  These jobs are carried our by RNA  There are three varieties of RNA involved in protein synthesis:  1. transfer RNA (tRNA)  2. ribosomal RNA (rRNA)  3. messenger RNA (mRNA)
  108. 108. Protein Synthesis  Protein Synthesis occurs in two major phases:  1. Transcription – when complementary mRNA is made at the DNA gene  2. Translation – when the information carried in the mRNA molecules is “decoded” and used to assemble proteins
  109. 109. Protein Synthesis - Transcription  Transcription involves the transfer of information from DNA’s base sequence into the complementary base sequence of mRNA  Occurs in the nucleus  Only DNA and mRNA are involved in transcription  Each DNA triplet (three-base sequence) complements a mRNA codon
  110. 110. Protein Synthesis - Transcription  So if the DNA sequence is:  ATG – TCT – GAA  (triplets)  The transcribed mRNA sequence is:  UAC – AGA – CUU  (codons)
  111. 111. Protein Synthesis - Translation  In translation the language of nucleic acids (the base sequence) is “translated” into the language of proteins (amino acids)  Occurs in the cytoplasm  Involves three major varieties of RNA
  112. 112. Protein Synthesis - Translation  Once the mRNA attaches to the ribosome, tRNA comes into the picture  Each tRNA carries or “transfers” an amino acid to the ribosome  They match a three-base anticodon with the codon of the mRNA as it reads through the ribsome
  113. 113. Protein Synthesis - Translation
  114. 114. Protein Synthesis - Translation  Once the first tRNA has moved itself into the correct position, the ribosome moves the mRNA strand along, bringing the next codon into position to be read by the tRNA  As each amino acid is brought in, they are joined together by enzymes  As the amino acids join, each tRNA is released  When the last codon, or “stop” codon is read, the protein is released
  115. 115. Protein Synthesis
  116. 116. Body Tissues  Tissues: groups of cells that are similar in structure and function  Four primary tissue types:  1. Epithelial (covering)  2. Connective (support)  3. Muscular (movement)  4. Nervous (control)
  117. 117. Epithelial Tissues  Epithelial Tissue (epithelium): the lining, covering and glandular tissue of the body  Helps form boundaries and separate  Nearly all substances the body gives off or receives must pass through the epithelium
  118. 118. Epithelial Tissues  Functions of the epithelium:  Protection  Absorption  Filtration  Secretion
  119. 119. Epithelial Tissues - Characteristics  1. Fit closely together (except glandular cells)  Bound together by many desmosomes and tight junctions  2. One free edge or surface  Apical surface  3. Lower surface rests on a basement membrane  4. No blood supply of their own  Avascular  Depend on diffusion from the capillaries  5. Regenerate themselves, if well nourished
  120. 120. Epithelial Tissues - Classification  Each epithelium is given two names  The first indicates the relative number of cell layers
  121. 121. Epithelial Tissues - Classification  The classifications by cell arrangement are:  Simple epithelium – one layer  Stratified epithelium – more than one layer
  122. 122. Epithelial Tissues - Classification  The second indicates the shape of the cell.  There are:  Squamous – flattened like scales  Cuboidal – Cube-shaped  Columnar – Column-shaped  (stratified epithelia are named for the cells at the free surface not those on the basement membrane)
  123. 123. Epithelial Tissues - Classification
  124. 124. Epithelial Function  Simple Epithelia are concerned mainly with absorption, secretion and filtration  Stratified epithelia function primarily to protect
  125. 125. Glandular Epithelium  A gland consists of one or more cells that make and secrete a particular product  This product is called a secretion  Usually consists of protein molecules in an aqueous solution fluid
  126. 126. Glandular Epithelium  Two major types of glands develop from epithelial sheets:  1. Endocrine glands  2. Exocrine glands
  127. 127. Endocrine Glands  Endocrine glands: glands that lose their connection to the surface or duct (also called ductless glands)  Secretions diffuse directly into the blood vessels that weave through the gland  Ex. thyroid, adrenals, pituitary
  128. 128. Exocrine Glands  Exocrine glands: gland that retain their ducts  Secretions empty through the ducts to the epithelial surface  Ex. sweat and oil glands, liver, pancreas
  129. 129. Glandular Epithelium  The term secretion also indicates an active process in which the glandular cells obtain needed materials from the blood and use them to make their secretion, which they then discharge
  130. 130. Connective Tissue  Connective Tissue: connects body parts  Found everywhere in the body  Most abundant and widely distributed of the tissue types
  131. 131. Connective Tissue  The characteristics of connective tissue include:  1. Variations in blood supply  Most connective tissue is well vascularized  Exceptions – Ligaments, Tendons, Cartilages ○ As a result these heal very slowly  2. Extracellular Matrix  Varying amounts of a nonliving substance outside the cells
  132. 132. Connective Tissue  The extracellular matrix distinguishes connective tissue from other cell types  Has two main elements – a structureless ground substance and fibers
  133. 133. Connective Tissue  The ground substance of the matrix is composed largely of water plus some adhesion proteins and large, charged polysaccharides  The adhesion proteins are the “glue” that allows the connective tissues to attach themselves to matrix fibers embedded in the ground substance  The charged polysaccharides trap water as they intertwine
  134. 134. Connective Tissue  Various types and amounts of fibers are in the matrix and form parts of the matrix itself  Including collagen (white) fibers, elastic (yellow) fibers and reticular (fine collagen) fibers
  135. 135. Connective Tissues  Because of the extracellular matrix, connective tissue can form soft packing tissue around organs, bear weight, and withstand stretching and other abuses
  136. 136. Connective Tissue  There is great variation in connective tissue  The major classes are:  Bone  Cartilage  Dense Connective  Loose Connective  Blood
  137. 137. Connective Tissue - Bone  Bone (osseous tissue)  Composed on bone cells sitting in cavities called lacunae (pits) and surrounded by layers of a very hard matrix that contains calcium salts and large numbers of collagen fibers  Important in protecting and supporting other body organs
  138. 138. Connective Tissue - Bone
  139. 139. Connective Tissue - Cartilage  Less hard and more flexible than bone  Found a few places in the body  Most widespread is hyaline cartilage: abundant collagen fibers hidden by a rubbery matrix with a glassy blue-white appearance
  140. 140. Connective Tissue - Cartilage  Forms supporting structures in the larynx, attaches ribs to the breastbone, covers ends of bones at joints
  141. 141. Connective Tissue  There are other types of cartilage:  Fibrocartilage: highly compressible that forms the cushionlike disks between the vertebrae of the spinal column  Elastic cartilage: is found where a structure where elasticity is desired  Ex. external ear
  142. 142. Connective Tissue  Dense Connective Tissue: collagen fibers as its main matrix element  Crowded between the collagen fibers are rows of fibroblasts that manufacture the building blocks of the fibers  Forms tendons and ligaments
  143. 143. Connective Tissue  Tendons: attach skeletal muscles to bones  Ligaments: connect bones to bones at joints  Ligaments are more stretchy and elastic than tendons
  144. 144. Connective Tissue  Loose Connective Tissue: softer, have more cells and fewer fibers  Areolar Tissue: most widely distributed connective tissue variety in the body  Cushions and protects body organs
  145. 145. Connective Tissue  When a body region is inflamed, the areolar tissue in the area soaks up the excess fluid like a sponge, and the area swells and becomes puffy  This is called an edema
  146. 146. Connective Tissue  Adipose Tissue: commonly called fat, areolar tissue in which fat cells predominate  Forms subcutaneous tissue
  147. 147. Connective Tissue  Reticular connective tissue: a delicate network of interwoven reticular fibers associated with reticular cells, which resemble fibroblasts  Forms stroma, the internal framework which can support many free blood cells and in lymphoid organs
  148. 148. Connective Tissue  Blood: (vascular tissue) is considered connective tissue because it consists of blood cells surrounded by nonliving, fluid matrix called blood plasma  The “fibers” of blood are soluble protein molecules that become visible only during blood clotting
  149. 149. Muscle Tissue  Muscle tissue: highly specialized to contract, or shorten, to produce movement
  150. 150. Muscle Tissue  Three main types:  1. skeletal muscle  2. cardiac muscle  3. smooth muscle
  151. 151. Muscle Tissue  Skeletal Muscle  attached to the skeleton  can be controlled voluntarily  when contracted they pull on bones or skin  the cells of skeletal muscle are long, cylindrical, multinucleate and have obvious striations
  152. 152. Muscle Tissue  Cardiac Muscle  Found only in the heart  As it contracts, the heart acts as a pump and propels blood through the blood vessels  Has striations  Uninucleate, relatively short, branching, and fit tightly together through intercalated disks  Under involuntary control
  153. 153. Muscle Tissue
  154. 154. Muscle Tissue  Smooth Muscle (visceral muscle)  No visible striations  Single nucleus, spindle-shaped  Found in the walls of hollow organs  As it contracts, the cavity of an organ contracts or enlarges  Contracts more slowly than the other two types  Ex. peristalsis
  155. 155. Nervous Tissue  Think neurons  All neurons receive and conduct electrochemical impulses from one part of the body to another  Irritability and conductivity are their two major functional characteristics
  156. 156. Nervous Tissue  Drawn out cytoplasm, allow for long signal transmission  With supporting cells, neurons make up the structures of the nervous system
  157. 157. Tissue Repair  Tissue repair occurs in two major ways:  Regeneration – replacement of destroyed tissue by the same kind of cells  Fibrosis – involves repair by dense connective tissue by the formation of scar tissue  Depends on the type of tissue damaged and the severity of the injury
  158. 158. Tissue Repair  Tissue injury sets the following steps in motion:  1. capillaries become permeable  Fluid rich in clotting proteins seep into the injured areas  2. granulation tissue forms  Delicate pink tissue composed largely of new capillaries  3. surface epithelium regenerates  Makes its way across the granulation tissue
  159. 159. Tissue Repair
  160. 160. Three other important terms:  Neoplasm: an abnormal mass of proliferating cells  Benign or malignant  Hyperplasia: when certain body tissues may enlarge because there is some local irritant or condition that stimulates the cells  Atrophy: a decrease in size in an organ or body area that loses its normal stimulation

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