Chapter 4: The Tissue Level of Organization

1
Chapter 4 The Tissue Level of Organization
2
Introduction

• Tissue
• Collection of specialized cells that perform
  limited number of functions
• Histology
• The study of tissues
• What are the four tissues of the body?

3
The four tissues of the Body

• Epithelial Tissue covering
• Covers exposed surfaces
• Lines internal passageways
• Forms glands
• Connective Tissue support
• Fills internal spaces
• Provides structure and strength to support other
  tissues
• Transports materials
• Stores energy

4
The four tissues of the Body

• Muscle Tissue movement
• Specialized for contraction
• Skeletal muscle, heart muscle, and walls of
  hollow organs
• Neural Tissue control
• Carries electrical signals from 1 part of the
  body to another

5
Primary Germ Layer

• Embryonic layers give rise to all four tissue
  types in adults
• Ectoderm nervous, epithelial (epidermis)
• Mesoderm muscle, connective, epithelial
  (endothelium mesothelium)
• Endoderm epithelial (mucosa)

6
KEY CONCEPT

• Tissues are collections of cells and cell
  products that perform specific, limited functions
• 4 tissue types form all the structures of the
  human body
• epithelial, connective, muscle, and neural

7
Epithelial Tissues

• 2 categories
• Epithelia
• layers of cells covering internal or external
  surfaces
• Glands
• structures that produce fluid secretions

8
Special structures and functions of Epithelial
Tissues.
9
Characteristics of Epithelia

• Structures of Epithelia
• Cellularity
• little extracellular matrix, mostly cells
• Contacts
• cells linked by tight junctions
• Polarity
• apical basal surfaces, separate functions
• Attachment
• attached to connective tissue (CT) via basal
  lamina
• Avascularity
• diffusion of CT
• Regeneration
• high turnover, stem cells at basal surface

10
Characteristics of Epithelia

• Functions of Epithelia
• Provide physical protection
• abrasion, dehydration, infection
• Control permeability
• semi-permeability, covers all surfaces
• Provide sensation
• sensory neurons
• Produce specialized secretions (glandular
  epithelium)
• protection, chemical messengers

11
Free Surface and Attached Surface

• 1. Apical Surface exposed to environment, may
  have
• Microvilli absorption or secretion
• Cilla fluid movement
• 2. Basolateral Surface attachment to
  neighboring cells via intercellular connections

Figure 41
12
Intercellular Connections

• Support and communication
• General Adhesion Large Connections
• 1. CAMs (cell adhesion molecules)
• Connect adjacent membranes or binds extracellular
  materials (e.g. basal lamina)
• 2. Intercellular cement
• Thin layer of hyaluronan (proteoglycan)
• Attach adjacent membranes
• Specific AdhesionCell Junctions
• Tight Junctions
• Gap Junctions
• Desmosomes

13
Cell Junctions

• Form bonds with other cells or extracellular
  material
• Tight Junctions
• interlocking proteins, bind lipid portion of
  membrane, water tight seal
• Gap Junctions
• connexons form channel, allow molecules to pass
  for communication
• Desmosomes
• CAMs intercellular cement on dense area
  attached to cytoskeleton, resist stretching and
  twisting

14
Tight Junctions

• Between 2 cell membranes
• interlocking proteins, bind lipid portion of
  membrane, water tight seal
• Prevents passage of water and solutes

Figure 42b
15
Gap Junctions

• Connexons form protein channels, allow molecules
  to pass for communication
• Rapid communication
• Allow ions to pass
• Coordinated contractions in heart muscle

Figure 42c
16
Desmosomes

• Cell Adhesion Molecules
• intercellular cement on dense area
• are attached to the cytoskeleton
• - resist stretching and twisting
• Belt Desmosomes
• -continuous band in apical region, attached
  to microfilaments
• Button Desmosomes
• - spot weld, attached to intermediate
  filaments
• 3. Hemidesmosomes
• - Half button desmosome at basal
• surface, attaches to basal lamina

Figure 42d
17
Basal Lamina (a.k.a. basement membrane)

• Lamina lucida
• Produced by epithelia
• Glycoproteins fine filaments restrict large
  molecule movement
• Lamina densa
• Produced by connective tissue
• Coarse protein fibers
• Provides strength and filtration

18
Repairing and Replacing Epithelia

• Epithelia stem cells are anchored to lamina
  lucida
• Epithelia are replaced by division of germinative
  cells (stem cells)
• Stem cells divide and migrate toward apical region

19
Classes of Epithelia

• Based on shape and layers
• Shape (all are hexagonal from the top)
• Squamous flat, disc shaped nucleus
• Cuboidal cube or square, center round nucleus
• Columnar tall, basal oval nucleus

Table 41
20
Layers

• Simple epithelium
• single layer of cells
• Function
• absorption, secretion, filtration
• Stratified epithelium
• 2 or more layers of cells
• Function
• Protection
• In stratified, name for apical cell shape

21
Eight Types of Epithelial Tissues

• Simple squamous epithelium
• Stratified squamous epithelium
• Simple cuboidal epithelium
• Stratified cuboidal epithelium
• Transitional epithelium
• Simple columnar epithelium
• Pseudostratified columnar epithelium
• Stratified columnar epithelium

22
1. Simple Squamous Epithelium

• Thin, delicate
• Locations found in protected regions
• Mesothelium (serosa), endothelium (blood vessels,
  heart), kidney tubules, cornea, and alveoli of
  lungs
• Functions
• Absorption, diffusion, filtration, or secretion

Figure 43a
23
2. Stratified Squamous Epithelium

• Basal cells look cuboidal, apical cells squamous
• Found on exposed surfaces
• Functions provide protection from abrasion,
  pathogens, and chemicals
• Two types
• Nonkeratinized mucosa
• - Kept moist
• - All cells are nucleated
• Location mouth, esophagus, anus, and vagina
• Keratinized epidermis
• - dry, apical cells dead
• - cells contain keratin protein to resist
  dehydration and adds strength

Figure 43b
24
3. Simple Cuboidal Epithelia

• Location Functions
• Kidney tubules - Secretion
• Pancreas -Absorption
• Salivary glands
• Thyroid

25
4. Stratified Cuboidal Epithelium

• Rare
• Typically 2 layers
• Location Function
• Some sweat glands - Secretion
• Some mammary glands - Absorption

Figure 44b
26
5. Transitional Epithelium

• Relaxed looks like stratified cuboidal
• Stretched looks squamous
• Location Function
• Urinary bladder - tolerate excessive
  stretching
• Ureters

Figure 44c
27
Columnar Epithelia

• Simple columnar epithelium
• absorption and secretion
• Pseudostratified columnar epithelium
• cilia movement
• Stratified columnar epithelium
• protection

28
6. Simple Columnar Epithelium

• Nuclei line up near the basal lamina
• Apical surface of cells often has microvilli
  brush border (in intestine)
• Goblet cells often present secrete mucus
• Locations
• Stomach, intestine, gall bladder, uterine tubes,
  and collecting ducts of kidney
• Functions
• Absorption or secretion

Figure 45a
29
7. Pseudostratified Columnar Epithelium

• Several cell types varying shapes and functions
• All cells contact basal lamina
• Some too short to reach apical surface
• Nuclei scattered so it appears stratified
• Tall cells have cilia on apical surface
• Goblet cells (mucus) often present
• Location
  Function
• Nasal cavity, trachea, bronchi -
  move material
• Male reproductive tract
  across surface
• Female uterine tubes

Figure 45b
30
8. Stratified Columnar Epithelium

• Rare
• Two layers or multiple layers with only apical
  layer columnar
• Locations (tiny parts of)
• Pharynx, epiglottis, anus, mammary glands,
  salivary glands, and urethra
• Functions
• Minor protection

Figure 45c
31
Glandular Epithelia

• For secretion, makes up glands
• Endocrine glands internally secreting
• -secrete into interstital fluid ? blood
• -secretions hormones
• -regulate and coordinate activities
• e.g. pancreas, thyroid, thymus, pituitary
• Exocrine glands externally secreting
• -secrete into duct ? epithelial surface
• -e.g. digestive enzymes, perspiration,
  tears, milk, and mucus
• -Classified three ways
• 1. Mode of Secretion
• 2. Type of Secretion
• 3. Structure

32
A. Modes of Secretion

• 1. Merocrine secretion
• -product released from secretory vesicles by
  exocytosis
• -e.g. mucus, sweat
• Apocrine Secretion
• - product accumulates in vesicles
• - apical region of cell which vesicles is
  shed to release product
• -e.g. milk

Figure 46a
33
Modes of Secretion

• 3. Holocrine secretion
• - product accumulates in vesicles
• - whole cell is lysed to release product
• - cell dies, must be replaced by stem cells
• e.g. sebum

Figure 46c
34
B. Types of Secretion

• Serous Glands water enzymes
• - e.g. parotid salivary gland
• Mucus Glands mucin
• (water mucus)
• - e.g. goblet cell
• Mixed exocrine glands
• (serous mucus secretion)
• -e.g. submandibular salivary gland

35
C. Gland Structure

• Exocrine glands can be classified as
• unicellular glands 1 cell
• E.g. goblet cell which are scattered among
  epithelia
• Found in intestinal lining
• multicellular glands group of cells named for
  shape and structure

36
Structure of Multicellular Exocrine Glands

• Structural classes of exocrine glands

Simple Glands undivided
tube shape blind
pockets chamberlike
Figure 47 (1 of 2)
37
Structure of Multicellular Exocrine Glands
Compound Glands Divided
tube shaped blind pockets
chamberlike
Figure 47 (2 of 2)
38
Which of the following is NOT a characteristic of
epithelial tissue?
A. It is composed entirely of cells. B. It
stores energy reserves. C. It is avascular. D.
It is capable of regeneration.
39
An epithelial surface bears many microvilli.
What is the probable function of this epithelium?
A. absorption B. secretion C. transportation D.
sensation
40
What is the functional significance of gap
junctions?
A. They maintain water-tight passages. B. They
resist stretching and twisting. C. They
coordinate the function of tissue. D. They
attach cells to extracellular matrix.
41
Using a light microscope, you examine a tissue
and see a simple squamous epithelium on the outer
surface. Can this be a sample of the skin
surface?
A. Yes B. No
42
Why do the pharynx, esophagus, anus, and vagina
have the same epithelial organization?
A. All are subject to mechanical trauma. B. All
are subject to abrasion. C. All must be able to
expand. D. A and B are correct.
43
The secretory cells of sebaceous glands fill with
secretions and then rupture, releasing their
contents. Which type of secretion is this?
A. acinar B. apocrine C. merocrine D. holocrine
44
A gland has no ducts to carry the glandular
secretions, and the glands secretions are
released directly into the extracellular fluid.
Which type of gland is this?
A. exocrine gland B. endocrine gland C. acinar
gland D. tubular gland
45
Structures and functions of different types of
Connective Tissues.
46
Connective Tissues

• Features
• Never exposed to the environment
• Usually vascularized
• Consists of cells in a matrix
• Components
• Specialized cells
• Produce matrix, provide protection
• 2. Extracellular protein fibers
• - Support, strength
• 3. Ground Substance
• - gel fluid, consists of
• interstitial fluid, cell adhesion molecules,
  and
• GAGs (glycosaminoglycans)
• - proteoglycans that form a gel
• Fibers Ground Substance Matrix

47
The Matrix

• The extracellular components of connective
  tissues (fibers and ground substance)
• majority of cell volume
• determines specialized function

48
Functions of Connective Tissue

• Establish structural framework
• Transport fluid and dissolved materials
• Protect organs
• Support, surround, interconnect tissues
• Store energy reserves
• Insulate body
• Defend against pathogens

49
Classification of Connective Tissues

• Connective tissue proper
• Many cell types and fiber types in thick ground
  substance
• Loose open fiber framework
• Dense tightly packed fibers
• Fluid connective tissues
• May cell types in watery matrix with soluble
  fibers
• Supportive connective tissues
• Limited cell population in tightly packed matrix

50
Connective Tissues Derived from Mesenchyme
Embryonic CT - mesenchymal cells in
gelatinous matrix with fine fibers
51
1. Connective Tissue Proper

• Viscous ground substance
• Varied extracellular fibers
• Varied cell population
• Ground substance rich in GAG
• -viscous, prevents microbe
• penetration
• Fiber types
• 1. Collagen fibers collagen protein
• 2. Reticular fibers collagen protein
• Elastic fibers elastin protein

Figure 48
52
1. Connective Tissue Proper

• Fiber types
• 1. Collagen fibers collagen protein
• -rope like, long, straight
• -resists force
• -most common
• 2. Reticular fibers collagen protein
• -branchy, forms framework
• -framework of an organ stroma
• (functional cells of an organ
  parenchyma)
• Elastic fibers elastin protein
• -wavy, flexible
• - Designed to stretch

53
8 Cell Types of Connective Tissue Proper

• Mast cells
• Lymphocytes
• Microphages

• Fibroblasts
• Macrophages
• Adipocytes
• Mesenchymal cells

54
Cell Types of CT Proper

• Fibroblasts
• - most common, most abundent
• - secretes ground substance
• hyaluronan protein GAGs
• - secrete fiber proteins (collagen,
  elastin)
• - some specialized types chondrocytes
  (cartilage)
• 
  osteocytes (bone)
• Mesenchymal Cells
• - stem cells
• - differentiate to replace CT cells after
• Injury (e.g. fibroblasts,
  adipocytes)
• Adipocytes (fat cells)
• - store triglycerides
• - organelles pushed to periphery
• -number, size and location of cells varies
• Macrophages
• - phagocytic for defense
• - (eat pathogens and damaged
  cells)
• - some fixed in tissues

55
Cell Types of CT Proper

• Microphages
• - neutrophils and eosinophils
• - phagocytic
• - migrate from
• blood to site of injury
• Lymphocytes B and T cells
• - involved in immune response
• - make antibodies
• - attack foreign cells
• - increased number during infection
• - constantly migrate between
• - blood and tissues and lymph
• Mast cells
• - contain histamine and heparin
• - stimulate inflammation in response to injury

56
Categories of Connective Tissue Proper

• Loose connective tissue
• more ground substance, less fibers
• e.g., fat (adipose tissue)
• Dense connective tissue
• more fibers, less ground substance
• e.g., tendons

57
A. Loose Connective Tissue

• Highly vascularized
• Varied cell types
• Functions
• Fill space
• Cushion support tissues
• Store fat
• Feed epithelial layers
• Three types
• Areolar CT
• Adipose Tissue
• Reticular Tissue

58
Loose Connective TissueAreolar CT

• 1. Areolar CT
• Most common
• Least specialized
• Open framework
• Matrix mostly ground substance
• All fiber types
• Location deep to epithelium
• Functions
• Reservoir for water and salts
• Absorbs shock and distortion
• Fills space
• Feeds epithelium

59
A. Loose Connective TissueAdipose Tissue

• 2. Adipose Tissue
• -90 adipocytes
• - Locations
• - deep to skin, surrounding eyeballs,
  kidneys, heart
• - Functions
• - padding, insulation, and energy storage
• -Two types
• - White fat adults, triglyceride
  storage, insulation
• - Brown fat infants, high mitochondria
  content for heat
• generation

60
A. Loose Connective TissueAdipose Tissue

• Reticular Tissue
• -stroma (supportive fibers) of organs
• -consists of reticular fibers
• Locations some organ
• e.g. lymph nodes, bone marrow,
  liver
• Function support parenchyma (functional)
  cells

61
B. Dense Connective Tissue

• Poorly vascularized
• Mostly fibers, little ground substance
• Only fibroblasts
• Three types
• Dense Regular CT
• Dense Irregular CT
• Elastic CT

62
B. Dense Connective TissueDense Regular CT

• Dense Regular CT
• -bundles of parallel collagen fiber, aligned
  with direction of force
• -Location
• - tendons (muscle to bone)
• - ligaments (bone to bone)
• - muscle coverings and fascia
• -Function
• - high strength attachment
• - stabilize positions

63
B. Dense Connective TissueDense Irregular CT

• 2. Dense Irregular CT
• - mesh of collagen fibers
• - Location
• -capsules of organs
• -perioteum (sheath around bone)
• -perichondrium (around cartilage
• -dermis (deep skin)
• -Function
• -resist tension from
• many directions
• -attachment
• Strength in Many Directions

64
B. Dense Connective TissueElastic CT

• Elastic CT
• -mostly elastic fibers, some collagen
• -Location
• -vertebral ligaments and artery walls
• -Function Strength with stretch and flex

Figure 411c
65
Fluid Tissue Transport Systems

• Cardiovascular system (blood)
• arteries
• capillaries
• veins
• Lymphatic system (lymph)
• lymphatic vessels

66
Fluid Connective Tissues

• Fluid connective tissues
• A. Blood
• - Matrix plasma serum (fluid)
• plasma proteins (produced
  by liver) fibers
• are soluble until clot
  forms
• - Cells Formed elements
• originate from hemocytoblast (stem
  cells) in
• bone marrow
• -Location contained in blood vessels
• -Function
• -transport nutrients, wastes and defense cells
  
• throughout the body
• Plasma ? Interstitial Fluid ? Lymph ?
  Plasma

67
Formed Elements of Blood

• Erythrocytes (RBCs) carry oxygen
• Leukocytes (WBCs) defense
• Neutrophils, Eosinophils, Basophils, Lymphocytes
  (B and T cells), Monocytes (Macrophages)
• Platelets carry clotting factors

Figure 412
68
Fluid Connective Tissues

• B. Lymph
• -Matrix lymph (recollected plasma fluid)
• -Cells lymphocytes (immune defense)
• -Location
• -contained in lymphatic vessels
• -Function
• -purify and return fluid to blood

69
Lack of vitamin C in the diet interferes with the
ability of fibroblasts to produce collagen. What
effect might this interference have on connective
tissue?
A. Tissue is unable to phagocytose. B. Tissue is
unable to produce melanin. C. Tissue is weak and
prone to damage. D. Tissue is unable to produce
heparine.
70
Many allergy sufferers take antihistamines to
relieve their allergy symptoms. Which type of
cell produces the molecule that this medication
blocks?
A. eosinophils B. mast cells C. basophils D. B
and C
71
Which type of connective tissue contains
primarily triglycerides?
A. areolar B. adipose C. reticular D.
mesenchyme
72
Supportive Connective Tissues

• Strong framework, few cells, fibrous matrix
• Function support and shape
• Mature cells in lacunae
• Two types
• 1. Cartilage
• gel-type ground substance
• for shock absorption and protection
• 2. Bone
• calcified (made rigid by calcium salts, minerals)
• for weight support

73
1. Cartilage

• Composition
• Matrix 80 water, firm gel of glycoaminoglycans
  made of chondroitin sulfate and hyaluronic acid,
  fibers
• Cells chondrocytes in lacunae (chambers)
• Cells formed the matrix
• Structure
• No innervation
• Avascular (no blood vessels)
• chondrocytes produce antiangiogenesis factor
• Surrounded by Perichondrium
• Outer layer dense irregular CT
• Function protection, attachment
• Inner layer cellular (fibroblasts)
• Function growth and repair

74
Growth of Cartilage Not common in adults

• Interstitial Growth (embryos)
• Chondroblasts in matrix divide
• Daughters produce more matrix
• Mature cells chondrocytes

Figure 413a
75
Cartilage Growth

• 2. Appositional Growth (children, minor repair
  in adult)
• New layers added by cells of inner perichondrium
• Serious Injury scar cartilage replaced by
  fibrous collagen

Figure 413b
76
Types of Cartilage

• 1. Hyaline cartilage
• 2. Elastic cartilage
• 3. Fibrocartilage

77
Types of Cartilage

• 1. Hyaline cartilage
• translucent matrix
• Contains fine, closely packed collagen fibers
• Tough, springy
• Location
• Ribs, nose, respiratory tract, articular surfaces
  
• no perichondrium
• Function
• Provide stiff flexible support
• Reduce friction between bones

78
Types of Cartilage

• 2. Elastic cartilage
• Matrix contains tightly packed elastic fibers
• Flexible support
• Location
• Auricle (external) of ear, epiglottis
• Function
• Resilient, flexible, shape holding support

79
Types of Cartilage

• Fibrocartilage
• - Matrix contains dense interwoven collagen
  fibers with little ground substance
• tough, durable
• Location Function
• Knee (meniscus) - Resist Compression
• Pubic symphasis - Absorb Shock Pads knee
  joints
• Intervertebral discs - Prevents
  bone-to-bone contact

Figure 414c
80
2. Bone/Osseous Tissue

• Highly vascularized
• Little ground substance
• Matrix
• 2/3 calcified calcium salts deposits for
  strength
• Calcium phosphate calcium carbonate
• 1/3 collagen for flexibility to resist shatter
• Cells Osteocytes
• Cells formed the matrix
• Located in lacunae arranged around central canals
  within matrix
• Connected by cytoplasmic extensions that extend
  through canaliculi
• Canaliculi excess blood supply
• Canaliculi necessary for nutrient and waste
  exchange, no diffusion through calcium

81
Bone/Osseous Tissue

• Surrounded by Periosteum covers bone surfaces
• Outer fibrous layer for attachment
• Inner cellular layer for growth and repair
• Location Bones
• Function
• Support Protection
• Levers for movement
• Storage of minerals

82
Structures of Bone

• Osteocytes
• Connected by cytoplasmic extensions that extend
  through canaliculi (small channels through
  matrix)
• Canaliculi necessary for nutrient and waste
  exchange

Figure 415
83
Comparing Cartilage and Bone
Table 42
84
Why does cartilage heal so slowly?

• It lacks a direct blood supply, necessary for
  proper healing.
• Chondroitin sulfate prevents healing.
• Matrix inhibits cellular regeneration.
• Interstitial fluid, necessary for proper healing,
  is excluded.

85
If a person has a herniated intervertebral disc,
which type of cartilage has been damaged?
A. elastic cartilage B. fibrocartilage C.
hyaline cartilage D. areolar cartilage
86
Which two types of connective tissue have a fluid
matrix?
A. lymph and cartilage B. cartilage and bone C.
blood and bone D. blood and lymph
87
Connective tissues form the framework of the
body.
88
Special Connective Tissue Structures

• 1. Fascia
• Connective tissues that provides a framework to
  connect organs to the body
• Function
• provide strength and stability
• maintain positions of internal organs
• provides routes for blood vessels, lymphatic
  vessels, and nerves

89
1. Fascia

• Bodys framework of connective tissue
• Layers and wrappings that support or surround
  organs

Provides insulation and padding
Resists force and anchors position
Prevents distortion by muscles
90

• Epithelial and
• connective tissues combine to
• form 4 types of membranes.

91
2. Membranes

• Membranes
• are physical barriers
• that line or cover portions of the body
• Consist of
• an epithelium
• supported by connective tissues

92
4 Types of Membranes

• Mucous
• Serous
• Cutaneous
• Synovial

Figure 416
93
1. Mucous Membrane

• 1. Mucous membranes (mucosae)
• Epithelium areolar connective tissue called
  lamina propria
• Line passageways that connect to external
  environment
• Epithelium kept moist with mucus secretions
• Location
• digestive, respiratory, urinary, and reproductive
  tracts

94
2. Serous Membranes

• 2. Serous Membranes/Serosa
• - mesothelium areolar connective tissue
• - lines body cavities to reduce friction
• - pleura, peritoneum, pericardium
• - Double Membrane
• - Parietal layer lines cavity
• - Visceral layer around organ
• - Epithelium kept moist by serous fluid
  (transudate)

Figure 416b
95
Cavities and Serous Membranes

• Pleural membrane
• lines pleural cavities
• covers lungs
• Peritoneum
• lines peritoneal cavity
• covers abdominal organs
• Pericardium
• lines pericardial cavity
• covers heart

96
3. Cutaneous Membrane

• 3. Cutaneous membrane
• Epidermis dermis skin
• Keratinized stratified squamous epithelium
  areolar and dense irregular connective tissue
  only dry membrane
• Thick and waterproof

Figure 416c
97
4. Synovial Membranes

• Areolar connective tissue with woven collagen,
  proteogycans and glycoproteins in matrix
• Lines joint capsules
• Produce synovial fluid (lubricant)
• Reduces friction of articular (hyaline cartilage)
• Protect the ends of bones
• Lack a true epithelium
• Only membrane with no epithelium

98
Structure of Synovial Membranes
Figure 416d
99
Which cavities in the body are lined by serous
membranes?
A. cranial and abdomenal B. pleural, peritoneal,
and pericardial C. synovial and fascial D.
nasal, urinary and reproductive
100
The lining of the nasal cavity is normally moist,
contains numerous goblet cells, and rests on a
layer of connective tissue called the lamina
propria. Which type of membrane is this?
A. mucous B. serous C. cutaneous D. synovial
101
A sheet of tissue has many layers of collagen
fibers than run in different directions in
successive layers. Which type of tissue is this?
A. fascia B. cutaneous C. parietal D. synovial
102
Muscle Tissue

• Function Provide Movement
• Is specialized for contraction
• Features
• Highly vascularized
• Contains actin and myosin for contraction

103
Structures and functions of the three types of
muscle tissue.
104
Three Muscle Types

• Skeletal Muscle
• Cardiac Muscle
• Smooth Muscle

105
Classification of Muscle Cells

• Striated (muscle cells with a banded appearance)
  
• or nonstriated (not banded)
• Muscle cells can have a single nucleus
• or be multinucleate
• Muscle cells can be controlled voluntarily
  (consciously)
• or involuntarily (automatically)

106
3 Types of Muscle Tissue

• 1. Skeletal muscle Striated, voluntary, and
  multinucleated
• Cells fibers
• Up to 1 ft long
• Multinuclear
• No cell division
• Appear striated actin and myosin organized into
  myofibrils
• Some satellite cells (stem cells) present for
  minor repair after injury
• Location skeletal muscles (meat)
• Function
• Move skeleton
• Guard entrances/exit
• Generate heat

107
3 Types of Muscle Tissue

• 2. Cardiac Muscle cells
• - Striated Involuntary, usually single nucleus
  
• Cells cardiocytes
• Long, branched
• Usually single nucleus but up to 5
• No cell division
• Striated
• Neighboring cells connected by intercalated disc
  
• Desmosomes intercellular cement gap
  junctions Desmosomes cement
• - provide tight linkage of neighboring cells
• Gap junctions
• - allow exchange of ions to coordinate
  
• contraction

108
Cardiac Muscle Tissue

• Striated, involuntary, and single nucleus
• Location majority of heart
• Function move blood through body

Figure 418b
109
3 Types of Muscle Tissue

• 3. Smooth Muscle Tissue
• - Nonstriated, involuntary, and single nucleus
• - Cells, small, spindle shaped
• - uninuclear
• - capable of cell division
• - no striations no myofibril organization
• - Locations
• - walls of blood vessels
• - walls of hollow organs
• - digestive,respiratory,urinary,reproduct
  ive tracts
• - Function move materials through the organ

Figure 418c
110
Basic structure and role of neural tissue.
111
Nervous/Neural Tissue

• Function
• specialized for conducting electrical (nervous)
  impulses
• rapidly senses internal or external environment
• process information and controls responses
• Location
• Most in brain and spinal cord Central Nervous
  System
• 2 in Peripheral Nervous System
• Cells
• Neuroglia Cells
• Support, repair, and supply nutrients to nervous
  tissue
• Neurons
• Transmit information
• Up to 3 ft long
• Large soma (cell body)
• Large nucleus, visible nucleoli
• Many dendrites receive info
• One axon transmits info
• No Cell division

112
Cell Parts of a Neuron

• Cell body
• contains the nucleus and nucleolus
• Dendrites
• short branches extending from the cell body
• receive incoming signals
• Axon (nerve fiber)
• long, thin extension of the cell body
• carries outgoing electrical signals to their
  destination

113
Injuries affect on tissues of the body.
114
Tissue Injuries and Repair

• Tissues respond to injuries to maintain
  homeostasis
• Cells restore homeostasis with 2 processes
• inflammation
• Regeneration (repair)
• Inflammation
• Prevent spread of injury or infection
• Characterized by swelling, redness, warmth and
  pain
• Process to remove necrotic cells and infectious
  agents

115
The Process of Inflammation
Damaged Cells Release prostaglandins
Undergo necrosis Trigger inflammation
Endothelial Cells Vessels leak and plasma
enters wounds delivering leukocytes and
clotting proteins
Fibroblasts migrate to the wound and are
stimulated to secrete collagen - form a fiber
scar to reinforce the clot and begin
repair Damaged tissue is Repaired or Replaced
116
Repair or Replacement

• Damaged tissue is repaired or replaced depending
  on the injury and type of tissue
• Regeneration
• replacement of collagen with original tissue type
• repair will not be visible
• Fibrosis
• Visible scar of collagen
• Tissue is completely replaced by a dense collagen
  patch
• Tissue type function is lost at the site of the
  scar

117
Summary Inflammation and Regeneration
Figure 420
118
Aging and Tissue Structure

• Speed and efficiency of tissue repair decreases
  with age, due to
• slower rate of energy consumption (metabolism)
• hormonal alterations
• reduced physical activity

119
Effects of Aging

• Chemical and structural tissue changes
• thinning epithelia and connective tissues
• increased bruising and bone brittleness
• joint pain and broken bones
• cardiovascular disease
• mental deterioration

120
Aging and Cancer

• Cancer rates increase with age
• 1 in 4 people in the U.S. develop cancer
• cancer is the 2 cause of death in the U.S.
• environmental chemicals and cigarette smoke can
  cause cancer

121
Injury and Cancer

• Repeat or chronic
• Inflammation causes damage
• Dysplasia change in normal shape, size,
  organization of tissue cells (reversible)
• Metaplasia more serious changes, abnormal
  division of stem cells (reversible)
• Anaplasia breakdown of tissue organization,
  genetic abnormalities of stem cells
  (irreversible)
• Cancer uncontrolled growth

122
Which type of muscle tissue has small, tapering
cells with single nuclei and no obvious
striations?
A. skeletal B. cardiac C. smooth D. all of the
above
123
A tissue contains irregularly shaped cells with
many fibrous projections, some several
centimeters long. These are probably which type
of cell?
A. neuroglia B. neurons C. myocytes D.
adipocytes
124
If skeletal muscle cells in adults are incapable
of dividing, how is new skeletal muscle formed?

• through the enlarging and splitting of existing
  cells
• through the atrophy of existing cells
• through the addition of new striations
• through the division and fusion of satellite cells

125
If skeletal muscle cells in adults are incapable
of dividing, how is new skeletal muscle formed?

• through the enlarging and splitting of existing
  cells
• through the atrophy of existing cells
• through the addition of new striations
• through the division and fusion of satellite cells

126
SUMMARY

• Organization of specialized cells into tissues
• epithelial tissue
• connective tissue
• muscular tissue
• nervous tissue
• Division of epithelial tissues into epithelia and
  glands
• epithelia as avascular barriers for protection
• glands as secretory structures
• Specializations of epithelial cells for sensation
  or motion
• microvilli
• cilia

127
SUMMARY

• Attachments of epithelia to other cells and
  underlying tissues
• polarity (apical surface and basal lamina)
• cell adhesion molecules (CAMs)
• cell junctions (tight junctions, gap junctions
  and desmosomes)
• Maintenance of epithelia
• germinative cells stem cells
• Classification of epithelial cells
• by number of cell layers (simple or stratified)
• by shape of cells (squamous, columnar or
  cuboidal)

128
SUMMARY

• Classification of epithelial glands
• by method of secretion (exocrine or endocrine)
• by type of secretions (merocrine, apocrine,
  holocrine)
• by organization (unicellular or multicellular)
• by structure (related to branches and ducts)
• The functions of connective tissues
• Structure, transport, protection, support,
  connections, and energy storage
• The structure of connective tissues
• Matrix, ground substance, and protein fibers

129
SUMMARY

• The classification of connective tissues
• connective tissue proper (cell types, fiber
  types, and embryonic connective tissues)
• fluid connective tissues (blood and lymph, fluid
  transport systems)
• supporting connective tissues (cartilage and
  bone)
• The 4 types of membranes that cover and protect
  organs
• mucous membranes (lamina propria)
• serous membranes (transudate)
• cutaneous membrane (skin)
• synovial membrane (encapsulating joints)

130
SUMMARY

• The fasciae (superficial, deep and subserous)
• The 3 types of muscle tissues (skeletal, cardiac,
  and smooth)
• The classification of muscle tissues by
  striation, nucleation, and voluntary control
• The 2 types of cells in neural tissue
• neurons and neuroglia
• The parts of a neuron (nerve cell)
• cell body, dendrites, and axon (nerve fiber)
• Tissue injuries and repair systems (inflammation
  and regeneration)
• The relationship between aging, tissue structure,
  and cancer