Chapter 5 - Histology Flashcards
1
Q
There are ____ trillion cells of ____ different cell types
A
There are 50 trillion cells of 200 different cell types
2
Q
Name the 4 broad categories of tissues
A
Epithelial tissue
Connective tissue
Nervous tissue
Muscular tissue
3
Q
Define histology
A
The study of tissues
4
Q
Define organ
A
A structure with discrete boundaries that is composed of two or more tissue types
5
Q
Define tissue
A
A group of similar cells and cell products working together to perform a specific role in an organ
6
Q
The four primary tissues differ from each other in what three ways?
A
- Types and functions of their cells
- Characteristics of the matrix (extracellular material)
- Relative amount of space occupied by cells versus matrix
7
Q
The extracellular matrix is composed of what two things?
A
1) Fibrous proteins
2) Ground substance (clear gel)
8
Q
What other names can be used for ‘ground substance’?
A
Tissue fluid, extracellular fluid (ECF), or interstitial fluid
9
Q
What are the six functions of epithelial tissue?
A
Covers body surfaces and lines body cavities
Protect deeper tissues from injury and infection
Produce and release chemical secretions
Excretion and absorption
Selectively filter substances
Makes up most glands
10
Q
Describe the characteristics of epithelial tissue
A
Cells are very close together High rate of mitosis (regenerative) Apical and basal surfaces Basal surfaces faces basement membrane Apical surfaces may have microvilli or cilia Avascular but innervated
11
Q
The ______ _______ anchors the epithelium to the connective tissue below it
A
basement membrane
12
Q
Describe the differences between simple and stratified epithelium
A
Simple epithelia: -Contain one layer of cells -Named by shape of cells -All cells touch basement membrane Stratified epithelia: -Contain more than one layer -Named by shape of apical cells -Some cells rest on top of others and do not touch basement membrane
13
Q
In _____ epithelia, not all cells touch the basement membrane
A
stratified
14
Q
In ______ epithelia, all cells touch the basement membrane
A
simple
15
Q
What are the four types of simple epithelia?
A
Simple squamous
Simple cuboidal
Simple columnar
Pseudostratified columnar
16
Q
Describe pseudostratified columnar cells
A
Every cell reaches the basement membrane but not all cells reach the free surface; Falsely appears stratified
17
Q
What are goblet cells?
A
Wineglass-shaped mucus-secreting cells in simple columnar and pseudostratified epithelia
18
Q
Describe simple squamous epithelium and where it can be found
A
- Permits rapid diffusion or transport of substances
- Secretes serous fluid
- Locations: air sacs of lungs (alveoli), inner lining of blood vessels & heart (endothelium), and serosa
19
Q
Describe simple cuboidal epithelium and where it can be found
A
- Absorption and secretion, mucus production and movement
- Locations: Kidney tubules and certain glands (thyroid, mammary and salivary glands)
20
Q
Describe simple columnar epithelium and where it can be found
A
- Single row of tall, narrow cells; oval nuclei in basal half of cell
- Absorption and secretion; secretion of mucus
- Brush border of microvilli, ciliated in some organs, may possess goblet cells
- Locations: lining of GI tract, uterus, and uterine tubes
21
Q
Describe pseudostratified epithelium and where it can be found
A
- Secretes and propels mucus
- Has cilia and goblet cells
- Looks multilayered, but all cells touch basement membrane
- Nuclei at several layers
- Locations: respiratory tract
22
Q
Describe stratified epithelia
A
- Range from 2 to 20 or more layers of cells
- Some cells rest directly on others
- Only the deepest layer attaches to basement membrane
23
Q
Describe the types of stratified epithelia
A
- Three stratified epithelia are named for the shapes of their apical surface cells
- Includes stratified squamous (only one expected to recognize and know functions)
- The fourth type is transitional epithelium
24
Q
What is the most widespread epithelium in the human body?
A
Stratified squamous epithelium
25
Describe stratified squamous epithelia and its two types
-Deepest layers undergo continuous mitosis
-Daughter cells push toward the surface and become flatter as they migrate upward
-Top layer is exfoliated
-Two kinds
Keratinized—top layer is dead
Non-keratinized—top layer not dead
26
Describe keratinized stratified squamous epithelium and where it's located
Resists abrasion; retards water loss through skin; resists penetration by pathogenic organisms
Locations: epidermis; palms and soles heavily keratinized
27
Describe non-keratinized stratified squamous epithelium and where it's located
Resists abrasion and penetration of pathogens
| Locations: tongue, oral mucosa, esophagus, and vagina
28
Describe transitional epithelium and where it's located
```
Permits stretching (distension); surface cells change from round to flat when stretched
Locations: ureter and urinary bladder
```
29
Describe the functions of connective tissue
```
Binding and Support
Physical protection
Immune protection
Movement
Storage
Transport
```
30
_____ tissue is the most diverse and abundant type of tissue
Connective
31
Give examples of each of the functions of connective tissues
Connecting organs—tendons and ligaments
Support—bones and cartilage
Physical protection—cranium, ribs, sternum
Immune protection—white blood cells attack foreign invaders
Movement—bones provide lever system
Storage—fat, calcium, phosphorus
Heat production—metabolism of brown fat in infants
Transport—blood
32
Describe the characteristics of connective tissue
-Cells occupy less space than matrix (usually a large amount of extracellular matrix)
-Most cells are not in direct contact with each other
-Highly variable vascularity
Loose connective tissues have many blood vessels, whereas cartilage has few or no blood vessels
33
List and describe the 5 basic categories of connective tissue
- Fibrous Connective Tissue (Connective Tissue Proper): most diverse category; fibroblasts produce fibers and ground substance of matrix.
- Adipose Tissue: may be classified with loose connective tissue proper
- Cartilage (has 3 types): chondroblasts form matrix
- Bone (Osseous tissue): osteoblasts form matrix
- Blood
34
List and describe the three types of fibers that can be found in fibrous connective tissue
- Collagen fibers: tough, flexible, and stretch-resisant
- Reticular fibers: branching collagen fibers that forms a network
- Elastic fibers (Elastin): Allows stretch and recoil
35
What is fibrous connective tissue made of?
Fibers and a ground substance
36
Describe the ground substance of fibrous connective tissues
Usually has a gelatinous to rubbery consistency
37
Describe collagen fibers and where they're found
Found in fibrous connective tissue, it is the most abundant protein: 25%. Tendons, ligaments, and deep layer of the skin are mostly collagen.
38
What is the most abundant proteines
Collagen (25%)
39
Describe reticular fibers and where they can be found
Found in fibrous connective tissue, it is thin collagen fibers coated with glycoprotein. Forms the framework of the spleen and lymph nodes.
40
Describe elastic fibers
Found in fibrous connective tissues, they branch and rejoin each other
41
What are the two main types of fibrous connective tissue? Describe them.
Loose connective tissue and dense connective tissue.
Loose connective tissue has more gel-like ground substance between cells, and its two types are areolar and reticular.
Dense connective tissue has fibers that fill spaces between cells, and its two types are dense regular and dense irregular.
42
What are the two main types of fibrous loose connective tissue?
Areolar and reticular
43
What are the two main types of fibrous dense connective tissue?
Dense regular and dense irregular
44
Describe areolar tissue (a type of fibrous loose connective tissue) and where it's found
All 3 fibers are found; loosely organized; abundant blood vessels.
Wraps & cushions organs; underlies epithelia, in serous membranes, between muscles, passageways for nerves and blood vessels.
Areolar tissue—loosely organized fibers, abundant blood vessels, and a lot of seemingly empty space
Possess all six cell types
Fibers run in random directions
Mostly collagenous, but elastic and reticular also present
Found in tissue sections from almost every part of the body
Surrounds blood vessels and nerves
Nearly every epithelium rests on a layer of areolar tissue
Blood vessels provide nutrition to epithelium and waste removal
Ready supply of infection-fighting leukocytes that move about freely in areolar tissue
45
Describe reticular tissue (a type of fibrous loose connective tissue) and where it's found
Mesh of reticular fibers and fibroblasts
Forms supportive framework for lymphatic organs
Found in lymph nodes, spleen, thymus, and bone marrow
46
Describe dense regular connective tissue (a type of fibrous dense connective tissue) and where it's found
Densely packed, parallel collagen fibers
| Tendons attach muscles to bones and ligaments hold bones together
47
Describe dense irregular connective tissue (a type of fibrous dense connective tissue) and where it's found
Dense, randomly arranged, collagen fibers
Withstands unpredictable stresses
Locations: dermis of skin; organ capsules
48
Describe adipose tissue
Space between adipocytes occupied by areolar tissue, reticular tissue, and blood capillaries
Functions: Energy storage, insulation, cushioning
Fat is the body’s primary energy reservoir
The quantity of stored triglyceride and the number of adipocytes are quite stable in a person
Fat is recycled continuously
New triglyceride synthesized while old molecules hydrolyzed and released to blood
49
Describe cartilage
Stiff connective tissue with flexible matrix
50
Describe what chondroblasts do
They produce the matrix that will trap them
51
Describe chondrocytes
Cartilage cells that are trapped in lacunae (cavities)
52
Describe perichondrium
A sheath of dense irregular connective tissue that surrounds elastic and most hyaline cartilage (not articular cartilage); contains reserve population of chondroblasts
53
Describe the characteristics of cartilage
-No blood vessels, which means that diffusion brings nutrients and removes wastes and it heals slowly.
-Matrix contains collagen fibers
-Types of cartilage vary with fiber composition
(Hyaline cartilage, fibrocartilage, and elastic cartilage)
54
List the 3 types of cartilage
Hyaline cartilage, fibrocartilage, and elastic cartilage
55
Describe hyaline cartilage and where it's found
Clear, glassy appearance because of fineness of collagen fibers
Locations: articular cartilage, costal cartilage, respiratory cartilage, fetal skeleton
56
Describe elastic cartilage and where it's found
Contains abundant elastic fibers; covered with perichondrium
Provides flexible, elastic support
Locations: external ear and epiglottis
57
Describe fibrocartilage and where it's found
Contains large bundles of collagen fibers
Resists compression and absorbs shock
Locations: pubic symphysis, menisci of knee, and intervertebral discs
58
Describe bone
Bone (osseous) tissue has a hard calcified matrix with collagen fibers
59
Define osteoblasts and osteocytes
Osteoblasts produce the matrix
| Osteocytes are mature bone cells within lacunae
60
What are the two types of bone?
Spongy bone: porous appearance
| Compact bone: denser, calcified tissue with no visible spaces
61
Describe compact bone
Compact bone is arranged in cylinders that surround central canals that run longitudinally through shafts of long bones
62
What type of tissue is blood, and what does it do?
Fluid connective tissue that transports cells and dissolved matter from place to place
63
Describe what blood is made of
```
Plasma (blood’s ground substance) and
formed elements (cells and cell fragments)
```
64
List and describe the formed elements of blood
Erythrocytes—red blood cells (RBCs)
Leukocytes—white blood cells (WBCs)
Platelets—cell fragments involved in clotting
65
What are the two types of excitable tissues?
Muscle and nervous
66
Define excitability
The ability to respond to stimuli by changing membrane potential
67
Define membrane potential
An electrical charge difference (voltage) that occurs across the cell membrane
68
Describe what happens when changes in voltage happen in muscle and nerve cells
In nerve cells: changes in voltage result in rapid transmission of signals to other cells
In muscle cells: changes in voltage result in contraction, shortening of the cell
69
Define nervous tissue
A tissue specialized for communication by electrical and chemical signals
70
What are the two components of nervous tissue?
Neurons (nerve cells) and neuroglia (glial cells)
71
Describe neurons
Detect stimuli
Respond quickly
Transmit information rapidly to other cells
Cannot replicate/ divide
72
Describe neuroglia
Protect and assist neurons
“Housekeepers” of nervous system
More numerous than neurons
Can replicate/ divide
73
What are the three parts of a neuron?
Axon, dendrites, and neurosoma
74
Describe muscular tissue and its functions
- Elongated cells that are specialized to contract (shorten) in response to stimulation
- Primary job is to exert physical force on other tissues and organs
- Creates movements involved in body and limb movement, digestion, waste elimination, breathing, speech, and blood circulation
- Important source of body heat
75
List the 3 types of muscle
Skeletal, cardiac, and smooth
76
Describe skeletal muscle tissue
Long thin cells called muscle fibers; multinucleate
Most skeletal muscles attach to bone
Striations—alternating dark and light bands
Voluntary—conscious control over skeletal muscles
77
Describe cardiac muscle tissue
Cardiomyocytes are branched, shorter than skeletal muscle fibers; uninucleate
Intercalated discs join cardiomyocytes end to end
Provide electrical and mechanical connection
Striated and involuntary (not under conscious control)
78
Describe smooth muscle tissue
Short, fusiform myocytes; uninucleate
Non-striated and involuntary
Most is visceral muscle—making up parts of walls of hollow organs
79
Describe the 3 parts of the neuron
```
Neurosoma (cell body)
-Contains nucleus & other organelles
-Controls protein synthesis
Dendrites
-Multiple short, branched processes
-Receive signals from other cells
-Transmit messages to neurosoma
Axon (nerve fiber)
-Sends outgoing signals to other cells
-Can be more than a meter long
```
80
Define cell junctions
Connections between two cells
81
Most cells are anchored to what?
Each other or the matrix
82
Describe the purpose of cell junctions
Cells communicate with each other, resist mechanical stress, and control what moves through the gaps between them
83
What are the 3 types of cell junctions?
Tight junctions, desmosomes, and gap junctions
84
Describe tight junctions and where they're found
- Seals off intercellular space, making it difficult for substance to pass between cells
- Found in the epidermis, stomach, and small intestines
85
Describe desmosomes and where they're found
- A type of cell junction that keeps cells from pulling apart—resist mechanical stress.
- Found in cardiac muscle, the uterine cervix, and the epidermis
86
Describe gap (communication) junctions and where they're found
- Formed by ring-like connexons; the cells now share part of their cell membrane.
- Ions, nutrients, and other small solutes pass between cells
- Found in cardiac and smooth muscle, embryonic tissue, lens and cornea
87
True or false: gap junctions are absent in skeletal muscle
True
88
Define and describe glands
- A cell or organ that secretes substances for use elsewhere in the body or releases them for elimination from the body
- Usually composed of epithelial tissue with a connective tissue framework and capsule
89
Describe the differences between secretion and excretion
Secretion—product useful to the body
| Excretion—waste product
90
Describe exocrine glands
- Maintain their contact with surface of epithelium by way of a duct
- Surfaces can be external (examples: sweat, tear glands) or internal (examples: pancreas, salivary glands)
91
Describe endocrine glands
-They have no ducts; instead, they secrete hormones directly into blood
92
Give some examples of organs that have both endocrine and exocrine responsibilities
The liver, gonads, and pancreas
93
Define hormones
Chemical messengers that stimulate cells elsewhere in the body
94
Give examples of endocrine glands
Thyroid, adrenal, and pituitary glands
95
Describe unicelluar glands and give examples
- Found in an epithelium that is predominantly nonsecretory
- Can be exocrine or endocrine
- Examples: mucus-secreting goblet cells in trachea or endocrine cells of stomach
96
What are the different characteristics we can use to describe exocrine glands?
Duct shape:
simple (unbranched) vs. compound (branched)
Gland shape:
Tubular: narrow secretory portion
Acinar: secretory cells form dilated sac (acinus or alveolus)
Tubuloacinar: both tubular and acinar portions
97
Describe the 3 different modes of secretion
1) Merocrine
- Uses vesicles that release their secretion by exocytosis.
- Used by eccrine glands.
2) Apocrine
- Lipid droplet covered by membrane and cytoplasm buds from cell surface
- Mode of milk fat secretion by mammary gland cells
3) Holocrine:
- Cells accumulate a product until they disintegrate
- Secrete a mixture of cell fragments and synthesized substances
- Ex: sebaceous glands of hair and skin, eyelid glands.
98
Describe the merocrine mode of secretion
- Uses vesicles that release their secretion by exocytosis.
| - Used by eccrine glands.
99
Describe the apocrine mode of secretion and give an example
- Lipid droplet covered by membrane and cytoplasm buds from cell surface
- Mode of milk fat secretion by mammary gland cells
100
Describe the holocrine mode of secretion and give examples
- Cells accumulate a product until they disintegrate
- Secrete a mixture of cell fragments and synthesized substances
- Ex: sebaceous glands of hair and skin, eyelid glands.
101
True or false: Membranes may be only epithelial, only connective, or a mix of epithelial, connective, and muscular tissues
True
102
What is the largest membrane in the body?
Cutaneous membrane (the skin)
103
Define and describe the cutaneous membrane
- Cutaneous membrane (the skin) is the largest membrane in the body.
- Composed of stratified squamous epithelium (epidermis) resting on a layer of connective tissue (dermis)
- Relatively dry layer serves protective function
104
What are the two main types of internal membrane?
Mucous membranes and serous membranes.
105
Describe mucous membranes (mucosa)
- Layers consists of epithelium, areolar tissue (lamina propria), and smooth muscle (muscularis mucosa)
- Lines cavities/passages that open to the external environment
- Produces mucus (thicker, stickier)
106
What 4 organ systems have mucous membranes?
Reproductive, digestive, respiratory, and urinary
107
Describe serous membranes (serosa)
- Composed of simple squamous epithelium resting on a layer of areolar tissue
- Internal membrane; lines cavities with no connection to the outside
- Produces serous fluid
108
What are some membranes made up of only epithelium?
Anterior surfaces of cornea and lens of eye
109
What are 4 membranes made up of only connective tissues?
Dura mater (meninges)
Synovial membranes
Periosteum
Perichondrium
110
Define tissue growth
Increasing the number of cells or size of existing cells
111
Define hyperplasia
Growth through cell multiplication
112
Define hypertrophy and give two examples
The enlargement of preexisting cells
| Examples: Muscle growth through exercise, accumulation of body fat
113
Define and describe neoplasia
The development of a tumor (neoplasm)
| -It can be benign or malignant, and is composed of abnormal, nonfunctional tissue
114
What are the 3 types of tissue growth?
Hypertrophy, hyperplasia, and neoplasia
115
Define, describe, and give examples of the two modes of tissue repair
1) Regeneration: replacement of dead or damaged cells by the same type of cell as before
- Restores normal function
- Examples: repair of minor skin or liver injuries
2) Fibrosis: replacement of damaged cells with scar tissue
- Scar holds organs together, but does not restore function
- Examples: repair of severe cuts and burns, scarring of lungs in tuberculosis
116
List the steps of healing a skin wound
1) Inflammation: brings white blood cells, platelets, etc to the area. Creates swollenness, warmth, and redness.
2)Initial patch up and cleaning:
Blood clot forms; forms scab that temporarily seals the wound and blocks infection.
Macrophages clean up the scene.
3) New capillaries sprout from nearby vessels.
Fibroblasts deposit new collagen
Begins 3-4 days after the injury and lasts up to 2 weeks.
4) Regeneration, fibrosis, and remodeling: epithelial cells around the wound multiply and migrate beneath the scab (tissue regenerates)
Fibrosis: Underlying connective tissue undergoes fibrosis
Remodeling (maturation) phase begins several weeks after injury and may last up to 2 years
117
Categorize body tissues by how well they repair themselves into groups of good, moderate, poor, and almost no repair
Good: epithelial, bone, blood, areolar, dense irregular
Moderate: dense regular, smooth muscle
Poor: cartilage, skeletal muscle
Almost none: cardiac muscle, neurons (in CNS)
