Tissues Flashcards
1
Q
What is a tissue?
A
A group of cells, with a common embryonic origin, that functions together to carry out specialized activities.
2
Q
What is special about the mesoderm?
A
It produces all connective tissues
3
Q
Describe what we mean by embryonic germ layers and name them
A
A few weeks after fertilization, a developping embryo is comprised of three distinct layers called germ layers, which will give rise to all of the body’s tissues. They are the ectoderm (sueprficial), the mesoderm and the endoderm (deep).
4
Q
What are the four primary adult tissues?
A
Epithelial tissue, connective tissue, muscular tissue and nervous tissue.
5
Q
What is the function of muscular tissue?
A
Generate the physical force needed to make the body structures move
6
Q
What is the function of nervous tissue?
A
Detects changes inside and outside the body and initiates and transmits nerve impulses (action potentials) that coordinate body activities to help maintain homoestasis.
7
Q
What is the function of epithelial tissue ?
A
It covers body surfaces: lines hollow organs, body cavities, ducts, and forms glands, providing protection to the underlying tissues.
8
Q
What is the function of connective tissue?
A
It protects and supports the body and its organs, binds organs together, stores energy reserves as fat and provides immunity.
9
Q
What are the two types of epithelial tissue?
A
Surface epithelium and glandular epithelium
10
Q
What are the general features common to all epithelium?
A
- Consists of closely packed cells with little extracellular material between them
- Cells are arranged in continuous sheets, single or multiple layers
- An epithelial cell has an apical surface and a basal surface attached to a base membrane
- Epithelia adhere firmly to nearby connective tissue through a thin extracellular layer called the basement membrane
- High capacity for renewal
- Epithelial tissue is avascular, exchange of materials between epithelium and adjacent connective tissue is by diffusion
- They have common functions
11
Q
What are the functions of epithelial tissue?
A
Protection for underlying tissue, filtration, lubrification, secretion, digestion, absorption, transportation, excretion, sensory reception, form glands, and reproduction
12
Q
What are the three types of cell junctions?
A
Tight junction, gap junction and anchoring junctions
13
Q
What is the function and location of tight junctions in the cell ?
A
Tight junctions are barrier forming junctions located in the apical side of the cells. They prevent anything from passing between neighbouring cells.
14
Q
What is the function and location of gap junctions?
A
Gap junctions create communication canals between cells to facilitate ion and small molecule movements between cells, and they are located on the lateral of the cells.
15
Q
What are the three types of anchoring junctions and their locations?
A
Desmosome (lateral) , adherens (lateral) and hemidesmosomes (basal)
16
Q
What is the general function of anchoring junctions?
A
Stabilizing the epithelium.
17
Q
What is the basement membrane of epithelial tissue made of?
A
Cellular layer of collagen and glycoproteins called basal lamina, often underlained by a layer of reticular fibres and glycoproteins called the reticular lamina
18
Q
What are the two criteria to classify surface epithelium?
A
The arrangement of cells in layers and cell shapes
19
Q
What are the types of cell arrangements in surface epithelium?
A
Simple epithelium (single layer of cells), pseudostratified (appears to have multiple layers because nuclei appear at different levels but all cells rest on the basement membrane) and stratified (two or more layers)
20
Q
What is the use of stratified epithelium?
A
The top layers protect the basement layer in locations where there is considerable wear and tear
21
Q
What are the different cell shapes?
A
Squamous, cuboidal, columnar and transitional
22
Q
What are squamous cells and what is their use?
A
Thin cells that allow for the rapid passage of substances through them
23
Q
What are cuboidal cells and what is their use?
A
Cubic or hexagonal cells that can have microvili at their apical surface and function in secretion or absorption
24
Q
What are columnar cells and what it their use?
A
Cells much taller than wide that protect underlying tissue. Their apical surfaces may have cilia or microvili, often specialized in secretion and absorption.
25
What are transitional cells and what is their use?
Cells that change shape from flat to cuboidal, as organs like the urinary bladder stretch.
26
What are the different types of surface epithelia?
Simple epithelium
- Simple squamous epithelium
- Simple cuboidal epithelium
- Simple columnar epithelium (ciliated and non-ciliated)
- Pseudostatified columnar epithelium (ciliated and nonciliated)
Stratified epithelium
- Stratified squamous epithelium (keratinized and nonkeratinized)
- Stratified cuboidal epithelium
- Stratified columnar epithelium
- Transitional epithelium
27
Describe a simple squamous epithelium
Single layer of flat cells that ressembles a tiled floor when viewed from the apical surface. Centrally located nucleus that is flattened and oval or spherical in shape.
28
Where is simple squamous epithelium found?
In body parts subject to little wear and tear. The tissue that lines the heart, blood and lymphatic vessels is called the endothelium. The type that forms the epithelial layer of serous membranes such as the pleura, pericardium or peritoneum is called mesothelium. It also found in kidneys.
29
What are the functions of simple squamous epithelium?
Allow materials to pass through
by diffusion, and filtration, and secretes lubricating substances in serous membranes.
30
Describe simple cuboidal epithelium
Single layer of cube shaped cells, round, centrally located nucleus.
31
Where is simple cuboidal epithelium located?
In ducts and secretory portions of small glands, in kiney tubules.
32
What are the functions of simple cuboidal epithelium?
Secretion and absorption
33
Describe nonciliated simple columnar epithelium
Single layer of nonciliated column-like cells with nuclei near bases of cells. The category contains cells with microvili, microscopic finger-like projections that increase surface area of the plasma membrane and goblet cells that secretes mucus at their apical surfaces.
34
Where is nonciliated simple columnar epithelium found?
In most of the gastrointestinal tract, in gallblader and ducts of many glands
35
What are the functions of nonciliated simple columnar epithelium?
Secretion and absorption. Secretes mucus lubricates linings of digestive, respiratory and reproductive tracts.
36
Describe ciliated simple columnar epithelium
Single layer of ciliated column-like cells with nuclei near bases, contains goblet cells in some location
37
Where is ciliated simple columnar epithelium found?
Bronchi, uterine tubes and uterus
38
What are the functions of ciliated simple columnar epithelium?
Mucus secreted by goblet cells form a film over respiratory surface that traps inhaled particles. Cilia wave in unison and move mucus and any trapped foreign particles towards throat where is can be coughed up, swallowed of spit out .
39
Describe nonciliated pseudostratified columnar epithelium
Appears to have several layers because the nuclei of the cells are at several layers. Alls cells are attached to the basement plane, but not all cells reach the apical surface. Contain cells without cilia and lacks goblet cells.
40
Where is nonciliated pseudostratified columnar epithelium found?
In epididymis, larger ducts of parotid gland, male urethra
41
What are the functions of nonciliated pseudostratified columnar epitelium?
Absorption and secretion
42
Describe ciliated pseudostratified columnar epithelium
Appears to have several layers because the nuclei of the cells are at several layers. Alls cells are attached to the basement plane, but not all cells reach the apical surface. Contain cells with cilia and goblet cells.
43
Where is ciliated pseudostratified columnar epithelium found?
Lines the airway of most of the upper respiratory tract
44
What are the functions of ciliated pseudostratified columnar epithelium?
Secretes mucus that traps foreign particles and the cilia sweeps the mucus away for eventual elimination.
45
Describe stratified squamous epithelium
Two or more layers of cells. Cells in apical layer and few layers deep are squamous. Those in the deeper layer are cuboidal to columnar. Basal cells continually undergo cell division. They are pushed towards the surface. As they go farther from the connective tissue, they become dehydrated, shrunken. In the apical layer, they loose cell junctions and are replaces by other basal cells.
46
What is the difference between keratinized and nonkeratinized stratified squamous epithelium?
In keratinized squamous epithelium, a thick layer of keratin (protein resistant to friction) is deposited on the surface of cells, whereas the ones that do not have keratin remain moist.
47
Where is stratified squamous epithelium found?
The keratinized variety forms the superficial layer of the skin. Nonkeratinized variety lines wet surfaces like mouth, esophague, vagina, tongue.
48
What are the functions of stratified squamous epithelium?
Protection, provides first line of defense against microbes
49
Describe stratified cuboidal epithelium
Two or more layers of cube-shaped cells, fairly rare
50
Where is stratified cuboidal epithelium found?
Ducts of adult sweat glands
51
What is the function of stratified cuboidal epithelium?
Protection
52
Describe stratified columnar epithelium
Basal layers with shortened, irregularly shaped cells. Apical layers with columnar cells. Uncommon tissue
53
Where is stratified columnar epithelium found?
In parts of the urethra, some large execretory ducts of some glands
54
What are the functions of stratified columnar epithelium?
Protection and secretion
55
Describe transitional epithelium
The appearance is variable. In its relaxed state, it looks like a stratified cuboidal epithelium, except that the cells in the apical layer are large and rounded. In its stretched state, it looks like a stratified squamous epithelium.
56
Where is transitional epithelium found?
In hollow structurres that are subject to expansion from within, like urinary bladder, portions or urethers and urethra
57
What are the functions of transitional epithelium?
Allows the urinary organs to stretch and hold variable amounts of fluid without rupturing, while still serving as a protective lining
58
What is a gland?
A gland is a single cell or a mass of epithelial cells adapted for secretion.
59
Describe an endocrine gland
Secretory products (hormones) diffuse into blood after passing through interstital fluid
60
Where are endocrine glands found?
Pituitary glands at the base of the brain, pineal gland in the brain, adrenal glands superior to kidney, pancreas, etc.
61
What is the function of endocrine glands?
Produce hormones that regulate various body activities
62
Describe exocrine glands
The secretory products are released into ducts
63
Where are exocrine glands found?
Sweat, oil and earwax glands of the skin, digestive glands like salivary glands
64
What is the function of exocrine glands?
Produce substances such as sweat, saliva or digestive enzymes
65
What are the four criteria to distinguish exocrine glands?
1) their mode of secretion 2) the nature of their secretion 3) their structure 4) the shape of their ducts
66
Name the three modes of glandular secretion and describe them
Merocrine glands release their secretions via exocytosis, apocrine glands pinch off their apical surfaces along with secretory vehicules, and holocrine glands lyse and are destroyed after accumulating their products in their cytoplasm
67
Name one example of gland per type of glandular secretion
Merocrine glands are lubricant mucin and eccrine sweat glands, apocrine glands are apocrine sweat glands, holocrine glands are sebaceous glands
68
What are salivary glands composed of ?
serous and/or mucous glands.
69
What are serous and mucous glands releasing?
Serous glands release a thin liquid of water and proteins like the digestive enzyme amylase, whereas mucous glands release mucus, a thicker product.
70
Name general features of connective tissue
- Most abundant and widely distributed tissue in the body
- Composed of two basic elements: extracellular matrix and cells
- Do not occur on body surfaces
- Highly vascular (except cartilage which is avascular)
- Except for cartilages, supplied with nerves
71
Name functions of connective tissue
- Binds together, supports and strengthens other body tissues
- Protects and insulates internal organs
- Compartimentalizes structures such as skeletal muscles
- Major transport system within the body (blood)
- Major site of stored enegy (adipose)
- Main site of immune responses
72
What are the elements in connective tissues?
Cells, extracellular matrix composed of ground substance and fibers
73
What are the three categories of connective tissue ?
CT proper, supportive CT and fluid CT
74
What is the classification of connective tissues?
1. Connective tissue proper
1.1 Loose connective tissue
A. Areolar connective tissue
B. Adipose tissue
C. Reticular connective tissue
1.2.Dense connective tissue
A. Dense regular tissue
B. Dense irregular tissue
C. Elastic
2. Supportive connective tissue
2.1. Cartilage
a) Hyaline cartilage
b) Fibrocartilage
c) Elastic cartilage
2.2. Bone tissue
3. fluid connective tissue
a) Blood
b) Lymph
75
Describe the extracellular matrix of connective tissue
It is the material between its widely spaced cells. It consists of protein fibres and ground substance, the material between the cells and the fibers. The extracellular matrix is usually secreted by the cells and determine the tissue's qualities.
76
Name the types of connective tissue cells
Fibroblast, macrophages, mast cells and adipocytes
77
What are fibroblasts?
Large, flat cells with branching processes. They are present in most connective tissues and are the most numerous. They move through connective tissue and secrete fibres and ground substance.
78
What are macrophages?
Phagocytes that develop from monocytes, a type of white blood cell.
79
What are mast cells?
Cells involved in the inflammatory response. Abundant along the blood vessels, they produce histamine, which dilates small blood vessels during inflammation and kill bacteria.
80
What are adipocytes?
Fat cell that store fat. Found below the skin and around organs.
81
What is the role of ground substance in connective tissue?
It is the component between the cell and fibres, it supports the cell, binds them together and provide a medium through which substances are exchanged between blood and cells.
82
What are the textures ground substance can take?
Fluid, semifluid, gelatinous, fibrous or calcified
83
What is the suffix of immature cells? And mature cells?
Immature cells end in 'blast' and mature cells in 'cyte'
84
What are the characteristics of mature cells?
Reduces capacity in cell division and matrix production, mostly involved in maintaining the matrix
85
Name substances found in the ground substance of the connective tissue
hyaluronic acid, chondroitin sulfate, dermatan sulfate and keratan sulfate.
86
What are the three types of fibres embebbed in the connective tissue extracellular matrix?
Collagen fibres, elastic fibres and reticular fibres
87
Describe collagen fibres
Very strong and resist pulling forces, but not stiff, so promote flexibility. Consist of the protein collagen. The most abundant protein in the body. Found in most types of connective tissues like bone, cartilage, tendon and ligaments.
88
Describe elastic fibres
Smaller diameter than collagen, branch together to form a network within a tissue. Consist of the protein elastin surrounded by the glycoprotein fibrillin. They are strong, very stretchable, can return to their original shape easily. Plentiful in skin, blood vessel walls and lung tissue.
89
Describe reticular fibres
Consist of collagen and a coating of a glycoprotein. Produced by fibroblasts, much thinner than collagen fibres. Provide support in the walls of blood vessels and provide branching networks around fat cells, nerve fibres, skeletal and smooth muscle cells. Also help form the basement membrane.
90
What distinguishes loose connective tissues?
The fibres in the tissue are loosely arranged among the many cells
91
Describe areolar connective tissue
One of the most widely distributed. Consists of all types of fibres arranged randomly and all types of cells embbeded in a semifluid ground substance.
92
Where is areolar connective tissue found?
In and around nearly every body structure, subcutaneous layer deep to skin.
93
What are the functions of areolar connective tissue?
Strength, elascticity and support
94
Describe adipose tissue
Has cells called adipocytes specialized for storage of tryglycerides.
95
Where is adipose tissue found?
Wherever areolar tissue is located. Subcutaneous layer deep to skin, around heart and kidneys, etc.
96
What are the functions of adipose tissue?
- Reduces heat loss through skin
- Serves as an energy reserve
- Supports and protects organs
- Generates considerable heat to maintain body temperature in newborns
97
Describe reticular tissue
Fine interlacing of reticular fibres and reticular cells
98
Where is reticular tissue found?
Stroma (supporting framework) of many organs like spleen and liver
99
What are the functions of reticular tissue?
- Forms stroma of organs
- Binds together smooth muscles tissue cells
100
What are the particularities of dense connective tissue?
Contains more numerous, thicker and denser fibers, but fewer cells than loose connective tissue
101
Describe dense regular connective tissue
Extracellular matrix looks shiny white, consists of many collagen fibers regularly arranged in bundles, with fibroblasts in row between bundles.
102
Where is regular dense connective tissue found?
It forms tendons, most ligaments and aponeuroses.
103
What is the function of dense regular connective tissue?
It provides a strong attachment between various structures. Tissue structure resists pulling (tension) along long axis of fibres.
104
Describe dense irregular connective tissue
Consists predominantly of collagen fibers randomly arranged and a few fibroblasts
105
Where is dense irregular connective tissue found?
In sheets, such as deeper region of dermis of skin or fasciae (tissue beneath skin and around muscles and other organs)
106
What is the function of irregular connective tissue?
Provide tensile strength in many directions
107
What is elastic connective tissue made of ?
Elastic fibers and fibroblasts.
108
What are the properties of elastic connective tissue ?
It is quite strong and can recoil to it's original shape
109
Where is elastic connective tissue found ?
Lung tissue and elastic arteries.
110
What are cartilages?
A dense network of collagen or elastic fibers embedded in chondroitin sulfate, a rubbery component of the ground substance.
111
How are called the cells of mature cartilage and where are they found?
Chrondocytes and they occur singly or in groups called lacunae in the extracellular matrix.
112
What is the pericondrium?
A membrane of dense irregular connective tissue that surrounds most cartilage
113
What are the three major types of cartilage ?
hyaline, fibrocartilage and elastic cartilage
114
What are the functions of bone tissue?
- Support soft tissues
- Protects delicate structures
- Work with skeletal muscles to create movement
- Stores minerals and houses blood-forming tissue
115
Describe blood tissue
A connective tissue with liquid extracellular matrix called blood plasma, a pale yellow fluid that contains water and dissolved subtances like nutrients, wastes, enzymes, etc. Suspended in the plama are red blood cells (erythrocytes), white blood cells (leukocytes) and platelets (thrombocytes).
116
What is the role of red blood cells?
Transport oxygen to body cells and remove carbon dioxide from them
117
What is the role of white blood cells?
Involved in phagocytosis, immunity and allergic reactions
118
What is the role of platelets?
Participate in blood clotting
119
Describe hyaline cartilage
Contains a resilient gel as ground substance in which are embedded fine collagen fibers. Prominent chondrocytes are found in lacunae, surrounded by perichondrium. Most abundant type of cartilage in the body.
120
What are the functions of hyaline cartilage?
- Provides smooth surfaces for movement at joints
- Provides flexibility and support
- Weakest type of cartilage (can be fractured)
121
Describe fibrocartilage
Consists of chondrocytes scattered among visible thick bundles of collagen fibers within extracellular matrix, lacks perichondrium. Strongest type of cartilage
122
Where is fibrocartilage located?
Pubic symphyis, intervertebral discs
123
What are the functions of fibrocartilages?
- Support and joining structures together
| - Strength and rigidity
124
Describe elastic cartilage
Chrondrocytes located in a threadlike network of elastic fibers within the extracellular matrix, perichondrium present
125
Where is elastic cartilage located?
Epiglottis, part of external ear
126
What are the functions of elastic cartilages?
- Provide strength and elasticity
| - Maintains shape of certain structures
127
What is lymph?
A fluid that flows in lymphatic vessels. Consists of several cells in a clear extracellular matrix similar to blood plasma, but with less protein.
128
Describe the extracellular matrix and cells for bone tissue
The matrix contains mineral salts and collageneous fibers and cells called osteocytes
129
What are the two types of bone tissue?
Compact or spongy
130
What is the basic unit of compact bone and what is its four parts?
The osteon.
1. The lamella are concentric rings of matrix that consist of mineral salts that give the bone its hardness, and collagen fibers that give bones its strength.
2. Lacunae are small spaces the lamellae that contain mature bone cells called osteocytes
3. Canalinaculi are minute canals-containing the process of osteocytes, which provide routes for nutrients and waste transport
4. A central canal contains the blood vessels and nerves. Spongy bone has trabeculae rather than osteons.
131
Describe muscle tissue
Consists of elongated muscle fibers that are highly specialized to generate force.
132
What are the functions of muscle tissue?
- Produce motion
- Maintain posture
- Generate heat
- Offers protection
133
What are the three types of muscle tissue?
Skeletal muscle, cardiac muscle tissue and smooth muscle tissue
134
Describe skeletal muscle tissue
Attached to the bones, voluntary and striated.
135
Describe cardiac muscle tissue
Forms most of the heart walls, striated, usually involuntary
136
Describe smooth muscle tissue
Located in the walls of hollow internal structures, is nonstriated and involuntary. It provides motion for constriction of blood vessels, propulsion of food through the gastrointestinal tract, contraction of urinary bladder
137
What are the two kinds of cells in the nervous system?
Neurons and neuroglia
138
Describe neurons
Convert stimuli into nerve impulses (action potentials) and conduct these impulses to other neurons, to muscle fibers or to glands. Composed of dendrites and axions
139
Describe neuroglia
Do not generate nerve impulses, have protective and supportive functions. Often the site of tumours of the nervous system.
140
What is a membrane?
A flat pliable sheet of tissue that covers or lines a part of the body
141
What is an epithelial membrane?
The combination of the epithelial layer and underlying connective tissue
142
What are the principal epithelial membranes of the body?
Mucous, serous and cutaneous
143
What is a synovial membrane?
A membrane that lines joints, bursae and tendon sheaths. It contains connective tissue, but no epithelium. It secretes synovial fluid.
144
Where are mucous membranes?
Lines body cavity that opens directly to the exterior. They line the entire digestive system, respiratory and reproductive systems.
145
What is the use of the epithelial layer of a mucous membrane?
It secretes the mucus, which traps particles, prevents the membrane from drying out, lubricates and acts as a barrier from pathogens.
146
What is the use and name of the connective tissue for a mucous membrane?
The name is lamina propria, and it helps bind the the epithelium to the underlying structures, plus provides the epithelium with oxygen and nutrients, and eliminates wastes.
147
What is a serous membrane?
A membrane that lines a body cavity that does not open to the exterior, and covers the organs that lie inside the cavity.
148
What are the two parts of a serous membrane and what is their use?
A parietal layer that is attached to the cavity wall and a viceral layer that covers and attaches to the organs inside these cavities.
149
Give examples of serous membranes
Pleura (lining the thoracic cavity and covering the lungs), peritoneum (lining the abdominal cavity and covering the abdominal organs) and pericardium (lining the heart cavity and covering the heart)
150
Which part of the serous membrane secretes the serous fluid and what is its use?
The mesothelium, and it allows organs to glide easily over one another or to slide against wall of cavities.
151
What is tissue repair?
The process of replacing damaged or dead cells.
152
When does tissue repair occur?
When inflammation process is complete.
153
What is inflammation ?
The tissue's response to injury in an attempt to contain the damage caused, and initiate the repair and regenerative processes.
154
What are the four cardinal signs of inflammation ?
erythema (redness), swelling, pain, and local heat
155
What happens during inflammation ?
Histamine or other inflammatory mediators increase blood flow to the injured tissue through vasodilatation. These mediators also cause local blood vessels to become leaky, causing local edema or swelling, which presses on pain receptors, causing pain.
156
How does cancer arise?
From a genetic mutation that affects cell growth, causes local blood vessel proliferation, and can spread to the rest of the body.
