1
Q
What are the main body systems?
A
- Integumentary
- muscular
- skeletal
- nervous
- digestive
- reproductive
- cardiovascular
- lymphatic
- endocrine
- respiration
- urinary
2
Q
What are the 4 main types of tissue and what do they do?
A
- Epithelial: covers the of the body, lines body cavities and cavities of organs, and forms the secretory portions of glands
- Connective: binds organs together and provides protection and support for organs and the entire body
- Nervous: coordinates body functions via the transmission of nerve impulses
- Muscle: contracts to enable movement of the body and body parts
3
Q
What is the function and location of epithelial tissue?
A
Location: Body cavities and ducts, blood vessels, bladder, GI tract, skin, respiratory passage.
Function: protects, covers and lines, provides sensory input, manufacture secretion and excretion
4
Q
What is the function of nervous tissue?
A
Coordinates body function through nerve impulses
5
Q
Body cavities
A
Dorsal
Ventral
Thoracic
Abdominal
6
Q
Thoracic cavity membranes and what they line
A
Visceral pleura: lines thoracic organs
Parietal Pleura: lines thoracic wall
Mediastinum: separates 2 halves of the chest down a median plane
7
Q
Abdominal cavity membrane
A
Visceral Peritoneum: lines abdominal organs
Parietal Peritoneum: lines abdominal wall
8
Q
Body membranes and cavities
A
- Between these membrane linings is a ‘potential space’ lubricated by pleural or peritoneal fluid
- This fluid is secreted by the membranes lining the body (pleura and peritoneum)
- Serves to reduce friction as lungs move during
respiration and organs move within the abdomen. - Inflammation (pleuritis/pleurisy or peritonitis) is very painful.
- Note that another term used to generally refer to this type of body fluid (regardless of where it is found) is serous fluid.
- The heart is also enclosed in its own membrane, derived from the mediastinum.
o This is called the pericardium
o forms a layer over the heart as well as a loosely formed sac surrounding the heart
o contains serous fluid to reduce friction
9
Q
Levels of organization
A
Cells
Tissues
Organs
Systems
Organism
10
Q
Cells
A
- Cell is made up of organic molecules and water molecules (avg 20%:80%)
- Cells are highly specialized, depending on their function in the body, but all cells have 3 basic parts:
o cell membrane_(plasma membrane or
plasmalemma)
o nucleus
o cytoplasm
11
Q
Tissue level of organization
A
Made up of cells of the same type
12
Q
Epithelial tissue
A
composed entirely of cells and functions to
cover and protect the surface of the body. Body surfaces include skin, as well as the lining of the GIT, respiratory
system, cardiovascular system, reproductive system, and bladder.
Some groups of epithelial cells have specialized to form glands, such as sweat glands, salivary glands, and mammary glands.
13
Q
Connective tissue
A
‘connects body cells’ to provide support and structure to the soft cells. Composed of cells and intercellular substances such as fibers for added strength. Can range from fat (adipose tissue) to cartilage and bone.
14
Q
Muscular tissue
A
move the body. Includes striated and smooth muscle. Operates under both conscious (i.e. skeletal muscle) and
unconscious (i.e. cardiac and smooth muscle – GIT, urinary bladder) control.
15
Q
Nervous tissue
A
transmits information, including sensory, around the body and helps to control functions and movement within the body.
16
Q
Organ level of organization
A
- An organ is made up of a variety of tissues that work together
- Example: stomach – contains all 4 basic tissue types
- Some occur in pairs (kidneys, eyes), others singly (brain, heart)
17
Q
System level of organization
A
- System is made up of several organs that perform related functions
- Probably the most logical approach to understanding anatomy and physiology
18
Q
Integumentary system
A
- Integumentary
o Includes skin and the ‘epidermal derivatives’ such
as nails, glands, and hair.
o Functions include sensation, protection,
immunity, excretion, blood reservoir, vitamin D synthesis,
and temperature regulation
19
Q
Skeletal system
A
o Includes the axial skeleton (skull, vertebral column, and
ribs) and appendicular skeleton (pectoral and pelvic
girdles, front and hind extremities)
o Involves bones, ligaments, and associated cartilages.
o Functions in support, protection, movement, blood cell production, and mineral storage
20
Q
Muscular system
A
o Skeletal muscle moves the body through the environment
o Cardiac and visceral move parts internally
▪ Note that there is overlap with cardiovascular
system and others
o Functions in movement and heat production
21
Q
Nervous system
A
o Includes brain, spinal cord, nerves, ganglia, sensory receptors, and special senses organs
o Functions in regulation and coordination of body activities, detection of changes both internal and external, consciousness, memory and learning
22
Q
Endocrine system
A
o Includes hormone – producing glands such as
hypothalamus, anterior & posterior pituitary, thyroid, parathyroid, adrenal cortex & medulla, kidneys, pancreas, stomach, duodenum, testes, ovaries, placenta, thymus, pineal gland
o Functions to regulate and coordinates body activities through hormone secretion
23
Q
Cardiovascular system
A
o Includes heart, blood vessels (arteries, veins, and capillaries) and blood
o Functions to transport food, wastes, gases, and hormones to and from body cells
24
Q
Lymphatic system
A
o Includes bone, lymph vessels & nodes, spleen, thymus, and lymphoid tissue
o Functions in defense against infection, return of
extracellular fluid to blood, and formation and differentiation of WBC’s
25
Respiratory sytem
o Includes nose, pharynx, larynx, bronchi, bronchioles, and lungs
o Functions in the exchange of carbon dioxide and
oxygen between air and blood in the lungs and the
regulation of hydrogen ions
26
Digestive system
o Includes mouth, pharynx, esophagus, stomach, intestines,
salivary glands, pancreas, liver, and gall bladder
o Functions in digestion and absorption of nutrients, salts, and water
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Urinary system
o Includes kidneys, ureters, urinary bladder, and urethra
o Functions in regulation of excretion of organic
wastes, salts, and water to control plasma composition
and volume
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Reproductive system
o Includes male (testes, penis, associated ducts and glands)
and female (ovaries, uterine tubes, uterus, vagina,
mammary glands) organs
o Functions for male involve production and transfer of
sperm to female; functions for female include egg
production and an environment in which the embryo can
develop.
29
Organism level of organization
* Contains all systems working together.
* Requires communication and a precise balance of all systems to maintain a state of health (homeostasis)
o Immune system protects body
o Temperature regulation
30
Homeostasis
Homeostasis is maintenance of a relatively stable internal environment, also referred to as a ‘dynamic equilibrium’ within the body (i.e. a changing or active balance) * Involves sensors, control centers and responders
* Despite constant fluctuations in the external environment and substances entering and leaving the body a constant internal environment is maintained
* Examples include the control of body temperature and acid-base balance
* Maintenance of a healthy state requires proper functioning of all levels of organization and preserving homeostasis
31
Epithelial tissue
Epithelial tissue is composed of sheets of cells that cover and line other tissues. It lines all of the body cavities and ducts, all blood vessels, the bladder and the gastrointestinal tract, as well as the skin and respiratory passages.
32
Functions of epithelial tissue
1. Protects, covers and line
2. Filters biochemical substances
3. Absorbs nutrients
4. Provides sensory input
5. Manufactures secretions(mucin, hormones, enzymes)
6. Manufactures excretions (sweat, milk)
* Tends to be classified as
1) covering and lining epithelium
2) glandular epithelium
33
General chracterisitcs of epithelial tissue
- They are polar
- Attached by later complex junctions
- Avascular
- Variably innervated
- Regenerate
1. They have a “right side up” and are polar. They have an Apical Surface and a Basal surface.
The apical surface is the surface of the cell which is:
* Exposed to a body cavity
* Lining an internal organ, or facing the lumen
* Exposed to the exterior
The basal surface is the surface of the cell which is attached to a basement membrane, or faces underlying tissue
❖ Epithelial cells have sides or lateral surfaces that attach to neighboring cells by junctional complex.
3. Epithelial cells are avascular (no blood vessels) and rely on underlying connective tissue to supply needed nutrients and waste exchange
4. Some epithelia lack nerves, others are innervated and provide valuable sensory information to the body
5. Epithelial tissues regenerate rapidly by mitotic division of cells – large numbers are being destroyed and replaced daily.
34
Cellular attachments
Cells are held together in a number of ways
* Sides of cells fit together with an interlocking pattern
* Have matrix-filled channels running between cells
* Membranes are joined with junctional complexes that provide strength
35
Tight junctions
form a fluid-tight seal between cells
o The outer layers of plasma membrane between two cells are fused
o Tends to be found in a strip around the circumference of the cell like a belt
o Prevents penetration of substances and leakage
o Very important in the urinary bladder and digestive tract (keeps toxins and digestive enzymes from the bloodstream)
36
Desmosomes
or Anchoring junctions: fasten cells to one another or to extracellular materials like the basement membrane
o Made up of a plaque of interlocking filaments
o Some of the filaments penetrate from the plaque into the cytoplasm of (like an anchor) to stabilize the bond
o Important in areas which have lots of stretching/tension, like in the skin, heart, and uterus
37
Gap junctions
Gap (or Communicating) junctions: form fluid-filled tunnels between cells. Connexons: tubular channel proteins link adjoining cells
o Cytoplasm is joined by this ‘tunnel’ and allow exchange of nutrients and ions
o Most common in the intestinal epithelial cells, heart, and smooth muscle.
o Help coordinate the actions of cells by their ability to transport ion change signals quickly. Also common in cardiac and smooth muscle for similar reasons.
38
Basement membrane
attaches the epithelium to the underlying connective tissue. Function to resist rubbing and erosion. Not a true membrane, so often referred to as basement (or basal) lamina.
It is acellular, consisting of a colloidal (gelatinous and viscous fluid) complex of protein, polysaccharide, and reticular fibers. It is also important to help control the movement of nutrients and waste from underlying tissue to the epithelium and reverse. Oxygen and nutrients and epithelial cell wastes diffuse across the basement membrane from and into the blood vessels in the connective tissue below.
39
Simple squamous epithelium
* Description: single layer of flat, smooth, scale-like cells with irregular outlines and central nucleus. May resemble tiles of a mosaic from surface view
Flat and smooth
* Function: reduce friction, filtration, nutrient exchange by diffusion, * Not strong, so needs to be supported
* Location. Lines:
o Air sacs of lungs (assist O2 and CO2 exchange)
o Inner lining of blood vessels and heart (called endothelium
in the C-V system),
o Peritoneal, pleura and pericardial cavities
▪ Called mesothelium
▪ Or serous membranes as they secrete a watery
lubricating fluid
40
Simple cuboidal epithelium
* Description: single layer of cube-shaped cells (on cross-section) with a central nucleus (described as a string of pearls on cross-section). Location: covers surface of ovary, lines anterior surface of lens, forms pigmented epithelium of retina, and lines kidney tubules (where
resorption of materials occurs) and smaller ducts of many exocrine glands
such as salivary, and pancreas, as well as lining the endocrine gland, the thyroid.
* Function: _lining, secretion, absorption and provides little protection from abrasion
* Provides little protection from abrasion
41
simple columnar epithelium
Nonciliated
* Description: single layer of elongated cells.
* Location: lines gastrointestinal tract from stomach (where it secretes digestive juices and absorbs nutrients) to anus. Form the ducts of many glands, kidney collecting tubules, and gallbladder
* Function:
♦ Absorption and secretion – this type often has microvilli
♦ Protection – goblet cells in epithelium secrete a sticky glycoprotein called mucin which forms a protective and lubricating barrier
Ciliated
* Description: single layer of ciliated rectangular cells. Contains goblet cells in some locations, nucleus is towards the bottom of the cell
* Location: lines uterine tubes, uterus, paranasal sinuses, and central canal of the spinal cord
* Function: moves fluids or particles along a passageway by ciliary action
42
Stratified squamous epithelium
* Description: several layers of cells; cuboidal to columnar shape in deep layers with a squamous layer on top and irregular, polyhedral cells in the middle. Occurs in 2 distinct forms: keratinized (forms the outer layer of skin) and nonkeratinized
* The bottom, or basal layer, contains the actively growing and multiplying cells.
* Tend to be roughly cuboidal, but become more flattened, tougher, and slowly die as they are pushed toward the surface
* May be keratinized at sites of particularly rough abrasion e.g. skin
* Keratin is a waterproofing substance that is incorporated onto the outer layer of keratinized stratified squamous epithelium to protect against water loss to the external environment
* This process of the dead cells becoming keratinized is also sometimes called cornification
* The superficial, cornified layer of the skin often becomes very thick in areas of friction, forming calluses
* Location:
▪ Keratinized: Skin
▪ Non keratinized: Upper GI tract - oral cavity, tongue surface, lining of mouth, _esophagus, epiglottis, vagina, and cornea_, . In ruminants, it also lines the forestomach (rumen, reticulum, and abomasums).
▪ Epiglottis, vagina, cornea
* Function: protection
43
Stratified cuboidal epithelium
* Description: two or more layers of cells with the surface cells being _cube shaped__
* Location: ducts of sweat glands, mammary glands, salivary glands, part of the male urethra
* Function: protection
44
Stratified columnar epithelium
* Description: several layers of cells with column shaped cells of height only in the superficial layer
* Location: rare – parts of male urethra, large excretory ducts (like some salivary ducts), pharynx, portions of anal mucous membranes, and conjunctiva of the eye
* Function: protection and secretion
45
Pseudostratified epithelium
Columnar Epithelium (not a true stratified tissue – rather is more properly identified as simple)
* Description: all cells attached to the _basement membrane__ but not all reach the surface. The nuclei are found at different levels. Gives the appearance of stratification because it appears to have two levels of cells. Can be plain or ciliated and often possess _goblet cells__ for mucin production
* Location:
* Plain: male urethra and epididymis, lining of large glandular ducts (parotid gland).
* Ciliated: upper respiratory tract (trachea and bronchi), auditory tubes, and part of the middle ear.
* Function: protection, secretion and movement of mucus (= mucin plus fluid) by ciliary action
* Mucus protects host from disease
46
Transitional epithelium
* Description: variable appearance depending on the degree of _distention__ or _stretching_ . Can appear as large, round, dome-shaped cells that may be binucleate on the surface. When stretched, become thin and flat and look like squamous__ epithelial cells. Can even sometimes stretch as thin as one cell deep! Deeper layers may be cuboidal, columnar, and polyhedral and are not as closely packed as other types of epithelium (i.e. there are spaces between the cells). This allows a degree of elasticity in the tissue
* Location: lines _urinary bladders_, calyces of the kidneys, and portions of the ureters and urethra – allow for urine accumulation
* Function: permits distention without leakage
47
Glandular epithelium
▪ A gland is a cell or group of cells that make and secrete a product
▪ Product is usually protein made in the RER (rough endoplasmic reticulum), modified and packaged in the Golgi Apparatus, and released (secreted) from the cell
▪ Glands were originally an infolding of the epithelium during embryological development
▪ Some were cut off from their contact with the external environment (endocrine glands)
48
Endocrine gland
➢ Lack __ducts__ – secretions are released into the blood or the lymph to be carried to target tissues
➢ Includes anterior pituitary, thyroid and parathyroid, ovaries and placenta, GIT (enteroendocrine cells), pancreas (pancreatic islets), testes and prostate, thymus, and kidneys
➢ Part of the endocrine system: i.e. produce hormones to be carried around the blood and impose humoral control on the body’s activity and homeostasis
➢ Will be further investigated with the endocrine system chapter
49
Exocrine gland
➢ Have ducts , or small tubes, that carry secretions to specific areas – usually an epithelial surface (secretions do not enter circulation)
➢ Exception is the __goblet cell_, which is a single-celled gland, and doesn’t possess a duct
➢ Includes salivary, sweat, liver, pancreatic digestive (note, pancreas is also endocrine), sebaceous (oil), and ceruminous (ear wax) glands
➢ Classified by
b. Structure
c. Manner of secretion of the cellular product
d. Type of secretion
50
Exocrine structure classification
* Can be unicellular or multicellular: The only example of a unicellular gland is the goblet cell, which is found among columnar cells of the respiratory and digestive tracts and in the conjunctiva of the eye. Secrete mucin
(thick, sticky protein/carbohydrate mixture which becomes mucus when water is added and helps trap bacteria and foreign particles)
* Multicellular- Divided into _secretory unit_ (where secretions are produced) and _duct_ (which carry secretion its destination): Secretory unit: may have contractile cells called myoepithelial cells to help with forcing out secretions
* Tubular or alveolar (acinar): terms used to describe if the secretory portion of the duct resembles a tube or a hollow ball. Can be
tubuloalveolar if the gland is composed of a combination of tubular and alveolar secretory structures
* Simple or compound: depending on if the duct branches
* Compound glands can be further subdivided into lobes, then lobules ♦ Partitions dividing compound glands are often called septa, giving us interlobar septa and interlobular septa, depending on whether they are subdividing lobes, or lobules.
♦ Ducts draining the glands can also be identified the same way: as interlobar ducts, and interlobular ducts
51
Manner of secretion of the cellular product in exocrine glands
➢ Holocrine gland cells fill with secretory material and discharge the entire cell contents into the gland lumen – destroys the cell e.g. sebaceous glands associated with hair follicles of the skin
➢ Merocrine glands create vesicles which pass secretory products through the cell membrane without any significant loss of cytoplasm ▪ most common e.g. pancreas, sweat glands, salivary glands
➢ Apocrine glands are intermediate to the above two – some cytoplasm and cell membrane is lost with the secretion e.g. mammary tissue, prostate and some sweat glands
52
Types of secretion
➢ Serous secretions: watery, lots of enzymes
➢ Mucus secretions: thick, viscous, composed of glycoproteins. Common in digestive and respiratory tracts.
➢ Mixed contain both mucous and serous secretions. Mandibular salivary glands, some cells produce mucous, others enzymes
53
General features of connective tissue
Matrix: consists of organic and inorganic _ground substance_ mixed with fluid and _fibers_ (collagen, elastic, and reticular). Is a non-living _extracellular_ substance. It is a product of the cells in the tissue and the proportion of matrix to cells depends on the tissue type, though tends to be high. Provides strength and support to the tissue. Accounts for the very wide range of connective tissue types
➢ Tends to have relatively few, loosely arranged cells
➢ Cell Types: fibroblasts (secrete matrix), macrophages (phagocytes), white blood cells, plasma cells (secrete antibodies), mast cells (produce histamine), adipocytes (store lipids).
➢ _Never found on exposed surfaces_
➢ Is vascularized (degree varies from bone (poor) to adipose tissue (good))
54
Functions of connective tissue
Binds, supports, and strengthens other body tissues; Protects and insulates internal organs; Compartmentalize structures such as skeletal muscles; transports substances through the body; acts as an energy reserve; important role in healing and fighting infections
55
Matrix-ground substance
▪ Amorphous, homogeneous material
▪ May be liquid, gel, or calcified solid
➢ Soft connective tissue often contain glycosaminoglycans,
which are linear glycoprotein chains. Most common is
hyaluronic acid.
▪ Acts as a:
➢ Medium for exchange of nutrients and waste
➢ Shock-absorber
56
Fibers of connective tissue
▪ Collagenous, (white) thick, strong, flexible, and non-elastic. There are varying amounts and arrangements from loose in fat to dense in tendons. Collagen appears wavy when not stretched.
▪ Excess production of collagenous fiber during healing results in scars. These are called adhesions if they attach tissues together abnormally.
(Collagen can be broken down by heat (as in cooking meat to make it more tender), or strengthened by tannic acid (as in tanned leather))
▪ Reticular: minute networks of fine threads of collagen. Often form a delicate framework for the cells in organs like spleen, liver, lymph nodes, and endocrine glands. May also support _blood vessels_ (including capillaries), nerves, and muscle fibers.
▪ Elastic(Yellow)___: contain __elastin protein__ – coiled bundles of microfibrils that can stretch. Tend to be branched. Not as strong as collagenous fibers, but provide elasticity to tissues. often found in the connective tissue of organs that _change shape___ (vocal cords, lungs, skin, and blood vessel walls).
57
fixed cells
Stay where they are in CT
58
fibroblasts
make fibers and ground substance to form matrix. Different fibroblasts are characteristic to each tissue
i.e. chondroblasts (cartilage), osteoblasts (bone), fibroblasts
(CT). They are large, irregularly shaped cells that can
reproduce themselves. Tend to convert to chondrocytes,
osteocytes, and fibrocytes when mature, which is a less active form. Can revert back if necessary
59
Adipocytes
(fat cells): storage cells for fat. If in groups, can form adipose tissue – most common subcutaneously (SC or SQ) (in cats wall of ventral abdomen), around kidneys, and in omentum.
60
Reticular cells
flat, star-shaped, long projections. May contact each other in tissues to form a ‘net’. Most common in lymph nodes, spleen, and bone marrow –Important in
immunity and making reticular fibers.
61
Wandering cells
Move in and out through CT
often involved in protection and repair
62
Mast cells
: contain large granules of histamine and heparin. Release these products in response to antigenic stimulation and cause inflammation or an allergic response by increasing blood flow and making the vessels leaky and decreasing clotting. Tend to be found near blood vessels
63
Leukocytes
generally circulate in the blood, but can enter tissues in response to infection. Five different types: some phagocytize bacteria, others make antibodies to help fight infection
64
Macrophages
can be fixed as well as wandering: very large phagocytes that engulf bacteria, dead cells, and debris for lysosomal digestion. Tend to congregate around infection and inflammation (very important parts of the immune system). Can be given different names, depending on where they are in the body.
65
Connective tissue proper
* Most of the CT in the body
* Can be loose or dense CT
* Fibers may differ in protein composition and density, but primarily consist of collagen or elastin
* Form the basic supporting framework of organs
66
Loose connective tissue
▪ _Areolar connective tissue_ (most abundant proper CT in the body). Loosely organized cells and extracellular substances.
* Composition: fibroblasts (primarily), macrophages, mast cells, adipocytes, and plasma cells. Also, collagen, elastic, and reticular fibers; semifluid ground substance.
* Location: Most common tissue type. __Skin_ (SC layer and papillary region – this allows deposition of fat and, movement; mucous membranes. Around and within blood vessels (allows them to move, but also protects them), nerves, __muscles_ , and body organs. Basically, found throughout the body as the supporting tissue of many organs.
* Function: To provide __cushinig , elastic and flexible support, strength and a continuous network within organs; __nutrition_ to nearby cells due to its capillary network; an area for the immune system to work; __attachement of_ skin to underlying tissues
* Can tear relatively easily
* Can stretch when excess extracellular fluid is present (edema) * Called ‘pitting’ edema because the tissue retains a pitted appearance when the fluid is squeezed out by pressure.
67
Adipose (fat)
* Composition: adipocytes and reticular fibers
* Location: skin (SC layer), around __heart__ and _kidneys_ , yellow bone marrow, padding around joints, and behind _eyeball_ in eye socket. Can often be found in small amounts throughout the body, or in larger amounts to make up body fat.
* Function: _energy reserve_ (stores triglycerides), _insulation__ , support, and protection (cushioning)
* Fat cells are very large and rounded. Can have as much as 95% of the mass as stored fat in a cellular inclusion that pushes the cytoplasm and nucleus of the cell to the side
* There tends to be a fine network of reticular fibers among the cells
* Highly __vascularized_ to allow access to fat stores
* Most fat tends to be _white_ , but it can appear yellow due to fat soluble carotenoids in the feed.
68
Reticular connective tissue
Composition
Reticular cells
reticular fibers in 3-D network, and matrix (matrix + reticular fibres = stroma or supporting framework of organs)
Location: Liver spleen, lymph nodes, basal lamina
Function: Bind together smooth muscles cells
Forms the framework of many organs
69
Dense regular connective tissue
Differs from loose connective tissue
Has fewer cells, ground substance, and capillaries.
Is made predominantly of fibrous elements
Composition
Fibroblasts are the principal cell
Tend to be scarce
The bundles of collagen fibers are arranged longitudinally with some elastic fibers in between.
Location
Tendons (attaches muscle to bone)
Ligaments (attaches bone to bone)
Fascia
Aponeurosis (attach muscle to muscle)
Function
Provide a very strong attachment between various structures
Collagen fibre bundles have great strength that can withstand strong pulling force
Still flexible
Only works in the direction it runs
70
Dense irregular connective tissue
Composition
A few fibroblasts, predominantly collagen fibres
Woven in flat sheets with fibres running all over the place
Location
Skin(dermis)
Fascia
Periosteum of bone
Perichondrium of cartilage
Joint capsules
Heart valves
Membrane capsules around various organs
Function
Provides strength- strong covering, resistant to tearing, but is flexible
Strong in different direction
71
Elastic CT
* Composition: fibroblasts, few collagenous fibers, primarily elastic fibers, which are kinked in appearance and tend to regain their original shape after being stretched. Fibers may be aligned
parallel or interwoven.
* Location: lung tissue, trachea and bronchial tubes, ligaments between vertebrae, _vocal cords__, elastic arteries, suspensory ligament of penisnuchal ligament in horses and cattle, __stomach__and __bladder__ wall
* Function: allows stretching
72
Bones and cartilage charactrized by
Bones and cartilageo Characterized by:
▪ Solid, flexible, yet strong extracellular matrix
▪ Cells contained in matrix cavities called lacunae
▪ External covering (periosteum or perichondrium) that can generate new tissue
73
Cartilage
* Consists of a stiff, plastic matrix that has lubricating and weight bearing capability
* Found in areas that require support and movement (skeleton and joints)
* Provide a smooth surface for bones to articulate
* All types of cartilage consist of cartilage cells (chondrocytes_) embedded in a matrix of ground substance and fibers in little spaces called lacunae.
* Proportion of matrix: chondrocytes is very high
* Matrix is made up of:
▪ GAG’s (glycosaminoglycans) called chondroitin sulfate and hyaluronic acid
▪ fibers: collagen and elastin
▪ tissue fluid
* No vascular supply
* Receives all nutrients through _diffusion from the perichodrium_(membrane surrounding the cartilage). This limits thickness of cartilage
* No nerves, therefore pain free
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Hyaline cartilage
Composition: chondrocytes in a bluish white and glossy ground substance, which is a firm gel made up of chondroitin sulfate and collagen fibers.
Cells will be found individually or in small clusters of
several cells, the sides of the cells may be flattened. Often areas around the lacunae may appear denser in X-section.
Location: most abundant cartalige in the body. Found on ends of long bones, ends of ribs, nose, parts of larynx, tracheal rings, and bronchial tubes
Function:
allows movement at joints
flexibility and support
Makes up most of the fetal skeleton, and is gradually replaced with bone during development, except for certain areas
Remains in the growth plate of long bones while the young animal is growing
Most rigid type of cartilage
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Elastic cartilage
Composition: chondrocytes, cartilage substance (matrix) and elastic fibers.
Similar in basic structure to hyaline cartilage, but has more elastic fibres.
Location: external external ear (pinna), auditory (Eustachian) tube, epiglottis of larynx
Function: gives support and maintains shape
Very flexible and elastic
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Fibrocartilage
Composition: rare chondrocyte groups (rows or clumps) scattered among bundles of collagen fibers in a cartilage matrix. Lacks a perichondrium
Location: Intravertibral discs, menisci of knee joint (half-moon shaped cartilages on the proximal tibia), pubic symphysis
Function: support and fusion. Acts as a cushion in strategic joint ligaments and tendons
Very tough and adapted to absorb shock by resisting compression and tension
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Bone (Osseous tissue)
Characteristics
Hard, unyielding, strong, relatively lightweight
Has a fiber framework that give the bone strength without brittleness
Can be visualized as a living organic “concrete”
Hard ground substance
Organic secretion/mineral salt mix (calcium phosphate), collogan
Special cells
Osteoblasts, osteoclasts, osteocytes
Blood vessels
Nerves
Location
Found where maximum weight bearing and protection is required by the body.
Function
Forms the frame of the animal and protects vital organs
Provides a calcium reserve for the body
Bone marrow stores fat and produces blood cells
Develops from fetal cartilage or fibrous tissue precursors
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Blood (Vascular tissue)
Specialized type of CT
Consists of numerous formed elements (or blood cells) suspended in a liquid matrix(plasma)
Formed Elements: RBC’s, WBC’s, and platelets
Red Blood Cells = erythrocyte
White Blood Cells = leukocyte
Platelets = thrombocytes
Plasma is the matrix
Ground substance consists of water with dissolved nutrients, ions, hormones, gases
Plasma: consists of water with dissolved nutrients, ions, hormones, gasses, and plasma proteins – some of which are important for blood clotting
Need to differentiate:
Plasma:
Fluid part of uncloted blood
Useful as a substitute for blood in transfusions because proteins will provide oncotic pressure
Serum:
Supernatant fluid that remains after clotting and binds the cellular components of blood
Similar to plasma but lacks most of the clotting factors
Contains antibodies, so is sometimes useful to prevent or treat disease
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Epithelial membranes
epithelial layer overlying a connective tissue layer
Three common types of epithelial membranes are: mucous, serous, and cutaneous
Tend to receive vascular supply by blood vessels in the connective tissue underneath
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Mucous membrane aka Mucosa
Line body cavities that open to the external environment
Have goblet cells which secrete mucin to coat the membrane surface
Mucus is a secretion of water, electrolytes, and mucin (protein)
Provides lubrication and moistness
Also is sticky and has antibodies in it that can trap and destroy bacteria and particles
Layers of mucous membranes:
1. Usually either stratified squamous, psuedostrattified_or simple columnar epithelium
2. Loose connective tissue called lamina propria
3. Connective tissue called submucosa
▪ Examples include the digestive, respiratory, reproductive and urinary tracts – all lined with mucous membranes
Function
Secrete mucus or absorb nutrients
Mucous is the membrane, mucus is the sticky material it secretes
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Serous membrane
Line internal body cavities (i.e. pericardial, pleural, peritoneal) and most of the internal found in body cavities
Help form mesenteries, (e.g. stomach and uterus)
Secrete a serous fluid to reduce friction during movement
Fluid is a transcudate – thin, watery secretion with electrolytes (no mucin)
Can be called pleural, pericardial, or peritoneal fluid, depending on location
During disease, it may become more dense with cells and proteins – called exutdate
May develop abnormally large volume of fluid, called ascites, in conditions like CHF, malignant cancers, and peritonitis
Serous membranes form a potential space between the serous membrane lining the organ and the membrane lining the wall of the body cavity
The portion of the membrane which lines the cavity wall is called the parietal, and the portion that covers the outer surface of organs is called the visceral.
if damaged, adhesions may form between the organ and wall and this may be very painful
Very permeable
Layers:
Simple squamous epithelium
Loose connective tissue
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Cutaneous membrane
The skin covering the body
Free surface is dry, composed of non-living cells, and is exposed to the environment
Layers: keratanized stratified squamous epithelium (epidermis)
* Keratin is a waxy substance that fills cells as they move to the outside of the skin and die. Provides waterproofing and resists abrasion
Next layer is dermis, or dense irregular connective tissue (gives strength and elasticity, can be tanned into leather)
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Connective tissue membrane
specialized membranes composed only of connective tissue, usually fibrous CT
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Meninges
Fibrous membranes that envelope the brain and spinal cord
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Perichondrium
Fibrous membrane covering the surface of cartilage. Contains blood vessels, which are the cartilage’s only blood supply.
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Periosteum
Fibrous membrane covering the surface of bones. Contains blood vessels with also supply the bone
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Synovial membrane
Line joints, bursae, and tendon sheaths.
Secrete a watery synovial fluid which helps reduce friction in the joint Muscle Tissue
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Signs of inflammation
PRISH
Pain
Redness
Immobility
Swelling
Heat
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1st step of inflammation
Initial vasoccontristion (helps control hemorrhage).
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2nd step of inflammation
Followed by sustained vasodilation due to histamine and heparin release from mast cells – increases capillary permeability and blood flow ➔ causes redness and swelling brings nutrients to the area
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3rd step of inflammation
Fluid (plasma-enzymes, antibodies, proteins) enters area ➔ further swelling ➔ irritates nerves to cause pain/tenderness
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4th step of inflammation
Clot forms: platelets clump, fibrinogen (lots found in swollen tissues) is converted to fibrin (forms a woven net to provide support, isolate the site, and give a framework for cell migration to the area). Called a scab if on the skin, which helps protect and cover the wound
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5th step of inflammation
macrophages (phagocytic cells) enter area and clear debris and bacteria ➔ die quickly to contribute to the formation of pus (accumulation of dead and degenerated neutrophils and macrophages)
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6th step of inflammation
Histamine and heparin levels drop (washed away by increased blood flow) ➔ capillary size and permeability
Returns to normal ➔ swelling, heat, and redness settles down.
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Granulation tissue
the formation of granulation tissue
* If infected, wound healing is delayed
* Macrophages and neutrophils must clear the area
* Bright pink granulation tissue forms under the scab
* Composed of collagen fibers (made by fibroblasts)
▪ Lots of small capillaries – look like granules, hence the name granulation tissue
▪ Provides lots of nutrients to the cells working to heal the wound
▪ Extremely resistant to infections (produces lots of bacterial-inhibiting substances)
▪ Forms proud flesh if too thick (exuberant – may need to cut away to allow healing)
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Regeneration or fibrosis of tissue repair
epithelialization occurs & granulation tissue is replaced by scar tissue
* Epithelial tissue grows to try to cover the granulation tissue – called epithelialization
* scab falls off
* Fibroblasts manufacture collogen fibres ➔ replace granulation tissue ➔ contact down (pull edges together)
* Location of the scar and its size is important
▪ May almost disappear as tissue remodels
▪ Can constrict vital organs e.g. fibrous pericarditis
▪ In abdomen or thorax, may form adhesions – can cause
later problems such as pain, restricting movement or
trapping loops of bowel
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Classification of wound repair
➢ First intention healing has wound edges held in close apposition with minimal scarring
➢ Second intention healing has wound edges separated, granulation tissue forms across the gap, moderate scarring
➢ Third intention healing has large, extensive wound gaps with more severe
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Brown fat
a special type of fat used to generate heat and protect against cold in some young or hibernating animals. It is found internally, not subcutaneously.
✓ Energy from fat in brown fat tissue is used exclusively for heat production
✓ Very vascular – helps move heat to the rest of the body
APHY 101
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