Vet A&P Tissues + Body Cavities

4 types of tissue

• epithelial - lines body cavities, absorbent or secretory

• connective - connect/support body parts, carries nutrients/waste (blood, fibrous connective tissue, cartilage, bone)

• muscle - movement (striated, smooth, cardiac)

• nervous - conduct nerve impulses

Each tissue consists of three main components:

• Cells - one type forms the majority

• Intercellular products - produced by cells

• Fluid - interstitial fluid flows through specialized channels

Epithelial tissue lines the ____

It can be ___ or ___

body cavities

absorbent - small intestine

secretory - glands

_____ is epithelium inside the heart, blood vessels, and lymph vessels

endothelium

Simple epithelium is ____ cell thick

one

Stratified or compound epithelium is ____ cell thick

more than one

Squamous cells are ___ in shape

flattened

Cuboidal cells are ___ in shape

square or cube

Columnar cells are __ in shape

column (height > width)

The least specialized type of epithelium is ___

simple cuboidal

Simple cuboidal epithelium is ___ thick

Found in ____

Absorptive or secretory?

one cell thick

glands and ducts

both

Simple squamous epithelium is ____ thick and must be _____

Found lining the ____

one cell thick (thin and delicate)

easily permeable to oxygen

lining blood vessels and alveoli

Simple columnar epithelium is ____ thick and the cells are ___

Absorptive or secretary?

one cell thick

cells are tall and narrow

absorptive (small + large intestine)

secretory (digestive glands)

Ciliated epithelium functions to _____

Found in _____

waft particles along the epithelial surface

upper respiratory tract (trap inhaled solid particles)

uterine tubes (move fertilized egg along tract)

Stratified epithelium is ____ and found in ___

multilayered (thicker and tougher)

in areas subject to shearing forces (epidermis)

Pseudostratified epithelium is ___ thick, but appears ____ because ____

ONLY ONE LAYER, but appears mutilayered bc of irregular nuclei (found in trachea)

squamous cell carcinoma originates from ____

adenoma develops in ______ tissue

transitional cell carcinoma develops in _______

squamous cells in the skin

glandular

bladder wall

______ is most at risk for canine parvovirus (CPV)

unvaccinated puppies between 6 weeks to 6 months

canine parvovirus (CPV) targets _____ cells

highly infectious virus targets rapidly dividing cells (intestinal epithelium) affecting absorption of nutrients and increasing fluid loss

hemorrhagic (bloody) diarrhea and vomiting

puppy rapidly becomes weak and dehydrated

no drug that can cure the virus

treatment based on supportive care and management of symptoms (IV fluid, nutrient replacement, drugs to reduce vomiting, antibiotics if there is secondary bacterial infection due to weak immune system)

Glandular tissue

modification of epithelial tissue

secretory membrane

unicellular or multicellular

Unicellular glands

individual secretory cells interspersed throughout tissue

goblet cell (secrets mucus directly on membrane)

Epithelium is aka _____ membrane

mucous; traps particles, extra protection, lubricates

found covering oral cavity, vagina, trachea

Multicellular gland

many secretory cells folded to form complex gland

exocrine glands

system of ducts through which secretory products are transported directly to site

endocrine glands

ductless glands; secretions (hormones) carried by blood to target organ

Simple tubular gland

Stomach, intestine

Simple coiled tubular

Sweat glands

Simple branched tubular

Stomach, mouth, tongue, oesophagus

Simple alveolar

Sebaceous glands

Branched alveolar (acinar)

Sebaceous glands

Compound tubular

Bulbourethral glands, mammary glands, kidney tubules, testes, mucous glands of the mouth

Compound alveolar gland

mammary glands

Compound tubuloalveolar

salivary glands, pancreas, respiratory passages

Connective tissue consists of cells embedded in an _______

extracellular matrix or ground substance (properties depend of type of connective tissue)

7 types of connective tissue in order of increasing density

1. blood

2. haemopoietic tissue

3. areolar tissue or loose connective tissue

4. adipose or fatty tissue

5. fibrous connective tissue or dense connective tissue

6. cartilage

7. bone

Blood functions to ____ and cells are in a ground substance called _____

carry nutrients and oxygen to cells, carry waste to organs of excretion

plasma

haemopoietic tissue

jelly-like tissue forms in bone marrow of long bones

responsible for formation of blood cells

areolar tissue

areolar (spaces)

most widely distributed connective tissue

beneath skin, around vessels/nerves, between organs and muscle bundles

the ground substance of areolar tissue contains ___ (4 things)

collagen fibers - high tensile strength secreted by fibroblasts

elastic fibers - enable tissue to stretch and return to former shape

fat cells in varying quantities depending on location/obesity

macrophages - phagocytosis

adipose tissue

matrix of fat filled cells closely packed together

energy reserve

insulates and reduce heat loss - in dermis

protective - around kidney

lipoma

common benign tumor that develops in adipose tissue

frequently in older dogs

can become very large if not removed

may cause discomfort depending on position

dense connective tissue

densely packed collagen fibre bundles with few fibroblasts or other cells

arrangements of dense connective tissue can be ____

Parallel - regular fibrous connective tissue

• tendons - muscle to bone, strong bands of fibrous tissue

• ligaments - bone to bone

Irregularly interwoven fibers - forms sheets, fascia, aponeuroses

• dermis of skin

• capsules of joints

• testes, lymph nodes

Ehlers-Danlos syndrome (EDS) causes _____

defective collagen synthesis

cutaneous asthenia (weakness)

rare inherited condition that affects connective tissue

skin is excessively stretchy, loose, fragile, and tears easily

can affect joint stability

cartilage

rigid but flexible, resilient, able to bear weight

composed of cells (chondrocytes) and fibers with gel-like ground substance

cartilage has no _____ and nutrition us provided by ___

blood supply, fibrous sheath (perichondrium)

hylaine cartilage

translucent, blue-white appearance

forms articular surfaces of joints, provides support in the nose, larynx, trachea, and bronchi

forms skeleton of embryo before endochondral ossification

same refractive index as gel matrix, can’t see under microscope

most common type of cartilage

elastic cartilage

has chondrocytes within a matrix and numerous elastic fibers

support and flexibility (external ear, epiglottis)

fibrocartilage

higher proportion of collagen fibers

intervertebral discs, menisci of stifle joint

attaches tendons and ligaments to bone

osteoarthritis

degeneration of articular cartilage

rickets

young animals on a diet in which there is imbalance of calcium and vitamin D

signs related to problems with ossification of growing bones

osteochondritis dissecans (OCD)

disturbance in endochondral ossification

intermittent lameness in shoulder adn elbow joints of large breeds (Great Dane)

panosteitis

young dogs

idiopathic inflammation of all bone tissues

presenting as pain in long bones

bone is a ____tissue

living, capable of remodeling and repairing itself

provides rigid supportive framework

forms a system of levers for locomotion

Bone extracellular matrix contains the protein ____ and _____ fibers, which forms the organic material called _____

osteonectin, collagen

form osteoid (unmineralized component of bone matrix before calcification)

calcification causes _____ to become trapped in______

osteocytes, lacunae spaces

Haversian canals carry ___ and are surrounded by ___

blood vessels and nerves

lamellae (series of concentric cylinders of matrix material) and osteocytes in lacunae

compact bone is ___ and found ____

solid and hard

found in outer later of all types of bone

Haversian systems densely packed together

Cancellous (spongy) bone consists of _____

internal meshwork of trabeculae, spaces between filled with red bone marrow

found in ends of long bones, core of short, irregular and flat bones

osteosarcoma

most common type of malignant tumor of bone tissue

affects any breed of dog, most commonly in large breeds

affects limbs but can occur anywhere

can spread rapidly

affected limb is often amputated

Muscle tissue is responsible for _____

The 3 types are ___-

organized movement of the body

skeletal/striated, smooth, cardiac

skeletal/striated muscle

found attached to skeleton and brings about movement

voluntary and conscious control

long/cylindrical fibers lie parallel to each other

nuclei lie on outer surface of cell bc presence of myofibrils push cell structures to outer margins

skeletal muscle cells are multi____ because __

multinucleated due to the fusion of multiple precursor myoblasts during development.

leads to single, long muscle fiber containing multiple nuclei

Skeletal muscle is composed of bundles of ______ made of ___ and ___

microfilaments (myofibrils)

actin (thin filaments) and myosin (thick filaments)

Muscle fibers are grouped together in bundles called ___

fasicles

Muscle fibers (cells) are surrounded by ____

Fascicles are surrounded by ___

The entire muscle is surrounded by

endomysium

perimysium

epimysium (continuous with tendon_

smooth muscle is controlled by _____

autonomic nervous system

unstriated, involuntary, visceral

long, spindle shaped

surrounded by small amounts of connective tissue that bind cells into sheets/layers

found in walls of blood vessels, digestive tract, respiratory tact, bladder, uterus

cardiac muscle forms the ___

myocardium of the heart

only found in the hea

responsible for rhythmic and automatic contraction, involuntary and unconscious

increased or slowed by nerves supplying heart

cardiac muscle cells branch to form _____ which are linked by ____ that enable ____

a network of fibers linked by intercalated discs

enables nerve impulses to be conveyed across the myocardium quickly

striated and cylindrical in shape

Toxoplasmosis

caused by protozoan parasite toxoplasma gondii

inflammation of muscle tissue (myositis)

Cushing’s disease

generalized myopathy

muscular weakness, muscle wasting, atrophy

Myasthenia gravis

lack of receptors for acetyl choline at neuromuscular junctions

presents as chronic fatigue

nervous tissue

formed by neurons

functions to transmit nerve impulses

structure of neuron

cell body - contains nucleus

dendrons - short processes, carry info toward cell body

axon - long process, carry info away from cell

myelin - fatty material covering axon, increases speed of transmission, protects

Schwann cell - secretes myelin

synapse - transmits to next cell

demyelination

loss of myelin surrounding nerve, caused by inflammatory/immune mediated diseases

slows the rate of transmission of nerve impulse

muscle weakness or paresis

seen in diseases affecting CNS or PNS (canine distemper virus)

serous membrane

single continuous layer of epithelium that produces watery or serous lubricating fluid between surfaces of cavity and organs within it

• parietal - lines boundaries or sides of cavity

• visceral - covers all organs within cavity

mucus

thicker that serous fluid, more proteinaceous

has protective function

3 body cavities

Thoracic

Abdominal

Pelvic

thoracic cavity contains

heart, lungs, other associated structures

entrance - cranial thoracic inlet formed by first thoracic vertebra, first pair of ribs and manubrium

exit - caudal border filled by diaphragm

mediastinum

potential space formed by double layer of parietal pleural that separates pleural cavities

contains pericardial cavity (contains heart, aorta, trachea, oesophagus, thymus)

costal parietal pleura

continuation causes division into two pleural cavities

visceral (pulmonary) pleura

cavity also contains lungs and serous pleural fluid

diaphragmatic parietal pleura

mediastinal pleura

pleuritis

inflammation of serous membrane of thoracic cavity

caused by bacterial infection, leads to pleural effusion (fluid in lung) and respiratory problems

peritonitis

inflammation of serous membrane of abdominal wall

caused by infection (damage to abdominal wall from external wound as the result of perforation of intestinal wall by ingested foreign body)

abdominal cavity

digestive system, urogenital system, associated vessels and nerves

1 - liver

2 - stomach

1 - diaphragm

2 - coronary ligament

1 - greater mesentery

the visceral peritoneum is folded on itself in a way that keeps organs separate, suspending the organs within the abdominal cavity

• mesoduedenum - suspends duodenum

• mesovarium - suspends ovary

1 - lesser omentum (lesser curvature of stomach)

2 - greater omentum (greater curvature of stomach)

mobile fold of peritoneum that contains lacy network of fine vessels and fat

1 - stomach

2 - pancreas

3 - uterus

4 - bladder

feline infectious peritonitis (FIP)

viral disease in cats caused by feline enteric corona virus

causes inflammation of blood vessels, results in leakage of fluid into abdominal cavity (ascites)

presents as non-painful distension of abdomen

pelvic cavity

contains urinary bladder, rectum, reproductive organs

no physical separation between abdominal and pelvic cavity