Tissue Extracelluar Matrix

Question 1

Four basic types of human tissues:

Answer 1

Epithelial
Muscle
Neural
Connective

Question 2

Connective tissue

Answer 2

binds the cells
and organs of the body together
(forming its structure)

Question 3

Connective
tissue:
Functions

Answer 3

Support + protection
Transportation
Energy reserve storage
Defence

Question 4

Extracellular
matrix:Connective tissue fibres

Answer 4

Collagen fibres - High tensile strength
• Elastic fibres- Stretch + recoil
• Reticular fibres – Form the internal
structure/skeleton of soft organs (e.g., spleen)

Question 5

Extracellular
matrix:
Ground substance

Answer 5

• Fills spaces between cells +
surrounds connective tissue
fibres
• Contains mostly water, some
cell adhesion proteins & large
polysaccharide molecules

Question 6

Types of
Connective
tissue:

Answer 6

1. Connective tissue proper
   • Loose connective tissue
   • Densely packed connective tissue
2. Fluid connective tissues
   • Blood
   • Lymph
3. Supportive connective tissues
   • Cartilage
   Bone

Question 7

Loose Connective tissue

Answer 7

fill spaces between organs,
provide cushioning and support to epithelia
Types
• Areolar tissue – forms layer that separates skin
from deeper structures; extensive blood supply
(caters to metabolic requirements of
surrounding epithelial tissue); provides padding;
elastic
• Adipose tissue – fat cells/adipocytes (e.g., fills
bony sockets behind eyes)
• Reticular tissue – stabilises position of functional
cells in bone marrow and lymph nodes

Question 8

Dense connective tissue

Answer 8

Collagen fibres – densely packed: tough, strong,
durable, resist distortion, tension and interconnect
bones and muscles.
Types
• Dense regular connective tissue
• Tendons – attach skeletal muscle to bones
• Ligaments – connect one bone to another, can
stretch
• Dense irregular connective tissue
• Strengthens and supports areas subject to
stresses; gives skin its strength, covers bone
and cartilage, forms capsule which surrounds
internal cavities

Question 9

Specialised
cells of
connective
tissue proper

Answer 9

Fibroblasts - produce connective tissue fibres +
ground substance
Fibrocytes - maintain connective tissue fibres in
connective tissue proper
Macrophages - phagocytize (engulf) pathogens or
damaged cells
Fat cells/adipocytes
Mast cells – mobile cells, contain histamine and
heparin (chemicals released after injury/infection)

Question 10

Fluid connective tissue

Answer 10

Blood
• Red blood cells (Erythrocytes)
- transport O2 and CO2
• White blood cells
(Lymphocytes) - Immune
system
• Platelets - blood clotting
• Plasma

Lymph
Forms as interstitial fluid
drains into lymphatic vessels
that return to cardiovascular
system. Immune cells monitor
lymph composition and
respond to signs of infection/injury

Question 11

Supporting connective tissue: Cartilage

Answer 11

Firm gel containing embedded fibres
• Chondrocytes – only cells in cartilage matrix
• Avascular – thus chondrocytes must get nutrients & eliminate waste by diffusion through
matrix
Types
• Hyaline - provides support, reduces friction, between bony surfaces
• Elastic - provides support, tolerates distortion without damage
• Fibrocartilage - resists compression, prevents bone to bone contact, limits movement

Question 12

Supporting connective tissue: Cartilage

Answer 12

Firm gel containing embedded fibres
• Chondrocytes – only cells in cartilage matrix
• Avascular – thus chondrocytes must get nutrients & eliminate waste by diffusion through
matrix
Types
• Hyaline - provides support, reduces friction, between bony surfaces
• Elastic - provides support, tolerates distortion without damage
• Fibrocartilage - resists compression, prevents bone to bone contact, limits movement

Question 13

Epithelial tissue + examples

Answer 13

Group of cells that cover the exterior
surfaces of the body, line internal cavities
and passageways, and form certain
glands.
Examples
- Skin
- Lining of digestive, respiratory, and
urinary tract
- Lining of cavities surrounding heart and
lungs
- Lining of fluid filled chambers in the eye rain and ear

Question 14

Epithelial tissue + examples

Answer 14

Group of cells that cover the exterior
surfaces of the body, line internal cavities
and passageways, and form certain
glands.
Examples
- Skin
- Lining of digestive, respiratory, and
urinary tract
- Lining of cavities surrounding heart and
lungs
- Lining of fluid filled chambers in the eye rain and ear

Question 15

What is Epithelial tissue
Composed of ?

Answer 15

Epithelia: The cells that
cover external and internal
surfaces

Glands: cells that secrete
fluid
Most glands are formed
during development by
proliferation of epithelial
cells so that they project
into the underlying
connective tissue

Question 16

What is Epithelial tissue
Composed of ?

Answer 16

Epithelia: The cells that
cover external and internal
surfaces

Glands: cells that secrete
fluid
Most glands are formed
during development by
proliferation of epithelial
cells so that they project
into the underlying
connective tissue

Question 17

Functions of Epithelial
tissue:
Epithelia

Answer 17

1. Control permeability
2. Provide protection- from dehydration, abrasion,
   chemical & biological agents
3. Sensation
4. Secretion (by glandular cells)
   • Exocrine secretions - released onto epithelial
   surface
   • Endocrine secretions – released into surrounding
   tissue fluid (interstitial fluid) and blood
   • Hormones= chemical messengers that co-
   ordinate and regulate activities of tissues, organs, cells

Question 18

Characteristics of Epithelial tissue: Epithelia

Answer 18

Characteristics:
• Cells are closely bound
• Attached surface (basement membrane)- connected to
connective tissue
• Exposed surface (apical surface) –either an internal
passage/chamber or the environment
• Damaged/lost cells at exposed surface are continuously
regenerated
• Avascular – lack blood vessels

Question 19

Intercellular connections

Answer 19

Epithelial cells must be firmly attached to basement membrane + each other to
form an effective lining. Damage/breakage results in exposure to pathogens.
• Intercellular connections - Join epithelial cells to one another and to adjacent
tissue and aid in providing an effective barrier.
• Interconnected by cell adhesion molecules (proteins that bind to each
other and extracellular materials by a layer of proteoglycans)
• Specialised attachment sites
• Cell junctions - attach 1 cell to another or to extracellular matrix
• Include: tight junctions, gap junctions, and desmosomes

Question 20

Basement membrane

Answer 20

Connects the epithelial
cell to the underlying
connective tissue
• Provides a barrier
• No cells - protein fibres

Question 21

Epithelial surface

Answer 21

Apical surface – exposed surface
• Microvilli - usually line internal passageways
• increased surface area
• resulting in more effective absorption or secretion of
substances

Question 22

Epithelial Renewal and repair

Answer 22

Epithelial cells are constantly replaced by stem cells

Question 23

Epithelial cell classification based on layering

Answer 23

Simple
Stratified
• Single layer of cells covering
basement membrane
• Found inside the body - line
internal compartments and
passageways
• usually also found in areas
where secretion/absorption occurs

Stratified
Greater protection- multiple
layers above basement
membrane
• Found in areas that are exposed
to chemical/mechanical stress eg mouth skin

Question 24

Epithelial cell shapes

Answer 24

Squamous
Cuboidal
Columnar

Question 25

Glandular Epithelia

Answer 25

Endocrine secretion- hormones; produced by endocrine glands and released into blood/tissue fluids. Exocrine secretion- exocrine glands release products through duct/tube onto an external surface. • Unicellular (goblet cells) or Multicellular • Mode of secretion- • Merocrine- secretion released from secretory vesicles by exocytosis • Apocrine- loss of cytoplasm containing secretion; gland cell must repair before additional secretion • Holocrine- superficial gland bursts releasing secretion and replaced by underlying stem cells (Ex. Sebaceous gland • Type of secretion • Serous • Mucous • Mixed

Question 26

Muscle tissue

Answer 26

Made up of cells that contract when excited • Contract due to interaction between filaments of myosin and actin

Question 27

Skeletal muscle

Answer 27

Large multinucleated cells • Muscle cells are called: muscle fibres • Incapable of dividing- however, stem cells differentiate to provide new muscle fibres. • Striated voluntary muscle • Myosin + Actin filaments arranged into repeating patterns à gives striated appearance • Contract when stimulated by nervous system

Question 28

Cardiac muscle

Answer 28

In heart • Striated involuntary muscle • Cardiac muscle cell: cardiocyte • Limited ability to repair itself due to reduced stem cells • Ability to efficiently conduct stimulus and force contraction: cells branch and form extensive connections with each other (interconnected at intercalated discs- attachment sites containing gap junctions and desmosomes) • Sinus node (Pacemaker) - establish regular contraction, nervous system can alter rate of contraction

Question 29

Smooth muscle

Answer 29

Small, slender No striations – actin and myosin filaments are scattered throughout cytoplasm. Nonstriated involuntary muscle

Question 30

Nervous tissue

Answer 30

Nervous tissue transmits electrochemical signals via nerve impulses from one region to another. • 2 types of cells • Neurons - communicate via electrochemical signals • Supporting cells (neuroglia)- support and nourish neural tissue • Longest cells in body (reaching 1m), cannot divide thus difficult to regenerate after injury • 3 main parts • Cell body - nucleus • Dendrites - branching projections, receive information • Axon – 1 projection, carry information to other cells, nerve fibres (ending at axon terminal here info passed from one neuron toanother

Question 31

Ageing changes

Answer 31

Tissue repair (speed and efficacy) decreases with age Epithelia thins Connective tissue becomes more fragile Irreplaceable tissue (cardiac)

Question 32

Synovial membranes

Answer 32

• Lines joint cavities + produce fluid within joint • Areolar tissue + incomplete layer of epithelial tissue • Ends of bones are covered with hyaline cartilage + separated by synovial fluid • Synovial fluid • Produced by fibroblasts in connective tissue of synovial membrane • Lubricates joint + provides smooth movement

Question 33

Cutaneous membrane

Answer 33

Simple epithelium + areolar tissue • They line sealed internal cavities which are not open to exterior • 2 sections • Parietal- lines inner surface • Visceral- lines outer surface (e.g., visceral pericardium covers heart, parietal pericardium lines inner surface of pericardial sac) • 3 Types • Pleura - covers lungs, lines pleural cavity • Peritoneum- lines peritoneal cavity + covers liver/stomach • Pericardium – lines pericardial cavity + covers heart

Question 34

Mucous membranes

Answer 34

Line passageways + chambers • Coated with mucous gland secretions • Areolar tissue portion of mucous membrane= called lamina propria (supports epithelial layer) • Usually simple epithelia (secretory/absorptive functions)