Tissues

Question 1

Epithelial tissue (and 2 forms)

Answer 1

• Refers to an epithelium that covers a body surface or lines a body cavity.

2 forms as listed below:
- Covering and lining epithelium, which forms the outer layer of the skin, dips into and lines the open cavities of the urogenital, digestive and respiratory systems and covers the walls and organs of the closed ventral body cavity.

Glandular epithelium, which surrounds the glands within the body.

Question 2

4 characteristics of epithelial tissue

Answer 2

Polarity — All epithelium has an apical surface and a lower attached basal surface that differ in structure and function.

Specialised contacts — Epithelial cells fit close together and form a continuous sheet. They do this with tight junctions and desmosomes.

Supported by connective tissue — All epithelium are supported by connective tissue. The basement membrane reinforces the epithelium and helps to resist stretching and tearing.

Avascular and innervated — The epithelium is avascular, or contains no blood vessels. It is highly innervated, or supplied by nervous fibres. Epithelium has a high ability to regenerate and can reproduce itself as long as it receives adequate nutrition.

Question 3

Epithelial classification (5 ways)

Answer 3

Single - simple layer of cells
Stratified - two or more stacked cell layers

Squamous cells - flat and scale-like
Cuboidal cells - box like
Columnar cells - tall, column-shaped

Question 4

A gland is one or more cells that produce and secrete a specific product. (water-based fluid that usually contains proteins) Glands are classified according to two sets of traits — where they secrete their fluids and how many cells they contain:

Answer 4

Endocrine (Internally secreting)

Exocrine (Externally secreting)

Unicellular glands
(One cell type)

Multicellular glands
(More than one cell type)

Question 5

connective tissue functions (BPIST)

Answer 5

Binding and supporting
Protecting

Insulating
Storing reserve fuel

Transporting substances within the body

Question 6

Ground substance

Answer 6

clear, colourless, viscous fluid that fills the space between the cells and fibres

Question 7

Types of fibres

Answer 7

Collagen - fibrous protein that is extremely tough and provides high tensile strength

Elastic - Elastin stretches and recoil

Reticular - Reticular fibres are short, fine collagenous fibres and branch extensively to form a delicate network.

Question 8

Cyte vs blast

Answer 8

cyte - mature cell: can maintain the health of the matrix; can revert to their active, immature state to repair and regenerate the matrix.

blast - immature cell: Actively proliferating and secreting the ground substance and the fibres characteristic to their particular matrix

Question 9

Connective tissue (types)

Answer 9

connective tissue proper
bone
cartilage
blood

Question 10

connective tissue proper

Answer 10

Loose Connective Tissue: Areolar, Adipose, Reticular

Dense Connective Tissue: Dense Regular, Dense Irregular, Elastic

Question 11

Cartilage

Answer 11

Hyaline Cartilage
Elastic Cartilage
Fibrocartilage

Question 12

Loose connective tissue (areolar) function (SDHS):

Answer 12

Supporting and binding other tissues

Defending against infection

Holding body fluids
Storing nutrients

Question 13

Loose connective tissue (areolar) appearance:

Answer 13

• Most widely distributed
• Fibroblast = dominant cell type
• Loose arrangement of fibres
• Lots of ground substance

Question 14

Adipose tissue (function)

Answer 14

Store Energy (Lipids)

Cushions and insulates the body

Question 15

Adipose tissue (appearance)

Answer 15

Sparse

Closely packed adipocytes (fat cells)

Accumulates in subcutaneous tissues where it cushions and insulates the body

Question 16

Reticular connective tissue

Answer 16

Limited to specific areas where it can support immune cells in the lymph nodes, spleen and bone.

Function:
Internal frameworks that can support immune cells

Question 17

Reticular connective tissue (appearance)

Answer 17

Delicate network of reticular fibres

Question 18

Hyaline cartilage
(function and appearance)

Answer 18

Function:
Provides strong support while providing pads for shock absorption.

Appearance:
Large number of collagen fibres, its matrix appears transparent or glassy

Chondrocytes

Question 19

Elastic cartilage (appearance and function)

Answer 19

Function:
Maintain the shape of the structure while allowing flexibility

Skeleton of the external ear and in the epiglottis

Appearance:
Similar to hyaline cartilage but has many more elastic fibres

Chondrocytes

Question 20

Fibrocartilage (appearance and function)

Answer 20

Function:
Compressible and resists tension.

Found in the intervertebral discs of the bony vertebrae and knee meniscus.

Appearance:
Rows of Chondrocytes alternating with rows of thick collagen fibres

Question 21

Bone: functions

Answer 21

Supports and protects body structures

Stores calcium and other materials and fat

bone marrow = site for synthesising blood cells

Question 22

Bone (appearance)

Answer 22

Hard, calcified matrix containing many collagen fibres

Osteocytes, reside in the lacunae

Osteoblasts
Osteons formed of concentric rings of bony matrix (lamellae)
surrounding central canals containing blood vessels and nerves

Question 23

Blood (appearance and function)

Answer 23

Function:
Delivers necessary substances such as nutrients and oxygen to the cells

transports metabolic waste products away from those same cells.

Appearance:
Red and white blood cells surrounded by a non-living fluid called plasma

Question 24

Muscle cells (skeletal) function:

Answer 24

attach to bones to enable us to produce voluntary movement

Attach to move bones through contracting and relaxing in response to voluntary messages from the nervous system

Long, cylindrical, multinucleate cells; striated appearance

Question 25

Muscle cells (smooth) function:

Answer 25

line hollow organs to help squeeze substances through these organs. Spindle-shaped cells with central nuclei, no striations; cells arranged closely to form cells Propels substances (food, urine) or objects along internal passageways Involuntary

Question 26

Cardiac muscle: function

Answer 26

lines the walls of the heart to propel blood through blood vessels to other parts of the body Branching, striated, generally uninucleate cells that connect at specialised junctions called intercalated discs. Found only in the myocardium, it contracts in response to signals from the cardiac conduction system to make the heart beat, and propel blood around the body.

Question 27

Nervous tissue (structure)

Answer 27

Primary tissue found in the central nervous system and the peripheral nervous system i.e. brain, spinal cord, nerves Regulate and control body function Made up of neurons - sense stimuli and transmit nerve impulses around body

Question 28

Neurons (components)

Answer 28

Cell Body: The central cell body contains the neuron’s nucleus and other organelles. Nerve Processes: projections from the cell body that are able to conduct and transmit signals. Axons - carry signals away from the cell body Dendrites - carry signals toward the cell body

Question 29

Nervous tissue: Glial cells (functions SASRMNP)

Answer 29

Support nervous system Astrocytes form blood brain barrier Supply of nutrients to neurons Removes excess neurotransmitters Maintains electrolyte balance Nervous system repair Protection against microorganisms

Question 30

Tissue healing (epithelial vs nervous)

Answer 30

Epithelial tissue e.g. fingers - takes a few days to completely repair Nervous tissue e.g. spinal cord injuries - can lead to long lasting and permanent impairments

Question 31

Tissue healing: regeneration

Answer 31

proliferation of cells and tissue. Complete restoration of lost tissue structures.

Question 32

Tissue healing: repair

Answer 32

proliferation of cells, tissue and scar formation. Tissue structure will not be restored. If tissue is incapable of complete restoration or is severely damaged; connective tissue is laid down causing scars , leading to structural rearrangements. Fibrosis - connective tissue replaces normal tissue; excess connective tissue - tissue remodelling.

Question 33

Regeneration capacity

Answer 33

Regenerates extremely well. e.g. Epithelial tissue, bone, dense irregular connective tissue, blood-forming tissue. Moderate Regenerative Capacity e.g. Smooth muscle and dense regular connective tissue Weak Regenerative Capacity e.g. Skeletal Muscle and Cartilage Loss of ability to divide after early development and virtually have no functional regeneration capacity - routinely replaced by scar tissue e.g. nervous tissue and cardiac muscle