Tissues Flashcards
What are the 4 types of tissue in the body?
Epithelial
Connective
Muscle
Nervous
What do epithelial tissues do?
Cover surfaces, separate different compartments etc
What defines the function in epithelial tissues?
Cells.
Can epithelial tissues form secondary structures?
Yes- glands, heat/touch receptors etc.
What does connective tissue do?
Connects tissues of the body.
Give some examples of connective tissue.
Blood, bone, adipose (fat).
What defines function within connective tissue?
Extracellular matrix and fluid.
What matrix exists in connective tissue?
Liquid to solid matrix.
What do muscle cells do?
Exist as long thin cells which are contractile for movement. Shortens length and close down spaces through breadth of contractile apparatus existing in the cytoplasm.
What are the cytoplasms of muscle tissue cells filled with?
Contractile apparatus.
What do nerve cells do?
Generate, receive and transmit electrical signals. Function in body communication and integration of body systems. Includes neurones and support cells (e.g. glial).
What is the difference between epithelium and endothelium?
Epithelium = outside Endothelium = inside
What does the function of epithelial tissue depend on?
Cellular specialisation rather than that of the extracellular matrix.
How does epithelial tissue maintain the coverage of a surface?
No contact inhibition- cells can touch/stick to other cells
Cell-cell junctions
ECM junctions
What are cell-cell junctions?
Junctions between cells which maintain epithelial tissue coverage of surfaces.
What are densosomes?
Adhering junctions- provide a firm anchorage through large proteinaceous thickening connective fibrous proteins on either side of a cell membrane.
Give an example of densosomes in action.
Elbow stretching.
What are tight junctions?
Occluding junctions- seal tight intracellular spaces.
Give an example of tight junctions in action.
Bacteria in the intestinal lumen cannot get through these.
What are gap junctions?
Communicating junctions- allow cell-cell communication through formation of a hole in the centre which allows transmission of chemical/electrical signals.
Give an example of gap junctions.
Intercalated discs of cardiac cells allows electrical impulse transmission.
How is epithelium maintain integration with the connective tissue?
Basement membrane
Cell-ECM junctions
Why does the basement membrane exist?
To maintain contact between the epithelium and things below (ECM/connective tissue).
What is the basal lamina composition like?
Gel.
What is the reticular lamina composition like?
Net; stringy fibres.
What are Cell-ECM junctions?
Junctions which connect the cell to the extracellular matrix.
Give an example of a cell-ECM junction.
Hemidesmosomes- connect the cell to the basement membrane.
What do hemidesmosomes do?
Connect cell to basement membrane.
What are the secondary roles of thick epithelium?
To allow wear and tear- adaptive epithelial nature of repair.
What are the secondary roles of thin epithelium?
To allow diffusion and entry/exit of substances.
What can aid movement and absorption roles of epithelia?
Cillia for movement, microvilli for absorption.
What are the broad classifications of epithelia?
Simple
Stratified
What are the narrow classifications of simple epithelia?
Squamous
Cuboidal
Columnar
What are the narrow classifications of stratified epithelia?
Squamous Cuboidal Columnar Transitional Pseudostratified columnar epithelium
What are glands?
Collections of specialised secretory epithelial cells.
Are glands single-celled or multicellular?
Can be either.
What do exocrine glands do?
Secrete into TUBES.
What do endocrine glands do?
Secrete into BLOOD.
What are the classifications of gland?
Simple- tubular, acinar
Compound- tubuloacinar
What do mucus glands do?
Thick glands passing a secretion rich in proteoglycans- secretion + water gives mucus.
What are mucus gland secretions rich in?
Proteoglycans.
What do serous glands do?
Pass secretion rich in protein.
What do myoepithelial cells do?
Contract to squeeze out the secretion, found in basal lamina.
Where are myoepithelial cells found?
Epithelial basal lamina.
How do endocrine glands work?
They pass a proteinaceous secretion- the receptor is outside to allow the secretion to pass entry into a blood vessel.
Where are steroid glands found?
Inner glands of adrenal cortex.
When are steroid hormones synthesised?
On demand.
What are the epithelial components of the liver called?
Parenchyma hepatocytes.
How are hepatocytes arranged in the liver?
In rows between blood vessels.
What are the functions of parenchyma hepatocytes?
Line/support hepatic structures, secretion.
What are the epithelial components of the kidney called?
Parenchyma epithelial cells organised into nephrons.
What are nephrons?
Organised epithelial cells in the kidney.
What are the functions of parenchyma nephrons?
Support filtration of blood, partial absorption of filtrate, overall function to support urine excretion, support renal cells.
What are the abnormal functions of epithelial cells?
Over-proliferation / Under-proliferation
Over-secretion / Under-secretion
Loss of ciliary beat
What does abnormal function of the pituitary gland affect?
Growth hormone.
What does over production of growth hormone in the pituitary gland cause?
Pituitary giantism.
What does under production of growth hormone in the pituitary gland cause?
Pituitary dwarfism.
What faults can occur in the mucous glands of the uterine tube?
Chlamydia (STD)
Infertility
What is the ECM within connective tissue composed of?
Fibres (rope) Ground substance (jelly) Tissue fluid (liquid)
What fibres are found within the ECM of connective tissue?
Collagen
Elastin
What characterises collagen?
Tensile strength.
What is a Type I collagen?
Tendons.
What is a Type III collagen?
Reticulin.
What is a Type IV collagen?
Basal lamina.
What characterises elastin?
Elastic fibres, stretch x1.5 in length, seen as sheets.
What are examples of loose connective tissue (permanent fixed cells)?
Fibroblasts, macrophages, mast cells.
What is an example of a dense regular connective tissue?
Tendon.
What is an example of a dense irregular connective tissue?
Sebaceous gland.
What abnormal functions can arise in connective tissue?
Blood leukaemia, cartilage tears, osteoporosis in the bones.
