Tissues 2 Flashcards
What are glands?
Collection of secretory epithelial cells
How many cells do glands have?
They may be single cells (goblet cells) or multicellular (sweat glands)
What is an example of a single celled gland?
Goblet cells
What is an example of a multicellular gland?
Sweat glands
What are the two types of glands?
Exocrine (secrete into tubes)
Endocrine (secretes into the blood)
What are exocrine glands?
Glands that secrete into tubes
What are endocrine glands?
Glands that secrete into the blood
Why are exocrine glands locally acting whereas endocrine glands can effect distant tissue?
Because exocrine glands release their contents onto a nearby epithelial tissue whereas endocrine glands release their contents into the blood
What are the two forms of duct systems of an exocrine gland?
Simple (unbranched)
Compound (branched)
What are the 2 forms of excreoty components of an exocrine gland?
Tubular
Acinor
What is an example of a simple tubular exocrine gland?
Gastric glands
What is an example of a simple acinar exocrine gland?
Mucus secreting of penile urethra
What is an example of a compound tubular exocrine gland?
Brunner’s gland, empties into intestine
What is an example of a compound acinar exocrine gland?
Pancreas
What is an example of a compound tubuloacinar exocrine gland?
Siliva gland
What are the 3 ways that secretion from an endocrine gland may occur?
Merocrine
Apocrine secretion
Holocrine
What is merocrine secretion?
Involves exocytosis, proteins are usually produced
What is apocrine secretion?
Discharge of vesicles containing secretion, example being sweat gland
What is an example of apocrine secretion from an endocrine gland?
Sweat gland
What is holocrine secretion?
Discharge of whole secretory cells, disintegrate and release product, occurs in sebaceous glands
What is an example of holocrine secretion from an endocrine gland?
Sebacceous gland
How are the secretions often expelled?
From myoepithelial cells and they contract
What are myoepithelial cells?
Cells found in glandular epithelium as a thin layer above the basement membrane but bineath laminal cells
What are endocrines often the source of?
Hormones
What is a hormone?
A chemical messanger
How are most endocrine glands structured?
Clusters of secretory cells surrounded by small blood vessels
Why is the thyroid gland unusual?
It stores its hormones (thyroxine) within spherical cavities called follicles
How does secretion occur within the thyroid gland?
- Reabsorption of hormone from follicle
- Release into intercellular space
- Diffusion into blood stream
What is the secretion of hormones controlled by?
Metabolic factors
What are examples of exocrine organs?
Major silivary glands
Liver
What are examples of endocrine organs?
Thyroid
Adrenal
What organ is an example of both endocrine and exocrine glands?
The pancreas
What are parenchyma?
Functional tissue of an organ
Where is the parenchyma of the liver?
In hepatocytes (liver cells)
What are hepatocytes?
Liver cells
What are the functions of hepatocytes (liver cells)?
Secretion
Protein synthesis
Transformation of carbohydrates
How are hepatocytes arranged?
In rows between blood vessels
What does the basic structure of the kidney look like?
Composed of the cortex, medulla, pelvis and ureter
How are epithelial cells organised in the kidneys?
Into nephrones
What is a nephrone?
Functional unit of the kidney composed of epithelial cells
What are the functinos of the epithelial cells in the kidney?
Filtration of blood
Partial absorption of filtration
Release urine from the kindey
What are some abnormal functions of epithelial cells?
Over proliferation
Under proliferation
Over secretion
Under secretion
Loss of celia/celia beat
What are some abnormal functions of the pituitary gland (controls growth hormone)?
Over production (giantism)
Under production (dwarfism)
What are some abnormal functions of the mucous glands in the uterine tibe?
Over production, can be caused by chlamydia
Lead to thick mucous, ovum and sperm being trapped
What are some examples of connective tissues?
Bllod/bone marrow
Mucous
Reticular
Loose
Dense regular
Dense irregular
Cartilage
Bone
Adipose (fat)
What is adipose tissue (fat)?
Loose connective tissue composed of adipocytes that store energy
How is the fat in adipocytes stored?
As triaclycerides which contain lots of stored energy
What is white adipose tissue used for?
Storing energy
What is brown adipose tissue used for?
Generating heat
What are the 3 components of connective tissue?
Fibres
Ground substance
Tissue fluid
What are the 2 fibrous components of connective tissue?
Collagen (tendon), also reticulin (lymph)
Elastic (aorta)
How much of our body weight is made up by collagent?
30%
What are some properties of collagen?
Great tensile strength
Inelastic but flexible
How many types of collagen are there?
More than 19
What are some examples of the different types of collagen?
Type I in tendons
Type III in reticulum
Type IV in basil lamina
How does collagen end up in the ECM?
Secreted into it by connective tissue in the form of tropa-collagen monomer which are three polypeptide chains, they then form collagen fibrils
What does reticular fibre (type III collagen) form?
Delicate supporting network for many cellular organs like endocrine glands
How does elastin end up in the ECM?
Similar to collagen, it is secreted into it by connective tissues as the protein elastin which combines and forms elastic fibres
What does elastin allow?
Stretching
How is elastin usually structured?
In sheets rather than fibres
Where are elastin fibres found?
In the aorta
What is the ground substance composed of?
Glycoproteins
Tissue fluid
Carbohydrates
Salt
What is the function of the ground substance?
Involved in the development of tissues
Cells use it to exhange substances
What is dense connective tissue?
Connective tissues with fibres as its main element, encase things such as bone and cartilage
What is loose connective tissue?
Attatches epithelial to underlying tissues
What are the 4 permanent cells in loose connective tissue?
Fibroblasts (syntheis collagen)
Macrophages (destoys pathogens)
Adipocytes (stores energy as fat)
Mast cells (battles inflammation)
What do fibroblasts do?
Synthesis collagen
What do macrophages do?
Destroy pathogens
What do adipocytes do?
Store energy as fat
What do mast cells do?
Battles inflammation
What is a transient cell in loose connective tissue?
White blood cells (protects against pathogens)
What do white blood cells do?
Protect against pathogens
What are the two forms of dense connective tissue?
Regular (parralel)
Irregular (not parralel)
What is an example of a dense regular tissue?
Tendons
What is an example of a dense irregular tissue?
Sebaceous gland
What are some abnormal functions of connective tissues?
Blood/bone marrow (leukiamia)
Loose/dense (loss, abnormal fibres)
Cartilage (tear)
Bone (osteoporosis)