Exocrine And Endocrine Glands Flashcards
What are glands?
Epithelial cells that produce secretions
(Ectodermal origin)
What do endocrine glands do?
Do they have ducts?
Produce hormones
No ducts
Where do secretions (hormones) pass out of the endocrine glands?
Pass out into the interstitial tissue then into blood capillaries scattered within tissues of these glands
What type of secretions do exocrine glands produce and what do they secrete?
Mucous secretions and they secrete many different substances
Where do exocrine glands ducts release their secretions?
Lumen or onto surfaces of organs
Some are enzymes and some saliva
What are endocrine glands?
Part of epithelial surface (lining of digestive tract)
Or separate organs such as thyroid/ pituitary gland
What do endocrine hormone secretions do?
Regulate bodily functions
Maintain homeostasis
Name the 3 patterns of hormone secretion in endocrine glands?
Chronic
Acute
Episodic
What is chronic pattern of secretion like in endocrine glands?
Regular increases or decreases throughout the day
(Thyroxin)
What is acute pattern of secretion like in endocrine glands?
Amount secreted depends on stimulus
Ie. Some stimuli may cause secretion of large amounts (stressed)
While other stimuli may result in less hormones being secreted
(Adrenaline of cortisol)
What is episodic pattern of secretion like in endocrine glands?
Episodes of hormones produced and episodes of no production
Eg. Growth hormone
Insulin = increased secretion after eating
Name the 3 types of regulation of hormone secretion in endocrine glands ?
Humoral secretion
Neutral regulation
Hormonal regulation
Describe Humoral regulation in endocrine glands.
Prescience of blood borne molecules
Eg. High glucose levels stimulates insulin secretion
Describe neutral regulation in endocrine glands.
Neuron stimulates hormone production
Eg. Sympathetic nervous system (fight or flight) stimulates epinephrine release.
Describe hormonal regulation in endocrine glands.
Hormone secretion stimulus another hormone to be secreted
Eg. Hormones from pituitary gland stimulates tested to make testosterone
Give 3 classes of hormones?
Proteins and polypeptides
Steroids
Derivative of amino acid tyrosine
Describe proteins and polypeptides type of hormone.
Secreted by pancreas and parathyroid gland
Stored within cell and released on demand
Eg. Pancreas, parathyroid gland
Describe steroid type of hormone.
Synthesised from cholesterol
Released directly into circulation
Can’t be stored
Eg. Adrenal cortex, ovaries, placenta
Describe derivative of amino acid tyrosine type of hormone.
Secreted by the adrenal medulla and thyroid
Where is the thyroid gland located and what is it formed of?
Location in midline of neck in front of trachea
Formed from 2 parts joined together by central isthmus
How many parathyroid glands are there?
Where are they located?
What are they separated by?
4
Corners of thyroid gland
Separated from thyroid by layer of fibrous tissue
Structure of parathyroid glands?
Single layer of cuboidal epithelium
Contain colloid
Increase in size (columnar) when active
Structure of thyroid glands?
- what is main bulk made up of?
- what is follicular epithelium?
- what do follicles store?
Main bulk made up of follicles
Single layer of cuboidal epithelium that lines thyroid glands
Collied that is secreted by the follicular epithelial
What does colloid contain?
Thyroxine T4
Tri-iodothyronine T3 (active hormone)
What is 10% of thyroid gland made up of?
What is the structure of this?
Where is it found?
C cell
(Parafollicular cell)
Has clear cytoplasm
Present within interstitial tissues surrounding follicles
What do C cells produce?
Calcitonin
- hormone that regulates calcium