5 - Gland Intro Flashcards
Merocrine
Fusion of vesicles with the apical membrane (exocytosis)
Apocrine
Partial loss of cytoplasm
Example: sweat gland in the axillary
Halocrine
Complete loss of cytoplasm
Example: sebaceous gland
Constitutive secretion
Merocrine
Small vesicles Repopulate plasma membrane Not modified No granules No signal stimulus
Regulated secretion
Merocrine
Granules
Stimulus needed
Secretary granules are accumulated into large vesicles
Ca2+ is required
ATP is required
Granules are modified before secreted
Apocrine example
In neonates, Fats secreted by apocrine secretion via signet fragments.
When big they can take a portion of cytoplasm with them.
Glycosylation
Covalent attachment of sugars by enzymes to protein and lipids
- Aids protein folding
- Cell recognition
- Prevents lipase digestion
- Prevents protein digestion
Where does glycosylation occur
Golgi apparatus
Golgi mechanism
- RER transfers protein via vescicle to cis region of Golgi
- Then glycosylated
- Packaged into a vesicle at trans end and transported
Transcytosis
- Impermeable substance- endocytosis at one end
- Transported across the cytoplasm via vesicle
- Substance is secreted by exocytosis at other end
Difference between humoral, neural and hormonal
Humoral - negative feedback loop control (change in level of substance in fluid)
Neural - use nerves
Hormonal - use hypothalamus which release hormones to stimulate more hormones
Hypothalamo-hypophyseal portal sytem
Hypothalamus has neurones that stop at the hypthalamo-hypophyseal portal sytem.
Blood travels through 2 sets of cappilaries via the portal before entering the anterior pituitary
Anterior pituitary
ACTH LH FSH GH TSH
Prolactin
MSH- melanocyte stimulating
Posterior pituitary
Base of brain - hypothalamus
Oxytocin
Vasopressin
ADH- anti diuertic hormone
Thyroid
Butterfly shaped
Anterior to trachea
T4 and T3
Parathyroid
4 glands (2 pairs) Dorsal region of the thyroid
Parathyroid hormone
Adrenal glands
Top of each kidney - adrenal medulla and adrenal cortex
Corticosteroids
Oestrogen
Androgen
Progestin
Pancreas
Left and behind the stomach
Exocrine - digestive enzymes
Endocrine - insulin and glucagon
Stomach
Gastrin - gastric acid secretion Ghrelin - feeding behaviour Leptin - appetite control Somatostatin - inhibits hormones Secretin - stimulates water and bicarbonate secretion from the pancreas
Liver
Angiotensinogen
Angiotensin
Thrombopoietin
Duodenum
Secretin - stimulate release of water and bicarbonate ions by the pancreas
Kidney
Renin - converts angiotensin 1 to angiotensin 2
Erythropoietin
Calcitriol - ca2+ absorption by intestine
Thrombopoietin
Peptide hormones
Stored in secretory vesicles
Dissolved in plasma
Receptor on the plasma membrane
Activates 2nd messenger
E.g insulin, glucagon, ACTH, PTH, Gastrin
Steroid hormones
Synthesised on demand by precursors
Bound to carrier proteins
Receptors are present in the cytoplasm or nucleus
Activate transcription factors
E.g oestrogen, androgens, progesterone, aldosterone,cortisol
Catecholamines - amino acid derived
Mad in advanced Stored in vesicles Dissolved in the plasma Receptors of the plasma membrane Activate 2nd messengers
E.g adrenaline, noradrenaline
Thyroid hormones - amino acid derived
Made in advanced
Bound to carrier proteins
Receptor in the nucleus
Activate transcription factor
E.g T3 and T4
