Endocrinology Flashcards
What are the functional unit of nervous system?
neurons
What are the functional units of the endocrine system?
specialised secretory cells and glands- endocrine glands
What do endocrine glands do?
they secrete a different number of hormones, the specific hormone
Why is the nervous system faster than endocrine?
-speed of influence of the endocrine system on the body’s function is much slower than that of the nervous system as it does not directly act on the target organs
What are 2 macromolecules that hormones can be made from?
Give an example of each naming its macromolecule base?
proteins
e.g. insulin , glucagon , FSH , LH
lipids
e.g oestrogen , testosterone ,
What is the structure of the endocrine gland?
- ductless
- made up of hollow spherical follicles lined with secretory epithelial cells.
- they secrete hormones into interstitial fluid and diffuse into the surrounding capillaries.
What is each follicle surrounded by?
an extensive capillary network
Where are these hormones transported to?
the hormones produced are secreted in the interstitial fluid and diffuse into surrounding cells.
transported in the blood to their target organ, tissue or cells.
What are the endocrine glands?
Pineal Pituitary Thyroid Thymus Juxtaglomerular gland Adrenal Pancreas Ovaries Testes
Where are the thyroid and parathyroid glands?
situated in the neck, anterior to the trachea
-there are 4 parathryoid glands embedded in the posterior surface of the thyroid gland
What is the largest endocrine gland?
thyroid gland
as it synthesises and stores thyroid hormones that influence heart rate, blood pressure, body temperature , energy production and overall body metabolism
What are follicular cells?
epithelial cells with microvilli on their luminal (apical) surface
What are the inactive follicular cells?
they are cuboidal
What are the active follicular cells?
they are columnar
What is the pancreas structure?
12-15 cm long
leaf shaped organ that lies horizontally, deep to the stomach
What is the pancreas function?
- It functions as both endocrine and exocrine gland
- With 99% of its activity centred around the exocrine secretion of digestive enzymes and sodium bicarbonate
What are the 2 important function of the pancreas?
1- Specialised cells in the pancreas produce the hormones glucagon and insulin. these hormones control blood sugar levels by initiating the conversion of glycogen to glucose and vice versa
2- Function in digestion- producing an enzyme-rich pancreatic juice which helps break down proteins to amino acids, starch to maltose, fats into fatty acids and glycerol
What is most of the pancreas cells?
99% of the specialised cells are exocrine and produce a number of enzymes which help in the digestive process/
What is the Islets of Langerhans?
the remaining regions of the pancreas which contain specialised cells responsible for the endocrine role of the pancreas
What do the islets of Langerhans consist of?
the vast fenestrated capillary network surrounding them and the hormones released by each of these cells are secreted directly into the blood flow.
What does fenestrated mean?
pores between endothelial cells
What is the endocrine system?
its a collection of glands and specialised cells which secrete hormones into the bloodstream.
It works alongside the nervous system to regulate all aspects of body function.
What is a hormone?
-a chemical substance/messenger which is secreted by specialised endocrine cells directly into the blood to exert an effect on distant target cells to bring about specific changes in cellular function.
What is the duration of the response of the endocrine system?
the duration of the effect of a hormone on the body is longer lasting than a nerve signal and can cause permanant changes
- varies from seconds to years ( puberty)
What are examples of processes controlled by the nervous system?
Reflexes such as:
- Blinking
- Movement of limbs
- Fight, Flight and fright
What are examples of processes controlled by the endocrine system?
Growth:
-development of reproductive system
What is the nature of message of
:Nervous sytem
:Endocrine system?
- Electrical signals
2. Chemical messages
What is the area of response for the nervous system?
Localised- confined to one area of the body
What is the area of response for the endocrine system?
Many organs
-specific to many cells- as blood goes all throughout the body as hormones will travel in
How is nervous system fast?
Get nervous stimuli- for fast response- last for short period of time
What does TSH secrete?
T3 AND T4
Which lobe of the pituitary gland secretes more hormones into the systemic circulation?
Anterior lobe- secretes 5
What type of stimulation controls secretion from these endocrine glands: Posterior lobe? Medulla of adrenal gland? Thyroid gland? Anterior lobe? Parathyroid? Testes? Pineal gland?
- Neural- sends axon down to this posterior lobe- get signals
- Neural
- Hormonal
- Hormonal
- Humoral
- Hormonal
- Neural
Which 2 are the main nuclei of the hypothalamus involved in hypothalamic pituitary axis?
- Paraventricular nucleus
- Supraoptic
What is a morphological difference between endocrine and exocrine glands?
Endocrine- into bloodstrean
exocrine- into duct
What are the hormones that are produced by thyroid follicular cells within thyroid gland?
T3
T4
If blood sugar levels are too high, what happens to excess glucose?
Excess glucose stored via glycogen or fats
What is the pancreas?
both an endocrine and exocrine gland
secretes pancreatic enzymes - exocrine- into duodenum to aid digestion
endocrine- secretes insulin and glucagon
What is islets of langerhans?
the endocrine cells of the pancreas
Describe negative feedback in regulating hormone levels from the cortex of the adrenal gland
Hypothalmus secretes CRH
- Down portal vein
- Around the capillaries of the cells of the anterior lobe
- Corticotrophs are stimulated and release ACTH
- ACTH goes into hyphoseal vein, into systemic circulation, through the capillaries in the adrenal cortex
- Secretes glucocorticoids.
- If high levels of this it stimulates the pituitary gland to reduce ACTH secretion
- CRH is controlled by hypothalmus- so excess of glucocorticoids will inhibit this CRH from hypothalmus.
what stimulates hormone release ?
- humoral - hormone release caused by change in ion levels or nutrient level
- neural - hormone release caused by neural input
- hormonal - hormone release caused by another hormone
