Lab 15 - Endocrinology Flashcards
What is the speed of action for nervous system and endocrine system
Nervous system: Very rapid response to stimulus - s/ms
Endocrine system: Can be slow - mins,hours,days,years
What is the nature of the message for nervous system and endocrine system
Nervous system: Electrical impulses/signals travelling along nerves
Endocrine system: Chemical messages travelling in the blood stream
What is the duration of the response for nervous system and endocrine system
Nervous system: Usually completed within seconds/ms - very short. To prolong it you have to activate more neurones
Endocrine system: May take years before completed - longer lasting
What is the area of response for nervous system and endocrine system
Nervous system: Often confined to 1 area of body - localised
Endocrine system: Usually noticed in many organs - widespread
What is examples of processes controlled for nervous system and endocrine system
Nervous system: Reflexes such as blinking, movement of limbs/muscles. Innervation of muscle cells - muscles respond
Endocrine system: Growth, development of reproductive system, puberty
What is functional units for nervous system and endocrine system
Nervous system: Neurons
Endocrine system: Specialised secretory cells and glands
What two macromolecules can hormones be made from?
Proteins and lipids
Give an example of each macromolecule naming its macromolecule base:
Amino acid = polypeptide
Steroid - cholestrol
Insulin = dipeptide
What does endocrine system consist of
Collection of widely scattered glands and specialised cells that secrete hormones into the bloodstream. It works alongside the nervous system to regulate all aspects of body function.
What are hormones
Chemical messengers that circulate in the blood and act upon specific target cells to bring about specific changes in cellular function.
What does each endocrine gland release
Specific hormone, or number of hormones that have a defined role in the control of bodily function
Why is speed of influence and duration of effect of endocrine system on bodys function much slower than that of nervous system
- Much slower
- Does not act directly on the target organ
- Duration of effect of hormone on body is longer lasting than that of nerve signal, even causing permanent changes.
Structure of endocrine glands
Ductless, they are made up of hollow spherical follicles lined with secretory epithelial cells. Each follicle is surrounded by an extensive capillary network.
Function of endocrine glands
- They produce hormones which are secreted into interstitial fluid and diffuse into the surrounding capillaries.
- These hormones are transported in the blood to their target organ, tissue, or cells located elsewhere in the body.
Which glands are endocrine glands
Pituitary gland
Thyroid gland
Juxtaglomerular gland
Which glands are sweat gland and sebacceous gland
Exocrine
Where is Sweat gland found
Deep within skin
Where is pituitary gland found
Brain
Where is Mucous gland found
Gut, tracheae, conjunctiva, oesophagus
Where is Thyroid gland found
Throat, neck
Where is sebaceous gland found
Areas of skin
Where is Juxtaglomerular gland found
Kidney
In between bonus capsule and distal convulated tubule
What are the 2 main nuclei of the hypothalamus involved in the hypothalamic-pituitary axis?
Paraventricular nucleus
Supraoptic
Morphological difference between endocrine glands and exocrine glands;
Endocrine glands are ductless glands, exocrine glands are with ducts
What happens in secretion of exocrine glands
Secrete out of cell into extracellular fluid/matrix - diffuses into blood vessels
What is the cell type in anterior pituitary and hormone secreted into systemic circulation for each of the neuroendocrine signals
PIF - Lactotrophs - Prolactin
GnRH - Somatotrophs - growth hormone
TRH - Corticocrophs - follicle stimulating hormone and luteinising hormone
CRH - Thyrotrophs - adrenocorticotropin hormone
GHRH/GIH - Gonadotrophs - thyroid stimulating hormone
Thyroid stimulating hormone stimulates the secretion of which hormone?
TSH - Thyroid Stimulating Hormone, T3 and T4
Which lobe of the pituitary gland secretes more hormones into the systemic circulation?
Anterior
Which hormone secreted from the posterior pole of the pituitary gland is involved in regulating blood pressure?
Vasopressin ( ADH )
What type of stimulation controls secretion from these endocrine glands;
Has axons running from supraoptic
What type of stimulation controls secretions from these endocrine glands
Posterior lobe of pituitary gland - NEURAL
Medulla of the adrenal gland - NEURAL
Thyroid gland - HORMONAL
Anterior lobe of the pituitary gland - HORMONAL
Parathyroid gland - HUMORAL
Testes - HORMONAL
Pineal gland - NEURAL
Where are the thyroid and parathyroid glands located
In the neck, anterior to the trachea
Where are 4 parathryroid glands embedded
In the posterior surface of the thyroid gland
How are the parathyroid glands named
Due to their proximity to the thyroid gland, however, the two endocrine organs have clearly distinguishable functions.
Which hormones are produced by thyroid follicular cells within the thyroid gland
Thyroxine
Triiodothyronine
Properties of thyroid gland
- One of the largest endocrine glands in the body.
- It synthesizes and stores thyroid hormones that influence heart rate, blood pressure, body temperature, energy production, and overall body metabolism, ultimately affecting the development and functioning of the organs throughout the body.
What are follicular cells
Epithelial cells with microvilli on their luminal surface
Difference between active and inactive follicular cells
Inactive follicular cells are often cuboidal, but once actively secreting, they take on a columnar shape.
When there are high levels of thyroid hormones in the systemic blood circulation, what type of epithelium would line the thyroid follicles?
Simple cuboidal
Negative feedback - high levels of T3 and T4 - block secretion of TSH from pituitary gland and TRH from hypothalamus. Not stimulating thryoid glands to secrete T3 + T4 = inactive follicular cells.
Structure of pancreas
a 12-15 cm long, leaf-shaped organ that lies horizontally, deep to the stomach.
How does pancreas function
As both endocrine and exocrine gland with 99% of its activity centred around exocrine secretion of digestive enzymes and sodium bicarbonate.
What are two important functions of the pancreas
1) Specialized 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) The pancreas also has a function in digestion, producing an enzyme-rich pancreatic juice which helps break down proteins to amino acids, starch to maltose, and fats into fatty acids and glycerol.
What % of specialised cells of the pancreas are exocrine
99%
MAJORITY OF PANCREAS IS EXOCRINE
What do specialized exocrine cells of the pancreas produce
Number of enzymes - help in digestive process
What are the remaining regions of the pancreas known as
Islets of Langerhans and contain
What do the Islets of Langerhans contains
Specialized cells responsible for the endocrine role of the pancreas.
What is surrounding Islets of angerhans
A vast fenestrated capillary network, and the hormones released by each of these cells are secreted directly into the blood flow.
What are the 5 types of cells in the Islets of Langerhans
Alpha Beta Delta F cells Epsilon
Proportion of the total number of endocrine cells for cells in I.O.L
Alpha - 30-40% Beta - 50% Delta - 10-20% F cells - 10-20% Epsilon - 10-20%
Hormone secreted for cells in I.O.L
Alpha - Glucagon Beta - Insulin Delta - Somatostatin and gastrin F cells - Pancreatic polypeptide Epsilon - Ghrelin
Effect of hormone on body for cells in I.O.L
Alpha - Increases blood glucose levels
Beta - Decreases blood glucose levels
Delta - Inhibits somatostatin, regulates exocrine function of pancreas
F cells - Regulates digestive enzyme
Epsilon - Controls hunger, tells you when to eat
What does fenestrated mean?
Gaps/holes/pores between blood endothelial cells = free access/movement of fluid
What would be the effect on glycogen stores from an increase in insulin secretion?
Insulin decreases blood sugar levels – increase active uptake of glucose into muscle cells and adipocytes. AND Stimulate liver and kidney organs to take excess glucose store it as reserve if you don’t need it to make energy., stores as glycogen. So an increase in insulin secretion will turn more glucose into glycogen stores – more glycogen taking
What would happen to blood sugar levels if alpha cells were killed off?
Too low blood sugar levels - hypoglycaemic
Alpha cells secrete glucagon - increase blood sugar levels
If blood sugar levels are too high in a healthy person, what happens to excess glucose?
Stored as glycogen - if this is full, its converted to fatty acids, stored as triglycerides/adipocytes
