Exam 3 content Flashcards
to absolutely fucking crush this final exam
Are neurotransmitters considered hormones?
Yes, but they specifically act on target cells through the synaptic cleft.
Define a hormone:
A secreted molecule travels to target cells and exerts some effect based on an interaction with the receptor. Can go through blood or act locally. Can act as neurotransmitters or hormones based on the context.
Compare the endocrine system to the nervous system (two main control systems)
The nervous system is much faster and reaches fewer neurons. The endocrine system is much slower and reaches more cells.
In the endocrine system, organs are related _______ but not ________
functionally, physically
Insulin
Type of molecule (e.g. steroid, peptide) and solubility (water or lipid)
Cell type that produces hormone
Stimulus for secretion
What is the receptor (key properties of receptor)
What effect does hormones have?
- Insulin is a water-soluble peptide hormone that binds a transmembrane receptor
- Produced by beta islet cells in the pancreas, which are sensitive to high plasma glucose levels
- Receptors include skeletal muscle, adipocytes, and liver cells.
-Functions to decrease the amount of plasma glucose in the blood through absorption into liver, skeletal muscle, and adipocytes.
What is blood plasma?
Blood plasma is the non-cellular portion of blood
Describe how beta islet cells function as a sensor and controller
- Initially, high plasma glucose levels drives glucose transport via Glut2 into beta islet cells
- This influx of glucose leads to an increase in metabolic activity and an increase in ATP produced by the metabolism.ATP binding to potassium channels, blocking the release of potassium and increasing membrane potential
- This process opens voltage gated Calcium channels
- This leads to the exocytosis of insulin which is released in the blood
Outline the negative feedback loop for the hormone insulin
(drawing)
Describe the effect of actuating signal (insulin) on effector cells. FOR muscle and adipocytes (fat cells)
-Insulin is a water-soluble peptide hormone that binds a transmembrane receptor
-This stimulates glucose exocytosis and increases glucose uptake
- When insulin levels are low, Glut4 endocytosis is favored, reducing membrane permeability to glucose
Describe the effect of actuating signal (insulin) on effector cells. FOR liver cells
-Insulin is a peptide hormone that binds a transmembrane receptor
-This stimulates glycogen production from glucose,
- Leading to an influx of glucose from Glut2 (which is not under hormonal control).
Outline the negative feedback loop for the hormone insulin
(drawing)
Glucagon
Type of molecule (e.g. steroid, peptide) and solubility (water or lipid)
Cell type that produces hormone
Stimulus for secretion
What is the receptor (key properties of receptor)
What effect does hormones have?
-Water soluble
-Produced by alpha islet cells in the pancreas
-Sensitive to low glucose plasma levels
- Receptor is liver cells, has the impact of raising blood plasma glucose by releasing glucose held in stores
For Glut 2 in the liver, is the channel under hormonal control?
No, the channel is not under hormonal control
Describe the effect of the actuating signal (glucagon) on effector cells FOR liver cells
Glucagon is a water-soluble peptide hormone that binds a g-protein coupled transmembrane receptor. This binding leads to glucose production from glycogen (glycogenolysis) and the release of glucose from the cell via Glut2
_________ represents the production of glycogen from glucose, _______ represents the production of glucose from glyogen
- gluconeogenesis
- glycogenolysis
Describe diabetes mellitus. What are the symptoms?
Plasma glucose levels remain high. There are numerous possible symptoms, but two prominent examples include high volume of urine and thirst. There is too much glucose in blood plasma, consequently more glucose than typical enters the Bowman’s Capsule of a nephron. There are more solutes in the filtrate, changing osmotic balance such that less water is absorbed through Osmosis.
Characterize the two kinds of diabetes mellitus
Type 1: there is a problem with beta islet cells such that no insulin is produced
Type 2: insulin insensitivity in skeletal, adipocytes, or liver cells.
Production of calcium effectively ______ it’s own regulatory system by binding to ______, inhibiting the release of _______
turns off, CaSR, PTH
Describe the negative feedback loop involved in the control of plasma Ca2+
(draw)
So, overall, we increase plasma levels of calcium by increasing the amount we absorb in the intestine, increasing the amount we reabsorbed from filtrate, and by breaking down bone tissue and calcium stored in bone.
Describe the actions of the effectors in the chart (bone) in response to low calcium levels and the release of PTH
- 99% of the calcium in our bodies is stored in our bones
- PTH acts on osteoclasts via PTH receptors
- PTH receptors are g-protein coupled receptors
- Osteoclasts break down calcified extracellular matrix in bone tissue, which releases Ca2+ into blood plasma
Describe the actions of the effectors in the chart (distal tubule and collecting duct) in response to low calcium levels and the release of PTH
- PTH binds PTH receptors on epithelial cells to increase Ca2+ reabsorption by the kidney.
Describe the actions of the effectors in the chart (proximal tubule) in response to low calcium levels and the release of PTH
- PTH stimulates release of 1,25 dihydroxy vitamin D (1,25(OH)2D), a lipid soluble hormone which acts on receptors in the intestine to increase Ca2+ absorption
PTH
Type of molecule (e.g. steroid, peptide) and solubility (water or lipid)
Cell type that produces hormone
Stimulus for secretion
What is the receptor (key properties of receptor)
What effect does hormones have?
Water-soluble
Parathyroid gland cells, which express calcium sensing receptor
Low calcium levels in blood plasma
Increasing blood plasma levels of calcium by increasing amount absorbed in intestine, amount absorbed from filtrate, and by breaking down bone tissue and releasing calcium stored in bone.
Describe the hypothalamus and pituitary: regulation of cortisol
- Corticotropin Releasing Hormone (CRH) is released in the hypothalamus
- This leads to Adrenocorticotropic Hormone (ACTH) release from the anterior pituitary
-And this leads to cortisol being released from the adrenal glands
