Animal Hormones and Endocrine System Flashcards
What are animal hormones?
Chemical signals secreted into the circulatory system and reaches target cells with receptors for that hormone.
What long-lasting responses does the Endocrine system affect?
- Reproduction
- Development
- Energy Metabolism
- growth
- Behaviour
How does the endocrine system and nervous system interact?
High speed electrochemical signals are conveyed along specialized cells called neurons that regulate other cells including other neurons, muscle cells and endocrine cells.
How does endocrine signalling work? What does it do?
Hormones secreted from endocrine cells into extracellular fluids and reach their targets via the bloodstream. It maintains homeostasis, mediates responses to stimuli, and regulates growth and development.
What are local regulators?
Molecules that act over short distances reaching target cells solely by diffusion.
What is the difference between paracrine signalling and autocrine signalling?
Paracrine: target cells are near the secreting cells
Autocrine: target cell is also the secreting cell
What are synapses?
specialized junctions formed from neurons and target cells. It is paracrine if the target is muscle, and autocrine if the target is another neuron.
How does synaptic signalling work? What does it do?
Neurons at synapses secrete neurotransmitters that diffuse short distances and bind to target cell receptors. It triggers responses in cognition, movement, memory, and sensation.
How does Neuroendocrine signalling work?
- stimulus is received by sensory neuron, stimulating neurosecretory cell
- neurosecretory cell secretes neurohormone which enters the bloodstream and travels to target cells.
How does pheromone signalling work? What does it do?
Chemical signals are released into the external environment rather than the internal environment. It is used to mark trails leading to food, defining territories, warning predators, and attracting potential mates.
What are the three major classes of hormones in vertebrates?
- Polypeptides (proteins and peptides)
- Amines derived from amino acids
- Steroid hormones
What is the difference between lipid-soluble hormones and water-soluble hormones in terms of their molecules, how they are secreted, travelling through bloodstream, and their receptors.
Lipid-soluble: steroid hormones that diffuse through cell membranes. Receptor is in cytoplasm or nucleus.
Water-soluble hormones: polypeptides and amine hormones that are secreted by exocytosis and travel freely in the blood stream. Receptor is on the membrane of the cell.
How does gaseous signalling work? What is an example?
Cells produce gases that have local signalling effects due to their small size and lack of charge which gives them the ability to diffuse in lipid and water. (E.g. Nitric Oxide, gas that functions in the body as a local regulator and neurotransmitter.)
How is insulin made and what does it do?
Produced as a long inactive prohormone polypeptide stored in beta-cells. They are then cleaved and secreted by vesicular trafficking when needed to reduce blood glucose.
What are amide hormones? What are three examples?
Signalling factors produced from amino acids. (e.g. epinephrine made from tyrosine, thryoxine made from tryptophan, GABA made from glutamate)
What is the response of a pathway of a water-soluble hormone?
Responses in the cytoskeleton, enzyme activation, or change in gene expression.
What is the pathway of epinephrine?
- Epinephrine is released by adrenal gland
- Binds to receptors on the plasma membrane of liver cells
- Binding triggers release of messenger molecules that activate enzymes
- Messenger molecule activates enzyme that breakdowns glycogen to release glucose in the bloodstream
what is the response of a pathway of a lipid-soluble hormone?
Change in gene expression
What is the pathway for a steriod?
- Steroid binds to cytosolic receptor
- hormone-receptor complex moves into nucleus
- in the nucleus, the receptor part of the complex acts as a transcription factor to regulate the transcription of specific target genes.
What is the hormone that regulates metabolism in vertebrates, as well as the metamorphosis of a frog?
Thyroid hormone
What are endocrine glands?
Ductless organs that secret hormones directly into a surrounding fluid (e.g. thyroid, parathyroid, testes, ovaries)
What is the difference between an endocrine gland and an exocrine gland?
endocrine: secretions enter surrounding fluid direcetly
exocrine: secretions enter body cavities or go onto body surfaces.
What is a simple hormone pathway?
- Stimulus triggers release of hormones from an endocrine cell
- hormones travel through the bloodstream, and interact with specific receptors within a target cell
- Binding to receptors causes a physiological response
What parts of the brain regulates the coordination of endocrine and nervous systems? How does it do it?
hypothalamus receives information from nervous system and initiates responses through endocrine signalling.
whats the difference between posterior and anterior pituitary gland?
posterior: extension of hypothalamus that stores and secretes HYPOTHALAMUS hormones
anterior: releases ITS OWN hormones, controlled by releasing/inhibiting hypothalamus hormones
What are tropic hormones?
Hormones that regulate the function of other endocrine cells or glands
What is the negative feedback loop of thyroid hormone?
- thyroid level drops in blood
- hypothalamus senses this and secretes TRH from posterior pituitary
- release of TRH causes anterior pituitary to secrete TSH
- TSH stimulates release of thyroid hormone from the thyroid gland
What is hypothyroidism and hyperthyroidism?
hypothyroidism: too little thyroid function, leads to weight gain, fatigue, cold intolerance. may be caused by malnutrition
hyperthyroidism: excessive thyroid production, leads to high temperature, sweating, weight loss, irritability, and high blood pressure
What is the growth hormone? What does it do?
GH is secreted by anterior pituriatry and has both nontropic and tropic effects. It protmotes growth directly by stimulating production of growth factors
What is the negative feedback loop for Ca2+
Insufficient calcium:
PTH from parathyroid glands releases CA2+ from bone and stimulates reabsorption of Ca2+ from kidneys. Stimulates kidneys to activate vitamin D which promotes intestinal uptake of Ca2+
Excessive calcium:
Calcitonin from thyroid gland stimulates Ca2+ deposition in bones and secretion by kidneys.
Where are the adrenal glands? What do they do?
Found on each kidney, consists of the adrenal medulla (inner portion) and adrenal cortex. Adrenal glands secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) as a response to stress-activated impulses from the nervous system
What do epinephrine and norepinephrine do?
Trigger release of glucose and fatty acids into the blood, increase oxygen delivery to the body cells, and direct blood toward the heart, brain, and skeletal muscles, and away from skin, digestive system and kidneys.
What are corticosteroids?
Family of steroids that are triggered by a hormone cascade via hypothalamus and anterior pituitary. Can be glucocorticoids (influence glucose metabolism and immune system), or mineralocorticoids (influence salt and water balance)
What are the hormones produced in the gonads? What do they do?
Androgens: i.e. testosterone, stimulate development and maintenance of the male reproductive system. causes an increase in muscle and bone mass.
Estrogens: i.e. estradiol, responsible for maintenance of femal reproductive system and development of female secondary sex characteristics
Progestins: i.e. progesterone, involved in preparing and maintaining the uterus for growth and development of an embry.
What controls the synthesis of sex hormones?
Controlled by hormones of the anterior pituitary.
What is the pineal gland? What does it do?
Pineal gland is located in the brain and secretes melatonin. Secretion of melatonin is controlled by group of neurons in the suprachiasmatic nucleus (SCN) that sense light and dark cycles
