Hormonal Responses (CHPT 5) Flashcards
What is the role of the endocrine glands?
Release hormones directly into the blood
There are several classes based on chemical make up. What are these classes?
Amino acid derivatives, peptide/protein, steroids.
The effect of a hormone on a tissue is determined by what?
the plasma concentration and number of active receptors
What is plasma concentration determined by?
- Rate of secretion of hormones from endocrine gland
- rate of metabolism, or excretion of hormone
- quantity of transport proteins
-Changes in plasma volume
What are some factors that influence of secretion of hormones?
- increased plasma glucose
- increased plasma amino acids
- Sympathetic activity
- Increased parasympathetic activity 
What is the magnitude of effect of a hormone dependent on?
- Concentration of the hormone
- Number of receptors on the cell
- Affinity of the receptor for the hormone
What is downregulation?
- decrease in receptor number in the response to a high concentration of hormone
What is upregulation?
Increase in receptor number in response to low concentration of hormone
What are the mechanisms of hormone action? (modify, cellular activity)
- Activation of genes to alter protein synthesis
- activating second messengers in the cell via G protein
- Altering membrane transport
What kind of hormone activates gene to alter protein synthesis?
Steroid hormones
What activates second messengers in the cell via G proteins?
-cyclic AMP
-Ca++
-Inositol triphosphate
-diaclyglycerol
What is an example of altering membrane transport?
Insulin via tyrosine kinase.
Explain the mechanism of steroid hormone action.
- Hormone passes through plasma membrane.
- Hormone by zero receptor protein in the cytoplasm or nucleus
- Hormone receptor complex binds to hormone response element on DNA, regulating gene transcription
- Protein synthesis
- Change in protein synthesis is cellular response.
Describe the Cyclic AMP second messenger.
- I’m on Bryne’s to a G protein coupled receptor on the plasma membrane.
- The G protein activates adenylate cyclase which causes ATB to be converted to cyclic AMP
- The cyclic, AMP, activates protein, thinners a
- Which activates response, protein to alter cellular activity
Explain the phospholipase C messenger mechanism.
- hormone binds to GPCR on the plasma membrane and activates G protein
- G-protein activate the effector protein phospholipase C
- Causes phosphotidylinositol (PIP2) to be broken down into inositol triphosphate (IP3) and disygkycerol (DAG)
- IP3 causes release of calcium from the intra cellular organelles that activates a calcium binding protein calmodulin
- DAG activates protein kinase C to bring about additional cellular response
Explain insulin receptors.
- Insulin binds to the tyrosine kinase receptors, alpha subunits (outside the cell)
- Binding causes the beta subunits located inside the cell to phosphorylate themselves and activate signalling proteins
- the incident. Response proteins activate glycogen synthase to synthesise glycogen from glucose
What are the major endocrine glands?
Hypothalamus and pituitary glands, thyroid and parathyroid glands, adrenal glands, pancreas, testes and ovaries
What is the role of the hypothalamus?
Control secretions from the pituitary gland
What hormones are secreted by the anterior pituitary gland? (7)
Luteinizing hormone (LH).
Melanocyte-stimulating hormone (MSH).
Thyroid-stimulating hormone (TSH).
Growth hormone (GH).
Prolactin.
Adrenocorticotropic hormone (A C T H).
Follicle-stimulating hormone (FSH).
Which hormones are secreted by the posterior pituitary gland?
- oxytocin
- antidiuretic hormone (ADH)
What is the role of Adrenocorticotropic hormone (ACTH)?
- Stimulates cortisol release from adrenal glands
What is the role of Luteinizing hormone (LH)?
- Stimulates production of testosterone and estrogen
What does the growth hormone stimulate?
- Liver and other tissues
- Protein synthesis and growth
- Increases glyconeogenesis in liver
- Blocks, glucose entry to adipose cell to favour, fat metabolisation.
Which hormones from the anterior pituitary gland stimulate cell signaling mechanisms?
Melanocyte-stimulating hormone (MSH).
Thyroid-stimulating hormone (TSH).
Prolactin.
Growth hormone (GH).
What is the role of the thyroid stimulating hormone? (TSH)
- Controls thyroid hormone released from thyroid gland
Explain the role of (insulin like growth factors) IGFs
Responsible for muscle growth
(IGF-1)
Which hormone is responsible for amino acid uptake, protein synthesis, and long bone growth?
Growth hormone
How does a growth hormone spare plasma?
- Opposes insulin action, reduces the use of plasma
- Increases glucogenesis
- Metabolises fatty acids from adipose tissue
What can the growth hormone be used to treat?
- Childhood dwarfism
- Also used by athletes and elderly
What is the role of the antidiuretic hormone?
- Reduces water loss from the body to maintain plasma volume
What stimulates the release of the antidiuretic hormone?
- High plasma osmolality and low plasma volume
- Caused by sweat loss without water replacement
Does the antidiuretic hormone increase during exercise?
- Yes, above 60% of VO2 Max to maintain plasma volume
What are the roles of Triiodothyronine (T3) and thyroxine (T4)?
- Influences resting metabolic rate.
- Permissive hormones (permit full effect of other hormones)
Which gland secrete calcitonin?
The thyroid gland
What is the role of calcitonin?
- Involved in the regulation of plasma Ca++.
- Blocks Ca++ release from bone, stimulates excretion by kidneys
What is the role of the parathyroid hormone?
- Primary hormone in plasma Ca++ regulation.
- Stimulates Ca++ release from bone.
- Stimulates reabsorption of Ca++ by kidneys.
- Converts vitamin D3 into a hormone that increases Ca++ absorption from the GI tract.
What is the role of the adrenal medulla?
- Secretes the catecholamines (Epinephrine (E) and norepinephrine (N E))
- Bind to adrenergic receptors ( (α) and (β) )
What do Epinephrine (E) and norepinephrine (N E) do?
- Fast-acting hormones.
- Part of the “fight or flight” response.
What is the role of the adrenal cortex?
- secretes steroid hormones (derived from cholesterol)
- Mineralcoticoids
- sex steroids
- glucocorticoids
What is the role of mineralocorticoids?
- releases aldosterone
- Maintenance of plasma, sodium and potassium
What are examples of glucocorticoids? What is the role?
- cortisol
- Regulation of plasma glucose