KIN 103 (Chp: 22) Flashcards
What are the two main functions of the endocrine system?
MAINTAIN homeostasis
INTEGRATE nervous and immune system with most bodily systems
Problem with endocrine system (Hypersecretion of hormone)
Hypersecretion of hormone (tumours, exogenous source/drugs)
Problem with endocrine system (Hyposecretion of hormones)
Hyposecretion (atrophy or problem with secreting gland)
Problem with endocrine system (receptor defects)
Receptor or 2nd messenger defect (down-regulation of receptor, problems with 2nd messenger system)
Insulin (What does it do?)
- Insulin promotes glucose uptake and inhibits fat breakdown
- Insulin facilitates the opening of channels to let glucose in
What does glucose do in adipose tissue?
- In adipose tissue glucose comes in and becomes pyruvate
In muscle tissue what does glucose do?
- In muscle tissue glucose comes in and becomes pyruvate that gets used for energy
Glycemic index (GI) (What is it?)
Glycemic index (GI)
- higher number foods are better for sporting events
- Only useful if you eat the food in question alone
- (combining foods this does not work)
What do hormones control?
Hormones control:
- Growth and development
- Metabolism
- Regulate internal environment
○ H20, ions, electrolytes, temperature
- Reproduction
Hormones act on cells by controlling what?
Hormones act on target cells by controlling:
- Rate of enzymatic reactions
- Transport of ions or molecules across cell membranes
- Gene expression and protein synthesis
Why is solubility important in Hormones?
Why is solubility important?
- Receptor location (inside or out)
- Transport through plasma (free or bound)
- Length or action (long or short)
Hormone messengers (3 kinds)
Hormone messangers
- Peptides and proteins
○ Lipid soluble
- Steroid
○ Lipid soluble
- Amines
○ Lipid soluble (thyroid hormones)
○ Lipid insoluble (catecolamines)
Peptides and AMINE (characteristics)
- Made in advance stored in secretory vesicle
- Gets dissolved in plasma
- Half life is short
- Receptors on cell membrane
- Works in second messengers
- E.g.: insulin
Steroid (Characteristics)
- Synthesized on demand
- Bound to carrier
- Half life is long
- Receptors in cytoplasm/nucleus
- Works in gene synthesis
- androgen, estrogen, cortisol
How does transcription and translation work in hormone synthesis?
- Enzymes in the Endoplasmic reticulum (ER) chop off the signal sequence creating an inactive prohormone. The prohormone passes from the ER through the Golgi complex
- Enzymes chop off the active reportions of the now active hormone and it remains in the secretory vesicle with other fragments ready for secretion
What do peptides do when they reach their receptor?
This occurs through amplification (the upping in size of second messengers
Steroids (where are they synthesized)
Glands like the adrenal cortex, gonads, placenta
Aromatase (what does it do?)
It is used to convert testosterone to estradiol
5a-reductase (What does it do?)
It is important for development of secondary sex characteristics
Is cholesterol a hormone?
no it is not in itself
Steroid hormones in synthesis (step 1-3)
- hydrophobic steroids are bound to plasma protein carriers. Only unbound hormones can diffuse into the target cell
- Steroid hormone receptors are in the cytoplasm or nucleus
2a. some steroids also bind elsewhere to create rapid cellular responses - the receptor hormone complex binds to DNA and activates or represses one or more genes
Single amino acids (What are they made from?)
- Made from either tryptophan or tyrosine
○ (tyrosine leads to catecholamines)
○ Epinepherine from adrenal gland
○ Norepinepherine from neurons
§ These are both part of the stress response
Neurohormones (What are they?)
- Neurohormones (secreted by neuron into blood)
○ Catacholamines from adrenal medulla
○ Posterior pituitary hormones (like vasopressin/ADH and oxytoxin)
○ Hypothalamic neurohormones (most are trophic)
Long loop feedback (what is it?)
- Peripheral endocrine gland produces hormone that suppresses secretion of anterior pituitary and hypothalamic trophic hormones
- Most dominant feedback mechanism
Short loop feedback
- Pituitary hormone suppresses hypothalamic trophic hormone
- Secondary feedback mechanism
Posterior pituitary
- The posterior pituitary stores and releases two neurohormones
○ Neural tissue
○ Stores hormones produced in the hypothalamus
○ When hypothalamus is stimulated, posterior pituitary secretes two neurohormones: vasopressin, ADH, and oxytocin
Vasopressin (Where is it secreted by?)
By the posterior pituitary
- increases water conservation
- alters permeability of the collecting duct cells
Anterior pituitary
The anterior pituitary secretes six hormones
- Adrenocorticotrophic (ACTH), prolactin (PRL) etc
- Regulated by hypothalamic hormones
○ Somatostatin (SS) = growth hormone inhibiting hormone
Trophic hormones (What are they?)
- Trophic hormones stimulate secretion of other hormones
Corticotropin-releasing hormone (What does it do?)
- Corticotropin-releasing hormone causes the release of ATCH from the anterior pituitary. This causes the release of cortisol from the adrenal cortex (this results in long loop negative feedback
Cortisol (What does it do?)
it increases gluconeogenesis, lipolysis and PRO breakdown
Synergism (What is it?)
Synergism: the effect of interacting hormones is more than additive
Permissiveness
Permissiveness: hormone allows another hormone to exert its full effect
Antagonism
Antagonism: hormones have opposing effects
a. One substance opposes the action of another
b. Competitive inhibitors vs. functional antagonists
c. Insulin glucagon
What hormones inhibit insulin?
hypoglycemia hormones:
- glucagon
- adrenaline
- cortisol
What is the normal fasting range for humans?
4-6 millimoles (the average person)
What does glucose undergo in the body?
Glucose -> (glycolysis) -> pyruvate -> acetyl COA
Two competing states of hunger
- Two competing behavioral states
○ Appetite (or hunger)
○ Satiety (or fullness) (negative feedback on your will to eat)
Glucostatic theory (What is it?)
Glucostatic theory
- Glucose metabolism by hypothalamic centers regulate food intake
Lipostatic theory (What is it?)
Lipostatic theory
- Signals from fat stores to the brain modulate eating behavior to maintain a particular weight
How do we calculate total body energy
Total body energy = energy stored + energy intake + energy output
Anabolic pathways (What do they do?)
- Anabolic pathways synthesize larger molecules from smaller ones
○ Fed state, or absorptive state
Catabolic pathways (What do they do?)
- Catabolic pathways break large molecules into smaller ones
○ Fast state, or postabsorptive state
Ingested biomolecules have three fates (What are they?)
- Ingested biomolecules have three fates
- Energy to do mechanical work
- Synthesis for growth and maintenance
- Stored as glycogen or fat
What are the 3 uses for biomolecules in the body?
Sum of chemical reactions in the body 1. Use energy for work
2. Extract energy from nutrients
3. Store excess energy
Glycogenosis (What is it?)
○ Glycogenosis: fed state metabolism under the influence of insulin, enzyme activity for the forward reaction increases. Enzymes for glycogen breakdown are inhibited. Net glycogen synthesis results
Glycogenolyses (What is it?)
○ Glycogenolyses: in fasted state metabolism under the influence of glucagon enzymes that break down glycogen synthesis are inhibited. Het glucose synthesis results
What do enzymes do in metabolic control?
- Enzymes control the direction of metabolism through push-pull control
Catabolic processes (Glycolysis)
Glycolysis: the breakdown of glucose into pyruvate of lactate
Catabolic processes (Glycogenolysis)
- Glycogenolysis: the breakdown of glycogen
Catabolic processes (Lipolysis)
Lipolysis: lipid triglycerides are broken into a glycerol and free fatty acids
Anabolic processes (Gluconeogenesis)
Gluconeogenesis: synthesis of glucose from a precursor other than carbohydrate
Anabolic processes (Glycogenesis)
Glycogenesis: the synthesis of glycogen
Anabolic processes (Lipogenesis)
Lipogenesis: fatty acid synthesis and then triglyceride synthesis
3 Nutrient pools avalable in plasma for immediate use?
Nutrient pools are avalable for immediate use in plasma
1. Free fatty acid pools
2. Glucose pool is tightly regulated
i. Glycogenesis, glycogenolysis (breakdown of glycogen)
ii. Gluconeogenesis (synthesis of glucose from a precursor other than carbohydrate) and lipogenesis
3. Amino acid pool
When we are dieting what occurs?
- Fats make ATP
○ Beta oxidation
○ Aerobic oxidative phosphorylation - Excess fat is stored
○ Adipose tissue
○ Other tissues (liver, muscle) - Excess glucose and amino acids are converted to fat
What happens in the cytoplasm of a cell?
In the cytoplasm
1. Glycogen is present
2. Combines with glucose when abundant
3. Glycolysis occurs with glucose 6-phosphate
1. This forms ATP in the process
4. Pyruvate is formed
5. Anerobic or aerobic conditions dictate what happens next
In the cytosol through anerobic metabolism (from Glycolysis and glycogenolysis) what is the net ATP production?
NET 2 from glucose
NET 3 from glycogen
What is the total ATP from a fatty acid?
Total ATP from a fatty acid is about 6-7 times that from a glucose or glycogen molecule where both pyruvate molecules are used by mitochondria
Acetyl CoA (What does it do?)
- Acetyl CoA: generated from pyruvate or from fatty acid chains (beta oxidation)
Citric acid cycle (What does it do?)
Citric acid cycle: accepts acetyl CoA and generates electron donors (NADH + H+) for Oxidative phosphorylation
Oxidative phosphorylation (What does it do?)
Oxidative phosphorylation: oxygen is consumed and electron transport gradient is created by coenzymes and electron donors used to synthesize ATP
Carbon dioxide (How is it produced?)
Carbon dioxide: is produced with Acetyl CoA and in the citric acid cycle
The fed state (What is it?)
○ State following ingestion of nutrients is anabolic: absorbed nutrients are being used for energy, synthesis and storage
The fed state (What happens in it?)
Fed-state
- Glucose makes ATP
○ Excess is converted to glycogen or fat
- Amino acids assembled into proteins, amine hormones, neurotransmitters
○ Excess amino acids are converted to fat
- Fats assembled into triglycerides in liver and adipose tissues
Fasted state (What is it?)
Fasted state: once nutrients have been digested, absorbed and distributed to various cells, plasma concentrates of glucose begin to fall. Hormones that regulate and maintain blood glucose homeostasis ensure that the energy demands of the tissues and the brain are met
Fasted state metabolism (What happens in it?)
- Glycogen converts to glucose in glycogenolysis
- Proteins may be used to make ATP
- Lipids broken down through lipolysis
○ Glycerol -> glycolysis
○ Fatty acids -> beta oxidation
Keytone bodies (What are they?)
Excess Acetyl CoA (in the fasted state) become Ketone bodies
(KEYTONE BODIES ARE BASICALLY PRODUCED WHEN THERE IS AN ABSENSE OF SUGARS IN THE BODIES)
What hormone dominates in the fasted state?
- Fasted state = glucagon dominates (Alpha cells secrete glucagon)
○ Glycogenesis
○ Gluconeogenesis
○ Ketogenesis
What hormone dominates in the fed state?
- Fed state = insulin dominates (Beta cells secrete insulin)
○ Glucose oxidation
○ Glycogen synthesis
○ Fat synthesis
○ Protein synthesis
What does the pancreas do in hormone production?
- Endocrine pancreas secretes hormones
○ Insulin by beta cells and
○ Glucagon by alpha cells in the islets of Langerhans
Type 1 diabetes:
Type 1: characterized by insulin deficiency from beta cells destruction
Type 2 diabetes:
Type 2: known as insulin-resistant diabetes
Blood glucose level in normal humans
Fasting blood glucose: less than 100mg/dL
After 2 hour test: less than 140mg/dL
Blood glucose levels in person with diabetes
Fasting blood glucose: over 125mg/dL
After 2 hour test: over 199mg/dL
