Hormones that Affect Blood Sugar and Stress

Diana Pham & Anny TangFebruary 21, 2013

• “Islets of Langerhans”

• Discovered by Paul Langerhans

• this region comprises 1-2% of pancreas mass

• contains endocrine (hormone-producing) cells

The Pancreas

Glucagon

• Released from alpha cells in the pancreas when blood sugar is low

(from heavy exercise or fasting)

• Glycogen: – multibranched polysaccharide– secondary long term energy storage in

animals (the first is adipose tissue)– made and stored in liver and muscle

cells

GLUCAGON GLYCOGEN GLUCOSE

BREAKS DOWN INTO

Glycogenolysis

Insulin• Released from beta cells in the pancreas when blood sugar is high – meal digestion, stress hormones,

steroids, infections and trauma

• Converts glucose into glycogen storage in liver and muscle cells– Via glycogenesis

• Released insulin forces 2/3 of body cells (mainly muscle and fat tissue cells) to take glucose from blood via GLUT4 transporter

GLUT4 Transporters1. Insulin binds to cell

surface receptors.

2. Protein activation cascade causes transporters plasma membrane via exocytosis

3. Transporters become available for moving glucose into cells via facilitated diffusion.

Entering glucose phosphorylated into Glucose 6 Phosphate keeps sugar in cell

RESULT: Glycogen synthesis Also glycolysis (glucose pyruvate) and fatty acids

• Chronic disease with no cure affecting more than 2 million Canadians

• Leading cause of death by disease

• Hyperglycemia: without sufficient insulin, blood sugar levels rise very sharply

• Glucose can't move into cells because without insulin, cells aren't permeable to glucose

• Diabetic cells are starved for glucose, and turn to metabolizing fats and proteins (inaccessible sources, leads to problems such as acetone as byproduct)

• Diabetics can keep their diabetes under control by exercise. When you exercise more, you produce more GLUT4 transporters to help force sugar into cells.

• Insulin, control diet, exercise

STRESS• A form of somatic response to incidents that upset your body’s balanced

or stable state of mind• Stressors are the incidents or causes that induce stress (ex: dangers,

money, work)• Your body provides you with better alertness and reflexes to deal with

danger

Brain perceives threat.

FLIGHT OR FIGHT RESPONSEby sympathetic nervous system

Hypothalamus sends nerve signals Sympathetic nervous system Adrenal medulla (inner part

of adrenal gland)

Signals trigger secretion of:

EPINEPHRINE or ADRENALINENOREPINEPHRINE or NORADRENALINE

Stress Hormones…

Increase heart rate and stroke volume Increase blood pressure

Increase rate of muscle contraction, relaxation

Blood pushed away from skin, digestive organs, kidneys…

…to vital organs: lungs, heart, brain, Blood flow to liver increase glycogen breakdown into blood glucose more fuel for cellular respiration

Bronchioles dilate increase oxygen uptake and breathing rate

Effect on Blood Sugar

• Adrenaline– First messenger hormone– Works on liver to facilitate glycogenolysis– Binds to the beta-adrenergic receptors on the liver,

Triggers adenylatcyclase cascade (cAMP cascade)– Stimulates conversion of glycogen into glucose

• Noradrenaline– Released independently of adrenaline from nerve

endings– Binds to alpha2-adrenergic receptors, interacts with

G protein-coupled receptors to activate G proteins to inhibit insulin release (ie. By lowering cAMP levels)

– When insulin release in inhibited, liver releases glycogen into bloodstream as sugar and liver releases glucose into blood

•Parasympathetic nervous system turns on the relaxation response•Lowers blood pressure, breathing and heart rates•Reduces fatigue, muscle tension, and levels of chemicals in your blood due to anxiety and stress •Requires conscious effort to turn on relaxation response

Relaxation Response

Brain perceives threat.

Neurosecretory cell of hypothalamus sends CRH anterior lobe of pituitary gland

releases ACTH (Adrenocorticotropic hormone)Adrenal cortex via blood

ACTH stimulates endocrine cells to secrete corticosterioids (steroids produced in adrenal cortex in vertebrates) from the zona fasciculata and reticularis of the adrenal cortex.

mineralocorticoids (ie. aldosterone)

glucocorticoids (ie. cortisol)

How Cortisol WorksPlasma proteins(corticosteroid-binding

globulin)

Glucocorticoid receptor in cytoplasm

Nucleus

DNA response element

Changes transcription and phenotype

Positive Effects of Cortisol

• Quick burst of energy for survival reasons– Cortisol raises blood sugar levels by

stimulating the release of glucose from cellular glucose stores

• Inhibits immune system and inflammatory response

• Helps maintain homeostasis in the body – Cortisol’s main function is to restore

homeostasis following exposure to stress (i.e: retaining sodium and secreting potssium ions pH balance)

Cortisol

• Blood sugar imbalances– Hyperglycemia

• Over production of Cortisol– Crushing’s Syndrome

• Higher blood pressure– Stimulate ADH and aldosterone to retain water

and NaCl

• Impaired cognitive performance and memory loss– Excess of cortisol can impair the hippocampus

by preventing it from being able to form a new memory and retrieving an existing memory

Negative Effects of Cortisol

Responsible for processing and storing memory

Arginine Vasopressin (ADH)

• Thyroid Gland– Thyroxine (T4) and triiodothyronine (T3)

hormones regulate body metabolism, growth and differentiation of tissues

– Hypothyrodism and hyperthyroidism– Permissiveness: increases for

epinephrine’s effect on target cells

Metabolism

• Parathyroid Glands – Maintain homeostasis by

responding directly to chemical changes in their immediate surroundings

– Example: Low blood calcium level

• Growth Hormone (somatotropin)– Causes a switch in cellular fuels from glucose to fatty acids increases fatty acid

levels in the blood by breakdown fats in adipose tissue (under dermis tissue of skin) increase in blood sugar levels

Hormones that Affect Blood Sugar and Stress

StressBlood SugarHormones

3 candies

2 candies

1 candy 1 candy

2 candies

3 candies

1 candy

2 candies

3 candies

Hormones that Affect Blood Sugar and Stress

HormonesQuestion 1:

List two functions of insulin.

Answer: It converts glucose into glycogen and forces cells to take in glucose.

HormonesQuestion 2:

What is Adrenaline and what does it affect?

Answer: Adrenaline is the hormone epinephrine which is released from the adrenal cortex in respond to short-term stress. It binds to beta-adrenergic receptors (G-protein-coupled receptors) in liver which triggers cAMP cascade. This increases rate of glycogenolysis and thus blood sugar.

HormonesQuestion 3:

How do low levels of thyroxine and triiodothyronine affect metabolism and what are the associated conditions called?

Answer: Thyroxine is converted to Triiodothyronine, which help in oxidizing glucose sugar and breaking down nutrients in cells. High levels of T4 causes hyperthyroidism and low levels of T4 causes hypothyroidism.

Blood SugarQuestion 1:

What are the Islets of Langerhans?

Answer: The Islets of Langerhans is a region of the pancreas containing endocrine (hormone-producing) cells, which takes up 1-2% of pancreas mass.

Blood SugarDaily Double!!!Question 2:

Explain the functions of glucagon and insulin hormones.

Answer: When blood sugar is low, glucagon converts glycogen into glucose via glycogenolysis, thus increasing glucose in blood. Insulin does the opposite of glucagon and convert excess glucose into glycogen through glycogenesis and forces cells to take in blood sugar thus reducing blood sugar.

Blood SugarQuestion 3:

What is diabetes and how does it affect blood sugar?

Answer: Diabetes or hyperglycemia is a condition whereby blood glucose levels are very high because of insufficient insulin to move glucose into cells to be used for metabolic purposes. Therefore, fats and proteins are metabolized as energy sources instead.

StressQuestion 1:

What is the name of the reaction associated with short-term stress response?

Answer: The reaction is known as “Fight or Flight” response

StressDaily Double!!! Question 2:For long term stress response, the hypothalamus perceives threat and releases what? Describe the negative feedback system associated with this response.Answer:

The hypothalamus releases CRH (corticotropin-releasing hormone) to anterior lobe of pituitary gland. Anterior lobe releases ACTH (adrenocorticotropic hormone) which is carried to adrenal cortex endocrine cells in cortex synthesize and secrete corticosteroids. This response is regulated by negative feedback, in which high level of corticosteroid suppresses CRH and ACTH release.

Stress Question 3:

List three positive and three negative effects of cortisol.Answer: Positive effects: 1)Quick burst of energy for survival reasons, 2)Heightened memory functions, 3)Lower sensitivity to pain, 4)Helps maintain homeostasis in the body. Negative effects: 1)Blood sugar imbalances (may leads to hyperglycemia), 2)Over production of cortisol Cushing’s syndrome, 3) Higher blood pressure, 4)Impaired cognitive performance and memory loss.