9.3 Stress Response and Blood Sugar

Transcription

1 9.3 Stress Response and Blood Sugar

2 Regulate Stress Response Regulate Blood Sugar

3 Stress Response Involves hormone pathways that regulate metabolism, heart, rate and breathing

4 The Adrenal Glands a pair of organs Composed of 2 layers: 1. Adrenal medulla (inner layer) Regulated by nervous system 2. Adrenal cortex (outer layer) Regulated by hormones

5 Adrenal Medulla: Short-term Stress Response In response to a stressor: Neurons in the sympathetic nervous system carry a signal from the hypothalamus to the adrenal medulla (fight-orflight response) adrenal medulla secretes epinephrine and norepinephrine increase in breathing rate, heart rate, blood pressure, blood flow to the heart and muscles, and the conversion of glycogen to glucose in the liver

6 Adrenal Medulla: Short-term Stress Response Epinephrine works quickly can be used in anaphylactic emergencies to open up air passages and restore breathing (eg. Epi-pen)

7 Produces 3 types of hormones: 1. Glucocorticoids: Cortisol is the most abundant increases amino acids in blood to recover from stress The liver converts the amino acids into glucose to produce energy during times of stress 2. Mineralocorticoids: Adrenal Cortex: Long-term Stress Response Aldosterone increases sodium retention in the blood and water reabsorption by the kidneys to increase blood pressure 3. Small amounto of sex hormones

8 Adrenal Cortex: Long-term Stress Response The hypothalamus secretes a releasing hormone anterior pituitary gland secretes adrenocorticotropic hormone (ACTH) adrenal cortex secretes cortisol Promotes breakdown of fats and muscle protein to increase blood glucose levels also an anti-inflammatory and immune system suppressant

9 Adrenal Cortex: Long-term Stress Response Cortisol levels are controlled in a negative feedback loop High level of cortisol in the blood can inhibit the release of tropic hormones from the hypothalamus or pituitary However, chronic high levels of cortisol can impair thinking, damage the heart, and cause early death.

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11 Addison s Disease Damage to adrenal cortex insufficient glucocorticoid and mineralocorticoid secretion low blood sugar (hypoglycemia), sodium and potassium imbalances, and weight loss need to be treated within a few days because it can be fatal

12 Regulating Blood sugar: Pancreas involved in both the digestive and endocrine systems over 2000 islets of Langerhans (endocrine cells) scattered throughout the pancreas beta cells secretes insulin lowers blood glucose alpha cells secretes glucagon increases blood glucose Both hormones are regulated by negative feedback loops

13 Hormones of Pancreas When blood sugar levels are high: beta cells release insulin Makes cells in the liver, muscles and adipose tissue more permeable to glucose Lowers blood glucose

14 Hormones of Pancreas When sugar levels are low alpha cells release glucagon Stimulates the liver and adipose tissue to break down glycogen or fat increase blood sugar levels

15 Diabetes Mellitus 1. body does not produce enough insulin 2. or does not respond properly to insulin Glucose stays in the blood after meals instead of entering the cells Hyperglycemia (high blood sugar but no sugar in the cells) Fatigue begins to use fat and protein for metabolic energy glucose is excreted in the urine Over the long term, permanent damage to the eyes, nerves, and kidneys. Severe infection (gangrene) can occur in the limbs.

16 Interpreting Blood Sugar Levels

17 Causes of Diabetes Type 1 Type 1 (Juvenile Diabetes): immune system attacks and destroys beta cells in the pancreas diagnosed in childhood need daily insulin injections Type 2 (Adult-Onset Diabetes): Insulin receptors on the body s cells stop responding to insulin overweight greater chance of developing this condition usually diagnosed in adulthood can be controlled with diet, exercise, and oral medications

18 Toward a Cure for Diabetes In 1921, Canadian scientists Frederick Banting and Charles Best isolated insulin and use it successfully to treat a person with diabetes. Today, transgenic bacteria are used to produce synthetic insulin in large quantities for diabetes treatment. Successful islet cells transplants have also been performed to restore beta cell function.