1. 6.6 Hormones & Reproduction

2. Endocrine system Produces and releases hormones
Hormones travel in the blood to target tissues
Long distance communication between cells
Endocrine Glands
Blood stream
Hormone
Target Tissue

3. Homeostasis
Ability of the body to maintain stable internal conditions regardless of external conditions
Hypothalamus monitors the following:
Blood pH
Carbon dioxide concentration
Blood glucose concentration
Body temperature
Water balance

4. Negative Feedback Loop
When a change in the body is detected, the body elicits are response to being the altered level back to where it was before the change.

5. Thermoregulation Maintaining body temperature at 98.6 degrees
Regulated by hypothalamus and thyroid

6. Thermoregulation chart
Cooling Mechanisms
Warming Mechanisms
Sweat glands release sweat for evaporative cooling
Sweat glands do not release sweat in order to limit evaporative cooling
Arterioles leading to the skin’s surface dilate and bring more blood to the surface for cooling
Arterioles leading to the skin’s surface constrict and keep blood in the body’s core tow warm vital organs
The body spreads out (wide arms and legs) to increase the surface are for cooling
The body pulls inwards (arms and legs very close to the body) to decrease surface area and retain heat
Muscle cells relax and prevent shivering that would further heat the body
Muscle cells contract to induce shivering to produce heat to warm the body

7. Blood glucose levels Must be maintained within a narrow range
Regulated by the hypothalamus
Regulated by two antagonistic hormones by produced by the pancreas (pancreatic islet cells)
Alpha cells produce glucagon (increase glucose levels)
Beta cells produce insulin (decrease glucose levels)

8. Blood Glucose Regulation
Rise in Blood Glucose Levels
Drop in Blood Glucose Levels
Insulin is released from beta cells
Glucagon is released from alpha cells
Liver cells store glucose as glycogen, removing glucose from the bloodstream
Liver cells break down stored glycogen into glucose and release the glucose into the bloodstream
Cells take up glucose from the bloodstream (capillaries)
Cells take up very little glucose from the bloodstream (capillaries)
Blood sugar levels fall to homeostatic levels
Blood glucose levels rise to homeostatic levels

9. Type I and Type II Diabetes
Disease where you are unable to control glucose levels
Type I
Islet cells lose their ability to produce insulin
Possible causes
Autoimmune response, viral infection or genetics
Type II
Results when cellular receptors for insulin fail to respond to the hormone
Causes
Obesity or possibly genetics
Can be reversed by diet and exercise

10. Type I and Type II Diabetes
Type I Diabetes
Type II Diabetes
Onset
Sudden
Gradual
Prevalence
Less common
More common
Age of onset
Mostly in young children
Usually in adults but due to childhood obesity becoming more common in children
Insulin levels
No insulin production or very low levels
Normal insulin or altered (higher or lower) levels
Insulin needs
Must have insulin injections for survival
Vary with individual
Treatment
Insulin injections/diet changes
Weight loss with diet and exercise may use insulin injections

11. Applications of Hormone Use
Can be used to treat or detect disorders of the endocrine system

12. Hormone applications Hormone Source Mode of action Application Insulin
Beta cells of the pancreas
Lowers blood glucose levels
Used to treat type I diabetes
Thyroxin
Thyroid gland
Increases metabolic processes and thermoregulation
Used as replacement therapy for patients with reduced thyroid function
Leptin
Adipose tissue
Acts on the hypothalamus inhibiting appetite
Used to help diagnose causes of obesity by testing levels of leptin in obese individuals
Melatonin
Pineal gland
Circadian rhythms (sleep cycles)
Used to treat jet lag