Endocrine System & Diabetes Study Guide

In your own words, describe how hormones work in the body. What makes them different from nutrients or oxygen in the blood?

Chemical messengers that coordinate and direct specific activities of the body

• Nutrient and oxygen are supplies while hormones give orders

Compare how the endocrine system and nervous system send messages, include:

• Speed

• Method of communication

• Duration of effects

Feature	Endocrine System	Nervous System
Speed	Slower (seconds to days/weeks)	Very fast (milliseconds)
Method of communication	Bloodstream	Electrical impulses/Action potenial (via nerves)
Duration of effects	Long-lasting and sustained	Short-term, response stops when stimulates stops

Why is the pituitary gland often called the “master gland”? Give one specific example

The hormones it produces regulate other glands

• The TSH hormone stimulates the thyroid

What is a negative feedback loop? Create your own example using any endocrine gland

The output of a process reduces or stops that same process to maintain homeostasis, reverses a change to bring the system back to its optimal set point

Example: Pancreas and Blood Sugar

1. Stimulus: After eating, glucose levels rise

2. Sensor/Control Center: The pancreas detects high glucose and releases insulin

3. Effectors: Insulin signals cells to absorb glucose and the liver to store it

4. Negative Feedback: Blood glucose levels fall back to a normal range

5. Result: The lower blood sugar stops the pancreas from releasing more insulin (the output inhibits further production)

Key Concept: If blood sugar gets too low, the pancreas instead releases glucagon to raise it, demonstrating a constant, automatic balance.

Define each of the following and explain how they are connected:

• Glucose

• Glycogen

• Glucagon

Glucose: A simple sugar (monosaccharide) that travels through the bloodstream to fuel cells, the body's main source of fuel

Glycogen: A complex carbohydrate (polysaccharide) made of thousands of linked glucose molecules, acts as the body's quick-access energy reserve stored mainly in the liver and muscles

Glucagon: A hormone produced by the pancreas that acts as the opposite of insulin, tells the liver to break down glycogen into glucose when blood sugar levels are too low

Connection: When blood glucose levels are high, insulin facilitates the conversion of glucose into glycogen. When blood glucose drops, the pancreas releases glucagon. Glucagon signals the liver to convert the stored glycogen back into glucose, which is then released into the bloodstream to stabilize blood sugar.

What is the role of insulin? What happens to blood glucose when insulin is released?

Role:

• Allows glucose from food to leave the bloodstream and enter cells to be used for energy

Affect on Blood Glucose:

1. Lowered Concentration: Insulin facilitates the rapid movement of glucose out of the bloodstream and into cells

2. Increased Uptake: Cells, muscle and adipose/fat, increase their uptake of glucose

3. Blood Sugar Normalization: As glucose enters the cells, the high blood sugar levels resulting from digestion subside, returning the body to a stable, resting state

4. Inhibits New Glucose Production: Insulin stops the liver from creating new glucose and breaking down stored glycogen

What is the role of glucagon? When is it released?

Role:

• Counter-regulatory mechanism to insulin, increases blood sugar

When it’s Released:

• Low blood sugar, prolonged fasting/starvation, exercise

Which organ produces insulin and glucagon? Name the specific cells responsible for each

Pancreas

• Insulin = beta cells

• Glucagon = alpha cells

Describe what happens in the body:

• After eating a large meal

• After skipping meals for a long period

After Eating a Large Meal:

• Rapid influx of glucose triggers massive insulin release

• Blood sugar crashes as sugar moves into cells, causing fatigue

• Increase in metabolism to break down excessive calories

After Skipping Meals for a Long Period:

• Blood sugar drops causing dizziness, shakiness, brain fog, fatigue

• Body releases cortisol and adrenaline

• Metabolism slows

Compare Type 1 and Type 2 diabetes:

• Cause

• Insulin presence

• Typical onset

Feature	Type 1	Type 2
Cause	Autoimmune reaction, immune system destroys insulin-producing beta cells in the pancreas	Insulin resistance, lifestyle
Insulin Presence	Little to no insulin is produced, must be taken daily to survive	Produced, but ignored
Typical Onset	Rapid onset (usually diagnosed in children, teenagers, or young adults)	Develops gradually, usually in adults over 45

Identify three common symptoms of uncontrolled diabetes and explain why they occur

1. Frequent Urination: When blood sugar is too high, the kidneys work overtime to filter and remove the excess sugar from the body (glucose attracts water leading to increased urine)

1. Excessive Thirst: As a result of increased urination, the body compensates for fluid loss by diluting the high concentration of sugar in the blood, triggering an intense thirst response

1. Extreme Fatigue: The cells can’t get glucose leaving the body exhausted and low on energy

What is HbA1c, and what does it tell healthcare providers?

A blood test that provides an average blood glucose level over the past 2–3 months, measures the percentage of glucose attached to hemoglobin in red blood cells

• Shows reliable, long-term picture of glucose management

What is considered a normal fasting blood glucose level?

70 to 99 mg/dL

Identify one major risk factor for Type 2 diabetes and explain why it increases risk

Obesity

• The body releases inflammatory substances that interfere with the insulin receptor signaling pathway, creating insulin resistance

• Due to resistance, cells do not readily absorb glucose from the blood, compelling the pancreas to overproduce insulin

• Over time, the pancreas cannot keep up, resulting in elevated blood glucose levels

Explain the difference between:

• Basal insulin

• Bolus insulin

Basal insulin: Long-acting, providing a constant "background" supply for 24 hours

• 40-50% of the total daily insulin dose to replace insulin overnight, when you are fasting and between meals

Bolus insulin: Rapid-acting, taken specifically to cover meals or correct high blood sugar

• The other 50-60% of the total daily insulin dose is for carbohydrate coverage (food) and high blood glucose correction

Why might a patient be prescribed both a long-acting and rapid-acting insulin?

To mimic a natural and healthy prancreas

When should rapid-acting insulin typically be given in relation to meals?

10 to 15 minutes before meals

What should you check before administering insulin? List at least 4 safety checks

1. Insulin Type and Appearance

2. Verify Dose

3. Confirm Blood Glucose Level

4. Select and Inspect Injection Site

A patient eats 45g of carbs. Their insulin-to-carb ratio is 1:15. How many units of insulin do they need?

3 units

• Carbohydrate insulin dose = Total grams of carbohydrate in the meal÷ I:C ratio

A patient’s blood glucose is 180 mg/dL. Target is 120 mg/dL. Correction factor is 1:60. How many units are needed to correct?

1 unit

• High blood sugar correction dose = Difference between actual blood glucose and target blood glucose*÷ correction factor or ISF

  • *Actual blood glucose minus target blood glucose

Combine BOTH:

• 60g carbs

• BG = 240 mg/dL

• Target = 120

• I:C = 1:15

• CF = 1:60

What is the total insulin dose?

Carbohydrate Insulin Dose: 4 units

High Blood Sugar Correction Dose: 2 units

Total Insulin Dose: 6 units

Why should patients never walk barefoot, especially with diabetes?

High blood sugar can cause nerve damage and poor circulation, preventing them from feeling injuries like cuts or burns

Describe proper foot care for a diabetic patient

• Daily inspections for cuts, blisters, or redness

• Washing with warm water and moisturizing (to prevent infection)

Where are the best injection sites for insulin?

• Abdomen (at least 2 inches from the belly button)

• Thighs

• Upper arms

Why is site rotation important?

To ensure consistent insulin absorption and prevent complications like skin damage

What should you do if insulin looks cloudy when it should be clear?

Immediately discard the vial or pen

Why must hands be cleaned before a fingerstick glucose check?

To ensure accuracy by removing food residues, dirt, or sugar that can cause falsely elevated readings

Where on the finger should you perform a fingerstick—and why?

Side of fingertip

• Minimize pain and maximize blood flow, less nerve endings

What is a lancet, and what is it used for?

Small, disposable medical implement with a tiny, sharp needle or blade

• Used to prick the skin to obtain a small blood sample

What is a continuous glucose monitor (CGM)?

Small sensor is inserted under the skin to measure glucose levels continuously

• Provides real-time data and trends

• Advantages:

  • Reduces the need for fingersticks

  • Helps detect fluctuations in glucose levels

Why might a patient still need a fingerstick even if they have a CGM?

• Verify accuracy when symptoms do not match readings

• During rapid glucose changes (ex. after eating or exercise)

• If the sensor is malfunctioning

What should a patient do if their symptoms don’t match their CGM reading?

Perform a finger-stick blood glucose meter check

What hormone is released during a stress response, and what are two effects it has?

Cortisol

• Increases blood sugar

• Suppresses non-essential function

What does the thyroid gland produce, and what is required for it to function properly?

Triiodothyronine (T3) and Thyroxine (T4)

• Iodine (allows for production of hormones)

What does TSH do in the body?

Stimulates the thyroid gland

What gland does ACTH target, and why?

Adrenal Cortex

• Simulate the production and release of cortisol

What are the roles of:

• Oxytocin

• Prolactin

Oxytocin

• Stimulates contractions of the uterus in females during childbirth and milk flow during breastfeeding

Prolactin

• Develops breast tissue and produces milk in females after childbirth

How does breastfeeding help the uterus return to normal size?

Triggers the release of oxytocin which stimulates uterine contractions

• these contractions shrink the uterus more rapidly and help limit postpartum bleeding

What are androgens, and what physical changes do they cause in both sexes?

Steroid hormones that trigger male physical characteristics

Male:

• Puberty, development of the penis, scrotum, and prostate, as well as vocal cord lengthening (deep voice) and the growth of the Adam's apple

• Promotes increased muscle mass, bone density, and height during pubert

• Triggers facial, scalp, chest, underarm, and genital hair growth

• Essential for initiating and maintaining spermatogenesis

Female:

• Triggers secondary sexual characteristics, including pubic and underarm hair growth

• Crucial for maintaining libido and sexual arousal

• Regulates menstrual cycles and aids in conception

• Aids in preventing bone loss (osteoporosis) and maintaining muscle mass

What happens if the pineal gland is disrupted?

Impairs melatonin production

• Significant sleep-wake cycle disturbances

• Chronic fatigue and insomnia

What is the role of the thymus gland in childhood?

Helps with childhood immunity

• Produces, matures, and educates T-cells

What happens when the body has too little growth hormone (GH) in childhood?

Slows growth leading to a short stature while maintain normal proportions

Function of the Endocrine System

To secrete hormones directly into the bloodstream

What are hormones?

Chemical messengers that coordinate and direct specific activities of the body

What are some of the effects of aging on the Endocrine System?

Almost every gland is affected

• Hypothalamus and Pituitary: impaired thus affecting homeostasis

• Thyroid gland: becomes lumpy and metabolism slows

• Parathyroid: levels change, which contributes to osteoporosis

• Insulin receptor cells decrease which may lead to Type 2 diabetes

• Gonad glands are affected, so estrogen, progesterone, and testosterone drop

How does the Endocrine System interact with the Integumentary System?

Estrogen influences skin hydration

How does the Endocrine System interact with the Skeletal System?

Calcitonin influences blood levels of calcium in the blood and storage in the bones

How does the Endocrine System interact with the Muscular System?

Thyroid hormones influence muscle metabolism and production of energy

How does the Endocrine System interact with the Nervous System?

Epinephrine influences the sympathetic nervous system

How does the Endocrine System interact with the Circulatory System?

Epinephrine affects the heart rate and blood pressure

How does the Endocrine System interact with the Lymphatic System?

Thymosin influences the production of T-cells in the lymph system

How does the Endocrine System interact with the Respiratory System?

Epinephrine dilates the bronchioles to take in more oxygen

How does the Endocrine System interact with the Digestive System?

Thyroid hormone influences the metabolism of the digestive system

How does the Endocrine System interact with the Urinary System?

Antidiuretic hormone influences water and electrolyte balance

How does the Endocrine System interact with the Reproductive System?

Oxytocin influences birth

poly-

much or excessive

-glycemia

blood sugar

thyr-

shield

-oid

resembles

adren-

towards the kidney

Levels of Organization of the Endocrine System

1. Hormones

2. Islet Cells

3. Interstitial Tissue

4. Pancreas

5. Endocrine System

Hyperthyroidism

Overactive thyroid

• Symptoms:

  • Nervousness

  • Irritability

  • Weight loss

  • Goiter

  • Bulging eyes

  • Rapid pulse

• Treatment:

  • Remove part or all of the thyroid gland

Hypothyroidism

• Underactive thyroid

• Symptoms:

  • Fatigue

  • Slow mental function

  • Weight gain

  • Coarse skin

  • Slow pulse

• Treatment: 

  • Replace thyroid hormones

Graves Disease

• Hyperthyroidism

  • The immune system mistakenly attacks the thyroid gland, causing it to produce excessive amounts of thyroid hormones

  • Increased heart rate and palpitations

  • Anxiety and nervousness

  • Weight loss despite increased appetite

  • Heat intolerance and sweating

  • Tremors

  • Bulging eyes (ophthalmopathy)

  • Irregular menstrual periods 

Hypopituitarism

• Growth failure (short stature)

• Delayed puberty

• Delayed or absent menstrual periods

Hyperpituitarism

Acromegaly

• Enlarged hands and feet

• Enlarged facial features

• Coarse, oily skin

• Excessive sweating and body odor

Tetany

• Hypoparathyroidim 

  • Tetany is a symptom of hypocalcemia, 

  • Muscle cramps

  • Numbness around the mouth

  • Paresthesias in the hands and feet

  • Spasms of the voice box, and seizures

Cushing Syndrome

•  A disorder caused by prolonged exposure to high levels of the hormone cortisol

  • Central obesity: Fat accumulation around the face, abdomen, and upper back

  • Moon face: A rounded, puffy face

  • Thinning skin: Fragile skin that bruises easily

  • Purple stretch marks: Striae on the skin, particularly on the abdomen, thighs, and breasts

Gestational Diabetes

• Diabetes that develops during pregnancy

• Monitoring blood glucose is essential for the health of both mother and baby

What is considered a normal after meal blood glucose level?

Less than 140 mg/dL

Rapid-Acting Insulin

• Examples: Humalog

• Onset: 10-15 minutes

• Peak: 1-2 hours

• Duration: 3-5 hours

• Usage: Given before meals to control meal time blood sugar spikes

Short-Acting Insulin (Regular Insulin)

• Examples: Humulin R

• Onset: 30-60 minutes

• Peak: 2-3 hours

• Duration: 5-8 hours

• Usage: Typically injected 30 minutes before meals

Long-Acting Insulin

• Examples: Lantus, Basaglar

• Onset: 1-2 hours

• Peak: No pronounced peakDuration: Up to 24 hours (or longer for some formulations)

• Usage: Used for continuous insulin coverage, typically injected once or twice daily

Normal and Target A1C Range for Non-Diabetics and Diabetics

Non-Diabetics: Less than 5.7%

Diabetics: Typically less than 7%, as per doctor's advice