Endocrine Physiology II Flashcards
Thyroid Gland
- largest
- produces two hormones
- Thyroid synthesis requires
- what does is secrete
-Largest pure endocrine gland
-Follicles and areolar connective tissue
-Produces two hormones
Thyroid hormone (TH)
Calcitonin
Thyroid hormone synthesis – T3 and T4
- Requires Iodine
Secretes Thyroid hormone (eg., if cold)
-Thyroxine, TH, T3, T4
Acts on the cells
- Increases metabolism
* Increases heat
Thyroid Gland Diseases
- Grave’s disease
- what is
- treatment
Hyperthyroidism- Autoimmune condition
- excessive thyroxine, tumour in thyroid gland
- high activation
Treatment:
⬧ Medication
⬧ Radiation
⬧ Surgery
Thyroid Gland
-Secretes Calcitonin (CT) when
Released if blood Ca2+ high
Acts to ↓ Blood Ca2+
* gut - ↓ Ca2+ absorption
* Kidney - ↑ Ca2+ excretion
* Bones - ↑ Ca2+ absorption
Parathyroid Glands
- Secretes PTH (Parathyroid hormone) when
Antagonist to CT
-Released if blood calcium is low
Acts to ↑ blood Ca2+
* gut - ↑ Ca2+ absorption
* Kidney - ↓ Ca2+ excretion
* Bones - Ca2+ released
Vitamin D
- Activated by PTH, what does it do
- Vitamin D deficiency
- Stimulates Ca2+ and PO43- absorption from intestine
-Can be synthesized from cholesterol derivative when exposed to sunlight - Via liver and kidney
Children – rickets
Adults – osteomalacia
Decalcification of the bone
-Muscle weakness
-weight loss, bone pain
Adrenal Hormones
- Medulla
- Cortex
Epinephrine
* Longer sympathetic
effect
* Increased heart rate
* Increased breathing
* Increased metabolism
Steroids
Mineralcorticoids
* Aldosterone
Glucocorticoids
* Cortisol
Androgens
Aldosterone
- released when and does what
- Also part of the RAAS system
-Released if blood volume or Na+ is low
(or K+ is high)
- Acts on renal tubules in kidney
Speeds up Na+/K+ pump
* ↑ Na+ reabsorption
* ↑ H20 reabsorption
- Plays a role in blood pressure control
Androgens
- Secretes both male and female sex
hormones in both sexes
- DHEA
Males produce estrogen / females produce testosterone
Dehydroepiandrosterone (DHEA)
* Overpowered by testicular testosterone in males
* Physiologically significant
in females
⬧ pubic and axillary hair
⬧ pubertal growth spurt
⬧ female sex drive
Androgens in:
- Men
- Women
Men
- Estrogen important for bone health / cholesterol levels
- Low estrogen may contribute to increased belly fat and poor bone health
- High Estrogen may contribute to breast development, erectile dysfunction, infertility
Women
- Low testosterone may contribute to fatigue, loss of sex drive, loss of muscle, mood changes
- High testosterone – male characteristics may develop
* Hair, lower voice, more muscle, etc.
Cortisol
- Glucocorticoid
Glucocorticoid
- Plays role in glucose balance
- Increases blood glucose
Stimulates hepatic gluconeogenesis
Inhibits glucose uptake by the cells - Stimulates protein break-down in muscle
- Facilitates lipolysis
- What is cortisol
- what effects does it have
“Stress Hormone”
- High blood glucose and fatty acids
- Plays key role in adaptation to stress
- Anti-inflammatory and immunosuppressive effects
- Can result in sickness if cortisol is high
Three phases of the stress response
Can be divided into 3 phases:
- The Alarm Phase (fight/flight)
- The Resistance Phase
* Cortisol response - The Exhaustion Phase
* Abnormal body function
* Organ system failure
Immediate Effects of Stress
- Sympathetic nervous response
- Adrenal response
Sympathetic nervous response
-Epinephrine and norepinephrine
- Time: 2 to 3 seconds
Adrenal response
- Epinephrine and norepinephrine from adrenal medulla
- Time: 20 to 30 seconds
↑ heart rate
↑ breathing
↑ BP
The Stress Response - many unique ones
- The resistance reaction is the second stage in a stress response
- The Stress Response Involves
-Cortisol is the primary hormone
- Thyroid hormone and hGH are also involved
-Lasts longer than the fight/flight phase
-Higher blood sugar and blood fatty acids
- Stress adaptation
- Cortisol
- Human Growth Hormone
- Thyroid hormone
Adrenal Gland Diseases
- Cushing’s syndrome
Cushing’s syndrome
↑ cortisol
* Hyperglycemia
* Hyperlipidemia
* Poor immune function
* Weight gain
* Sweating
Pancreas
- exocrine cells
- endocrine cells
Exocrine cells
- Acinar cells
* secrete digestive enzymes
Endocrine cells
- Pancreatic islets
* Islets of Langerhans
⬧ ~1 million
⬧ Alpha () cells
⬧ glucagon
⬧ Beta () cells
⬧ insulin
The pancreas
- alpha cells
- beta cells
- delta cells
Alpha cells
15% - glucagon
Beta cells
80% - insulin
Delta (∂) cells
5% - secrete somatostatin
* Inhibits secretion of insulin and glucagon
Insulin
- Released when
- causes
- also promotes
Released when blood glucose high
Causes glucose to move into the cells
-↓ blood glucose
- Glycogen formation
Also promotes cellular uptake of:
fatty acids
amino acids
enhances their conversion
triglycerides and proteins
Glucagon
- Released when
- acts to
Released if blood glucose low
Acts to ↑ blood glucose by
- Gluconeogenesis
- Glycogenolysis
* Break-down of glycogen
ketogenesis
Feeding States
- Absorptive states
- Post-absorptive state
Absorptive states
- 3-4 hours after eating
- Insulin is the main controller
* Move nutrients into cells and storage
Post-absorptive state
- 4+ hours after eating
- Glucagon is the main controller
* Moves nutrients out of storage and cells
Diabetes Mellitus
- Insulin hyposecretion
- symptoms
Insulin hyposecretion
- High blood glucose
- High glucose in urine
* Exceeds renal maximum
- High urine volume
Symptoms:
* Frequent urination
* Thirst
* Hunger
Diabetes Mellitus
- Type I
Low insulin
* aka insulin-dependent diabetes
* Aka juvenile diabetes
* autoimmune disorder
* Affects people before age 25
* Requires daily injections of insulin
⬧ Diet control
⬧ Blood monitoring
Diabetes Mellitus
- Type II
Low insulin response
* More common in adults
* Gradual onset
⬧ Obesity
⬧ over age 40
* ↓ sensitivity of cells to insulin
* “wearing out” of islets of Langerhans
* Controlled with diet, exercise
⬧ Helps control insulin secretion
Diabetes Mellitus
- Type II early vs late
Early Type II
- Poor response to insulin (insulin levels are high)
These patients need diet control and exercise to re-sensitize to insulin
* Insulin injections would de-sensitize even more, not beneficial
Late Type II
Beta cells dysfunctional and insulin levels drop
* These patients may now need insulin injections
