endocrine physiology Flashcards
1
Q
What is the difference between diabetes mellitus & diabetes insipidus?
A
Diabetes mellitus = high blood glucose
Diabetes insipidus = due to ADH levels (kidneys can’t concentrate urine)
2
Q
What type of control is fast acting & short-lasting?
A
Control via nervous system
- Fast acting bc of nerve impulses
- Short lasting bc NTs are removed from synaptic cleft asap
3
Q
Explain control via the endocrine system
A
Controls tissues via hormones which are transmitted through the blood & tissue fluids. Hormones act on target tissues
4
Q
What type of control is slow acting, and long-lasting?
A
Control via endocrine system
- slow acting bc hormones need time to get released & to get to the target tissue
- long-lasting bc hormones stay in the bloodstream longer
5
Q
Name two ways that the endocrine system is controlled?
A
- Nervous system
- Endocrine system
6
Q
How do hormones act on tissues?
A
- target tissues have a receptor
- hormones will only act on specific target tissues if they have the corresponding receptor
7
Q
List the three categories of hormones
A
- Steroid hormones
- tyrosine derivatives
- protein hormones
8
Q
Where are steroid hormones secreted from?
give examples of each
A
- adrenal cortex = cortisal, aldosterone
- testes = testosterone
- ovaries & placenta = estrogen, progesterone
9
Q
What is the composition of steroid hormones?
A
cholesterol-based
* made of sterol rings
10
Q
Where are tyrosine derivatives secreted from?
give examples of hormones
A
- thyroid gland = T3 & T4
- adrenal medulla = epinephrine & norepinephrine
11
Q
Where are protein hormones secreted from?
give examples of hormones
A
3 P’s
1. pituitary = ACTH, GH, TSH, ADH, oxytocin
2. parathyroid = PTH
3. pancreas = insulin, glucagon
12
Q
List the 3 types of control of endocrine secretion
A
- neural control
- endocrine control
- humoral control
13
Q
Explain neural control
endocrine secretion
A
- autonomic nervous system (ANS) directly stimulates the endocrine gland
- endocrine gland secretes hormone
- secretion stops when there are sufficient levels of hormone or when levels get too high
Ex. adrenal medulla releases NE & E when stimulated by ANS
14
Q
How are hormone levels regulated?
type of feedback
A
Negative feedback
15
Q
Explain endocrine control
endocrine secretion
A
- uses tropic hormone to stimulate endocrine gland
- 2 glands & 2 hormones
- endocrine gland A releases tropic hormone
- tropic hormone stimulates endocrine gland B
- endocrine B releases hormone
Ex. TSH stimulates thyroid gland to release T3 & T4
16
Q
Explain humoral control
endocrine secretion
A
- endocrine tissue senses blood levels (internal environmental stimulus)
- internal stimulus is sensed by endocrine gland
- endocrine gland releases hormone
ex. high blood sugars are sensed by pancreas –> pancreas releases insulin to lower blood sugar
17
Q
What is the hypophysis?
A
- pituitary gland
- location: cranial floor (base of skull)
- size = very small –> has an anterior & posterior lobe
18
Q
How is the hypothalamus connected to the pituitary gland?
A
via the pituitary stalk
19
Q
What is the neurohypophysis?
A
- posterior lobe of the pituitary gland
- directly connected to the hypothalamus via **hypophyseal tract **
- composed of nerve tissue
20
Q
What is the adenohypophysis?
A
- anterior lobe of the pituitary gland
- made of glandular epithelium
21
Q
What hormones does the anterior pituitary secrete?
state the function of hormones
A
FLAT GP hormones
FSH = sperm & follicle development
LSH = testosterone & ovulation
ACTH = adrenal cortex
TSH = thyroid gland
GH = growth hormone
Prolactin = milk production
22
Q
Which hormones secreted from the anterior pituitary are tropic hormones?
A
TSH –> stimulates thyroid gland to produce T3 & T4
ACTH –> Sstimulates thyroid gland to secrete epinephrine & norepinephrine
23
Q
What hormones does the posterior pituitary secrete?
state the function of hormones
A
neurohormones (bc of neural tissues)
- ADH = for water retention
- oxytocin = birthing process/uterine contractions; milk secretion
24
Q
How is the anterior pituitary controlled?
A
via the hypophyseal portal system
25
Are both lobes of the pituitary controlled the same way?
No
*anterior pituitary* is controlled via **hypophyseal portal system**
*posterior pituitary* is controlled via **hypophyseal tract**
26
Explain step by step how the anterior pituitary is controlled
1. hypothalamus senses internal environmental stimulus
2. hypothalamic neurons release hormone #1 (releasing hormone) into the **primary capillary**
3. goes to anterior pituitary via **hypophyseal portal venule**
4. anterior pituitary secretes its hormone into the **secondary capilary**
5. hormones travels (via blood) to the rest of the body to **target organs/tissues**
6. target organs secrete their hormones
27
How is cortisol regulated?
| list the steps & explain
regulated via **hypophyseal portal**
1. hypothalamus gets signal that *cortisol levels are low*
2. hypothalamus releases **ACTRH** (releasing hormone)
3. goes to anterior pituitary via **hypophyseal portal venule**
4. anterior pituitary produces & releases **ACTH** into **secondary capillaries**
5. ACTH travels in the blood
6. Goes to **adrenal cortex **(target tissue)
7. adrenal cortex releases cortisol
when hypothalamus senses high cortisol blood levels, it stops releasing ACTRH which stops producing ACTH & cortisol = **NEGATIVE FEEDBACK**
28
How is estrogen regulated?
| list the steps & explain
regulated via **hypophyseal portal**
1. hypothalamus gets signal that *estrogen levels are low*
2. hypothalamus releases **FSHRH** (releasing hormone)
3. goes to anterior pituitary via **hypophyseal portal venule**
4. anterior pituitary produces & releases **FSH** into **secondary capillaries**
5. ACTH travels in the blood
6. Goes to **ovaries **(target tissue)
7. ovaries releases estrogen
when hypothalamus senses high estrogen blood levels, it stops releasing FSHRH which stops producing FSH & estrogen = **NEGATIVE FEEDBACK**
29
How is TSH regulated?
| list the steps & explain
regulated via **hypophyseal portal**
1. hypothalamus gets signal that *thyroid hormone levels are low*
2. hypothalamus releases **TSHRH** (releasing hormone)
3. goes to anterior pituitary via **hypophyseal portal venule**
4. anterior pituitary produces & releases **TSH** into **secondary capillaries**
5. TSH travels in the blood
6. Goes to **thyroid gland **(target tissue)
7. thyroid gland releases thyroid hormones (T3 & T4)
when hypothalamus senses high thyroid hormone levels, it stops releasing TSHRH which stops producing TSH & thyroid hormone = **NEGATIVE FEEDBACK**
30
What is the priniciple of **hypophyseal portal control**?
| explain what it needs
**3 organ/gland & 3 hormones**
**anterior pituitary only!**
1. **organ #1** (hypoithalamus) secretes **hormone #1** (releasing hormone) *in response to internal environment stimulus*
2. hormone #1 travel to *organ #2 (anterior pituitary) via hypophyseal portal venule*
3. **organ #2** secretes **hormone #2** into *blood*
4. *hormone #2 travels to organ #3 *(target tissue/organ)
5. **organ #3** secretes **hormone #3**
31
How is the posterior pituitary controlled?
via **hypophyseal tract**
* *axons of hypothalamic neurons project* to the posterior pituitary (like an extension of the hypothalamus)
* axon terminals secrete **neurohormones** (oxytocin & ADH) directly into blood when stimulated
32
Explain step by step how the posterior pituitary is regulated
1. hypothalamus senses change in **internal environment stimulus**
2. **hypothalamic neurons** send nerve impulses to posterior pituitary
3. **axon terminals** secrete **neurohormone** into blood
4. neurohormone travels to **target tissue** & carries out its function
33
How is blood osmolarity regulated?
via the hypophyseal tract
1. hypothalamus senses **low blood osmolarity**
2. **ADH** is released at axon terminals
3. ADH travels through blood and goes to **kidneys** (target tissue)
4. kidneys **conserve water** (water retention)
34
What are the 2 thyroid hormones ?
T3 = triiodothyronine
T4 = thyroxine
35
What are the precursors of thyroid hormones?
| explain their composition
**tyrosine & iodine**
T3 = MIT + DIT
T4 = DIT + DIT
| MIT = tyrosine + 1 iodine ; DIT = tyrosine + 2 iodines
36
What is the thyroid gland?
| include location & function
2 lobes *lateral to the trachea* connected by **isthmus**
Function = produces thyroid hormone (T3 & T4) & calcitonin
37
Which thyroid hormone is more abundant & longer-lasting?
| include what you name this type of hormone
T4
**circulating hormone**
38
Which thyroid hormone is more potent?
| include what you name this type of hormone
T3
**cell-activating hormone**
| 4x more potent (binding & activation)
39
What is the function of thyroid hormones?
| under normal conditions
Increases:
1. BMR
2. temperature
3. CNS activity & muscular activity
40
What is a goiter & what does it indicate?
* It is an enlargment of the thyroid gland
* It may indicate hypothyroidism or hyperthyroidism (further tests needs to be done to confirm)
41
What is the condition where there an excess of thyroid hormone?
| state the common cause
**hyperthyroidism**
common cause = **Grave's disease**
* characterized by bulging eyes
42
What are the clinical manifestations of hyperthyroidism?
1. weight loss (due to high BMR)
2. muscle tremors
3. excessive perspiration
4. nervousness
5. heat intolerance (always feel warm)
43
What is the condition where there is thyroid hormone deficiency?
| state the common cause
hypothyroidism
common cause = Hashimoto's thyroiditis
44
What are the clinical manifestations of hypothyroidism?
1. weight gain
2. muscle weakness
3. dry skin
4. fatigue
5. cold intolerance
45
What part of the adrenal gland secretes cortisol, aldosterone and androgens?
adrenal cortex
* under hormonal control
46
what is the function of cortisol?
fucntion = metabolism of body cells
***Increases:***
1. **blood glucose levels** (by increasing amino acid & fatty acid release for gluconeogenesis & by decreasing glucose utilization by cells)
47
How does high levels of cortisol affect connective tissue?
It **decreases formation of cartilage & bone formation**
* because it is trying to redirect the body's energy into producing more glucose
48
Why is cortisol called the stress hormone?
* in response to stress, the body releases cortisol
* cortisol increases blood sugar level in order to cope with the stress (need more energy)
49
What is cortisol's effect on inflammation?
anti-inflammatory
50
What is cortisol's effect on immune response?
immunosuppressive
51
What do you become at risk for if you have high cortisol levels?
| state clinical manifestations
***Cushing's syndrome***
* presence of **striae** in lower abdominal regions
* moon face
* thin extremities
* increase in abdominal fat
52
What does the adrenal medulla do?
produces **catecholamines** (E & NE)
* controlled by the ANS
* under **neural control**
53
What is the function of the pancreas?
Mixed gland
* **exocrine function** = produces pancreatic juice for the digestive process
* **endocrine function** = produces insulin & glucagon to control blood glucose levels
* location = posterior to the stomach
54
What do you call pancreatic cells?
| what is it made of?
**islet of langerhans **
* composed of **alpha & beta cells**
55
Which cells produce glucagon?
| explain how they do it
**alpha cells**
* increases breakdown of glycogen (stored glucose)
* increases formation of glucose from fats*
* result = **increases blood glucose**
56
what do beta cells produce?
| explain how they do it
**insulin**
* increase movement of glucose from blood to tissues
* decreases breakdown of glycogen (stored glucose)
* decreases formation of glucose from fat
* result = **decreases blood glucose**
57
What are the normal lab values for blood glucose?
**3.9-5.5 mmol/L** or **70-100 mg/dL**
58
why do cells require glucose?
| explain what would happen if levels were too low or too high
glucose is used for **energy** (by brain) & is required for **circulation**
* *high glucose levels* = damage to blood vessels & organs
* low blood glucose = brain fog, fatigue*
59
What is type I DM?
* **no insulin can be produced** due to destruction of beta cells --> breakdown of islets
* cause = autoimmune
* duagnosed earlier in life
60
What is type II diabetes?
* cells stop responding to insulin leading to insulin resistance
* cells can produce insulin
* more common
* occurs later on in life
61
What is someone with Type I at risk of developing?
| explain pathophysiology
DKA = diabetic ketoacidosis
* lack of glucose forces the body to break down fats to create ATP
* ketones are produced as a by-product but stay in the blood
* makes blood acidic --> can lead to **metabolic acidosis**
* occurs in type I diabetic pts
62
What is polyuria?
* excess glucose in urine
* glucose in urine pulls water by osmosis
NORMAL = 100% of glucose is rebasorbed
