Lecture 7 - hormones of adrenal medulla

Question 1

Hormones of the Adrenal Medulla

Answer 1

Epinephrine and norepinephrine​

Question 2

Question 3

Sympathetic pathway: ​

Answer 3

Preganglionic neuron originating in the CNS, whose axonal fiber terminates on a second peripheral post-ganglionic neuron, which terminates on the effector organ.

In picture:
N= nicotinic cholinergic receptor​
Ach = Acetylcholine​
NE= Norepinephrine​
1 and 2 Adrenergic receptors​

Question 4

Question 5

Question 6

Many of epinephrine exclusive 2 receptors are located in tissue not supply by sympathetic nervous system, but are reached by epinephrine through blood. ​

Question 7

Epinephrine & norepinephrine exert similar effects in many tissues, with epinephrine generally reinforcing sympathetic nervous activity.

Question 8

This slide is very important – you must know all the different adrenergic receptors, their location, which catecholamine innervated them, the typical responses which are elicited.​

Question 9

Epinephrine reinforces sympathetic nervous system​
Effects on organ systems​

Answer 9

• Support peak physical exertion in emergency or stressful situations​
• Fight- or flight response ([ ] blood epinephrine  up to 300x normal)​
  Increase the rate and strength of cardiac contraction​
  Increase cardiac output​ (by Bonding to beta heart receptors )
  Vasoconstrictor effect- + total peripheral resistance​
  Vasodilation of coronary and skeletal muscle blood vessels by actions of epinephrine shift blood to heart and skeletal muscle​
  Epinephrine dilates respiratory airways​
  Epinephrine and norepinephrine reduce digestive activities, inhibit bladder emptying​

​

Question 10

Epinephrine reinforces sympathetic nervous system​
Metabolic effects

Answer 10

• Mobilize stored carbohydrate and fat to provide energy to fuel muscular work​

Epinephrine increases blood glucose levels: ​
1. stimulates hepatic gluconeogenesis and glycogenolysis, ​

2. stimulates glycogenolysis in skeletal muscle (breakdown of muscle glycogen releases lactate into blood, liver removes lactate from blood and converts it to glucose), ​

3.inhibiting secretion of insulin, ​

4. stimulating glucagon secretion, ​

increase levels of blood fatty acids by promoting lipolysis, ​
increase general metabolism​

Question 11

Epinephrine reinforces sympathetic nervous system​
Other effects

Answer 11

Epinephrine stimulates CNS to promote “state of arousal” – permits quick thinking​

Epinephrine and norepinephrine cause sweating, body gets rid of extra heat generated by  muscular activity​

Epinephrine dilate pupil and flatten lens – adjust eyes for quick view of threatening scene

Question 12

Anaphylactic shock: circulatory hypotension​

Answer 12

relaxing arteriolar smooth muscle – widespread arteriolar vasodilation - ↓peripheral resistance and arterial blood pressure​

↑ capillary permeability – shift of fluid from plasma to interstitial fluid​

↑ bronchoconstriction

Question 13

Why do doctors recommend that people who are allergic to bee stings and thus are at risk for anaphylactic shock carry a vial of epinephrine for immediate injection in case of a sting?​

Answer 13

Anaphylactic shock = histamine via mast cells  severe hypotension occurs  increases permeability of blood vessels, too (oedema)  increased bronchoconstriction ​

Thus, epinephrine will combat the effects of histamine: Alleviates all symptoms to produce opposite effects

Question 14

Increased adrenaline = due to tumour in gland  affects medulla and cortex hormones ​
Cushing’s ​
Pheochromocytoma = in medulla ​
Hyperaldosteronism

Answer 14

Question 15

Factors which influence the [plasma] of a hormone​

Answer 15

• can be measured in urine

The hormone’s rate of secretion into the blood by the endocrine gland.​

The rate of metabolic activation or conversion: modification of hormone at peripheral organs, eg thyroxine  tri-iodothyronine (liver & kidney)​

Extent of binding of hormones to plasma proteins​

The rate of removal from blood by metabolic inactivation and excretion in urine: inactivated by enzymes in liver, kidneys, blood or target cells​:

Peptide hormones: hydrolysis of peptide bonds​

Insulin: target cell engulfs hormone-receptor complex by endocytosis and degrades intra-cellularly​

Catecholamines: enzymatically converted to biologically related inactive molecules​

Lypophilic steroid- and thyroid hormone: inactivated by alterations of active portion of molecule – liver added charged group to make them more water soluble – freed from plasma protein-carrier and eliminated in urine

Question 16

Typical blood tests for suspecting patient has pheochromotoma (tumour of adrenal medulla) ​

Symptoms: increased when response is activated

Question 17

Hypersecretion of E and NE​

Answer 17

Tumour of adrenal medulla
– PHEOCHROMOCYTOMA​

Symptoms:​
Hypertention​
Hyperglycemia​
Glucose in urine (glucosuria)​
Nervousness​
Digestive problems​
Sweating​
Elevated metabolism​
Body becomes totally fatigued – patient susceptible to other diseases​

Question 18

Question 19

Stress Response:

Answer 19

Pattern of reactions to a situation that threatens homeostasis
How our body responds to stress -> generalized response to stress ​
Acute vs chronic ​
Acute: Fight or flight short-term, immediate threat ​
Chronic: constant state of psychological stress, usually ​

Question 20

Stress​

Answer 20

Generalized nonspecific response of body to any factor that overwhelms or threatens to overwhelm the body’s ability to maintain homeostasis​

Question 21

Stressor ​

Answer 21

Any noxious stimulus that brings about the stress response

Question 22

DISCUSS STRESS RESPONSE: KNOW THIS ​
Vasopressin: only released if blood volume = lost (like in an accident) ​

Question 23

All organs affected by stress response ​
Shortening of dendirtes in brain

Question 24

Stress and prefrontal cortex​

Answer 24

Repeated and chronic stress causes dendritic shortening in the medial prefrontal cortex​

This results in impairment in attention set shifting

Question 25

Action of a stressor on the body.​
Chronic response

Answer 25

Question 26

All stress response actions are coordinated by the

Answer 26

Hypothalamus

Question 27

Generalized stress response​

Answer 27

Activation of sympathetic nervous system accompanied by epinephrine secretion​

Activation of CRH-ACTH-cortisol system​

Elevation of blood glucose and fatty acids​

Maintenance of blood volume and blood pressure

Question 28

NB

Question 29

Question 30

Mineral corticoids: ESSENTIAL FOR LIFE​
RAAS (renin-angiotensin-aldosterone system)​
Regulation of aldosterone secretion is largely independent of anterior pituitary control

Question 31

Endocrine Control of Fuel Metabolism​

Answer 31

Metabolism​
All the chemical reactions that occur within the cells of the body​

Intermediary metabolism or fuel metabolism​
Includes reactions involving the degradation, synthesis, and transformation of proteins, carbohydrates, and fats​

Nutrient molecules are broken down through the process of digestion into smaller absorbable molecules​
Proteins → amino acids​
Carbohydrates → monosaccharides (mainly glucose)​
Dietary fats (triglycerides) → monoglycerides and free fatty acids

Question 32

Normal cells will use fatty acids ​
Brain cells and CNS use glucose

Question 33

Anabolism​

Answer 33

Buildup or synthesis of larger organic macromolecules from small organic subunits​
Reactions usually require ATP energy​
Reactions result in​:
Manufacture of materials needed by the cell​
Storage of excess ingested nutrients not immediately needed for energy production or needed as cellular building blocks

Question 34

Catabolism ​

Answer 34

Breakdown or degradation of large, energy-rich organic molecules within cells​
Two levels of breakdown​:
Hydrolysis of large cellular molecules into smaller subunits​
Oxidation of smaller subunits to yield energy for ATP production

Question 35

Most interconversion of organic molecules occurs in

Answer 35

• liver

Glycerol → glucose​
Lactate → glucose

Essential nutrients (certain amino acids, fatty acids and vitamins)

Question 36

Food intake is intermittent – nutrients must be stored for use between meals​

Answer 36

Excess circulating glucose​
- Stored in liver and muscle as glycogen​
- Once liver and muscle stores are “filled up”, additional glucose is transformed into fatty acids and glycerol and stored in adipose tissue​

Excess circulating fatty acids​
- Become incorporated into triglycerides​

Excess circulating amino acids​
- Converted to glucose and fatty acids​

Question 37

Stored Metabolic Fuel in the Body ​

Answer 37

Question 38

Metabolic States​

Answer 38

• Absorptive state
• Postabsorbsorptive state

Question 39

Absorptive state

Answer 39

• Fed state​
• Glucose is plentiful and serves as major energy source

[after a meal, lots of glucose, major energy source ]

Question 40

Postabsorptive state​

Answer 40

Fasting state​
Endogenous energy stores are mobilized to provide energy

[fasting state, endogenous energy stores are mobilized to provide energy]

Question 41

Question 42

Livers roles in metabolic states

Answer 42

Primary role in maintaining normal blood glucose levels​

Principal site for metabolic interconversions such as gluconeogenesis

Question 43

adipose tissue roles in metabolic states

Answer 43

Primary energy storage site​

Important in regulating fatty acid levels in the blood

Question 44

Muscle roles in metabolic states

Answer 44

Primary site of amino acid storage​

Glycogen is converted to lactate during glycolysis​

Major energy user​

Lactate is converted to glucose by liver

Question 45

Brain roles in metabolic states

Answer 45

Normally can only use glucose as an energy source ​

Does not store glycogen ​
- Blood glucose levels be maintained​
- Prolonged starvation (glucose sparing): Liver converts fatty acids to acetyl-CoA → ketone bodies​
- Brain uses ketones instead of glucose as energy source​
- Death due to starvation is mostly due to protein wasting, rather than to hypoclycemia​
- High blood ketone levels inhibit protein degradation in muscle​