Question

Physiology of Exercise:

1. Explain hormone receptor interactions. How do they work?

2. Explain protein to me and it's properties, importance, etc.

3. Describe "Muscle Actions" and give examples of movements as well as "Types of Muscle Action".

4.Explain carbohydrates to me and it's properties, importance, etc.

5. Explain protein intake and common misconceptions around it.

6. Give a detailed explanation of the Glycemic index and how it is important to athletes, regular population, and diseased population.

7. Give a detailed explanation of the three different types of muscle fiber types. Their characteristics and which muscle types are associated with what type of sports

8. Explain fats to me and it's properties, importance. etc.

9. Give detailed write-ip of factors that influence the secretion of insulin and why they do.

10. Explain and describe the diseases that can negatively impact muscle function

11. An elite powerlifter would most likely have a higher percentage of which fiber type?

12. Explain blood glucose homeostasis during exercise. Talk about the hormone involved and the actions they take to control our blood glucose.

13. How do athlete's differ from the general population in hormone and receptor number.

14. What are some of the common fare markers (fats & triglycerides) that are seen in a blood test and what do they mean and how can someone change those levels.

Answer 1

1. On target cell, the hormone in combination with the receptor acts by any of the following mechanisms :

• By changing permeability of cell membrane
• By activating intracellular enzymes
• Through effect on gene expression
• Through tyrosine kinase activation

Action Through Change in Membrane Permeability

Hormone bind with receptors present in cell membrane leading to its conformational change causing either closing or opening of ion channels. Ex: adrenaline, noradrenaline act by this mechanism.

Action Through Activating Intracellular Enzymes (via secondary messengers)

The hormone which acts on a target cell is called first messenger. This hormone in combination with the receptor forms hormone-receptor complex. This in turn activates enzymes of cell and causes formation of second messengers (cAMP, IP3, DAG, Calcium calmodulin). The release of second messengers is mediated by GTP binding proteins (G proteins). Ex: the peptides and biogenic amines are two principal classes of hormones which act via this mechanism.

Action Through Effect on Gene Expression

The sequence of events involved in this mechanism are as follows :

1. Transport :- after secretion, the hormone is carried to target tissue by serum binding protein.
2. Internalization :- being lipophilic, the hormone easily diffuse through plasma membrane.
3. Receptor-hormone complex (RHC) formed by bnding of hormone to specific receptor inside the cell.
4. Conformational change in receptor protein leading to activation of receptors.
5. The activated RHC then diffuse into nucleus and binds on specific region on DNA, initiating transcription.
6. Binding of RHC to DNA alters rate of transcription of mRNA.
7. The mRNA moves out of nucleus and reaches ribosomes. Here it promotes translation process. In this way new proteins are formed which initiate specific responses.

Ex: Thyroid hormones and steroid hormones act by this mechanism.

Action Through Tyrosine KInase Activation (enzyme linked hormone receptors)

These enzyme linked receptors have their hormone binding site on the outside of cell membrane and their catabolic or enzyme binding site on the inside. When hormone binds to the extracellular portion of receptor, an enzyme is activated inside the cell immediately (without G protein intermediates as in second mechanism described above). The activation of tyrosine kinase occurs by two mechanisms :

1. Due to binding of hormone to receptor, the receptor itself becomes a tyrosine kinase that phosphorylates tyrosine residue on intracellular protein substrates. This sets into motion a series of events leading to enzyme activation and gene expression.
2. Hormone binding to extracellular portion of receptor can attract intracytoplasmic tyrosine kinases and then activates them. This causes phosphorylation of transcription factor proteins and ultimately modulate gene expression.

Ex: Insulin, IGF (Insulin-like Growth Factor), EGF (Epidermal Growth Factor), PDGF (Platelet-Derived Growth Factor), ANF (Atrial Natriuretic Factor), GABA (Gamma Amino Butyric Acid) etc. act by this mechanism.