Human Body Water Compartmentalization

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Questions and Answers

Which of the following is the alcohol group in sphingomyelin?

Choline (correct)

Sphingosine

Ceramide

Fatty acid

What percentage of the human body is composed of water?

50%

40%

60% (correct)

70%

Where are sphingomyelins primarily found in a cell?

Cytoplasm

Inner leaflet of the cell membrane

Outer leaflet of the cell membrane (correct)

Nucleus

What is the main function of the cell membrane in terms of water distribution?

To separate intracellular and extracellular fluids Signup and view all the answers

What is the main function of the myelin sheath?

To insulate and protect neuronal axons Signup and view all the answers

What is the function of specific transporters and ion channels in cell membranes?

To generate selective membrane permeability Signup and view all the answers

What is the function of gap junctions in cell membranes?

To allow adjacent cells to communicate by exchanging material Signup and view all the answers

What is the characteristic of the lipid bilayer in cell membranes?

It is a dynamic, highly fluid structure Signup and view all the answers

What is the result of a mutation that affects the attachment of the GPI anchor to certain proteins in erythrocytes?

Paroxysmal nocturnal hemoglobinuria Signup and view all the answers

What is the characteristic feature of glycolipids?

Presence of an attached carbohydrate or carbohydrate chain Signup and view all the answers

What is a characteristic of the carrier protein in facilitated diffusion?

It undergoes a conformational change Signup and view all the answers

What is the backbone of glycosphingolipids?

Sphingosine Signup and view all the answers

What is the difference between intracellular fluid and extracellular fluid?

ICF provides a specialized environment for the cell, ECF is distributed between plasma and interstitial spaces Signup and view all the answers

What is the role of the plasma membrane in terms of cell-cell interactions?

To play key roles in cell-cell interactions and transmembrane signaling Signup and view all the answers

What is the hydrophilic region of glycosphingolipids?

Carbohydrate moiety Signup and view all the answers

Where are glycolipids primarily distributed in the body?

Nervous tissue Signup and view all the answers

What is the primary function of glycolipids in the plasma membrane?

To contribute to cell surface carbohydrates that form the glycocalyx Signup and view all the answers

What is a characteristic of facilitated diffusion?

It can be saturated Signup and view all the answers

What is the function of GLUT4 in adipocytes and skeletal muscle cells?

To transport glucose into the cell Signup and view all the answers

What is used to solubilize integral and transmembrane proteins?

Detergents Signup and view all the answers

Where is the SGLT-1 system commonly found?

In the epithelial cells of enterocytes Signup and view all the answers

What is the effect of carbohydrates on the outer surface of the plasma membrane?

It forms a carbohydrate layer known as the glycocalyx Signup and view all the answers

What can affect water balance and ion flux in the cell?

Changes in membrane components Signup and view all the answers

How does insulin regulate glucose uptake in fat and muscle cells?

By stimulating glucose transporter 4 (GLUT4) Signup and view all the answers

What is a characteristic of various cellular membranes?

They have different lipid and protein compositions Signup and view all the answers

What is an example of secondary active transport of glucose?

Glucose transport by SGLT-1 Signup and view all the answers

What is the function of channel proteins in the cell membrane?

To facilitate transport of ions and small molecules across the membrane Signup and view all the answers

What type of bonds do peripheral proteins generally use to bind to cell membranes?

Hydrogen bonds Signup and view all the answers

What is the purpose of aquaporins in certain cells?

To augment water movement by simple diffusion Signup and view all the answers

What is a 'ping-pong' mechanism involved in?

Facilitated diffusion Signup and view all the answers

What type of cellular membrane has the highest lipid content?

Myelin Signup and view all the answers

What type of proteins can be classified as integral proteins?

Transmembrane proteins Signup and view all the answers

What is the effect of unesterified-cholesterol on the fluidity of the membrane at values below the transition temperature?

It increases the fluidity Signup and view all the answers

What is the primary function of the carbohydrate layer on the surface of eukaryotic cells?

To serve as an information-rich surface for cell-cell recognition and adhesion Signup and view all the answers

What is the role of glycoconjugates in the cell?

To participate in cell-cell recognition and adhesion Signup and view all the answers

What is the term for the process of attaching a GPI anchor to certain proteins?

Glycosylphosphatidylinositol Signup and view all the answers

What is the function of glycophorin in human erythrocytes?

To increase the flip-flop frequency of membrane phospholipids Signup and view all the answers

Where are carbohydrates also present in addition to the glycocalyx?

In apoprotein B of plasma lipoproteins Signup and view all the answers

What is the effect of cholesterol on the fluidity of the membrane?

It is inversely proportional to the fluidity of the membrane Signup and view all the answers

What is the relationship between the hydrophilic/hydrophobic values of a phospholipid and its interaction with water?

Higher hydrophilic/hydrophobic values indicate good interaction with water Signup and view all the answers

Where is pro-insulin processed to form mature insulin and C-peptide?

In the Golgi apparatus Signup and view all the answers

What is the biological function of angiotensin II?

To stimulate aldosterone production and retain sodium Signup and view all the answers

What type of hormones are synthesized in their final active form?

Steroid hormones and 1,25(OH)2-D3 Signup and view all the answers

What is the function of renin in the renin-angiotensin-aldosterone system?

To catalyze angiotensinogen to produce angiotensin I Signup and view all the answers

What is the significance of C-peptide?

It is a marker for endogenous insulin Signup and view all the answers

How are catecholamines stored in the adrenal medulla?

In granules Signup and view all the answers

What is the effect of angiotensin II on renin release?

It inhibits renin release Signup and view all the answers

What is the result of the renin-angiotensin-aldosterone system activation?

Sodium retention and increased blood pressure Signup and view all the answers

What is the precursor molecule for thyroid hormones?

Tyrosine Signup and view all the answers

Which of the following hormones is a peptide hormone?

Follicle-stimulating hormone (FSH) Signup and view all the answers

What is the characteristic of Group I (Class I) hormones?

Lipophilic Signup and view all the answers

What is the duration of the reserve supply of catecholamines in chromaffin cells?

Several hours Signup and view all the answers

Which of the following is NOT a catecholamine?

Serotonin Signup and view all the answers

What is the condition that triggers the secretion of PTH from parathyroid cells?

Low Ca2+ levels Signup and view all the answers

What is the biological active form of Group I (Class I) hormones?

Free hormone Signup and view all the answers

What percentage of insulin is stored in the β cells of the pancreas?

15 to 20% Signup and view all the answers

What is the duration of the reserve supply of T3 and T4 in the thyroid follicles?

Several weeks Signup and view all the answers

Which of the following is a tyrosine derivative?

Thyroid hormones Signup and view all the answers

What is the effect of binding to a carrier protein on the half-life of Group I (Class I) hormones?

Increases the half-life Signup and view all the answers

What is the normal ratio of insulin to C-peptide secreted by β cells of the pancreas?

1:1 Signup and view all the answers

Which of the following hormones is NOT a glycoprotein?

Estrogen Signup and view all the answers

What triggers the processing of pro-insulin to insulin in β cells of the pancreas?

High glucose levels Signup and view all the answers

In which structure are T3 and T4 stored in the thyroid gland?

Thyroglobulin Signup and view all the answers

What is the stimulus that releases T3 and T4 from the thyroid gland?

TSH Signup and view all the answers

What is a characteristic of hormones in terms of their concentration in the extracellular fluid?

Present at very low concentrations, generally in the femto- to nanomolar range Signup and view all the answers

Which of the following is a way to classify hormones?

By chemical composition, solubility properties, location of receptors, and the nature of the signal used to mediate hormonal action Signup and view all the answers

What is true about hormones in terms of their action?

They can act on adjacent cells, on the cell in which they were synthesized, and on distant cells Signup and view all the answers

Which of the following hormones is synthesized from cholesterol?

Glucocorticoids Signup and view all the answers

What is true about the action of hormones on cells?

A given hormone can affect several different cell types Signup and view all the answers

Which of the following is NOT a way to classify hormones?

By their molecular weight Signup and view all the answers

What is a characteristic of hormone synthesis?

Hormones are synthesized from protein/peptides of various sizes Signup and view all the answers

What is true about the effect of hormones on cells?

Hormones can exert many different effects in one cell or in different cells Signup and view all the answers

Where do polypeptide/protein hormones and catecholamines bind to receptors?

On the plasma membrane Signup and view all the answers

What is the mechanism by which hormones that bind to surface receptors communicate with intracellular metabolic processes?

Through the generation of second messengers Signup and view all the answers

How are hormones derived from cholesterol synthesized?

In final form and secreted immediately Signup and view all the answers

What is the role of the ligand-receptor complex in hormone signaling?

It is the intracellular messenger Signup and view all the answers

How are catecholamines synthesized and stored?

In final form and stored in the producing cells Signup and view all the answers

What is the mechanism by which lipophilic steroid, retinoid, and thyroid hormones interact with intracellular receptors?

Directly providing the signal, generally affecting the transcription rate of specific genes Signup and view all the answers

How are hormones like insulin synthesized and secreted?

As precursor molecules that are processed and secreted upon a physiologic cue Signup and view all the answers

What is the role of the plasma membrane in hormone signaling?

It spans the hormone receptors Signup and view all the answers

What is the characteristic of hormones in Group I (Class I)?

They are lipophilic and associate with plasma transport or carrier proteins. Signup and view all the answers

Which of the following hormones is a derivative of tyrosine?

Thyroid hormones (T3, T4) Signup and view all the answers

What is the effect of binding to a protein on the half-life of lipophilic hormones?

It increases the half-life. Signup and view all the answers

Which of the following hormones is a derivative of tryptophan?

Serotonin Signup and view all the answers

What is the characteristic of the biologically active form of lipophilic hormones?

It is the free hormone. Signup and view all the answers

Which of the following hormones is a glycoprotein?

Thyroid-stimulating hormone (TSH) Signup and view all the answers

What is the characteristic of hormones in Group II (Class II)?

They are water-soluble and do not need a carrier protein. Signup and view all the answers

Which of the following is NOT a characteristic of lipophilic hormones?

They are water-soluble. Signup and view all the answers

What is the most potent natural glucocorticoid hormone in humans?

Cortisol Signup and view all the answers

What is the primary plasma binding protein for cortisol?

Transcortin (Corticosteroid-binding globulin) Signup and view all the answers

Which of the following steroids is a prohormone that can be converted into a more potent androgen?

Dehydroepiandrosterone (DHEA) Signup and view all the answers

What is the main function of the binding proteins in steroid hormone transport?

To provide a circulating reservoir of hormones Signup and view all the answers

Which of the following stimulates the production of aldosterone?

All of the above Signup and view all the answers

What is the final product of androgen synthesis in the adrenal cortex?

Testosterone Signup and view all the answers

Which of the following is a characteristic of testosterone?

It is a prohormone Signup and view all the answers

What is the significance of the conversion of cholesterol to pregnenolone in the adrenal cortex?

It is identical in the adrenal, ovary, and testis Signup and view all the answers

What is the major product of the adrenal medulla?

Epinephrine Signup and view all the answers

What is the enzyme responsible for the conversion of tyrosine to epinephrine in the adrenal medulla?

Phenylethanolamine-N-methyltransferase Signup and view all the answers

What is the percentage of catecholamines in the adrenal medulla that is epinephrine?

80% Signup and view all the answers

What is the rare element required for the bioactivity of triiodothyronine (T3) and tetraiodothyronine (T4) hormones?

Iodine Signup and view all the answers

What is the precursor molecule for thyroid hormones?

Thyroglobulin Signup and view all the answers

What is the storage site of T3 and T4 hormones in the thyroid gland?

Colloid Signup and view all the answers

What is the primary estrogen formed in the ovaries?

17β-Estradiol Signup and view all the answers

What is the hormone responsible for regulating the synthesis of T3 and T4 hormones?

Thyroid-stimulating hormone (TSH) Signup and view all the answers

What is the enzyme complex responsible for the formation of estrogens?

Aromatase enzyme complex Signup and view all the answers

What percentage of T4 and T3 in the body is in an extrathyroidal reservoir?

One-half to two-thirds Signup and view all the answers

What is the precursor for all steroid hormones?

Progesterone Signup and view all the answers

What is the active molecule synthesized from 7-dehydrocholesterol?

Calcitriol (1,25(OH)2-D3) Signup and view all the answers

Where is the majority of the precursor for 1,25(OH)2-D3 synthesis produced?

Skin Signup and view all the answers

What is the result of the hydroxylation at position C1 in the kidney?

1,25(OH)2-D3 Signup and view all the answers

What is the function of the vitamin D–binding protein?

It transports vitamin D3 and its metabolites Signup and view all the answers

What is the enzyme responsible for the conversion of testosterone to dihydrotestosterone (DHT)?

5α-Reductase Signup and view all the answers

What is the site of pro-insulin processing to form mature insulin and C-peptide?

Golgi apparatus Signup and view all the answers

What is the effect of angiotensin II on blood pressure?

Increases blood pressure Signup and view all the answers

What is the precursor molecule for angiotensin II?

Angiotensinogen Signup and view all the answers

What is the function of C-peptide?

Acts as a marker for endogenous insulin Signup and view all the answers

Where are catecholamines stored in the adrenal medulla?

In granules in the chromaffin cells Signup and view all the answers

What is the effect of insulin on blood glucose levels?

Decreases blood glucose levels Signup and view all the answers

What is the role of renin in the renin-angiotensin-aldosterone system?

Catalyzes angiotensinogen to produce angiotensin I Signup and view all the answers

What type of hormones are synthesized in their final active form?

Steroid hormones Signup and view all the answers

Study Notes

The Body's Internal Water Compartmentalization

Water makes up about 60% of the lean body mass of the human body, distributed in two large compartments separated by the cell membrane.
The two compartments are:
- Intracellular Fluid (ICF): two-thirds of total body water, providing a specialized environment for the cell.
- Extracellular Fluid (ECF): one-third of total body water, distributed between the plasma and interstitial compartments.

Ionic Compositions of Intracellular & Extracellular Fluids

(No specific details provided in the text)

Properties of Cell Membranes

Membranes are asymmetric lipid bilayers with distinct inner and outer surfaces.
Membranes are dynamic, highly fluid structures consisting of a lipid bilayer and associated proteins.
The plasma membrane exchanges material with the extracellular environment by exocytosis and endocytosis due to its flexibility.
Special areas of membrane structure, such as gap junctions, allow adjacent cells to communicate by exchanging material.
The plasma membrane has selective permeabilities.
Selective membrane molecular permeability is generated through the action of specific transporters and ion channels.

Cell Membrane Functions

The plasma membrane plays key roles in cell-cell interactions and transmembrane signaling.
Membranes form specialized compartments (organelles) within the cell, such as mitochondria, endoplasmic reticulum (ER), Golgi, lysosomes, and the nucleus.
Membranes localize enzymes.
Changes in membrane components can affect water balance and ion flux.

Membrane Lipids

Glycolipids are lipids with an attached carbohydrate or carbohydrate chain.
Glycolipids are particularly distributed in nervous tissue, such as the brain.
They occur in the outer leaflet of the plasma membrane, contributing to cell surface carbohydrates that form the glycocalyx.
The major glycolipids found in animal tissues are glycosphingolipids.

Glycosphingolipids (GSLs)

GSLs have a sphingosine backbone, being ceramide derivatives.
Examples of GSLs include cerebroside, sulfatide, globoside, and ganglioside.

Properties of Glycolipids

The green areas of glycoshingolipids are hydrophilic, while other areas are hydrophobic.
High hydrophilic/hydrophobic values of a phospholipid show its good interaction with water.

Carbohydrates in Cell Membranes

Glycoconjugates, including proteoglycans, glycoproteins, and glycolipids, form a carbohydrate layer (the glycocalyx) on the surface of eukaryotic cells.
The glycocalyx serves as an information-rich surface that the cell shows to its surroundings.
Carbohydrate chains are attached to the amino-terminal portion outside the external surface.
Carbohydrate presence on the outer surface of the plasma membrane has been shown with the use of plant lectins.

Glycoconjugates

Glycoconjugates are biologically active molecules formed by the covalent joining of carbohydrates to proteins or lipids.
Carbohydrates are present in apoprotein B of plasma lipoproteins.
Glycophorin is a major integral membrane glycoprotein of human erythrocytes, increasing the flip-flop frequency of membrane phospholipids.

Membrane Proteins

Transmembrane proteins can be classified under integral proteins.
Several transmembrane proteins serve as channels for water-soluble molecules or have receptor functions.
Detergents solubilize (release) integral and transmembrane proteins.
Peripheral proteins do not interact directly with the hydrophobic cores of the phospholipids in the bilayer.
Peripheral proteins bind to the hydrophilic regions of specific integral proteins and head groups of phospholipids and can be released from them.
Peripheral proteins can be released from the membrane by treatment with salt solutions of high ionic strength.

Protein Lipidation

Peripheral proteins generally bind to cell membranes with loose hydrogen bonds.
Some peripheral proteins bind to membrane lipids by covalent linkages, such as isoprenylation, cholesterylation, glycosylphosphatidylinositol (GPI), myristoylation, and internal cysteine S-prenylation and S-acylation.
Mutation resulting in deficient attachment of the GPI anchor to certain proteins of erythrocytes results in paroxysmal nocturnal hemoglobinuria.

Membrane Markers

(No specific details provided in the text)

Membrane Structure and Function

Membranes are complex structures composed of lipids, proteins, and carbohydrate-containing molecules.
Various cellular membranes have different lipid and protein compositions.

Passive Diffusion

Facilitated diffusion involves certain transporters.
Facilitated diffusion has different properties than simple diffusion:
- The rate of facilitated diffusion can be saturated.
- A "ping-pong" mechanism helps explain facilitated diffusion.
- A conformational change occurs in the carrier protein.
- This process is completely reversible, and net flux across the membrane depends on the concentration gradient.

Transport of Glucose

Glucose transport involves facilitated diffusion and secondary active transport.
Several different glucose transporters (GLUTs) are involved, varying in different tissues.
Glucose transport by GLUTs is an example of facilitated diffusion.
In adipocytes and skeletal muscle, glucose enters the cells by GLUT4 that is enhanced by insulin.
Glucose transport by SGLT-1 (Sodium Glucose Transporter-1) system is an example of secondary active transport.

Aquaporins

Aquaporins are specific transporters in facilitated diffusion, augmenting the movement of water by simple diffusion in certain cells.
Examples of cells where aquaporins are involved include red cells and cells of the collecting ductules of the kidney.

Insulin

Insulin is a polypeptide hormone synthesized as a preprohormone in pancreatic beta cells.
The pre-part is removed in the endoplasmic reticulum lumen, forming pro-insulin, an inactive form.
Pro-insulin undergoes site-specific peptide cleavages in the Golgi apparatus, resulting in equimolar amounts of mature insulin and C-peptide.
Insulin is released into circulation when blood glucose concentrations exceed normal ranges.
C-peptide is a marker for endogenous insulin.

Renin-Angiotensin-Aldosterone System

This system is activated when blood pressure is decreased.
Biologically active forms of angiotensin are Ang II and Ang III.
Angiotensinogen precursor is catalyzed by renin enzyme to produce angiotensin I.
Angiotensin-converting enzyme (ACE) forms angiotensin II from angiotensin I.
Angiotensin II inhibits renin release and stimulates aldosterone production, resulting in Na+ retention, volume expansion, and increased blood pressure.

Angiotensin II

Angiotensin II inhibits renin release and stimulates aldosterone production.
This results in Na+ retention, volume expansion, and increased blood pressure.

Variations in Storage and Secretion of Hormones

Steroid hormones and 1,25(OH)2-D3 are synthesized in their final active form and secreted as they are made.
Catecholamines are synthesized in active form, stored in granules in chromaffin cells, and released in response to neural stimulation.
PTH exists in storage vesicles, and its secretion is triggered by low Ca2+ levels in parathyroid cells.
Insulin is stored in β cells of the pancreas, and 15-20% of the hormone is stored.
Insulin and C-peptide are normally secreted in equimolar amounts.
T3 and T4 have a several-week supply in the thyroglobulin stored in colloids in the lumen of thyroid follicles.

Hormone Classification

Hormones can be classified based on:
- Chemical composition
- Solubility properties
- Location of receptors
- Nature of the signal used to mediate hormonal action within the cell

Hormone Classification by Chemical Composition

Hormones can be derived from:
- Amino acids (e.g., thyroid hormones, catecholamines)
- Cholesterol (e.g., glucocorticoids, mineralocorticoids, androgens)
- Proteins/peptides of various sizes (e.g., thyrotropin-releasing hormone, adrenocorticotropic hormone)

Hormone Classification by Solubility and Receptor Location

Group I (Class I): lipophilic hormones that bind to a protein in the circulation, increasing their half-life.
Group II (Class II): water-soluble hormones that don't need a carrier protein in the circulation.
Group I hormones bind to intracellular receptors, whereas Group II hormones bind to receptors on the plasma membrane.

Receptors

Polypeptide/protein hormones and catecholamines bind to receptors on the plasma membrane, generating a secondary messenger or signal.
Lipophilic steroid, retinoid, and thyroid hormones interact with intracellular receptors, directly affecting gene transcription.

Introduction to Hormones

Hormones provide intercellular, organism-wide communication.
Hormones are synthesized in one organ and transported by the circulatory system to act on another tissue.
Hormones can act on adjacent cells (paracrine action) and on the cell in which they were synthesized (autocrine action).
Hormones can affect multiple cell types and exert multiple effects in one cell or different cells.

Hormone Classification

Hormones can be classified based on their chemical composition:
- Tyrosine derivatives (e.g., thyroid hormones, catecholamines)
- Tryptophan derivatives (e.g., serotonin, melatonin)
Progestins (C21) and estrogens (C18) are steroid hormones
1,25(OH)2-D3 is a hormone derived from vitamin D

Hormone Classification by Solubility and Receptor Location

Group I (Class I) hormones:
- Lipophilic hormones that associate with plasma transport or carrier proteins in circulation
- Examples: steroid hormones, 1,25(OH)2-D3
Group II (Class II) hormones:
- Water-soluble hormones with peptide structure
- Examples: growth hormone, insulin, parathyroid hormone

Adrenal Steroidogenesis

Steroidogenesis involves the repeated shuttling of substrates in and out of the mitochondria
Cortisol is the most potent natural glucocorticoid hormone in humans
Stimulators of aldosterone production: renin-angiotensin system, K+ concentration, ACTH, and Na+ concentration

Hormone Transport

Cortisol is bound to transcortin (corticosteroid-binding globulin) in the plasma
Testosterone is carried in the circulation by sex hormone-binding globulin (SHBG) or testosterone-estrogen-binding globulin (TEBG)
Estrogens are bound to SHBG and progestins to CBG
These binding proteins provide a circulating reservoir of hormones

Androgen Synthesis

The major androgen precursor produced by the adrenal cortex is dehydroepiandrosterone (DHEA)
DHEA is converted into androstenedione, which is then reduced to form testosterone
Small amounts of testosterone are produced in the adrenal, but most conversion occurs in the testes (Leydig cells)

Testosterone

Testosterone can be considered a prohormone and is metabolized by two pathways
Some estradiol is formed from the peripheral aromatization of testosterone
Testosterone is converted into dihydrotestosterone (DHT) outside the testes

Ovarian Steroidogenesis

17β-Estradiol is the primary estrogen of ovarian origin
Estrogens are formed by the aromatization of androgens
Progesterone is produced and secreted by the corpus luteum

1,25(OH)2-D3 (Calcitriol)

The active molecule 1,25(OH)2-D3 is synthesized from 7-dehyrocholesterol
1,25(OH)2-D3 activates biologic processes in a manner similar to steroid hormones

1,25(OH)2-D3 Synthesis

Skin: 7-dehydrocholesterol is produced in the malpighian layer of the epidermis
Liver: vitamin D3 is 25-hydroxylated to form 25(OH)-D3
Kidney: 1,25(OH)2-D3 is produced by hydroxylation at position C1

Tyrosine Derivatives

Catecholamines (dopamine, norepinephrine, and epinephrine) are synthesized from tyrosine in the chromaffin cells of the adrenal medulla
The major product of the adrenal medulla is epinephrine
Norepinephrine is made in situ in organs innervated by sympathetic nerves

Catecholamine Synthesis

The conversion of tyrosine to epinephrine requires four sequential steps:
1. Ring hydroxylation
2. Decarboxylation
3. Side chain hydroxylation to form norepinephrine
4. N-methylation to form epinephrine

Thyroid Hormone Synthesis

Synthesis is regulated by TSH hormone
Triiodothyronine (T3) and tetraiodothyronine (thyroxine; T4) require iodine for bioactivity
They are synthesized as part of a precursor molecule called thyroglobulin
T3 and T4 are stored in an intracellular reservoir (colloid) and released into circulation in response to TSH stimulus

Insulin

Insulin is synthesized as a preprohormone in pancreatic beta cells
Pro-insulin is the inactive form, which undergoes site-specific peptide cleavages to form mature insulin and C-peptide
Insulin is released into circulation when blood glucose concentration exceeds normal ranges
C-peptide is a marker for endogenous insulin

Renin-Angiotensin-Aldosterone System

This system is activated when blood pressure is decreased
Angiotensin II is the biologically active form, which inhibits renin release and stimulates aldosterone production
Aldosterone results in Na+ retention, volume expansion, and increased blood pressure

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Description

Learn about the distribution of water in the human body, including intracellular and extracellular fluids, and their ionic compositions. Understanding the two main compartments of body water is crucial for human physiology.