Lecture 1 Flashcards
What is physiology?
Physiology
- Greek word
-Physis: nature
-Logos: study
•Study of the function and the regulation of the different systems of living things
•Study approach: teleological (“the why”) and mechanistic (“the how”) approaches
- Why and how the various systems work
State five branches of physiology
Difference between endocrine and exocrine
Branches of Physiology
•Egs:
- Cellular Physiology
- Reproductive Physiology
- Endocrine Physiology-exocrine and endocrine
Exocrine releases what the gland wants to produce through a duct into the site where it’s supposed to act
Endocrine secretes hormone into the blood and it travels to the various parts it wants to act. Example is Oxytocin
Here’s a simple way to remember the difference between exocrine and endocrine glands:
-
Exocrine: “Exo-“ means “outside.” Exocrine glands secrete their products out through ducts to a surface or cavity (like sweat glands secreting sweat onto the skin).
- Memory Tip: Imagine a duct as a “door” that leads out (exiting), just like how exocrine glands have ducts that let substances out.
-
Endocrine: “Endo-“ means “inside.” Endocrine glands release their hormones inside the body directly into the bloodstream (like the thyroid gland releasing hormones into the blood).
- Memory Tip: Think of “endo” as “enclosed” (inside) with no ducts, because the secretion goes directly into the bloodstream.
So, “Exo-“ = exit through a duct, and “Endo-“ = inside, no duct.
- Comparative Physiology-compares structures and their functions which are characteristics of different organisms
- Systems Physiology
What is homeostasis and why is it so important
Homeostasis
-Maintenance of nearly constant, stable conditions in the internal environment.
•Importance of homeostasis
- Basis of physiology (survival and functioning of cells) and clinical diagnostic procedures
•Egs.
- Body temp. regulation (37.5oC): integumentary, nervous systems etc.
-Lungs provide oxygen to the extracellular fluid to replenish the oxygen used by the cells
- Kidneys maintain constant ion concentrations
Who coined the term, milieu interieur?
Who brought the name homeostasis
milieu intérieur A TERM COINED BY
Claude Bernard
French physiologist.
“ Father of physiology.
• “La fixit du milieu intkrieur est fa condition de fa vie fibre.” (the constancy of the internal environment is necessary for free life).
CLAUDE BERNARD
1813-1878
Walter B. Canon NAMED THE FIXITY DESCRIBED BY
American physiologist
• Coined the term ‘homeostasis’.
Described homeostasis as-‘an evolutionary development of a metabolic wisdom that provides for internal constancy’.
1871-1945
What are body fluids comprised of
What percent of the body weight is fluid?
Which percent belongs to ECF and which to ICF
Water
•Solids
-Organic substances (glucose, amino acids, fatty acids, hormones, enzymes etc)
-Inorganic substances (Na, K, Ca, Mg, Cl etc)
•60% of body weight is fluid ie.
- Total body weight (ECF = 20% ie. 4% for plasma and 16% for interstitial fluid, ICF = 40%)
ICF -2/3rd body fluid and 40 percent of the 60 percent body weight that is fluid
What is the fluid content percentage of the following things:
1. Human body
2.plasma
Skin muscles and internal organs
Skeleton
Adipose tissue
Men
Youth
Item
% fluid content
Human body
40-80% but 60% on average
Plasma
> 90%
Skin, muscle, internal organs
70-80%
Skeleton
22%
Adipose tissue
10%
Men
Varies but > Women
Youth
Varies but > Aged
State the different compartments of fluid in the body and their percentages
Intracellular fluid (ICF)-40 percent body weight(24litres)
•Extracellular fluid (ECF):
-Interstitial fluid (IF) and lymph(Interstitial fluid that bathes cells in the interstitial spaces(spaces between cells) . 16% body weight,9.6 liters)
-Plasma(4% body weight,2.4 liters
-Fluid in bones
-Fluid in dense connective tissues like cartilage
-Transcellular fluid (CSF, intraocular fluid, digestive juices, pericardial fluid, peritoneal fluid, serous fluid, synovial fluid in joints, fluid in urinary tract).
The body’s fluid compartments and their respective percentages are as follows:
- 40% of body weight (approximately 24 liters in a 60 kg person)
- This is the fluid within cells.
- 20% of body weight (approximately 12 liters in a 60 kg person)
- This is the fluid outside cells and is divided into several compartments:
-
Interstitial Fluid (IF) and Lymph
- 16% of body weight (approximately 9.6 liters)
- Interstitial fluid bathes cells in the interstitial spaces (spaces between cells).
-
Plasma
- 4% of body weight (approximately 2.4 liters)
- The fluid component of blood.
-
Transcellular Fluid
- A small percentage of total body water, included in the ECF.
- Includes specialized fluids like:
- Cerebrospinal Fluid (CSF)
- Intraocular Fluid
- Digestive Juices
- Pericardial Fluid
- Peritoneal Fluid
- Serous Fluid
- Synovial Fluid in joints
- Fluid in the urinary tract
-
Other Fluids in the ECF
- Fluid in bones and dense connective tissues like cartilage.
- The exact percentage of these fluids is typically less emphasized in basic physiology but is part of the overall ECF volume.
- Intracellular Fluid (ICF): 40% of body weight.
-
Extracellular Fluid (ECF): 20% of body weight, further divided into:
- Interstitial Fluid and Lymph: 16% of body weight.
- Plasma: 4% of body weight.
- Transcellular Fluid: Included in ECF, but a very small component.
- Fluid in Bones and Dense Connective Tissues: Part of ECF.
Transcellular fluid is a small part of the extracellular fluid and includes all the specialized fluids found in different compartments of the body. It is not specifically measured in terms of body weight percentage but is understood to be part of the ECF.
What is the internal environment of the body ?
ECF
All the cells in the body live in
the same environment, the ECF. So, the ECF is also k/a ‘internal environment’ of the body or ‘milieu intérieur’
• They get nutrition from it & discharge their waste products in it
Where is sodium more abundant?
Where is calcium more abundant
Where is potassium more abundant?
Where is magnesium more abundant?
Where is phosphate more abundant?
Where are proteins more abjndant?
Where are amino acids more abundant?
Where is glucose more abundant?
Where are lipids more abundant?
Where is chloride more abundant?
Where is bicarbonate more abundant?
Electrolyte ECF ICF
Sodium 142 mEq/L 10 mEq/L
Calcium 5 mEq/L 1 mEq/L
Potassium 4 mEq/L 140 mEq/L
Magnesium 3 mEq/L 28 mEq/L
Chloride 103 mEq/L 4 mEq/L
Bicarbonate 28 mEq/L 10 mEq/L
Phosphate 4 mEq/L 75 mEq/L
Sulfate 1 mEq/L 2 mEq/L
Proteins 2 g/dL 16 g/dL
Amino acids 30 mg/dL 200 mg/dL
Glucose 90 mg/dL 0-20 mg/dL
Lipids 0.5 g/dL 2-95 g/dL
Partial pressure of
oxygen ECf-35 mm Hg
iCF-20 mm Hg
Partial pressure of
carbon dioxide ECF-46 mm Hg ICF-50 mm Hg
Water 15 to 20 L (18). 20 to 25 L (22)
pH. 7.4. 7.0
To remember the critical electrolyte values and whether they are higher outside the cell (ECF) or inside the cell (ICF), you can use mnemonic devices and associations. Here are some tips and mnemonics to help:
- ECF: 142 mEq/L, ICF: 10 mEq/L
- Mnemonic: “Salt outside” – Salt (sodium) is typically added to food (outside the body).
- ECF: 5 mEq/L, ICF: 1 mEq/L
- Mnemonic: “Calcium in bones” – Think of calcium being stored in bones (outside the cells).
- ECF: 4 mEq/L, ICF: 140 mEq/L
- Mnemonic: “Banana inside” – Bananas (high in potassium) get digested and absorbed into cells.
- ECF: 3 mEq/L, ICF: 28 mEq/L
- Mnemonic: “Magnet inside” – Think of a magnet attracting magnesium inside the cells.
- ECF: 103 mEq/L, ICF: 4 mEq/L
- Mnemonic: “Chlorine pool outside” – Chlorine (chloride) is often associated with swimming pools (outside).
- ECF: 28 mEq/L, ICF: 10 mEq/L
- Mnemonic: “Baking soda outside” – Bicarbonate, like baking soda, is commonly used outside the body.
- ECF: 4 mEq/L, ICF: 75 mEq/L
- Mnemonic: “Phosphorylation inside” – Phosphate is crucial for cellular functions like phosphorylation.
- ECF: 1 mEq/L, ICF: 2 mEq/L
- Mnemonic: “Sulfate slightly inside” – Sulfate has a slight preference for the inside.
- ECF: 2 g/dL, ICF: 16 g/dL
- Mnemonic: “Protein factories” – Cells are the factories producing proteins, so more inside.
- ECF: 30 mg/dL, ICF: 200 mg/dL
- Mnemonic: “Building blocks inside” – Amino acids are the building blocks for proteins, found inside cells.
- ECF: 90 mg/dL, ICF: 0-20 mg/dL
- Mnemonic: “Glucose goes in” – Glucose enters cells for energy, thus lower inside.
- ECF: 0.5 g/dL, ICF: 2-95 g/dL
- Mnemonic: “Lipid reserves inside” – Cells store lipids as energy reserves.
- ECF: 35 mm Hg, ICF: 20 mm Hg
- Mnemonic: “Oxygen outside” – Oxygen needs to enter cells, so higher outside.
- ECF: 46 mm Hg, ICF: 50 mm Hg
- Mnemonic: “CO2 produced inside” – Cells produce CO2, so higher inside.
- ECF: 15-20 L (18), ICF: 20-25 L (22)
- Mnemonic: “Water balance” – Both compartments have significant amounts of water but slightly more inside cells.
- ECF: 7.4, ICF: 7.0
- Mnemonic: “pH stability outside” – The ECF pH is more stable and slightly alkaline, while ICF is more acidic.
Using these mnemonics and associations can help you remember which electrolytes and other substances are higher in the ECF or ICF.
Where is sodium more abundant?
Electrolyte ECF ICF
Sodium 142 mEq/L 10 mEq/L
Calcium 5 mEq/L 1 mEq/L
Potassium 4 mEq/L 140 mEq/L
Magnesium 3 mEq/L 28 mEq/L
Chloride 103 mEq/L 4 mEq/L
Bicarbonate 28 mEq/L 10 mEq/L
Phosphate 4 mEq/L 75 mEq/L
Sulfate 1 mEq/L 2 mEq/L
Proteins 2 g/dL 16 g/dL
Amino acids 30 mg/dL 200 mg/dL
Glucose 90 mg/dL 0-20 mg/dL
Lipids 0.5 g/dL 2-95 g/dL
Partial pressure of
oxygen ECf-35 mm Hg
iCF-20 mm Hg
Partial pressure of
carbon dioxide ECF-46 mm Hg ICF-50 mm Hg
Water 15 to 20 L (18). 20 to 25 L (22)
pH. 7.4. 7.0
How is homeostasis used for diagnostic purposes
Homeostasis is used for clinical diagnostic procedures by seeing when something goes wrong. Example is seeing albumin in urine. Normally, it’s not supposed to be there.
Then another is testing for lactic acid or LDH. It’s not supposed to be seen in the blood but it will be seen when the cells are unable to receive oxygen and produce energy anaerobically
Which of the following clinical diagnostic findings indicates a disruption in homeostasis?
A) High levels of albumin in the blood
B) Presence of albumin in the urine
C) Low levels of lactic acid in the blood
D) Absence of lactate dehydrogenase (LDH) in the blood
Answer: B
Explanation: The presence of albumin in the urine indicates a disruption in homeostasis because albumin is typically retained in the bloodstream and not filtered into the urine. High levels of lactic acid and LDH in the blood can indicate cellular stress or damage, such as when cells are unable to receive sufficient oxygen and resort to anaerobic metabolism. However, low levels of these substances in the blood are normal, and their presence is abnormal.
How do the different body systems work together for homeostasis (state each system in the body and how they work)
Integumentary: Contributes to homeostasis by
protecting the body and helping regulate the body temperature.
It also allows you to sense pleasurable, painful and other stimuli in your external environment
Endocrine- endocrine function of the pancreas is producing insulin and glucagon. The insulin goes to bind to specific receptors on the cells which opens protein channels called GLAT transporters. There are four GLAT TRANSPORTERS. These are found in specific cells in the body. Example GLAT 1 is prepdomiannt in brain cells and erythrocytes
GLAT 4 is predominant in the skeletal muscles, heart and adipose tissues.
If there’s high glucose, body doesn’t need it to be so high in the intravascular space. So it tells pancrease to produce insulin. The insulin binds to receptors which open GLAT transporters to shuttle glucose into the various cells that need it more at that time.
GLAT 2 transporters send glucose into the pancreas. That’s how it maintains the proper amount of glucose supposed to be in the Intravascular space.
Macromolecules going through Circulatory system:
Fat through lymphatic system
Glucose into intravscular space
Digestive system: macromolecules are broken down into their smaller units to be sent to other parts
Respiratory: exchange of oxygen and carbon dioxide
Urinary System:
Musculoskeletal system:
Bones serves as a storage for calcium
Through the thyroid parathyroid system, the body knows if there’s too much or too little calcium. High calcium in blood; the body will push it into the bones. Low calcium; pushing calcium into the blood
Muscular system:
Musculovascular pump: muscles in limbs contract to pump the blood up back into the heart.
Helps regulate temperature
Gives posture
What are the characteristics of the homeostasis control systems
Homeostatic control mechanisms
•Functionally interconnected network of body components
that operate to attain homeostasis
•Characteristics of control systems:
-Detect deviations from normal in the internal
environment that need to be held within narrow limits
- Integrate the above information
-Make appropriate adjustments so as to restore
the parametre to its desired value
State the components of the homeostatic system and give an example of how everything works together using temperature regulation
When the NORMAL body function is occurring and there’s a DEVIATION, the SENSOR picks it up and tells the CONTROL CENTER which sends signals to the EFFECTOR and this causes CORRECTION of the DEVIATION
Example;
Example is temperature
So when your temperature deviates from the normal, your thermoreceptors in your skin will be sensors
It goes to control center which is the hypothalamus in the brain
The effector is the sweat glands.
This produces sweat which cools the system back to normal
- Sensor: Pancreatic beta cells detect elevated blood glucose levels.
- Control Center: Pancreas.
- Effector: Insulin-secreting cells in the pancreas.
- Correction: Insulin is released, promoting glucose uptake by cells, which lowers blood glucose levels back to normal.
- Sensor: Baroreceptors in the carotid sinuses and aortic arch detect changes in blood pressure.
- Control Center: Medulla oblongata in the brainstem.
- Effector: Heart and blood vessels.
- Correction: If blood pressure is too high, the heart rate is decreased, and blood vessels dilate. If blood pressure is too low, the heart rate increases, and blood vessels constrict, returning blood pressure to normal.
- Sensor: Chemoreceptors in the carotid bodies and aortic bodies detect changes in oxygen and carbon dioxide levels in the blood.
- Control Center: Respiratory centers in the medulla oblongata and pons.
- Effector: Respiratory muscles (diaphragm and intercostal muscles).
- Correction: If carbon dioxide levels are high or oxygen levels are low, the respiratory rate and depth increase, enhancing gas exchange in the lungs to restore normal levels.
- Sensor: Parathyroid glands detect low calcium levels in the blood.
- Control Center: Parathyroid glands.
- Effector: Bones, kidneys, and intestines.
- Correction: Parathyroid hormone (PTH) is released, stimulating the release of calcium from bones, increasing calcium reabsorption in the kidneys, and enhancing calcium absorption from the intestines, raising blood calcium levels back to normal.
- Sensor: Osmoreceptors in the hypothalamus detect changes in blood osmolarity.
- Control Center: Hypothalamus and posterior pituitary gland.
- Effector: Kidneys.
- Correction: If blood osmolarity is too high, antidiuretic hormone (ADH) is released, prompting the kidneys to reabsorb more water, which dilutes the blood and reduces osmolarity to normal levels.
- Sensor: Chemoreceptors in the blood and brain detect changes in pH levels.
- Control Center: Medulla oblongata (for respiratory adjustments) and kidneys (for metabolic adjustments).
- Effector: Respiratory system (lungs) and renal system (kidneys).
- Correction: If blood pH becomes too acidic, the respiratory rate increases to expel more carbon dioxide (which reduces acidity), and the kidneys excrete more hydrogen ions and reabsorb bicarbonate, restoring pH to normal levels.
These examples illustrate how the body maintains homeostasis through a network of sensors, control centers, and effectors that work together to correct deviations from normal physiological conditions.
State and define the four homeostatic control mechanisms
Intrinsic controls
- Local controls that are inherent in an organ
•Extrinsic controls
-Regulatory mechanisms initiated outside an organ
-Accomplished by nervous and endocrine systems
•Both controls operate on the principle of feedback and feedforward mechanisms
Homeostatic control mechanisms
•Feedforward
-Responses made in anticipation of a change.
-Corrective response prior to onset of change on set point values.
-Eg. Increased respiration and heart rate before activity in competitive sports. Feed forward example;
Hunger makes you salivate when you see food or even smell it. Salivation in anticipation of the food you’re about to eat.
•Feedback
-Responses made after a change has been detected.
-The output of the system “feeds back” to either modify or reinforce the action taken by the system.
-Positive or negative.
