Chap 25/26/27 Flashcards
What is HDL?
High-Density Lipoprotein, known as ‘good cholesterol.’
Function: Transports cholesterol from tissues to the liver for excretion or recycling.
What is LDL?
Low-Density Lipoprotein, known as ‘bad cholesterol.’
Function: Transports cholesterol to tissues; excess can lead to plaque buildup in arterial walls.
What does ATP stand for?
Adenosine Triphosphate
The primary molecule used for energy transfer in cells.
What are the three main uses of glucose?
- Generate ATP (energy)
- Be stored as glycogen
- Be converted into amino acids for protein synthesis
What occurs during glycolysis?
The complete breakdown of glucose into energy
Occurs in the cytoplasm, anaerobic, produces pyruvic acid, 2 ATP, and NADH.
What is formed when pyruvic acid is converted in the mitochondria?
Acetyl Coenzyme A
This conversion requires oxygen.
What does the Krebs Cycle produce?
- Reduced coenzymes (NADH, FADH2)
- CO2
Where is the Electron Transport Chain located?
In the mitochondrial inner membrane
Uses NADH and FADH2 to generate most of the ATP (~28-32 ATP per glucose molecule).
Define glycogenolysis.
Breakdown of glycogen to glucose for energy.
What is gluconeogenesis?
Formation of glucose from non-carbohydrate sources (e.g., amino acids, glycerol).
What is lipolysis?
Breakdown of triglycerides into glycerol and free fatty acids for energy.
How are ketone bodies formed?
During lipolysis, excessive fatty acid breakdown in the liver generates acetyl-CoA, which is converted into ketone bodies.
Occurs in conditions like starvation, low-carb diets, or uncontrolled diabetes.
How is excess energy stored in the body?
As triglycerides in adipose tissue for long-term energy needs.
What vitamin is produced by E. coli in the intestines?
Vitamin K
Vitamin K is essential for blood clotting as a coenzyme.
What is required as a coenzyme for blood clotting?
Vitamin K
It is produced by E. coli in the intestines.
Which cells synthesize most of the body’s cholesterol?
Hepatocytes
Hepatocytes are liver cells responsible for cholesterol production.
What must be obtained through diet as the body cannot produce them?
Essential Amino Acids
Essential amino acids are crucial for various bodily functions.
What effect does eating have on metabolic rate?
Increases heat production and metabolic rate
This is due to the energy required for digestion, absorption, and storage.
What acts as the body’s thermostat regulating temperature?
Hypothalamus
The hypothalamus also controls hunger, thirst, and other autonomic processes.
What can kidneys perform during prolonged fasting?
Gluconeogenesis
This process synthesizes glucose from non-carbohydrate sources.
What is reabsorbed in the proximal convoluted tubule (PCT)?
Filtered glucose
The PCT reabsorbs ~65% of solutes and water.
What is the average glomerular filtration rate (GFR) for males?
~125 mL/min
For females, the average GFR is ~105 mL/min.
What is filtered at the glomerular capsule?
Water, ions (Na, CI, K), glucose, amino acids
Large proteins and blood cells are not filtered due to size.
What is the descending limb of the loop of Henle permeable to?
Water
Water is reabsorbed into the medulla due to the high osmotic gradient, concentrating the filtrate.
What is actively reabsorbed in the ascending limb of the loop of Henle?
Sodium (Na), potassium (K), and chloride (Cl-)
The ascending limb is impermeable to water, diluting the filtrate.
Fill in the blank: The major site for solute and water reabsorption is the _______.
Proximal Convoluted Tubule (PCT)
The PCT reabsorbs glucose, amino acids, Na*, CI, bicarbonate, and water.
What is the primary function of the Distal Convoluted Tubule (DCT)?
Fine-tuning of water reabsorption, pH regulation, and removal of drug metabolites
The DCT is involved in the regulation of water through the action of antidiuretic hormone (ADH) and in maintaining acid-base balance.
Where is Aquaporin 1 located and what is its function?
Located in the descending limb of the nephron loop; facilitates water reabsorption
Aquaporin 1 makes the descending limb highly permeable to water.
What role does Aquaporin 2 play in the kidney?
Located in the DCT and collecting ducts; increases water reabsorption during dehydration
Its activity is regulated by antidiuretic hormone (ADH).
What does aldosterone stimulate in the DCT?
Na+ reabsorption and K+ excretion
Aldosterone also increases water reabsorption, contributing to increased blood volume and pressure.
How does Angiotensin II affect renal function?
Stimulates Na+ reabsorption in the PCT and triggers aldosterone release; constricts blood vessels to increase blood pressure
This hormone plays a crucial role in regulating blood pressure and fluid balance.
What is the function of the Na/K+ ATPase Pump in tubular cells?
Actively pumps Na+ out of tubular cells into the interstitial fluid
This creates a gradient for Cl- and water to follow passively.
What is Countercurrent Multiplication and where does it occur?
Occurs in the Loop of Henle; concentrates solutes in the medulla
Na+ and Cl- are actively transported out of the ascending limb, pulling water out of the descending limb.
What is the function of Countercurrent Exchange?
Maintains medullary osmotic gradient while allowing for gas, nutrient, and waste exchange
This process occurs in the vasa recta, the capillaries surrounding the nephron loop.
What percentage of total body water is intracellular fluid (ICF)?
Majority (~2/3) of total body water
ICF is found inside cells, playing a critical role in cellular function.
What does Extracellular Fluid (ECF) include?
Interstitial Fluid and Plasma
Interstitial Fluid surrounds tissue cells (~80% of CF), while Plasma is the fluid portion of blood (~20% of ECF).
What is the primary cation in Extracellular Fluid (ECF)?
Sodium (Na*)
Sodium is key for fluid balance and nerve function.
What is the primary anion in Extracellular Fluid (ECF)?
Chloride (Cl-)
Chloride follows sodium for osmotic balance.
What is the primary cation in Intracellular Fluid (ICF)?
Potassium (K*)
Potassium is essential for cellular functions like muscle contraction and nerve impulses.
What is the primary anion in Intracellular Fluid (ICF)?
Phosphate (HPO4^2-)
Phosphate is involved in energy storage and buffering.
What are the main sources of water for the body?
Ingested fluids
Drinking water is a key source of water.
How does water loss primarily occur?
Through urine
Water loss is dependent on NaCl loss; water follows solutes like sodium and chloride due to osmosis.
What is the role of Angiotensin II in water balance?
Stimulates Na* reabsorption in the kidney
This increases blood volume and pressure.
What does Aldosterone do?
Increases reabsorption of Na* and Cl- in the kidneys
Aldosterone controls potassium (K*) excretion.
What is the function of Atrial Natriuretic Peptide (ANP)?
Opposes aldosterone; promotes excretion of Na* and water
This action lowers blood volume and pressure.
What is the effect of Antidiuretic Hormone (ADH)?
Regulates water by increasing water reabsorption
ADH acts in the DCT and collecting ducts via aquaporins.
What are the major buffer systems in pH regulation?
Bicarbonate, Phosphate, and Proteins
These buffers act quickly to resist pH changes.
How does exhalation of carbon dioxide help maintain pH?
Removes CO2, reducing carbonic acid (H2CO3) formation
This helps maintain a neutral pH.
What is the role of the kidneys in acid-base homeostasis?
Excrete H* and reabsorb bicarbonate (HCO3-)
This is the slowest but most effective method of pH regulation.
True or False: Removing CO2 helps maintain a neutral pH.
True
Removing CO2 reduces carbonic acid (H2CO3) levels.
What are unique features of infant kidneys?
Limited urine concentration
Infant kidneys are immature, making them more prone to dehydration.
