Anatomy and Physiology Part 2 Flashcards
The ureters transport urine from what structure to another?
- From: Renal pelvis
- To: urinary bladder
What are the 3 layers of the wall of the ureter?
- Mucosa: inner layer
- Smooth muscle: middle layer
- Areolar connective tissue: outer layer
What is the urinary bladder?
Hollow muscular organ situated in the pelvic cavity behind the pubic symphysis
What holds the urinary bladder in place?
Folds of peritoneum
What is the average capacity of the urinary bladder?
700-800 mL
What does transitional epithelium allow for?
Stretching
What are the 3 layers of smooth muscle covering the urinary bladder called?
Detrusor muscle
What is the urethra?
Terminal portion of the urinary system
- small tube leading from the bladder to the exterior of the body
Where is the urethra in females?
Directly behind the pubic symphysis and embedded in the front wall of the vagina
What are the structures that the urethra passes through in males?
- Prostate
- Deep Perineal muscles
- Penis
What are the two sphincters in the urethra? Which is voluntary/involuntary?
- Internal sphincter: involuntary
- External sphincter: voluntary
In males, the urethra also serves what function?
Duct through which semen is discharged
What is micturition?
Urination
When the bladder exceeds what volume does stretch receptors transmit nerve impulses to the spinal cord?
200-400 mL
Where do nerve impulses sent from the bladder to spinal cord propagate and what reflex do they trigger?
- Lower part of the spinal cord
- Trigger micturition reflex
What initiates a conscious desire to urinate before micturition reflex takes place?
Sensation of fullness in the bladder
In lean adults, body fluids make up what percentage of total body mass?
55-60%
What are the two main compartments that fluid resides?
- Intracellular fluid (ICF or cystosol): 2/3 total fluid
- Extracellular fluid (ECF): 1/3 total fluid
What is the location breakdown of ECF?
- 80% is interstitial fluid
- 20% is blood plasma
What are the two barriers that separate interstitial fluid, intracellular fluid, and blood plasma?
- Blood vessel walls
- Plasma membrane
What processes provide for the continual exchange of water and solutes among body fluid compartments?
- Filtration
- Reabsorption
- Diffusion
- Osmosis
What is the primary means of water movement between ICF and ECF?
Osmosis
Most solutes in body fluids are what?
Electrolytes
Fluid balance primarily depends on what?
Electrolyte imbalance
How does the body gain water?
- Ingestion
- Metabolic reactions
What are the main sources of water?
- Ingested liquids: roughly 1600mL
- Moist foods absorbed from GI tract: 700 mL
- Total 2300 mL
- Metabolic water gain: 200 mL
Since body fluid remains constant, how much is secreted and how is it secreted?
- Kidneys 1500 mL through urine
- Skin evaporation: 600 mL
- Lungs exhale water vapor 300 mL
- GI through feces: 100 mL
How is additional water lost through woman of reproductive age?
Menstrual cycle
What governs the urge to drink?
Thirst center in the hypothalmus
What stimulates the thirst center in the hypothalmus?
- Osmoreceptors in the hypothalamus
- Angiotensin II in the blood
- Neurons in the mouth that detect dryness
WHat is the main factor that determines body fluid volume?
Extent of urinary salt (NaCl) loss
What are the three hormones that regulate the extent of NA and Cl reabsorption?
- Atrial Natriuretic Peptide
- Angiotensin II
- Aldosterone
What is the major hormone that regulates water loss?
Antidiuretic hormone (ADH)
What stimulates the release of ADH?
Increase of osmotic pressure in body fluid
Intake of plain water does what to osmotic pressure in blood and interstitial fluid?
Decreases osmotic pressure
What ions represent 90% of extracellular cations?
Sodium ions
- Accounts for almost half of the osmotic pressure in extracellular fluid
What are the most prevalent anions in extracellular fluid?
Chloride ions
What is the most prevalent cations in intracellular fluid?
Potassium ions
Potassium ions moved into or out of cells are often exchanged for what? This helps regulate what?
- Hydrogen ions
- Helps regulate pH
Where is about 98% of calcium in adults located?
Teeth and skeleton
What enhances reabsorption of Calcium from glomerular filtrate back into blood?
Parathyroid hormone
What are the four general functions of electrolytes in the body?
- Control osmosis of water between fluid compartments
- Help maintain the acid-base balance required for cellular activities
- Carry electrical current, allows for action potential
- Serve as cofactors needed for enzyme activity
Chief difference between the two fluids?
Blood plasma contains many protein anions while interstitial fluid has very few
What is a major homeostatic challenge in body fluids?
Keeping the hydrogen ion, pH, in appropriate range
What are buffers?
Substances that act quickly to temporarily bind hydrogen ions, removing highly reactive, excess H+ from solution
What do buffers do?
Prevent rapid, drasctic changes in pH of a body fluid by converting strong acids and bases into weak acids and bases
What are the three buffer systems?
- Protein buffer system
- Carbonic acid-bicarbonate system
- Phosphate system
Which buffer system is the most abundant buffer system in intracellular fluid and plasma?
Protein buffer system
What are the functional components of the protein buffer system?
- Carboxyl group (-COOH)
- At least one amino group (-NH2)
Can proteins work as acids and bases?
Yes
- Carboxyl (for bases) acts on rising pH
- Amino group (for acids) acts on falling pH
What is the carbonic acid-bicarbonate system based on?
- Bicarbonate ion (HCO3-) which acts as a weak base
- Carbonic Acid (H2CO3) which acts as a weak acid
Is the carbonic acid-bicarbonate system lost in the urine? Why/why not?
No, it is not lost in the urine
- kidneys reabsorb bicarbonate ion
How does the phosphate buffer system act?
Mechanism to the carbonic acid-bicarbonate system
Is the phosphate buffer system an important regulator of pH in the cytosol?
Yes, because the concentration of phosphates is highest in ICF
How does breathing play a role maintaining pH of body fluids?
Ventilation decreases CO2 which decreases hydrogen ion concentration, leading to an increase of pH
Relation of CO2, H+, and pH?
- Increase CO2, increases H+, decreases pH
- Decrease CO2, decreases H+, increases pH
The pH of body fluids and the rate and depth of breathing interact via what feedback loop?
Negative feedback
What is the slowest mechanism for action in removal of acids?
Cells of renal tubules secrete H+, which is then excreted in urine
- Also the only way to eliminate most acids
What is acidosis?
Condition in which arterial blood pH is below 7.35
What is the principal effect of acidosis?
Depression of the CNS through depression synaptic transmission
What pH level is so severe that the individual becomes disoriented, comatose, and may die?
7
What is alkalosis?
Blood pH above 7.45
What is a major physiological effect of alkalosis?
Over-excitability in both CNS and peripheral nervous system
If person has altered pH due to metabolic causes, what can be done?
Hypo or Hyper ventilate to bring blood pH back to normal range
If person has altered pH due to respiratory causes, what can be done?
Renal compensation, changes in secretion of H+ and reabsorption of bicarbonate ion
- may begin in minutes but take days to reach max effectiveness
