Renal System Flashcards
What are the fluid percentage differences in men and women and why?
55% in femaies, More essential fat, less water
60% in males, less fat, more skeletal muscle
What are the two main fluid compartments and what are there characteritics?
Intracellular: inside the cell
- 2/3 of body fluid
- Cytosol
Extracellular: Fluid outside the cell
- 1/3 of body fluid
- Interstitial fluid
Intravascular fluid: Plasma
What is primary means of water movement between interstital and intacellular fluid?
Osmosis since the concentration of solutes in these fluids determines the direction of water movement
What two mechanisms are involved in gaining water
Ingestion (1600ml) Metabolic Synthesis (200ml)
Name the four mechanisms by which water is lost from most to least?
Kidneys (1500ml)
Skin (600ml)
Lungs (300ml)
GI Tract (100ml)
What is Dehydration?
Increase in volume and increase in osmolarity of body fluids
What three ways are the thirst center of the hypothalamus?
Dry Mouth, pharynx, decreased salivation
Increased Blood Osmolarity- stimulates osmoreceptors
Decreased blood volume- decreased BP which increased renin secretion from kidneys resulting in increased angiotensin II formation
What is an Osmoreceptor?
Specialized chemoreceptor that only recognizes increases in sodium plasma concentration (Hypothalamus)
Explain what happens with osmolarity during hyponatremia
Water saturates the extracellular spaces causing low osmolarity, water rushes into cells causing them to rupture
What are the 4 main functions of electrolytes (ions)?
- Control Osmosis between fluid compartments
- maintain acid-base balance
- carries electrical current for AP
- Cofactors needed for optimal activity of enzymes
What ions are most concentrated in Extracellular fluid (plasma,interstitial)?
Cation: NA+
Antion: Cl-
What ions are the most concentrated in Intracellular fluid?
Cation: K+
Anions: proteins/phosphates (HPO4(2-))
What are some characteristics of Sodium?
- 90% of extracellular cations
- Accounts for almost half of osmolarity
- Needed for action potentials
- Mostly controlled by horomones
What are some characteristics of Chloride?
- Most abundant anion in extracellular fluid
- Balances cations
- Part of hydrochloric acid secreted into gastric juices
- affected by renal absorption of Na+
What are some characteristics of potassium?
- Establishing resting membrane potential
- Helps maintain normal intracellular fluid volume
- helps Acid-Base Balance in body fluid pH
- Controlled by aldosterone
Define Hyperkalemia
Causes increased aldosterone secretion which forces principle cells in collecting ducts to reduce the amount of K+ secretion
Define Hypokalemia
Causes decreased aldosterone secretion which forces principle cells in collecting ducts to reduce the amount of K+ secretion
What are Bicarbnate characteristics?
- Second most abundant extra anions
- Formed by CO2 combines with H20
- Increases blood flows through systemic capillaries
- Decreases as blood flows through pulmonary capillaries
- Kidneys are the main regulator of blood HC0(3-) concentration
What are some characteristics of Calcium?
- Most abundant material in the body (98% in bones)
- Plays role in:
- Blood Clotting
- Neurotransmitter
release
- Maintenance of
Muscle tone
- Excitability of tissue
What are some characteristics of Phosphate?
- 85% is in calcium phosphate salts
- Structural component of bone and teeth
What are some characteristics of Magnesium?
Essential for normal neuromuscular activity, synaptic transmission, myocardial functioning
What is the difference between afferent and Efferent?
Afferent- In to Something
Efferent- Out of Something (Think Exit)
How do kidneys regulate ionic compositon?
Regulate blood vessels of ions like (Na+, Cl-, K+, Ca2+, HPO)
How do kidneys help to regulate blood pH?
Excrete variable amount of hydrogen ions into urine and conserve bicarbonate ions, which buffers H+
How do kidneys help to regulate blood volume?
Adjust blood volume by conserving or elimintating water to urine
How do kidneys help regulate blood pressure?
Kidney cause RAAS pathway to increase BP
How do kidneys maintain blood osmolarity?
Regulates loss of water and loss of solutes in urine
How do kidneys help produce certain horomones?
Produce calcitrol and erthropoietin
How do kidneys help regulate blood glucose levels?
Use Gluconeogensis to release glucose into blood stream
What are the examples of wastes and foreingn substances that are excreted from the kidneys?
Urine:
- Ammonia and Urea- From deanimation of amino acids
- Bilirubin- catabolism of hemoglobin
- Creatinine- breakdown of creatine phosphate in muscle fibers
- Uric Acid- catabolism of nucleuic acid
Foreign Substances:
- From Diet
- Drugs
- Environmental toxins
What are the three external layers of the kidney?
Renal Fascia- Outermost layer
Adipose Capsule- Middle Layer
Renal Capsule- Innermost layer
What composes renal fascia?
Dense connective tissue anchors kidney to surrounding structure and abdominal wall
What composes the adipose capsule?
Fatty Tissues surrounding the renal capsule, protection and holds kidney in place in the cavity
What composes the renal capsule?
Smooth transparent connective tissue covering that is continuous with ureters, help maintain shape and offers protection
How much blood size receive in relation to its total body mass?
0.5% of total body mass
20-25% of resting cardiac output at all times
What is the functional unit of the kidney?
Nephron, 1,000,000 in each kidney
What are the two parts that it consists of?
Renal Corpuscle- Blood Plasma is filtered
Renal Tubule- Filtered fluid passes through
What are the two different types of nephrons?
Cortical Nephron: 80-85%
Juxtamedullary nephron 15-20%
Where do Cortical nephrons reside?
- lie in outer portion of renal cortex
- short loops of henle (outer region of medulla)
Where do Juxtamedullary nephrons reside?
- lie deep in the renal cortex
- long loops of henle (deep into medulla)
Where are the peritubular capillaries?
Intermingle throughout the convoluted tubules
Where are the vasa recta?
Intermingle throughout the loop of henle (in the medulla)
- Specific only to Jux Nephrins
- Important for keeping interstitial fluid hyperosmotic maintaining gradient different to allow movement across
- allow for very dilute or concentrated urine
What are some physical characteristics of the afferent arteriole?
Wider Lumen, thicker walls
What are some physical characteristics of efferent arterioles?
Smaller Lumen, thinner walls
- Brings some blood and larger molecules through the peritubular cappillaries (vasa recta)
What are the three structures of the Glomerulus?
Visceral layer- has podocytes Parietal Layer- (Bowmans Capsule) Capsular Space (Bowman's Space) - Filtered fluid from capillaries enters this space tp be pushed into the proximal convoluted tubule
Explain the function of juxtaglomerular cells contained in the afferent arterioles?
- Modified smooth muscle that detects low BP
- Secretes Renin (RAAS)
What are macula densa?
Located in the DCT, specialized cells detecting NACl concentrations
What are mesangial cells?
Located between afferent and efferent and DCT junction
Contract/relax to make regulatory changes in response to signals that other cells are sending
What three components make up the JGA
Juxtaglomerular cells, Masa densa, Mesangial cells
How much of filtrate is reabsorbed and secreted out?
99% reabsorbed, 1% (1-2L) urine
How is the filtration membrane described>
Glomerular capillaroes and podocytes form a leaky barrier
Tightly packed- only water/some solutes getting through
What are the three layers of the filtration membrane?
Slit membranes between pedicels
Basal Lamina (Middle Layer) Fenstrations of endothelium cells (Inner most layer)
Explain the positive pressure in the efferent arterial
Due to size of the efferent arteriole because it takes more pressure to get plasma out
What is GBHP?
Glomerular Blood Hydrostatic Pressure (pushing outward)
55MmHg
What is CHP
Capsular Hydrostatic Pressure (pushes inward)
- responsible for back pressure
- 15mmHg
What is BCOP?
30mmHg Blood Collid Osmotic pressure
Opposes filtration/pulls on fluid and solutes
What is the NFP
Net Filtration Pressure:
NFP=GBHP-CHP=BCOP
