Review from 3/29
What fluid are the Podocyte's slits filled with? Are they negatively or positively charged?
Extracellular matric fluid --> negatively charged
What is the normal GFR in humans?
80 - 130 mL/min/1.73m^2
Usual value is 90
What is the Osmotic Gradient concentration in the cortex? What is this isosmotic with?
300 mOsm
Isosmotic with blood.
What are the four layers of the GI tract?
Mucosa --> submucosa --> muscularis (longitudinal and circular) --> serosa (visceral peritoneum)
1. Glomerular Capillary
2. Glomerular Capsular space
3a. Parietal layer of glomerular capsule (SSE)
3b. Podocytes that make up visceral layer of glomerular capsule
3a + 3b = Glomerular Capsule
What is the Net Filtration Pressure if:
a. HP(gc) = 60
b. HP (cs) = 20
c. OP (gc) = 30
(HPgc) - (HPcs + OPgc)
60 - (20+30)
60 - 50
= 10 mmHg
What percent of water is reabsorbed in the:
A. PCT
B. Nephron Loop
C. DCT
D. Collecting Duct
PCT: 65%
Nephron Loop: 15%
DCT: 10%
Collecting Duct: 0-9%
What are the four main hormones in the GI tract?
Gastrin (G cells)
Histamine (ECL Cells)
Cholecystokinin (G cells via blood)
Somatostatin (D cells)
What makes up the gross structure of the Kidneys?
Connective tissue capsule, Renal Cortex, Renal Medulla, Renal Pyramid, Renal Column, Renal Papilla, Renal Pelvis, Renal Artery and Vein in Hilum
- both arise from efferent arterioles
- remove anything reabsorbed from filtrate
a. Passive Transport
b. Active Transport
c. Secondary Active Transport
d. Antiporters
e. Symporters
a. Molecules flow down their concentration gradients via simple diffusion and facilitated diffusion
b. Molecules are pumped against their concentration gradient using energy (ATP)
c. Molecules are transported against their gradient by transporting them with molecules that are moving down their concentration gradient (symporters or antiporters)
d. Molecules move in opposite directions
e. Molecules move in the same direction
Define the following terms and give examples of each:
A. Propulsion
B. Chemical Digestion
C. Mechanical Digestion
D. Absorption
A. Moving of food or feces in a oral or posteriorly.
ex. swallowing in the mouth or peristalsis in the esophagus, stomach, small intestines, and large intestines
b. Reactions that break down food molecules
ex. amino acids, proteins, tri and dipeptides
c. Processes that expose food to chemical digestion
ex. chewing in the mouth, churning (stomach), and segmentation
d. Nutrients are moved across lining of the digestive tract into the blood stream or lymphatic circulation
ex. water to the blood vessels in the large intestines or nutrients and water to blood vessels and lymph vessels
What are the components of the Urinary System? What is/are the functions of the Kidneys?
Components: Kidneys, Urinary Tract (Ureters, Bladder, Urethra)
Kidney Functions:
- Removal of Nitrogenous waste
- Maintains water and electrolyte balance
- Maintains blood volume and pressure
- Helps maintain acid/base balance
- Produces urine
- Endocrine role in Hemopoiesis
What are the Intrinsic and Extrinsic factors that regulate GFR?
Intrinsic:
Myogenic Mechanism
Tubuloglomerular Feedback
Extrinsic:
Neural Mechanism
Hormonal Mechanism
How is the Medullary Osmotic Gradient Formed?
Formed by the Nephron loop and Collecting Duct
NaCl leaves the tubular fluid --> NaCl becomes reabsorbed and goes into Medulla
Urea goes out of tubular fluid --> goes into the Nephron loop --> becomes osmotically active
- Both of these solutes build the gradient by becoming reabsorbed. This causes water to want to come out of the tubular fluid to match its concentration gradient. Once water comes out of the tubular fluid excess gets sucked up by the Vasa Recta and goes into the blood. These volumes can change depending on blood pressure.
What are the intrinsic and extrinsic innervations of the GI tract?
Intrinsic:
- Myenteric plexus: lays in between outer layer of muscle and inner circular muscle; Responsible for motility --> movements of contents of the GI tract
-Submucosal plexus: in between submucosa and serosa; responsible for secretion and blood flow
Extrinsic:
CNS --> PNS (vagus; excitatory) and SNS (inhibitory) --> dually innervates GI tract
- Targets: smooth muscle, mucosa and blood supply
What molecules are retained in the blood and what molecules are filtered?
Retained in the blood: Blood cells, Plasma proteins, Large anions, Protein-bound minerals and hormones, Most molecules > 8 mm in diameter, small proteins if negatively charged
Filtered: Water, Electrolytes, Glucose, Amino Acids, Fatty Acids, Vitamins, Urea, Uric Acid, Creatine
Explain how GFR is regulated by:
a. Myogenic Mechanism
b. Tubuloglomerular Feedback
Myogenic Mechanism:
If BP is high:
Afferent Arterials are stretched --> high GFR
Response: Afferent Arterioles vasoconstrict --> glomerular flood flows down --> GFR decreases
IF BP IS LOW:
Afferent Arterials are not stretched --> GFR is low
Response: Afferent Arterioles dilate --> glomerular blood flows up --> GFR rises
Tubuloglomerular Feedback:
If GFR is high --> faster blood flow --> not enough time for NaCl to reabsorb --> NaCl filtrate is high --> Macula densa cells send signal to EMC --> EMC sends signal to granular cells --> granular cells contract --> AAs vasoconstrict --> GFR decreases
If GFR is low --> more reabsorption of NaCl --> Vasodilation of AAs occur --> increase GFR
-
Explain the control of water reabsorption in the collecting duct when we are dehydrated and overhydrated.
Dehydrated:
1. The Hypothalamus/Pituitary gland releases ADH. An increase in ADH up-regulates Aquaporins --> more water will be reabsorbed
2.The JGA releases renin --> Angiotensinogen --> Angiotensin I --> Angiotensin II (stimulates vasoconstriction and thirst) --> Aldosterone is released from the Adrenal gland and goes to CD where it up-regulates Na/K pumps --> more NaCl becomes reabsorbed
With an increase in salt and water into our blood this increases blood volume and blood pressure --> concentrated urine
Overyhydrated:
1. The Hypothalamus/Pituitary does not release ADH --> no aquaporins open --> no water reabsorbed
2. The RAAS system does not occur due to us being overhydrated --> Atrial Natriuretic Factor is released which inhibits Aldosterone --> no Na/K pumps open
ANP promotes water and salt excretion in the body --> less water and salt is in the blood --> lower BP --> more dilute and frequent urine
Explain the functions of the following:
a. Stomach
b. Small intestine (duodenum mainly)
c. Pancreas
d. Gull bladder/liver
e. Large Intestine
a. Main function: secretion
- Secretes HCl, pepsinogen, and hormones
- churns contents to produce "chyme"
- HCl denatures proteins to allow enzymes to break down proteins further
b. Main function: digestion and absorption
- requires a large surface area: circular folds, villi, microvilli
- Duodenal glands: secrete alkaline into lumen to neutralize enzymes and acid chyme
c. Main function: secretes pancreatic juices (trypsin, chymotrypsin)
- Pancreatic lipase: digests fats
- Pancreatic amylase: digests carbs
- Pancreatic nucleases: digests nucleic acids
d. Main function: produces bile
- bile emulsifies fats
e. Function: absorbs H2O and electrolytes and secretes mucus to increase mobility