Pathophysiology - Quiz #6

adaptive immunity can be considered either active or passive - what determines this?

whether antibodies or T lymphocytes are produced in response to antigen or are administered directly

what is active immunity when considering specific adaptive immunity?

confers a protected state attributable to the body's immune response as a result of active infection or immunization

the development of active immunity requires the maturation and maintenance of memory B lymphocytes

on second exposure to an antigen, the antibody response is more amplified and rapid

active immunity develops (before/after) exposure to antigen and is (long/short) lived

after; long

how would an individual naturally acquire active immunity?

having the disease itself

how would an individual artificially acquire active immunity?

having immunizations (these doses stimulate the respective antibodies that help combat with the disease process)

what is passive immunity when considering specific adaptive immunity?

involves the transfer of plasma (SERA) containing performed antibodies against a specific antigen from a protected or immunized person to an unprotected or non-immunized person

passive immunity involves preformed ________ or __-________ that are administered that initiate a __________ immune response

antibodies or T-cells; temporary

with passive immunity being temporary, what antibodies cross the placenta that protect the newborn during the first few months of life?

maternal IgG

how would an individual naturally acquire passive immunity?

neonate receiving IgA antibodies from mothers via breastfeeding of colostrum, and breastmilk

how would an individual artificially acquire passive immunity?

serum injections with antibodies

what are the two types of adaptive immune responses?

humoral immunity and cell-mediated/ cellular immunity

humoral immunity

mediated by molecules (i.e. memory B cells that differentiate into plasma cels that produce antibodies) in the blood

the principle defense against extracellular microbes and toxins

bind to antigens on bacteria and viruses

cel-mediated or cellular immunity

mediated by specific T lymphocytes

defends against intracellular microbes such as viruses

B cells are involved in memory and ________ immunity

humoral

T cells are involved in memory and ________ immunity

cellular

antigen presentation - what two phagocytic cells process and present antigen peptides to CD4+ helper T cells?

macrophages and dendritic cells

antigen presentation - the capturing of antigens and that allows for macrophages and dendritic cells to be recognized by T cells help in the initiation of what type of immunity?

adaptive immunity

BIG PICTURE: active immunity involves the body producing antibodies (from itself/from another source) after having an infection or receiving a vaccination. it involves humoral immunity (and/or) cell-mediated immunity.

from itself; and

BIG PICTURE: passive immunity involve the body producing antibodies (from itself/from another source) after receiving maternal antibodies or immunoglobulin injections.

from another source; cell-mediated

what is the secretory (mucosal) immune system?

a primarily active form of immunity that include lymphoid tissues that protect the external surfaces of the body

antibodies are present in tears, sweat, saliva, mucus, and breast milk

IgA is the dominant immunoglobulin, with IgG and IgM presented in small amounts

what are functions of antibodies?

DIRECT - through action of antibody alone

INDIRECT - requiring activation of other components

describe the direct functions of antibodies

neutralization - antibodies physically surround the pathogen and prevent it from attaching or entering healthy cells

agglutination - antibodies that have multiple binding sites (i.e. IgM with ten sites and IgA with four sites) cross-link particulate antigens to form large, visible clumps

precipitation - soluble antibodies bind to soluble antigens to form large, insoluble lattice strictures that become visible and settle out of solution

describe the indirect functions of antibodies

inflammation - antibodies mark pathogens and infected cells, which enhance immune cell function

phagocytosis - through opsonization, the binding of antibodies to antigens on the surface of pathogens, forming a cross-linkage that allows phagocytes (i.e. macrophages and neutrophils) to adhere and engulf pathogens

complement - antibodies, when bound to pathogens, trigger the complement cascade pathway that enhances inflammation, tagging, and destruction of pathogens

what are primary responses?

antibody responses generated during the first exposure to an antigen

include a latent period or lag phase, where clonal selection occurs

after five to seven days, an IgM antibody for a specific antigen is detected

an IgG response equal or slightly less follows the IgM response

what are secondary responses?

subsequent exposures to the same antigens

more rapid

larger amounts of antibody are produced

rapidity is the result of memory cells that require less further differentiation

IgM may be transiently produced, but IgG is produced in considerably greater numbers

differentiating primary vs. secondary IgM & IgG production (slide 59) . . .

from the first exposure to an antigen to subsequent exposure to the same antigen, the graph shows ____ making an "M shape"

the ____ antibody will be produced in larger amounts and over a larger period of time aftr subsequent exposure

IgM; IgG

what are the kidneys responsible for?

. maintaining fluid and electrolyte homeostasis

. ridding the body of water-soluble wastes

the kidneys filter more than __ L of fluid per hour, then reabsorb approximately __%, producing a small amount of urine containing a high concentration of wastes

7; 99

what are the functions of the nephron?

filtration of water-soluble substances from the blood

reabsorption of filtered nutrients, water, and electrolytes

secretion of wastes or excess substances into filtrate

how does selective permeability support nephron function?

by controlling the movement of water and solutes, the nephron maintains concentration gradients rather than reaching equilibrium, which enables regulation of the filtrate concentration at the end

what is the glomerulus?

ball of capillaries that are the site of fluid filtration from blood to the nephron tubule

what is the significance behind the glomerulus being a high-pressure environment?

provides the net filtration pressure required to force water and small solutes out of the blood and into the bowman space

this pressure is maintained by the diameter difference between the wider afferent arteriole (the starting point) and the narrower efferent arteriole (the end point), which behaves as a resistance point to ensure efficient blood cleaning/filtration

the increased hydrostatic pressure resulted from the dilated afferent arteriole increases the drive of ____ and ______ into the capsule space

H2O and solutes (NOTE: ONLY small molecules pass through, such as glucose, electrolytes, urea, and amino acids)

what is the proximal convoluted tubule (PCT)?

continuation of capsular space of bowman's capsule that drains the glomerular filtrate directly into the proximal tubule segment

what is reabsorbed in the PCT?

sodium (majority), following water (ADH not required) and chloride into peritubular capillaries

glucose, potassium, amino acids, urea, and bicarbonate

* these are reabsorbed at safe levels *

the PCT secretes what two substances?

H+ and foreign substances

what is the loop of henle?

contains the descending limb that receives filtrate from PCT and deliver it to the ascending limb

the ascending limb contains powerful membrane pumps that co-transport ions from the filtrate and deposit them in the interstitial fluid surrounding the loops of henle and collecting ducts

generally, more sodium flows OUT in the loop of henle - what does this create?

a salty medulla and osmolarity gradient that pulls water into the collecting duct (CD)

when considering the descending limb, what makes the filtrate more concentrated?

water reabsorption promotes the inward diffusion of sodium, which allows the filtrate to become more concentrated

the permeability to ions of the ascending limb allows substances like sodium to be reabsorbed via active transport - what is forced to stay, and how does this affect the filtrate?

water is forced to stay

the loss of sodium and residing water makes the filtrate more diluted

what is the distal convoluted tubule (DCT)?

the part of the tubule distal to the ascending limb of the nephron loop

aldosterone and angiotensin II (AII) stimulate the tubule cells to reabsorb sodium and water

atrial natriuretic peptide (ANP) and urodilatin inhibit reabsorption

in the DCT, there is the reabsorption of . . .

. sodium

. water (ADH is required)

. bicarbonate

what products are secreted from the DCT?

. potassium

. urea

. H+

. NH3

. some drugs

what are the collecting ducts?

form the medullary pyramids, which empty into the minor calices through the papilla

travel through the high interstitial gradient of the medulla on their way to the renal pelvis

have two cel types: principle cells (P cells) and intercalated cells (I cells)

ultimately, what allows urine to become more concentrated in the CD?

the reabsorption of water under ADH regulation

what is the physics of filtration in terms of regulating of glomerular filtration?

the driving force for filtration that is hydrostatic pressure in the glomerular capillaries

what are factors affecting filtration pressure?

. blood volume

. obstructions

. disease processes

how does glomerular capillary hydrostatic pressure affect GFR?

PHYSIOLOGY: BP inside the glomerular capillaries forces fluid and solutes out of the blood into the nephron (via bowman's capsule)

increased hydrostatic pressure → higher GFR and increased filtration

decreased hydrostatic pressure → lower GFR and less fluid filtered

how does glomerular capillary osmotic pressure affect GFR?

PHYSIOLOGY: proteins in the blood (i.e. albumin) pull water back into the capillaries rather than filtering them out into the interstitial space

higher osmotic pressure → lowers GFR (more water is pulled back)

lower osmotic pressure → higher GFR (less pulling force from water)

how do hydrostatic and osmotic pressures in the bowman capsule affect GFR?

PHYSIOLOGY (hydrostatic pressure): fluid pressure inside the capsule that pushes back against filtration (so opposes fluid leaving the glomerulus)

higher capsular hydrostatic pressure → lower GFR (i.e. due to an obstruction, like a kidney stone)

PHYSIOLOGY (osmotic pressure): normally negligible because there are almost no proteins in filtrate, meaning it has little effect on GFR

if protein is present, water is pulled into the capsule → increased GFR

tubular filtration

urine filtrate flows through the tubular component of the nephron

as the filtrate flows through the tubule, the concentration of water and electrolytes in the filtrate changes due to . . .

reabsorption of water and solutes by tubular cells into the peritubular capillary blood

secretion from the blood into the tubular lumen

how is the reabsorption of glucose accomplished?

through the proximal tubule cell sodium-dependent transporters

how is acid-base balance regulated?

secretion of excess H+

reabsorption and creation of HCO3-

what promotes and regulates the secretion of potassium?

promoted by the activity of the Na+ - K+ pump on the basolateral cell membrane

regulated by aldosterone, which increases potassium excretion

what is the importance of the antidiuretic hormone?

increases permeability of collecting tubules to water, resulting in increased reabsorption and reduced blood osmolality

what do diuretic agents do?

alter the osmolality of the urinary filtrate and oppose the reabsorption of water, resulting in an increase in urine volume

what alter blood volume without affecting blood osmolaity?

aldosterone, AII, ANP, and urodilatin

what increase sodium and water reabsorption?

aldosterone and AII

what inhibit sodium and water reabsorption?

ANP and urodilatin

what two important endocrine hormones are secreted by the kidneys?

ERYTHROPOIETIN - growth factor for RBCs

ACTIVE VITAMIN D - cofactor for calcium absorption from intestine