DAT BIO - the excretory system

Exctretion

the process by which metabolic wastes are filtered out od the blood and removed from the body as urine

What are the kidneys responsible for

Filtration of blood and prep of urine product for secretion

key kidney functions

Acid base balance

blood pressure regulation

RBC generation stimulation

Nephron

functional unit of the kidney

Renal corpuscle

Consists of the glommerulus and bowmans capsule, site of filtration in the renal cortex

Where is the renal corpuscle located

in the renal cortex

Afferent arteriole

brings nutrient rich blood into the glommerulus for filtration

Podocytes

foot-like processes that form a fenestrated filtration barrier

what do podocytes do

they provide specificty to filtration

Efferent arteriole

blood vasculature that exits the renal corpuscle

What do efferent arterioles form

peritubular capillaries or the vasa recta

peritubular capillaries

blood vessels surrounding the convoluted tubules, formed by the efferent arterioles

Vasa recta

blood vessels that surround the loop of henle, formed by the efferent arterioles

where are the peritubular capillaries located near

the cortex

where are the vasa recta located near

the medulla

Proximal convoluted tubule

The site of the majority of reabsorbtion

How does the proximal converted tubule reabsorb

via active transport

What is reabsorbed in the proximal converted tubule

NaCl

Glucose and amino acids

What is secreted in the proximal converted tubule

H+

Loop of henle

nephron tube that decends into the kidney medula and exists between the proximal convoluted tubules and distal convoluted tubules

Descending limb

in the loop of henle, permeable to water,

Water flows out, urine concentration increases

ascending limb

Impermeable to water, and causes reabsorbtion of ions and salts

causing urine concentration to decrease

what goes into the loop of henle

urea

Distal convoluted tubule

Distal convoluted tubule

reabsorption of Na+and Cl-, and secretion of K+ and H+

What gets reabsorbed in the distal tubule

NaCl

What gets secreted in the distal tubule

H and K+

Collecting duct

Where there is a bulk passsive reabsorption of water and secretuion of K+

what happens to pee pee concentration in the collecting duct

it increases

whats the pathway of urine post-nephron

collecting duct → renal pelvis → ureter → bladder → the urethera

renin angiotensin aldosterone sytem

a system of hormones, tissures, and organs which are capable of increasing blood pressure and detcting low BP

what are Juxtaglommerular cells associated with

the afferent arteriole

what are Juxtaglommerular cells associated with

the afferent ateriole

What are juxtaglomerullar cells capable of doing

detecting BP changes

What are juxtaglommerular cells capable of secreting

renin

when do juztaglomerular cells release renin

in times of low BP

renin

an enzyme secreted by juxtaglommerular cells that activates angiotensin into angiotensin I

what does renin activate

angiotensinogen into angiotensin I

What is angiotensiogen released from

the liver

besides turning angiotensinogen into angiotensin I, what else can renin do

be stimulated by the fight or flight response

Angiotensin converting enzyme

ACE, converts angiotensin I into angiotensin II

what is ACE released by

the lungs

what is angiotensin II do

it increases blood pressure and volume

How does angiotensin II increase blood volume and pressure

1. aldosterone release

2. Na+ reabsorbtion

3. vasoconstriction

4. increases thirst

aldosterone

mineralocorticoid released from the adrneal gland that affects the kidney

what does aldosterone act on in the kidney

the distal tubules and the collecting duct

what happens at the nephron when exposed to aldosterone

Increased water and sodium reabsorbtion, and increased potassium secretion

what is Vasopressin released by

the posterior pituitary gland

what is Vasopressin made by

the hypothalamus

What does vasopressin do

increase blood volume and pressure

what effect does vassopressin ave on the collecting ducts

it increases aquaporins, which increase water absorption

what does alcohol do to adh

it inhibits it, causing increased urination

what is Atrial natriuretic peptide produced by

atrial heart cells in ressponse to atrial distension brought on by increased BP and volume

what does Atrial natriuretic peptide do

responds to atrial distension brought on by increased BP and volume

How does atrial natiuretic peptide decrease blood volume and pressure

It increases the glommerular filtration rate

decreases sodium reabsorption (water follows sodium)

increases sodium excretion

inhibits renin and the RAAS system

osmoregulation

absorption and secretion of water and solutes to maintain internal water balance by an organism

What are saltwater fish relative to their environment

hypotonic, meaning the environment has a higher solute concentration, leading to passive water loss

What do saltwater fish do to adapt to their hypertonic environment

they constantly drink

rarely pee

and secrete salt through their gills

What are freshwater fish relative to their environment

hypertonic

What do saltwater fish do to adapt to their hypertonic environment

they rarely drink

constantly pee

and absorb salt through their gills