Allence Bio 10

Front 1

micturition

Back 1

The micturition reflex normally produces a series of contractions of the urinary bladder. The flow of urine through the urethra has an overall excitatory role in micturition, which helps sustain voiding until the bladder is empty.

Front 2

kidney

Back 2

each of a pair of organs in the abdominal cavity of mammals, birds, and reptiles, that excrete urine.

Front 3

nephron

Back 3

is the functional unit of the kidney. It is a microscopic tubule that recieves fluid from the blood capillaries in the cortex and converts this to urine, which drains into the ureter

Front 4

glomerulus

Back 4

is a fine network of capillaries that increases the local blood pressure to squeeze fluid out of the blood. It is surrounded by a cup-or-funnel-shaped capsule which collects the fluid and leads into the nephron.

Front 5

Bowman's capsule

Back 5

Bowman's capsule (or the Bowman capsule, capsula glomeruli, or glomerular capsule) is a cup-like sac at the beginning of the tubular component of a nephron in the mammalian kidney that performs the first step in the filtration of blood to form urine. A glomerulus is enclosed in the sac.

Front 6

ultrafiltration

Back 6

The high hydrostatic pressure forces small molecules such as water, glucose, amino acids, sodium chloride and urea through the filter, from the blood in the glomerular capsule across the basement membrane of the Bowman's capsule and into the renal tubules. This process is called ultrafiltration.

Front 7

selective reabsorption

Back 7

The absorption of some of the components of the glomerular filtrate back into the blood as the filtrate flows through the nephrons of the kidney.

Front 8

Suggest why nephrons are convoluted

Back 8

To increase the length for greater surface area for absorption

Front 9

Why are there many capillaries around each nephron?

Back 9

So that materials reabsorbed from the fluid in the tubules can re-enter the blood

Front 10

Explain why reabsorption from the nephron must be selective?

Back 10

Some of the molecules in the nephron are waste and must be left in the fluid to be excrete. Other molecules are useful to the body and must be re-absorbed.

Front 11

afferent vessels

Back 11

The afferent arterioles branch from the renal artery, which supplies blood to the kidneys.The afferent arterioles later diverge into the capillaries of the glomerulus.

Front 12

efferent vessels

Back 12

The efferent arterioles are blood vessels that are part of the urinary tract of organisms. The efferent arterioles form from a convergence of the capillaries of the glomerulus. They play an important role in maintaining the glomerular filtration rate despite fluctuations in blood pressure.

Front 13

microvilli

Back 13

microscopic folds of the cell surface membrane that increase the surface area of the cell

Front 14

co-transporter proteins

Back 14

proteins in the cell surface membrane that allow the facilitated diffusion of simple ions to be accompanied by transport of a larger molecule such as glucose

Front 15

faciliated diffusion

Back 15

Facilitated diffusion (also known as facilitated transport or passive-mediated transport) is the process of spontaneous passive transport (as opposed to active transport) of molecules or ions across a biological membrane via specific transmembrane integral proteins.

Front 16

sodium-potassium pumps

Back 16

special proteins in the cell surface membrane that actively transport sodium and potassium ions against their concentration gradient

Front 17

endocytosis

Back 17

Endocytosis is a form of active transport in which a cell transports molecules (such as proteins) into the cell (endo- + cytosis) by engulfing them in an energy-using process.

Front 18

exocytosis

Back 18

In exocytosis, materials are exported out of the cell via secretory vesicles. In this process, the Golgi complex packages macromolecules into transport vesicles that travel to and fuse with the plasma membrane. This fusion causes the vesicle to spill its contents out of the cell.

Front 19

podocytes

Back 19

specialised cells that make up the lining of the Bowman's capsule

Front 20

hairpin countercurrent multiplier

Back 20

A countercurrent multiplier system is a mechanism that expends energy to create a concentration gradient.It is found widely in nature and especially in mammalian organs. For example, it can refer to the process that is underlying the process of urine concentration, that is, the production of hyperosmotic urine by the mammalian kidney.[

Front 21

osmoregulation

Back 21

Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes (salts in solution) to keep the fluids from becoming too diluted or too concentrated.

Front 22

distal convoluted tubule

Back 22

is the coiled portion of the nephron between the loop of Henle and the collecting duct.

Front 23

loop of Henle

Back 23

In the kidney, the loop of Henle is the portion of a nephron that leads from the proximal convoluted tubule to the distal convoluted tubule.

The loop of Henle's main function is to create a concentration gradient in the medulla of the kidney.

This gradient allows the collecting duct to respond to ADH (antidiuretic hormone) and create the required concentration on the urine

Front 24

antidiuretic hormone

Back 24

released from the pituitary gland and acts on the collecting ducts in the kidneys to increase their reabsorption of water

Front 25

osmoreceptors

Back 25

Osmoreceptors, as the name suggests, sense change in osmotic pressure. When the osmotic pressure of blood changes (i.e. it is more or less dilute), water diffusion into and out of the osmoreceptor cells changes. That is, they expand when the blood plasma is more dilute and contract with higher concentration. This causes an afferent neural signal to be sent to the hypothalamus, which increases or decreases vasopressin (ADH) secretion from the posterior pituitary to return blood concentration to normal.

Front 26

posterior pituitary gland

Back 26

is the hind part of the pituitary gland, which releases ADH

Front 27

neurosecretory cells

Back 27

Here hypothalamic neurosecretory cells release factors to the blood. Some of these factors (releasing hormones), released at the hypothalamic median eminence, control the secretion of pituitary hormones, while others (the hormones oxytocin and vasopressin) are released directly into the blood.