Mcat Biology (Chapter 10)

Front 1

excretory system

Back 1

serves many functions, including the regulation of blood pressure, blood osmolarity, acid-base balance and removal of nitrogenous wastes

Front 2

kidney

Back 2

produces urine, which dumps into the ureter at the renal pelvis; contains a cortex and a medulla; each one has a hilum, which contains a renal artery, renal vein and ureter; contains a portal system with two capillary beds in series

Front 3

bladder

Back 3

where urine is collected until it is excreted

Front 4

urethra

Back 4

what urine is excreted through

Front 5

afferent arterioles

Back 5

blood from the renal artery flows into these; these form glomeruli in Bowman's capsule (the first capillary bed of the kidney)

Front 6

efferent arteriole

Back 6

blood flows through this to the vasa recta, which surround the nephron (the second capillary bed of the kidney), before leaving the kidney through the renal vein

Front 7

detrusor muscle

Back 7

muscular lining of the bladder; under parasympathetic control; also has two muscular sphincters (internal urethral sphincter and external urethral sphincter)

Front 8

internal urethral sphincter

Back 8

consists of smooth muscle and is under involuntary (parasympathetic) control

Front 9

external urethral sphincter

Back 9

consists of skeletal muscle and is under voluntary control

Front 10

kidney participates in solute movement through these three processes

Back 10

filtration, secretion, and reabsorption

Front 11

filtration

Back 11

the movement of solutes from blood to filtrate at Bowman's capsule; the direction and rate of filtration is determined by Starling forces, which account for the hydrostatic and oncotic pressure differentials between the glomerulus and Bowman's space

Front 12

secretion

Back 12

the movement of solutes from blood to filtrate anywhere other than Bowman's capsule

Front 13

reabsorption

Back 13

movement of solutes from filtrate to blood

Front 14

proximal convoluted tubule (PCT)

Back 14

segment of the nephron; site of bulk reabsorption of glucose, amino acids, soluble vitamins, salts and water; also site of secretion for hydrogen ions, potassium ions, ammonia and urea

Front 15

descending limb of the loop of Henle

Back 15

segment of the nephron; permeable to water but not salt; therefore, as the filtrate moves into the more osmotically concentrated renal medulla, water is reabsorbed from the filtrate; the vasa recta and nephron flow in opposite directions, creating a countercurrent multiplier system that allows maximal reabsorption of water

Front 16

ascending limb of the loop of Henle

Back 16

segment of the nephron; permeable to salt but not water; therefore, salt is reabsorbed both passively and actively; the diluting segment is in the outer medulla; because salt is actively reabsorbed in this site, the filtrate actually becomes hypotonic compared to the blood

Front 17

distal convoluted tubule (DCT)

Back 17

segment of the nephron; responsive to aldosterone and is a site of salt reabsorption and waste product excretion, like the PCT

Front 18

collecting duct

Back 18

segment of the nephron; responsive to both aldosterone and antidiuretic hormone and has variable permeability, which allows reabsorption of the right amount of water depending on the body's needs

Front 19

aldosterone

Back 19

a steroid hormone regulated by the renin-angiotensin-aldosterone system that increases sodium reabsorption in the distal convoluted tubule and collecting duct, thereby increasing water reabsorption; the results in an increased blood volume (and pressure), but no change in blood osmolarity

Front 20

antidiuretic hormone (ADH or vasopressin)

Back 20

a peptide hormone synthesized by the hypothalamus and released by the posterior pituitary; its release is stimulated not only by low blood volume but also by high blood osmolarity; it increases the permeability of the collecting duct to water, increasing water reabsorption; this results in an increased blood volume (and pressure) and a decreased blood osmolarity

Front 21

selective reabsorption or secretion of bicarbonate or hydrogen ions

Back 21

how the kidney can regulate pH

Front 22

three major layers of the skin

Back 22

epidermis (top)

dermis

hypodermis (subcutaneous layer)

Front 23

five layers of the epidermis

Back 23

stratum corneum (top)

stratum lucidum

stratum granulosum

stratum spinosum

stratum basale

Front 24

stratum basale

Back 24

contains stem cells that proliferate to form keratinocytes

Front 25

keratinocyte nuclei

Back 25

lost in the stratum granulosum and many thin layers form in the stratum corneum

Front 26

melanocytes

Back 26

produce melanin

Front 27

melanin

Back 27

protects the skin from DNA damage caused by ultraviolet radiation; it is passed to keratinocytes

Front 28

Langerhans cells

Back 28

special macrophages that serve as antigen-presenting cells in the skin

Front 29

two layers of the dermis

Back 29

papillary layer (top)

reticular layer

Front 30

Merkel cells

Back 30

sensory cells located in the dermis; respond to deep pressure and texture

Front 31

free nerve endings

Back 31

sensory cells located in the dermis; respond to pain

Front 32

Meissner's corpuscles

Back 32

sensory cells located in the dermis; respond to light touch

Front 33

Ruffini endings

Back 33

sensory cells located in the dermis; respond to stretching

Front 34

Pacinian corpuscles

Back 34

sensory cells located in the dermis; respond to deep pressure and vibrations

Front 35

postganglioninc cholinergic sympathetic neurons

Back 35

innervate sweat glands

Front 36

vasodilation

Back 36

cooling mechanism

Front 37

piloerection

Back 37

warming mechanism in which arrector pili muscles contract causing hairs to stand on end (trapping a layer of warmed air around the skin)

Front 38

vasoconstriction

Back 38

another warming mechanism