ch 10 - homeostasis

Question 1

functions of excretory system

Answer 1

regulation of blood pressure, blood osmolarity, acid-base balance, and removal of nitrogenous wastes

Question 2

functional unit of the kidneys

Answer 2

nephron; each kidney has about 1,000,000

Question 3

path of kidney excretion

Answer 3

nephrons empty into the renal pelvis, which narrows to form ureter which urine travels through to the bladder and from the bladder through urethra

Question 4

cortex

Answer 4

kidney’s outermost layer

Question 5

medulla

Answer 5

sits within the cortex of the kidney

Question 6

renal hilum

Answer 6

part of each kidney; it is a slit in the center of kidney’s medial surface through which the renal artery, renal vein and ureter enter and exit

Question 7

renal pelvis

Answer 7

widest part of the ureter which spans the entire width of the renal hilum

Question 8

portal system

Answer 8

consists of two capillary beds in series through which blood must travel before returning to the heart

Question 9

three portal systems in the body

Answer 9

hypophyseal portal system, hepatic portal system, and kidney portal system

Question 10

path of blood in kidneys

Answer 10

renal artery - afferent arteriole - glomerulus - efferent arteriole - vasa recta - renal vein

Question 11

Bowman’s capsule

Answer 11

cuplike structure around the glomerulus which leads to a long tubule with many areas

Question 12

Areas of long tubule that Bowman’s capsule leads to

Answer 12

proximal convoluted tubule, descending and ascending limbs of the Loop of Henle, distal convoluted tubule and collecting duct

Question 13

Bladder’s muscular lining

Answer 13

detrusor muscle; parasympathetic activity causes it to contract

Question 14

internal urethral sphincter

Answer 14

one of two sphincters urine must pass through to leave the body; consists of smooth muscle and is normally contracted

Question 15

external urethral sphincter

Answer 15

one of two sphincters urine must pass through to leave the body; skeletal muscle under voluntary control

Question 16

path of urine to exit body

Answer 16

Bowman’s space - proximal convoluted tubule - descending limb of loop of Henle - ascending limb of loop of Henle - distal convoluted tubule - collecting duct - renal pelvis - ureter - bladder (stretch receptors signal nervous system bladder is full which causes parasympathetic neurons to fire and the detrusor muscle to contract; contraction causes internal sphincter to relax) - urethra

Question 17

micturition reflex

Answer 17

contraction of the detrusor muscle when bladder needs to be emptied reflexively causes internal sphincter muscle to relax

Question 18

three kidney function processes

Answer 18

filtration, secretion and reabsorption

Question 19

filtration

Answer 19

20% of blood that passes through glomerulus is filtered as fluid into Bowman’s space (called filtrate). This movement is governed by Starling forces.

Question 20

Secretion

Answer 20

nephrons secrete salts, acids, bases and urea directly into the tubule by either active or passive transport based on the needs of the body at the time. also mechanism for excreting wastes too large to pass through glomerular pores

Question 21

Reabsorption

Answer 21

certain substances such as glucose, amino acids, and vitamins are taken back up for use by kidneys

Question 22

proximal convoluted tubule (PCT)

Answer 22

area where filtrate first enters; here amino acids, glucose, water-soluble vitamins and majority of salts are reabsorbed along with water; also site of secretion of a number of waster products, including hydrogen ions, potassium ions, ammonia and urea

Question 23

interstitium

Answer 23

connective tissue surrounding the nephron

Question 24

descending limb of the Loop of Henle

Answer 24

dives into the medulla before turning around to become ascending limb of the loop of Henle; filtrate from proximal convoluted tubule enters here after proximal convoluted tubule; permeable only to water which causes water to be extracted into medulla that can be reabsorbed by the vasa recta

Question 25

concurrent multiplier system

Answer 25

created by the vasa recta and nephron; the flow of filtrate through the loop of Henle is in the opposite direction from flow of blood through vasa recta so that the filtrate is constantly exposed to hypertonic blood which allows maximal reabsorption of water

Question 26

Ascending limb of the loop of Henle

Answer 26

not permeable to water; only permeable to salts and salt is removed

Question 27

diluting segment

Answer 27

area where loop of Henle (after ascending limb) becomes thicker because the cells lining it are thicker here, at the transition from inner to outer medulla. The cells contain lots of mitochondria allowing the reabsorption of sodium and chloride by active transport; only portion of the nephron that can produce urine more dilute than the blood

Question 28

Distal convoluted tubule (DCT)

Answer 28

after loop of Henle; responds to aldosterone which promotes sodium reabsorption which will increase water volume; also site of waste product secretion

Question 29

Collecting Duct

Answer 29

tube that follows distal convoluted tubule; responsible to aldosterone and antidiuretic hormone (ADH or vasopressin); ever increasing water reabsorption. the water then enters interstitium and goes to vasa recta where it reenters bloodstream; when well hydrated not much water absorbs here, when not aldosterone and ADH absorb a lot here; this is the last opportunity for reabsorption

Question 30

Path of Aldosterone release

Answer 30

steroid hormone in decreased bp which also stimulates renin release from juxtaglomerular cells in kidneys; renin cleaves angiotensinogen (liver protein) to form angiotensin I which is then metabolized by angiotensin-converting enzyme in lungs to form angiotensin II which promotes release of this from the adrenal cortex.

Question 31

Function of Aldosterone

Answer 31

alters ability of distal convoluted tubule and collecting duct to reabsorb sodium; water follows this and increases BP; also increases potassium and hydrogen ion excretion

Question 32

Function of Antidiuretic hormone

Answer 32

ADH or vasopressin; peptide hormone synth in hypothalamus and released by posterior pituitary in response to high blood osmolarity; directly alters permeability of collecting duct allowing more water to be reabsorded by making cell junctions of the duct leaky; inhibited by alcohol and caffeine

Question 33

layers of the skin

Answer 33

deepest outward: hypodermis (subcutaneous layer), dermis, epidermis. Skin is derived from ectoderm

Question 34

layers of epidermis mnemonic

Answer 34

(strata) from outermost to deepest: stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale

Question 35

role of stratum basale

Answer 35

deepest layer of epidermis; contains stem cells and responsible for proliferation of keratinocytes (predominant cells of the skin that produce keratin)

Question 36

role of stratum spinosum

Answer 36

next deepest layer of epidermis above basale; connects cells from stratum basale (keratinocytes); also site of Langerhans cells

Question 37

role of stratum granulosum

Answer 37

third deepest layer of epidermis above spinosum; site where keratinocytes die and lose their nuclei

Question 38

stratum lucidum

Answer 38

second most superficial layer of epidermis under corneum (above granulosum) only present in thick, hairless skin such as sole of foot or palms

Question 39

function of stratum corneum

Answer 39

most superficial layer of epidermis; contains several dozen layers of flattened keratinocytes, forming a barrier that prevents invasion by pathogens and that helps to prevent loss of fluids and salt

Question 40

Melanocytes

Answer 40

cell type derived from neural crest cells; found in stratum basale; increased ultraviolet exposure increases activity of these and darkens skin; they produce melanin, a pigment that protects skin from DNA damage caused by UV radiation

Question 41

Langerhans cells

Answer 41

special macrophages that reside within stratum spinosum capable of presenting antigens to T-cells to activate immune system

Question 42

Layers of the dermis

Answer 42

from top to bottom:(beneath epidermis) papillary layer (connective tissue) - reticular layer

Question 43

Merkel cells (discs)

Answer 43

part of the dermis; sensory receptors present at the epidermal-dermal junction responsible for deep pressure and texture sensation in skin

Question 44

free nerve endings

Answer 44

sensory organ in skin which responds to pain

Question 45

Meissner's corpuscles

Answer 45

in dermis; respond to light touch

Question 46

Ruffini endings

Answer 46

in dermis; respond to stretch

Question 47

Pacinian corpuscles

Answer 47

in dermis; respond to deep pressure and vibration

Question 48

hypodermis

Answer 48

layer of connective tissue that connects skin to rest of body

Question 49

piloerection in thermoregulation

Answer 49

caused by contraction of arrector pili muscles; hair standing up traps a layer of heat close to skin; arterioles that feed capillaries of skin constrict limiting quantity of blood reaching skin

Question 50

white fat and brown fat

Answer 50

help to maintain heat; infants have brown fat which means more heat energy is released as fuel is burned