Homeostasis and Human Excretory System

Question 1

excretion

Answer 1

the removal of waste products of metabolism from the body

Question 2

nephron

Answer 2

the functional unit of the kidney

produces urine

Question 3

homeostasis

Answer 3

the maintenance of a constant internal environment

Question 4

endotherm (warm blooded animals)

Answer 4

keep body temperature constant even in cold external conditions by increasing metabolic rate (respiration)
eg birds, mammals

Question 5

ectotherms (cold blooded animals)

Answer 5

body temperatures vary with that of the environment

eg reptiles, fish, amphibians

Question 6

vasodilation

Answer 6

blood vessels near the surface of the skin dilate

Question 7

vasocontraction

Answer 7

blood vessels near the surface of the skin narrow (constrict)

Question 8

osmoregulation

Answer 8

the control of water or salt levels in the cell or organism

Question 9

active transport

Answer 9

absorption of substances into cells against a concentration gradient, requiring energy

Question 10

waste products of homeostasis

Answer 10

skin- source: sweat gland
sweat -> water and salt

lungs - source: break down of carbs in respiration
carbon dioxide

liver- source: deamination of amino acids
urea

Question 11

skin

Answer 11

regulates body temp

Question 12

liver and pancreas

Answer 12

regulate blood glucose level

Question 13

kidneys

Answer 13

regulate water and salt concentration

Question 14

importance of homeostasis

Answer 14

allows organisms to function efficiently and independently of their external environment
eg constant internal temp required for enzyme action to work efficiently

efficiency of exchange of substances is proportional to the surface area over which diffusion can take place

Question 15

how unicellular organisms function in homeostasis (amoeba)

Answer 15

no excretory organs: large surface area for exchange of materials

Question 16

how multicellular organisms function in homeostasis

Answer 16

in humans:
-lungs contain alveoli: excrete co2 which regulates blood pH

in plants:
-stomata: leaves are flat for efficient diffusion of gases

Question 17

human excretory system parts

Answer 17

kidney
skin
lungs

Question 18

renal artery

Answer 18

transport blood from heart to kidney

Question 19

renal vein

Answer 19

transport blood from kidney to heart

Question 20

kidney

Answer 20

• removal of waste products from the blood and production of urine
• osmoregulation

located in the lower abdominal cavity

Question 21

ureter

Answer 21

transport urine from kidney to bladder

Question 22

bladder

Answer 22

stores urine

Question 23

sphincter muscle

Answer 23

keeps urine in the bladder

Question 24

urethra

Answer 24

transports urine from bladder to outside the body

Question 25

adrenal gland

Answer 25

production of adrenaline

Question 26

cortex

Answer 26

filtration and reabsorption

Question 27

medulla

Answer 27

reabsorption

Question 28

ureter

Answer 28

transport urine from kidney to bladder

Question 29

steps in the production of urine

Answer 29

1. filtration : removal of waste products from the blood to the kidney 2. reabsorption: useful nutrients returned back into the bloodstream from the kidney 3. secretion: active transport of substances from blood to the kidney ( potassium ions, hydrogen ions, urea)

Question 30

glomerulus and bowman's capsule function

Answer 30

filtration

Question 31

items filtered out of the blood into the bowman's capsule

Answer 31

glucose urea salts and water

Question 32

items that remain in the blood from bowman's capsule

Answer 32

hormones (too big) protein (too big) RBCs, WBCs, platelets

Question 33

glomerular filtrate vs urine

Answer 33

g . f. more water more glucose amino acids urine less water no glucose no amino acids

Question 34

adaptation for efficient filtration at glomerulus

Answer 34

large surface area with capillary network many pores in glomerulus, b.cap. 1 cell thick blood pressure is high: efferent arteriole narrower than the afferent arteriole, so force filtering the plasma

Question 35

proximal convoluted tubule

Answer 35

``` function: reabsorption glucose vitamins amino acids 80% salts and water ``` method of reabsorption: diffusion and active transport

Question 36

adaptations for reabsorption in the proximal convoluted tubule

Answer 36

long (allows time for reabsorption) many villi in its cells (larger surface area) high conc. of mitochondria (energy) walls only one cell thick (diffuse easily)

Question 37

loop of henle

Answer 37

function: reabsorption of water and salts descending loop: water (osmosis) ascending loop: salts (diffusion/active transport)

Question 38

distal convoluted tubule

Answer 38

functions: reabsorption, secretion of k+ and h+ ions, drugs if blood is too acidic= h+ conc. very high h+ ions secreted into the urine at the d.c.t. by controlling the hydrogen ion conc. in blood, the kidneys control blood pH

Question 39

collecting duct

Answer 39

function: reabsorption of water hormone: ADH anti diuretic hormone site of production: hypothalamus site of secretion: pituitary gland site of action: collecting duct

Question 40

outline process of osmoregulation when body is low on water

Answer 40

``` blood = increased salt concentration ADH secreted from pituitary gland collecting duct becomes permeable more water is reabsorbed small volume of urine produced less salt in blood ```

Question 41

outline process of osmoregulation when body is high in water

Answer 41

blood = too dilute, decreased salt conc. ADH produced is inhibited collecting duct becomes impermeable less water reabsorbed into the blood larger volume of dilute urine is produced salt conc. is unchanged in blood

Question 42

functions of the skin

Answer 42

``` 1. protection epidermis- prevents entry of pathogens melanin- protects against UV rays sebum- keep hair moist, protects skin from cracking, acidic nature kills bacteria 2. excretion (water, salt, sweat) 3. temp regulation 4. vit D production ```

Question 43

epidermis cells

Answer 43

produce keratin build up of keratin causes hardening of cells more keratin causes cells in cornified layer to die

Question 44

malpighian layer

Answer 44

produces melanin (protects against UV)

Question 45

dermis

Answer 45

contains connective tissue (collagen) | protects internal organs

Question 46

why we sweat

Answer 46

skin receptors detect change in temp. send message to the brain: - more sweat is produced by sweat glands - vasodilation of skin arterioles

Question 47

vasodilation of skin arterioles

Answer 47

blood vessels near the surface of the skin dilate more blood flows near the skin surface heat lost by evaporation of sweat

Question 48

skin in cold conditions

Answer 48

skin receptors detect change in temp. send messages to the brain: - piloerection - vasoconstriction of skin arterioles - increased metabolism (more thyroxine produced, more heat generated from respiration)

Question 49

piloerection

Answer 49

erector muscles contract pull hairs erect for trapping more air thicker layer of air close to skin acts as a good insulator of heat

Question 50

vasoconstriction of skin arterioles

Answer 50

blood vessels near the surface of the skin narrow | to let less blood flow near the skin surface, reducing heat loss