the urinary system and special senses

Question 1

what is the function of the collecting ducts

Answer 1

to receive urine from many nephrons

Question 2

what is the difference between the effarent arteriole and affarent arteriole

Answer 2

the afferent arteriole has a larger diameter, which increases blood pressure in the glomerular capillaries. The high blood forces fluid and small solutes out of the blood into the glomerular capsule.

Question 3

a nephron is made of two parts, which are

Answer 3

the renal corpuscle (the bowman’s capsule and glomerulus) and renal tubule (PCT/Loop of Henle/DCT/Collecting duct)

Question 4

what are the three processes of urine formation

Answer 4

Glomerular filtration- Blood flows in the afferent arterioles into the glomerular capsule, water and solutes that are smaller than proteins are forced through the filtration membrane. Proteins and blood cells are too big to pass through into the filtrate and therefore remain in the blood.

Tubular reabsorption- this is the reabsorption of any needed substances such as water, glucose, amino acids and ions back into the capillary blood. the reabsorption begins in the PCT. Reabsorption can also occur in the DCT but mainly the PCT.

Tubular secretion- it is essentially tubular reabsorption in reverse. H+ , K+ creatinine and some drugs are extracted from the capillaries and secreted into the filtrate.

Question 5

what are the three main types of nitrogenous wastes and why

Answer 5

urea: formed by the liver as an end product of protein breakdown when amino acids are used to produce energy

uric acid: released when nucleic acids are metabolised

creatinine: it is associated with creatinine metabolism in the muscle tissue

Question 6

what are the characteristics of urine

Answer 6

• generally clear and pale to deep yellow

-urine is sterile and slightly aromatic

-when standing for awhile it has an ammonia odour

-Urine pH is slightly acidic (6)

-urine is denser due to water and solutes

Question 7

what is urochrome

Answer 7

a pigment that results from the body’s destruction of haemoglobin

Question 8

what is the function of the ureter

Answer 8

transport urine from the kidney to the bladder

Question 9

what is the trigone and why is it clinically important

Answer 9

it is the triangular region of the bladder and it is clincally important because infections tend to persist in this region.

Question 10

which two sphincters of the urethra control the flow of urine

Answer 10

internal and external urethral sphincter

Question 11

internal urethral sphincter

Answer 11

involuntary- keeps the urethra closed when (made of smooth muscle)

Question 12

external urethral sphincter

Answer 12

voluntary- formed by skeletal muscle

Question 13

what is the function of the urethra in men

Answer 13

it carries both urine and sperm from the body, but not at the same time.

Question 14

what is the function of the urethra in women

Answer 14

conduct urine from the bladder to the exterior

Question 15

what is the process of micturition or voiding

Answer 15

• the bladder collects urine
• stretching of the bladder wall activates stretch receptors
• which leads to impulses transmitted to the sacral region in the spine
• the impulses from the spine go back to the bladder
• the contractions become stronger and stored urine is forced past the internal urethral sphincter
• the person feels the urge to void
• the external urethral sphincter is voluntary so the person can hold it
• when they do void the reflec contractions stop

Question 16

blood composition depends on

Answer 16

diet, cellular metabolism and urine output

Question 17

what are the major fluid compartments of the body

Answer 17

intracellular fluid
extracellular fluid
plasma volume
interstitial fluid

Question 18

what is the thirst mechanism

Answer 18

an increase in plasma solute content
stimulates osmoreceptors in the hypothalamus which stimulates the thirst response

Question 19

what shape is the eye

Answer 19

sphere

Question 20

what are the accessory structures of the eye

Answer 20

extrinsic eye muscles
conjunctiva
eyelids
lacrimal apparatus

Question 21

what are the functions of the tarsal glands

Answer 21

produce an oily substance that lubricates the eye

Question 22

what is the function of the conjunctiva of the eye

Answer 22

lines the eyelid and covers part of the outer surface of the eyeball. it secretes mucus which helps to lubricate the eyeball and keep it moist

Question 23

what are the 6 extrinsic muscles of the eye

Answer 23

lateral rectus- moves eye laterally (abducens)

medial rectus- moves eye medially (occulomotor)

superior rectus- elevates eye and turns it medially (occulomotor)

inferior rectus- depresses eye and turns it medially (occulomotor)

inferior oblique- elevates eye and turns it laterally (occulomotor)

superior oblique- depresses eye and turns it laterally (trochlear)

Question 24

choroid

Answer 24

blood rich nutrtive tunic contains a dark pigment

Question 25

in close vision and bright light

Answer 25

the circular muscles contract
and the pupil constricts

Question 26

in distant vision and dim light

Answer 26

the radial muscle fibers contract to dilate the pupil which allows more light to enter the eye

Question 27

which cranial nerve controls the muscles of the iris

Answer 27

occulomotor

Question 28

what is the function of the pigmented layer in the retina

Answer 28

composed of cells that absorb light and prevent light from scattering inside the eye. They also act as phacocytes to remove dead or damaged receptor cells and store vitamin A for vision

Question 28

what is the function of the neural layer in the retina

Answer 28

contains rods and cones (photoreceptors) which respond to light. there are no photoreceptors at the optic disc (blindspot).