sugar Flashcards
1
Q
describe negative feedback
A
As a hormone increases in concentration, it inhibits the release of another hormone.
2
Q
describe positive feedback
A
As a hormone increases in concentration, it promotes the release of a hormone
3
Q
what hormones does the anterior pituitary secrete
A
(FLAGTOP) FSH – Follicle Stimulating Hormone LH – Luteinizing Hormone ACTH – Adrenocorticotropic hormone GH – Growth Hormone TSH – Thyroid Stimulating Hormone O – MelanOcyte stimulating hormone Prolactin
4
Q
what hormones does the posterior pituitary secrete
A
ADH/Vasopressin
Oxytocin
5
Q
describe the male HPG axis
A
LH -> Leydig cells -> Testosterone
FSH -> Sertoli Cells -> Stimulates production of ABP -> Spermatogenesis
6
Q
describe the female HPG axis
A
LH -> Stimulates ovulation + ovarian follicle maturation + corpus luteum formation.
FSH -> regulates development + growth of ovarian follicle + affects 1st half of menstrual cycle
7
Q
describe the oestrogen feedback mechanisms on the HPG axis
A
Moderate levels of oestrogen present will exert negative feedback on FSH and LH.
High oestrogen (with low progesterone) exerts positive feedback on LH and FSH.
Oestrogen in the presence of progesterone exerts negative feedback.
8
Q
describe the HPA axis
A
CRH -> ACTH (corticotrohps) -> Cortisol (ZF of adrenal cortex)
9
Q
cortisol functions
A
Gluconeogenesis and carbohydrate metabolism
Reduction of inflammation
Proteolysis and lipolysis
Reduction of bone formation, which can lead to osteoporosis over time
10
Q
describe the HPS axis
A
GHRH -> GH (somatotrophs)
Somatostatin (SST) -/-> GH
11
Q
what is GH involved in
A
Skeletal growth and bone density Muscle strength Protein synthesis Glycogenolysis Lipolysis
12
Q
describe the HPT axis
A
TRH -> TSH -> T3/T4
13
Q
what does TSH (thyroid stimulating hormone) do
A
increase metabolism
14
Q
describe the release of prolactin
A
- Suckling causes the release of prolactin as well as TRH.
- Dopamine inhibits release of prolactin
15
Q
what are the functions of prolactin
A
Initiate milk production in the breasts
Maintain milk production once is has been established
16
Q
what is the peptide hormone of GnRH
A
FSH + LH
17
Q
what is the peptide hormone of CRH
A
ACTH
18
Q
what is the peptide hormone of GHRH
A
GH
19
Q
what is the peptide hormone of TRH
A
TSH
20
Q
where is oxytocin synthesised and stores?
A
synthesised in hypothalamus (paraventricular nucleus)
stored in posterior pituitary
21
Q
what is the function of oxytocin
A
Oxytocin acts on the breasts to allow milk to move through the lactiferous ducts to be expressed through the nipple -> milk ejection during lactation
It also acts on the uterus to cause uterine contractions during labour-> promoting onset of labour
Oxytocin exerts positive feedback on itself
22
Q
where is ADH synthesised
A
hypothalamus - supraoptic nucleus
23
Q
how does ADH control osmolality
A
Osmoreceptors in the hypothalamus detect change
ADH binds to V2 receptors on the collecting ducts -> mobilisation of aquaporin 2 (AQP2) + insertion into cell membrane
These allow the passage of water from the collecting duct into the blood to reduce the plasma osmolality -> ↑water reabsorption
24
Q
how does ADH maintain Blood pressure
A
Maintains BP by acting on smooth muscle cells -> vasoconstriction -> ↑BP
25
which hormone inhibits GHRH
somatostatin
26
what do the alpha cells of the islets of langerhans secrete
glucagon
27
what do the beta cells of the islets of langerhans secrete
insulin
28
what do the delta cells of the islets of langerhans secrete
somatostatin
29
describe the mechanism of insulin secretion
1. Glucose moves into beta cells via GLUT2 channel
2. ATP is made
Closure of ATP-sensitive potassium channels
3. Depolarisation of the beta cell membrane
4. Opening of voltage-gated calcium channels
5. Vesicles containing insulin fuse with the cell membrane
30
describe the action of insulin in lowering blood glucose
Insulin binds to insulin receptors on muscle + fat cells
Triggers intracellular signalling cascade -> mobilisation of intracellular GLUT4 vesicles to cell membrane
GLUT4 vesicle integrates into cell membrane -> ↑number of membrane glucose transporters -> ↑rate of glucose facilitated diffusion into cell -> ↓blood glucose level
31
describe what happens when glucose levels rise
Insulin is released and glucagon release is inhibited
There is increased glycogenesis in the liver and muscles
Gluconeogenesis is inhibited
This reduces the blood glucose level
32
what level is the thyroid gland situated
C5-T1
33
what divides the thyroid into 2 lobes
isthmus
34
what 2 muscles does the thyroid gland lie between
sternohyoid and sternothyroid
35
how many parathyroid glands are there and where are they located
4
| posterior surface of the thyroid
36
what is the blood supply to the thyroid?
Superior thyroid arteries
Branch of external carotid artery.
Supply superior + anterior portion of gland
Inferior thyroid arteries
Branching of subclavian artery
Supplies posterior inferior aspect of gland
37
what protein is produced by the follicular cells
thyroglobulin
38
describe the production of T3 + T4 (ATE ICE)
A - (secondary) active transport of iodide via Na/I symporter
T - thyroglobulin is produced in the follicular cells
E - exocytosis of thyroglobulin into the follicular lumen
I - iodination of tyrosine residues on thyroglobulin (thyroid peroxidase) to form monoiodothyronine (MIT) and diiodothyronine (DIT)
C - coupling of MIT and DIT (T3) and DIT and DIT (T4)
E - endocytosis of T3 and T4 into follicular cells. Proteolysis occurs to free T3 and T4 from thyroglobulin
39
what is the function of T3 and T4
increases BMR & important in brain maturation
40
how does T3 increase BMR
1. T3 -> stimulates carbohydrate absorption in SI , ↑FA release from adipocytes
2. ↑BMR by providing more energy for metabolism
3. ↑body temp (homeostasis)
41
what are the 3 main layers to the skin
epidermis
dermis
subcutaneous
42
what are the 5 layers of the epidermis (top to bottom) (Come, Let's Get Sun Burnt)
```
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
```
43
what is adhesion in the skin provided by
Primary adherens junctions
Desmosomes (stratum spinosum)
Corneo-desmosomes keep corneocytes together
Tight junctions – epithelial layer (stratus granulosum)
Help with providing waterproofing
44
what is the function of NMF
Filaggrin -> natural moisturising factor (NMF)
| NMF allows the skin to remain hydrated and maintains the slightly acidic pH the skin has
45
what is the purpose of the skin being acidic
Acidity prevents protease activity to stop the breakdown of corneodesmosomes.
It also aids with the formation of the lipid lamellae.
46
what is the affect of increased pH on the skin
The proteases are no longer inhibited by the low pH so they break down the corneodesmosomes
The increased pH also impairs the formation of the lipid lamellae
This allows the skin cells to move apart which reduces water retention in the skin
Allergens can then penetrate
47
how do allergens create an inflammatory response
Allergen penetrates skin + attracts lymphocyte -> releases inflammatory cytokines -> inflammatory response
48
what is the cause of red skin
dilation of vessels to bring more lymphocytes to area
49
what is the cause of itchy skin
stimulation of proprioceptors by the release of histamine (from mast cells) or thermal/mechanical mediators
50
what is the cause of dry skin
skin cells leaking water
51
what do sebaceous glands do
produce a lipid-rich sebum which protects the hair
52
how does acne occur
Acne occurs when the hair follicle becomes blocked with sebum, skin cells, and bacteria.
Sebum -> free fatty acids (by bacteria) -> inflammation & attraction of neutrophils -> pus formation
53
what is the automatic nervous supply to the bladder
SympathetiC – HypogastriC nerves T12-L2 -> relaxation of detrusor muscle -> urine retention
ParaSympathetic – Pelvic Splanchnic nerves S2-4 -> contraction of detrusor muscle -> micturition stimulation
54
what is the somatic nervous supply to the bladder
Somatic system (voluntary) -> Pudendal nerves S2-4 -> Innervate EUS -> constricts (storage) or relaxes (micturition)
55
describe the process of bladder filling/ storage
Parasympathetic input to detrusor muscles is minimal -> detrusor muscle relaxes.
Strong sympathetic input to Internal urethral sphincter + Strong somatic motor neuron input to External urethral sphincter -> Both Sphincters closed
This allows the bladder to expand to prevent an increase in pressure as the volume increases (stress-relaxation phenomenon)
56
describe the bladder stretch reflex arc
Bladder fills and stretches -> activating stretch receptors
Afferent sensory nerves transmit signal to brain
Interneurons relay signal to parasympathetic efferent nerves (pelvic nerve)
Contracts detrusor muscle -> stimulate micturition
57
describe the mechanism of voiding
Detrusor muscle contracts to increase the pressure in the bladder
Internal urethral sphincter relaxes
Once it’s appropriate to void, the external urethral sphincter will be consciously relaxed to allow voiding
58
what part of the adrenal gland secretes cortisol
zona fasciculata
59
what part of the adrenal gland secretes androgens
zona reticularis
60
what part of the adrenal gland secretes mineralocorticoids (aldosterone)
zona glomerulosa
61
what does the adrenal medulla secrete
adrenaline
62
what nerve innervates the external urethral sphincter and what nerve roots does it comprise of
pudendal nerve S2-S4
63
what are the functions of the skin
```
barrier to infection
thermoregulation
protect against trauma
protection against UV
vitamin D synthesis
regulate H2O loss
```
64
what are corneocytes filled with
NMF
65
what is desquamation
when mature corneocytes are shed from the surface of the stratum corneum
66
what is the pH of normal skin
5.5
67
what does the lipid lamellae do
keep water inside the skin cells
68
describe the brick wall model
bricks = corneocytes
iron rods = corneodesmosomes
cement - lipid lamellae
69
what is the role of vitamin D for the skin
essential in producing the anti-microbial peptides necessary to defend the skin from bacteria and viruses
70
at what level are the kidneys found
T12 & L3
71
which kidney is lower
right - pushed down by liver
72
where is the hilum of the right kidney
L2
73
where is the hilum of the left kidney
L1
74
what is the cortex of the kidney composed of
renal corpuscles (glomerulus & bowman's capsule) and the proximal and distal convoluted tubule
75
what is a medullary ray
collection of loop of henle tubules in the cortex - concentrate urine. and collecting ducts
76
what is the medulla of the kidney comprised of
no real corpuscles or glomeruli
| loops of henle, collecting ducts and blood vessels
77
describe the composition of the kidney pelvis
lined by transitional epithelium
| tips of medullary pyramids project into pelvis - at this point the pyramids are composed purely of collecting ducts
78
describe the blood supply to the kidneys
renal artery (L1 of aorta) -> segmental -> interlobar -> arcuate-> interlobular -> afferent arterioles
79
what many nephrons in the kidney
1 million in each
80
what is the role of the renal corpuscle
filtering
81
what is the role of the PCT
reabsorbing solutes
82
what is the role of the loop of henle
concentrating urine
83
what is the role of the DCT
reabsorbing more water and solutes
84
what is the role of the collecting duct
reabsorbing water and controlling acid-base & ion balance
85
what is the glomerular tuft supported by
smooth muscle mesangial cells
86
what are the 3 main functions of the mesangial cells
1. structural support
| 2, contraction of muscles in the glomerulus to reduce GFR
87
what are the 2 components of the juxtaglomerular apparatus
afferent arteriole & distal convoluted tubule
88
what is the role of granular cells
detect blood pressure and secrete renin in response to a reduction in BP
89
what do the macula densa do
detect sodium levels
90
what do the macula densa cells do when filtration is slow
more sodium will absorbed -> macula densa signal to reduce afferent arteriole resistane -> increase GFR
91
what type of epithelium is the PCT composed of
cuboidal epithelium
92
what distinguishes PCT from DCT
PCT have microvilli - makes surface look fuzzy
93
what epithelium are thin loops of henle composed of
simple squamous
94
what epithelium are thick loops of henle composed of
low cuboidal
95
what supplies the loop of henle
rich vasa recta
96
describe the cells of the DCT
cuboidal
| contain mitochondria
97
what kind of epithelium lines the collecting ducts
cuboidal
98
what 2 cell types are found in the collecting duct
principal cells - respond to aldosterone & ADH
intercalated cells - responsible for exchanging acid for base (alpha - acid , beta - bicarbonate)
99
what epithelium is found in the renal pelvis
transitional epithelium
100
describe urothelium (transitional epithelium)
surface layer = umbrella cells with tight junctions
| basal layer = ceboidal cells
101
describe the muscle layers of the ureter
inner - longitudinal
| outer - circular
102
what are the layers of the bladder
```
lamina propria
muscularis mucosa
submucosa
muscularis propria
subserosa & serosa
```
103
what kind of muscle is the internal sphincter made of
smooth muscle from bladder
104
what kind of muscle is the external sphincter made of
skeletal muscle from pelvic floor
105
describe the female urethra
4-5cm long
proximally transitional epithelium
distally squamous epithelium
106
describe the male urethra
```
20 cm long
prostatic urethra
membranous urethra (transitional)
penile urethra (pseudostratified proximally, stratified squamous distally)
```
107
what percentage of cardiac output does each kidney receive
20%
108
what is the total renal blood flow to the kidneys
1L/min
109
what is the total urine flow
1ml/min
110
what are the 3 components of the glomerular filtration barrier
1. capillary endothelium
2. basement membrane
3. epithelium of bowman's capsule with podocyte foot processes
111
what are the 2 types of nephron and their percentages
15% juxtamedullary - renal corpuscle at junction, loop of henle plunges deep into medulla
85% cortical - renal corpuscles in outer cortex
112
what is the order of flow of the glomerular filtrate
1. glomerular capsule
2. proximal convoluted tubules
3. nephron loop
4. distal convoluted tubule
5. collecting duct
6. papillary duct
7. minor calyx
8. major calyx
9. renal pelvis
10. ureter
11. urinary bladder
12. urethra
113
how does hydrostatic and oncotic pressure vary along the glomerular capillary
hydrostatic - constant
| no oncotic in bowman' capsule - increases as you go along the glomerular capillary
114
GFR
the volume of fluid filtered from the glomeruli into bowman's space per unit time
115
what is GFR determined by
net filtration pressure
permeability of the corpuscular membranes
surface area
116
what is used to estimate GFR
creatinine
117
afferent arteriole dilation
high HP, high GFR
| low BP due to low TPR
118
afferent arteriole constriction
low HP, low GFR
| high TPR, high BP
119
efferent arteriole dilation
low HP, low GFR
| increased peritubular HP so less reabsorption
120
efferent arteriole constriction
high HP, high GFR
| low HP in peritubular so higher filtration rate
121
filtration fraction =
GFR/ renal plasma flow
122
renal clearance
the volume of plasma from which a substance is completely removed by the kidney per unit time
urine concentration x urine volume / plasma concentration
123
tubuloglomerular feedback
macula densa detect NaCl arrival
| release prostaglandins in response to a reduction in NaCl, triggers granular cells to release renin -> RAAS
124
what are the percentages of body fluid
2/3rds ICF
| 1/3rd ECF (75% interstitial, 25% plasma)
125
what is the major cation of the ECF
sodium
126
what is the major cation of the ICF
potassium
127
describe the thirst centre
stimulated by increase in plasma osmolarity and decrease in ECF volume
stimulates osmoreceptors-> vasopressin secretion -> increased H2O reabsorption
128
where is the most sodium reabsorbed in the nephron
proximal tubule 60%
129
briefly describe RAAS
angiotensinogen -> angiotensin I (renin)-> angiotensin II (ACE)-> aldosterone secretion ( zona glomerulosa) -> vasoconstrict especially at efferent -> increased GFR -> increased Na reabsorption -> stimulates thirst, vasopressin release and water retention
130
what affect does parathyroid hormone have on the kidneys
released in response to low levels of Ca2+-> increases reabsorption -> decreased excretion
stimulatess active form of vit D
131
normal range of pH
7.35-7.45
132
anion gap equation
[Na+] + [K+] - [Cl-] - [HCO3-]
133
what is a normal anion gap
10-16
134
causes of respiratory acidosis
hypoventilation
| COPD
135
causes of respiratory alkalosis
hyperventilation
| type 1 resp failure
136
causes of metabolic acidosis
renal failure
137
causes of metabolic alkalosis
vomiting
| alkali ingestion
138
where is erythropoietin produced
peritubular cells of renal cortex
139
blood supply to adrenal glands
superior middle and inferior adrenal artery
140
venous drainage of the adrenal glands
right adrenal vein - directly into IVC
| left adrenal vein - left renal vein
141
what 5 hormones does the adrenal cortex secrete
```
aldosterone
cortisol
corticosterone
DHEA
androstenedione
```
142
what are the 3 layers of the adrenal cortex and what do they secrete (GFR, Makes Good Sex)
zona glomerulosa - Mineralocorticoids
zona fasiculata - glucocorticoids
zona reticularis - sex hormones (androgens)
143
embryology of the thyroid gland
3-4w epithelial proliferation at base of pharynx - migrate down to below larynx - start producing thyroxine at 18-20w
144
what is stored in the follicle
iodine
145
what type of cells are follicular cells
simple cuboidal -> become columnar with increased metabolic activity
146
what do parafollicular cells produce
calcitonin for Ca2+ homeostasis
147
embryology of the pituitary gland
protrusion of ectoderm - rathke's pouch -> anterior pituitary
posterior is of neural origin
148
embryology of the pancreas
2 pancreatic buds fuse
exocrine - after birth
endocrine 10-15 weeks
149
percentage of cells in pancreas
98-99% acini - secrete digestive enzymes
| 1-2% islets of langerhans
150
what are incretins
secreted by endothelial cells in GI tract in response to eating - amplifies insulin response to glucose
151
role of glucagon
convert glycogen to glucose
| form glucose from lactic acids and amino acids
152
role of insulin
accelerate diffusion of glucose into cells
speed up conversion of glucose into glycogen
increase uptake of amino acids and increase protein synthesis
speed up FA synthesis
slow glycogenolysis and gluconeogenesis
153
what determines sex
male
154
male sex development
Y -> SRY gene -> wolffian ducts persist, mullerian regress - sertoli cells (MIF)-> testosterone (leydig cells) -> wolffian duct diffferentiates into epididymis, vans deferes, ejaculatory ducts ,seminal vesicles
later - DHT -> penis formation -> testes descend
155
female sex determination
no Y -> MIF secreted -> mullerian duct -> fallopian tubes + uterus
wolffian duct degenerates
vagina form
156
when does the second meiotic division occur in males
after puberty
157
when does the second meiotic division occur in females
after fertilisation
158
what is the epididymis lined by
pseudo-stratified columnar epithelium with stereocilia
159
what is expelled during ejaculation
60% seminal fluid
30% prostatic
10% sperm & trace of bulbourethral fluid
160
how much sperm is made per gram of testis per second
300-600
161
where is mitochondria form in the spermatozoa
midpiece
162
what is the tip of the nucleus of the spermatozoa covered by
acrosome - protein- filled vesicle containing enzymes to penetrate the egg
163
histology of ovary
simple cuboidal epithelium
| primordial germ cells surrounded by fibroblast- like stromal cells in the cortex
164
what epithelium lines the uterus
simple columnar ciliated
165
cervix epithelium
simple columnar
166
vagina epithelium
moist stratified squamous - keratinised at vulva end
167
how many ovaries are present at birth
2-4 million
168
describe the hormone levels at puberty
increase in levels of GnRH & GHRH
| increase in FSH, LH, GH and sex steroids
169
briefly describe the 2 phases of the menstrual cycle
1. follicular phase
mature/graffian follicle + secondary oocyte develop
2. Luteal phase
after ovulation and lasting until the death of the corpus luteum
170
where are oestrogen and progesterone produced
oestrogen - granulosa cells in follicular phase and corpus luteum after ovulation
progesterone - corpus luteum (major source), granulosa + theca (small amounts before ovulation)
171
what is hCG produced by
trophoblast cells
172
where does spermatogenesis occur
seminiferous tubules
173
what helps to keep the testes temperature low
heat exchange via the pampiniform plexus
174
what do the seminiferous tubules converge to form
rete testis
175
what is the epididymis lined by
pseudo-stratified columnar epithelium with stereocilia
176
summary of path of sperm to outside
```
seminiferous tubules
rete testis
efferent ducts
epididymis
vas deferens
ejaculatory duct
urethra
penile urethra
```
177
what forms the blood-testis barrier
adjacent sertoli cells joined by tight junctions
178
what do spermatogonia become after they mitotically divide
type A: remain outside blood-testis barrier, produce more daughter cells
type B: differentiate into primary spermatocytes
179
what do primary spermatocytes become after meiosis 1
secondary spermatocytes
180
what do secondary spermatocytes become after meiosis 2
4 spermatids
181
what do spermatids differentiate into
spermatozoa
182
how does FSH affect spermatogenesis
acts on sertoli cells - stimulate agents to initiate spermatogenesis
183
how does LH affect spermatogenesis
acts on Leydig cells to stimulate testosterone - diffuses into seminiferous tubules to facilitate spermatogenesis
184
describe the negative feedback mechanism of testosterone
inhibits LH secretion by acting in hypothalamus to reduce GnRH and acts on anterior pituitary to decrease LH response to GnRH
185
what do oogonia differentiate into
primary oocytes
186
what do primary oocytes become after meiosis 1
secondary oocyte + polar body
187
what does the secondary oocyte become after meiosis 2
ovum + polar body
188
what are primordial follicles
a primary oocyte surrounded by a single layer of granulosa cells
189
what do granulosa cells secrete
oestrogen
small amounts of progesterone
inhibin
190
what happens in the follicular phase of the menstrual cycle (day 1-13)
primordial follicles -> primary follicle (zona pellucida forms -> preantral follicle (theca cells - synthesise oestrogen) -> early antral follicle -> mature follicle (only dominant follicle)
191
what is ovulation and when does it occur
day 14
| walls of follicle rupture
192
what happens in the luteal phase of the menstrual cycle (day 14-28)
mature follicle collapses -> corpus leteum formed ->if not fertilised then aptosis -> menstuation
193
what does the corpus luteum secrete
oestrogen
progesterone
inhibin
194
what is another name for the mature follicle
graafian follicle
195
what happens to the level of FSH during the menstrual cycle
increases in early follicular phase - then decreases apart from a mid cycle peak
196
why is FSH required in the menstrual cycle
development of follicle beyond pre-antral and early antral
| stimulates granulosa cells to multiply and produce oestrogen
197
what happens to the level of LH throughout the menstrual cycle
constant for follicular phase then shows a very large mid-cycle increase
198
what happens to the levels of oestrogen throughout the menstrual cycle
remains fairly low and stable for first week - increases rapidly during second week as dominant follicle secretes more oestrogen
then decreases before LH peak
second increase due to secretion by corpus luteum
ends with rapid decrease
199
what happens to the progesterone levels during the menstrual cycle
small amount in follicular (by ovaries) -> corpus luteum secretes a lot after ovulation -> rapid decrease
200
what happens to inhibin levels during the menstrual cycle
increases during late follicular -> high in luteal -> decreases as corpus luteum degenerates
201
describe the menstrual phase of the menstrual cycle (uterine)
day 1
| endometrium degenerates - stimulated by withdrawal of progesterone
202
describe the proliferative phase of the menstrual cycle (uterine)
day 5
| menstruation stops - endometrium begins to thicken + growth of myometrium via influence of oestrogen
203
describe the secretary phase of the menstrual cycle (uterine)
soon after ovulation under influence of oestrogen and progensterone
endometrium secretes glycogen, glycoproteins and mucopolysaccharides
204
what helps sperm break into the zona pellucida
acrosomal enzymes
205
describe the stages of fertilisation
fertilisation-> zygote -> divides into morula -> blastocyst -> syncitrophoblast which implants into stroma
206
what is the role of HcG
maintains corpus luteum
207
how does maternal blood enter and leave the placental sinuses
uterine arteries and veins
208
what is the role of oestrogen during pregnancy
stimulates growth of uterine muscle mass, regulates progesterone, prepares breasts for feeding, increases through pregnancy
209
what is the role of progesterone during pregnancy
inhibits contractility, increases throughout pregnancy, increases thickness of uterine lining
210
what is the role of relaxin during pregnancy
limits uterine activity and involved in cervical ripening
211
what is the role of oxytocin in pregnancy
stimulates uterine contractions
212
what is the role of prostaglandins in pregnancy
initiates labour
213
what is parturation
birth process
214
how much K+ is reabsorbed in the PCT
90%
215
what part of the nephron can secrete K+
cortical collecting ducts
216
describe the phosphate urinary buffer
H+ excreted binds to phosphate and acid is excreted with phosphate
217
describe the ammonium phosphate buffer
glutamate both from lumen and PCT are broken down into ammonia and carbonate
carbonate enters blood
ammonia excreted into lumen as waste
218
what colour is pheomelanin
red/yellow
219
what colour is eumelanin
brown/black
220
what innervates the adrenal glands
splanchnic nerve
221
what does the medulla of the adrenal glands secrete
catecholamines - adrenaline + noradrenaline
222
what does the zona fasciculate secrete
glucocorticoids e.g. cortisol
