202 ES - Physiology Flashcards
1
Q
Anterior pituitary secretions (5)
A
Growth hormone
Prolactin
Adrenocorticotropin or corticotropin (ACTH)
Thyrotropin or thyroid-stimulating hormone (TSH)
Gonadotropins (FSH & LH)
2
Q
Posterior pituitary secretions (2)
A
Anti-diuretic hormone (ADH)
Oxytocin
3
Q
Secretory cells of pituitary gland & their secretion
A
Somatotropes (Acidophils) - somatotropin (Growth hormone GH) Corticotropes - corticoropin (ACTH) Thyrotropes - TSH Gonadotropes - FSH & LH Lactotropes - prolactin
4
Q
Growth hormone (GH)
A
Growth of body
5
Q
Thyrotropin (TSH)
A
Stimulate thyroid to produce hormones
6
Q
Corticotropin
A
Stimulates adrenal cortex to produce cortisol
7
Q
Prolactin
A
Stimulates milk production from breast
8
Q
FSH & LH
A
Reproductive function in males & females
9
Q
What controls anterior pituitary secretion?
A
Hypothalamus
- hypothalamic releasing & inhibitory hormones
10
Q
How do neurons from hypothalamus reach anterior pituitary gland?
A
From hypothalamic nucleus → hypothalamic-hypophyseal portal vessels
11
Q
Releasing hormones of hypothalamus & affected hormone
A
Thyrotropin-releasing hormone (TRH) - TSH
Corticotropin-releasing hormone (CRH) - ACTH
GH releasing hormone - GH
Gonadotropin-releasing hormone (GnRH) - FSH & LH
Prolactin releasing hormone - prolactin
12
Q
Inhibitory hormones of hypothalamus & affected hormone
A
GH inhibitory hormone (somatostatin) - GH
Prolactin inhibitory hormone (PIH/dopamine) - Prolactin
13
Q
Sheehan syndrome
A
Affects women, following post-partum hemorrhage
Reduced blood flow to pituitary → pituitary infarction & necrosis → pituitary hormone insufficiency
14
Q
Functions of growth hormone
A
Growth
Metabolic
Bone growth
15
Q
When does the lengthening of bone stop?
A
After fusion of epiphysis with shaft
16
Q
What is the effect of GH on bones after adulthood?
A
Thickening of bone
17
Q
Effect of GH on protein
A
↑ cellular protein synthesis; ↓ protein breakdown
Anabolic effect
18
Q
Effect of GH on adipocytes
A
↑ lipolysis → ↑ free fatty acids
19
Q
Why does lipolysis cause protein sparing?
A
Lipolysis mobilize free fatty acid, which supplies energy
20
Q
Protein sparing
A
Body derives energy from sources other than protein
21
Q
How does GH affect carbs metabolism?
A
- Decrease glucose uptake in tissue
- Increase glycogenesis
- Increase insulin secretion (compensatory)
22
Q
Diabetogenic effect of GH
A
It mimics insulin’s glucose-lowering effect
23
Q
GH effect on bone growth
A
- Increase protein production by chondrocytic & osteogenic cells
- Increased rate of reproduction of these cells
- Converting chondrocytes into osteogenic cells → deposition of new cartilage in epiphysis & conversion to bone
24
Q
Chondrocytic cells
A
Produce and maintain the cartilaginous matrix
25
Osteogenic cells
Only bone cells that divide
| Develop into osteoblasts → responsible for forming new bones
26
How does osteoblast affect bones after adulthood?
Increases bone thickness, mainly membranous bones
Protrusion of jaw
Bony protrusions over eyes
27
Somatomedin C
When GH acts on liver/cartilage
| aka. insulin-like growth factor 1 (IGF-I)
28
Factors affecting GH secretion
↓ Secretion: Aging
```
↑ Secretion
Exercise, excitement, trauma
Deep sleep
Ghrelin - produced before meals
Acute hypoglycemia
Chronic protein deficiency - Kwashiorkor
Low free fatty acid
Starvation
Stress
```
29
Regulation of GH secretion
Secretion: GHRH
Inhibition: GHIH
30
What happens if there's excessive GH?
Negative feedback → inhibition & decrease secretion
31
Panhypopituarism
Decreased secretion of all anterior pituitary hormones
- hypothyroidism, decreased secretion of adrenal hormones, decreased secretion of gonadotropins
32
Dwarfism causes
Decreased GH secretion during childhood
Deficiency of somatomedin C - African pygmies & Levi-Lorain syndrome
Part of panhypopituitarism - sexual maturation also impaired
33
Gigantism causes
Hypersecretion of hormone during childhood
| Pituitary tumors → hypersecretion
34
Acromegaly causes
Increased GH secretion after fusion of epiphysis
| GH producing tumor in anterior pituitary → increased thickness of bones
35
Signs of acromegaly
Protrusion of jaw - prognathism
| Enlarged, hands, feet & membranous bones
36
Deficiency of GH can lead to?
Dwarfism
37
Excess secretion of GH may lead to?
Gigantism
| Acromegaly
38
GH can ______ blood glucose in pt with hypoglycemia, why?
increase; due to negative feedback
39
Where does the anterior pituitary develop from?
Rathke's pouch
40
Where does the posterior pituitary originate from?
Neural ectoderm
41
Where are hormones produced in?
Hypothalamic nuclei (Supraoptic & paraventricular nuclei)
42
What is posterior pituitary mainly composed of?
Pituicytes (glial cells)
43
Hypothalamic-hypophysial tract
How hormones are transported from hypothalamic nuclei to pituitary
44
What happens if pituitary stalk is cut?
Decrease of hormone production, but normal after few days - secreted by the cut ends of the fibers by neurophysins
45
Where is ADH produced?
Suproptic nuclei
46
Where is oxytocin secreted?
Paraventricular nucleus
47
How are ADH & oxytocin secreted at nerve terminal?
Exocytosis
48
Function of ADH
Increases reabsorption of water from DCT & collecting duct
49
How does ADH increase reabsorption?
By inserting aquaporins in epithelium of DCT & collecting ducts - through V2 receptors → concentrated urine
50
Stimulus for ADH secretion
Hyperosmolarity of blood
| Decrease in blood volume
51
Osmoreceptors
Sense an increase in blood osmolarity → stimulate ADH secretion
52
Baroreceptors
Sense decrease in bp hence decrease blood volume → stimulate ADH secretion
53
Inhibition of ADH secretion
Alcohol
54
Diabetes insipidus
Secretion of ADH from hypothalamus decrease due to injury, infection, congenital
55
Signs of diabetes insipidus
Pt passes large volumes of dilute urine
Persists even with water deprivation
Results in dehydration
High blood osmolarity
56
Nephrogenic diabetes insipidus
Production of ADH normal, but the kidney is not responding to ADH
57
Treatment of diabetes insipidus
Desmopressin (DDAVP)
58
Treatment of nephrogenic diabetes insipidus
Doesn't respond to DDAVP
| Treat cause
59
Syndrome of inappropriate ADH secretion (SIADH)
Increased secretion of ADH
| - causing hyponatremia - water retention & decrease blood osmolarity
60
Neuroendocrine reflex (oxytocin - contraction of uterus)
Positive feedback:
1. Baby's head stretches cervix
2. Cervical stretch excites fundic contraction ( → stimuli reaches hypothalamus → release oxytocin)
3. Fundic contraction pushes baby down & stretches cervix more
4. Repeats until expulsion of baby
61
Main functions of oxytocin
Uterine contraction
| Milk ejection
62
Why is T4 converted to T3?
bc T3 is more potent than T4
| It has a shorter life and less amount, but more active than T4
63
Difference between T3 & T4
T3 - active thyroid hormone
| T4 - precursor of the thyroid hormone
64
What do thyroid follicles contain?
Filled w colloid made of glycoprotein thyroglobulin
| Lined by cuboidal epithelium
65
C cells
between follicles; secrete calcitonin
66
Calcitonin
Lower blood calcium
67
Synthesis of thyroid hormones
1. Thyroglobulin synthesis
2. Iodide trapping - sodium-iodide symport pump
3. Oxidation of iodide - by peroxidase
4. Transport of iodine into follicular cavity - by iodide-chloride pump - "pendrin"
5. Iodination of tyrosine (organification) - iodine binds with thyroglobulin
6. Coupling reactions
68
Coupling reactions of thyroid hormones
2 DIT - T4
| MIT + DIT = T3
69
Release of thyroid hormones
1. Thyroglobulin w hormone is taken up by epithelial cells by endocytosis
2. Vesicles fuses w lysosomes
3. Lysosomal enzymes cleave the hormone
4. Hormone exits cell through basolateral side into blood
70
Deiodinase
Remove iodine from MIT & DIT for reuse
71
Deficiency in deiodinase will result in?
Hypothyroidism
- bc iodine from MIT & DIT cannot be reused
72
How is thyroid hormone transported?
By binding to plasma proteins - thyroxine-binding globulin
73
MOA of thyroid hormones
Genomic - slower
| Non-genomic - faster
74
Thyroid hormone effect on metabolism
↑ metabolic activity
| ↓ body weight
75
______ can cause diabetes mellitus
Hyperthyroidism
- Hyperthyroidism is typically associated with worsening glycemic control and increased insulin requirements.
76
______ have high blood cholesterol
Hypothyroidism
- hypothyroidism LDL cholesterols not removed quickly, LDL accumulates
77
______thyroidism causes weight gain;
| ______thyroidism causes weight loss & increased appetite
Hypothyroidism; Hyperthyroidism
78
Thyroid hormone effect on growth
Important for skeletal growth & brain development
79
Why does hypersecretion of thyroid hormone cause reduced height?
Due to early fusion of epiphysis
80
Thyroid hormone effect on CVS
```
↑:
CO
HR
Force of contraction
↑ Systolic ↓ Diastolic
```
81
Thyroid hormone effect on GI
↑ GI secretion & motility
82
Diarrhoae in ______;
| Constipation in ______
hyperthyroidism; hypothyroidism
83
Thyroid hormone effect on CNS
Increase cerebration - working of the brain
84
Does hyperthyroidism or hypothyroidism cause extreme worry?
Hyperthyroidism
85
Thyroid hormone effect on hormones
↑ insulin secretion - bc hyperglycemia from carb metabolism
| ↑ PTH - bc ↑ skeletal growth
86
Thyroid hormone effect on sexual function
Hyposecretion - ↓ libido (M & F)
Hypersecretion - impotence (M)
Hypersecretion & hyposecretion - menstrual abnormalities (F)
87
Regulation of thyroid hormone secretion
Negative feedback:
1. Hypothalamus secretes TRH, stimulate anterior pituitary
2. Anterior pituitary secretes TSH, stimulate thyroid gland
3. Thyroid gland secretes thyroid hormones, ↑ in thyroid hormones → ↓ TSH & TRH
88
Goiter
Enlargement of thyroid gland indicating ↑ TSH
89
Antithyroid drugs - Thiocyanate
1. Bind to sodium-iodide transporter & inhibits the uptake of iodine
2. Thyroglobulin formed normally
3. Iodination & formation of thyroid hormones ↓
4. Lack of negative feedback → ↑ TSH → goiter
90
Antithyroid drugs - Propylthiouracil
1. Inhibits iodination & coupling
2. ↓ thyroid hormone secretion
3. ↓ negative feedback → ↑ TSH → goiter
91
Antithyroid drugs - Iodides
Given in high amounts can reduce thyroid secretory activity
Reduces size of thyroid gland & vascularity
Given 2-3 weeks before surgery to reduce bleeding
92
Grave's disease
Antibody against TSH receptor; increase secretion of thyroid hormones
93
Expothalamos
Protrusion of eyeballs
| Seen in hyperthyroidism
94
Hyperthyroidism:
| ______ thyroid hormones; ______ TSH
Increase; reduced
95
How to distinguish between Grave's disease & adenoma?
Grave's disease: the presence of antibodies
| Adenoma: antibody absent
96
Hyperthyroidism treatment
Surgical removal - adenoma
Antithyroid drugs
Radioactive iodine
97
Hashimoto's disease
Autoimmune thyroiditis
| Decrease secretion of thyroid hormones
98
Hypothyroidism:
| ______ thyroid hormones; ______ TSH
Low; elevated
99
Treatment of hypothyroidism
Thyroxine (T4) tablets
100
Cretinism
Congenital hypothyroidism
Affects growth and mental development
矮呆病
101
How is cretinism prevented?
By measuring TSH immediately after birth
102
What is important in thyroid hormone synthesis?
Iodine
103
Deficiency of thyroid hormone in childhood may lead to?
Crenism w short stature & mental retardation
104
Cause of hyperthyroidism
Grave's disease
| Adenoma
105
Cause of hypothyroidism
Iodine deficiency
106
What is parathyroid hormone important for?
Maintaining blood calcium
| ↑ calcium ↓ phosphate
107
Normal volume of calcium
9-11 mg/dL
108
Uses of ionized calcium
Contraction of skeletal, cardiac, smooth muscle
Blood clotting
Transmission of nerve impulses
109
Hypocalcaemia can cause?
Tetany
110
Hypercalcemia can cause?
Depression
111
Daily intake of calcium
~1000 mg/day
112
What controls calcium & phosphate absorption from intestine?
Vitamin D
113
How is calcium excreted?
Mainly feces
114
Calcium absorption from kidney is from?
PCT
DCT
Collecting duct
115
What are bones made of?
70% salts & 30% matrix
| Newly formed bone more matrix
116
Bone matrix contains?
Mainly collagen
| Also proteoglycans - chondroitin sulfate & hyaluronic acid
117
Bone salts are?
Calcium & phosphate in hydroxyapatite crystal form
118
Collagen give ______ strength;
| Hydroxyapatite crystals give ______ strength.
tensile; compressional
119
Mechanism of Bone Calcification
1. Osteoblast secrete collagen molecules → form osteoid
2. Osteoblast gets trapped in osteoid → form osteocytes
3. Calcium & phosphate start precipitating (non-crystalline - amorphous) → forms hydroxyapatite crystals
120
Regulation of Bone Calcification
Normally inhibited by: pyrophosphate
| Osteoblasts secretes tissue non-specific alkaline phosphatase (TNAP) to inhibit pyrophosphate
121
______ bone formation can cause ______ TNAP (Tissue Nonspecific Alkaline Phosphatase) in blood.
Increased; increase
122
Site of abnormal calcification
Blood vessels (atherosclerosis)
Old clots
Degenerating tissues
123
Osteoblasts
Help in formation of new bone
124
Osteoclasts
Cause resorption of bones under influence of PTH
125
PTH action of osteoblasts
Secrete RANKL, inhibit OPG
126
RANKL
Activates osteoclasts
127
OPG
Inhibits activation of osteoclasts
128
Oestrogen ______ OPG (osteoprotegerin) production, why?
stimulates;
| prevents osteoporosis in women
129
Steps of bone remodelling
1. Osteoclast eats bone & create tunnel
2. Osteoblast take over & deposit new bone in concentric circles - "lamellae"
3. Deposition continues until blood vessel reach - which runs through Haversian canal
130
Osteon
Area of new bone formation
131
Callus
New bone formation after fracture
132
Formation of Vitamin D
1. 7-dehydrocolestrol → Vitamin D3 (UV, skin)
2. Vitamin D3 → 25(OH)D (liver)
3. 25(OH)D → 1,25(OH)2D3 (kidney)
133
Functions of Vitamin D
↑ calbindin (calcium bindng) protein in intestinal epithelium
↑ phosphate absorption
↑ calcium & phosphate absorption from kidney
134
What are calcium sensing receptor (caSR)?
Sense calcium levels in blood, located on chief cells
↓ Calcium ↑ PTH
135
PTH action on bone
↑ bone resorption
136
PTH action on kidney
↑ calcium absorption
↑ phosphate excretion
↓ phosphate reabsorption from PCT
137
PTH action on intestine
↑ calcium & phosphate reabsorption
138
Where is calcitonin produced?
C cells
139
Function of calcitonin
↓ blood calcium levels
↑ calcium ↑ calcitonin
140
Signs of Hypoparathyroidism
↓ blood calcium levels → tetany
Chvostek sign - contraction of facial muscles provoked by lightly tapping over the facial nerve anterior to the ear as it crosses the zygomatic arch
Trousseau sign - carpopedal spasm
141
Chvostek sign
Tapping of facial nerve in front of tragus of ear causes contraction of facial muscles
Seen in hypoparathyroidism
142
Trousseau sign
Spasm of hand muscle on inflating BP cuff
Seen in hypoparathyroidism
143
Treatment of hypoparathyroidism
PTH
Vitamin D
Calcium injection
144
Signs of Hyperparathyroidism
↑ osteoclastic activity
| ↑ calcium ↓ phosphate
145
Cause of primary hyperparathyroidism
Adenoma of parathyroid gland secreting PTH
146
Cause of secondary hyperparathyroidism
Vitamin D deficiency
| Renal disease
147
Vitamin D deficiency in children causes?
Rickets
148
Vitamin D deficiency in children causes?
Osteomalacia
| 軟骨病
149
Adrenal medulla produces which 2 hormones?
Epinephrine
| Norepinephrine
150
Adrenal cortex produces which hormones?
Corticosteroids
151
What does zona glomerulosa produce?
Mineralocorticoid - aldosterone
152
What stimulates secretion of zona glomerulosa?
Angiotensin II
| Potassium
153
What does zona fasciculata produce?
Glucocorticoid - cortisol
154
What stimulates secretion of zona fasciculata?
ACTH
155
What does zona reticularis produce?
Adrenal androgens - dehydroepiandrosterone (DHEA) & androstenedione
156
Synthesis of adrenal hormones
1. Synthesised from LDL cholesterol
2. LDL cholesterol is taken up by cells - receptor-mediated endocytosis
3. Converted to pregnenolone by cholesterol desmolase in mitochondria
157
Function of aldosterone
Cause sodium & water reabsorption in kidney
158
Main stimuli for aldosterone
High blood potassium & angiotensin II
159
Function of glucocorticoid
| - Carbohydrate metabolism
↑ gluconeogenesis
160
Functions of glucocorticoid
```
Carbohydrate metabolism
Protein metabolism
Fat metabolism
Stress
Inflammation
```
161
Function of glucocorticoid
| - Protein metabolism
↓ protein synthesis & ↑ protein catabolism
162
Function of glucocorticoid
| - Fat metabolism
↑ lipolysis
163
What happens w excess cortisol?
Cortisol ↑ glucose uptake
| Excess cortisol → hyperglycaemia → diabetes
164
Buffalo hump
↑ fat deposition in certain areas of the body
165
Moon face
↑ fat deposition in face
166
What happens to glucocorticoid levels during stress?
Cortisol ↑ during physical & mental stress
as it ↑ blood glucose, a.a., f.f.a. may be useful in stress
167
Glucocorticoid role on inflammation
Blocks inflammation
168
Regulation of cortisol secretion
Controlled by ACTH (anterior pituitary), which is controlled by CRH (hypothalamus)
CRH (hypothalamus) → ACTH (anterior pituitary) → Cortisol (adrenal cortex)
169
What causes release of CRH?
Hypertrophy of zona fasciculata & reticularis
Pain stimuli reaches hypothalamus through brainstem
Mental stress activating limbic system
170
↑ cortisol causes ______ feedback ↓ of ACTH & CRH
negative
171
Cortisol levels are ______ during early morning.
higher
172
Effect of adrenal androgens in male
Early development of sex organs
173
Effect of adrenal androgens in female
↑ Libido
| Growth of axillary & pubic hair
174
What happens with excess ACTH?
Have MSH like activity - stimulation of melanocytes in skin & ↑ pigmentation
175
Causes of primary hypoadrenalism
Adrenal insufficiency/Addison's disease
Autoimmune destruction
Tuberculosis
Cancer invasion
176
Causes of secondary hypoadrenalism
↓ ACTH production by anterior pituitary
177
Clinical features of hypoadrenalism
Lack of mineralocorticoids
| Lack of glucocorticoids
178
Treatment of hypoadrenalism
Mineralocorticoids
| Glucocorticoids
179
Cushing's disease
↑ secretion of ACTH secretion from anterior pituitary tumor → hyperadrenalism
180
Causes of hyperadrenalism
Adenoma of adrenal cortex
↑ secretion from other tumors
↑ CRH secretion from hypothalamus
↑ secretion of ACTH secretion from anterior pituitary tumor - Cushing's disease
181
Suppression of Cushing's disease
High doses of dexamethasone
182
Cushing's syndrome
Hyperadrenalism - ↑ secretion of cortisol
183
Cushing's syndrome vs Cushing's disease
Syndrome - hyperadrenalism
| Disease - cause of hyperadrenalism
184
Clinical features of Cushing's syndrome
```
↑ facial hair & acne
Androgenic effects
Mineralocorticoid action
Muscle weakness
Purplish striae - tear of subcutaneous tissue
```
185
Treatment of Cushing's syndrome
Surgical removal of the tumor
| - drug treatment if surgery not feasible
186
Causes of hyperaldosteronism
Primary hyperaldosteronism - aka Conn's syndrome - caused by tumor of zona glomerulosa
187
Clinical features of hyperaldosteronism
Hyperkalaemia
| Metabolic alkalosis
188
Treatment of hyperaldosteronism
Surgical removal of tumor
| Aldosterone receptor blocker - spironolactone
189
Adrenogenital syndrome
Excess adrenal androgen production
190
Clinical features of adrenogenital syndrome - female
Growth of beard, deep voice, baldness
↑ body hairs
Enlargement of clitoris
↑ muscle mass
191
Clinical features of adrenogenital syndrome - male
Growth of beard, deep voice, baldness
↑ body hairs
↑ muscle mass
Enlargement of penis
192
Diagnosing feature of adrenogenital syndrome
↑ excretion of 17 ketosteroid in urine
193
What is cortisol important for?
Metabolism & stress response
194
Diabetes mellitus
A chronic disease that occurs when the pancreas is no longer able to make insulin (type 1) or when the body cannot make good use of insulin it produces (type 2)
195
The pancreas is made up of collections of cells called?
Islets of Langerhans
196
4 major cell types in islets of Langerhans & their secretion
Alpha - glucagon
Beta - insulin
Delta - somatostatin
PP cell - pancreatic polypeptide
197
Where is insulin synthesized?
rER
198
Steps in insulin synthesis
Preproinsulin → proinsulin (contains B chain, A chain, C peptide) → excise C peptide → insulin
199
What stimulates insulin secretion?
Stimuli that ↑ cAMP levels
- probably by ↑ intracellular Ca2+
200
2 incretin hormones
Glucose-dependent insulino-tropic polypeptide (GIP)
| Glucagon-like peptide (GLP-1)
201
The function of incretin hormones
Enhance the rate of insulin release from the pancreatic β cells in response to an ↑ in plasma glucose.
202
Where is GIP (Gastric inhibitory polypeptide) synthesized?
K cells of duodenum
203
Where is GLP-1 synthesized?
L cells in ileum & colon
204
What type of receptor is an insulin receptor?
Enzyme-linked receptor
205
Subunits of insulin receptor
2α
| 2β
206
Is insulin anabolic or catabolic?
Anabolic
- ↑ storage of glucose, f.a. & a.a.
207
Under what conditions are large amounts of glucose used by muscle?
1. Moderate/heavy exercise
| 2. Few hours after meal
208
Transporters for glucose
GLUT1 - BBB & erythrocytes
GLUT2 - renal tubular cells, liver cells, pancreatic beta cells
GLUT3 - neurons & placenta
GLUT4 - adipose tissue & striated muscle
SGLT1 - ~10% - distal proximal tubule (S3)
SGLT2 - ~90% - early proximal tubule (S1&S2)
209
Actions of insulin on carbohydrate metabolism
1. It ↑ the rate of transport of glucose across the cell membrane in adipose tissue and muscle
2. It ↑ the rate of glycolysis in muscle and adipose tissue
3. It stimulates the rate of glycogen synthesis in adipose tissue, muscle, and liver.
4. ↓ the rate of glycogen breakdown in muscle and liver
5. It inhibits the rate of glycogenolysis and gluconeogenesis in the liver.
210
GLUT1 is insulin-______;
| GLUT4 is insulin-______
independent; dependent
211
What happens to insulin actions on GLUT4 (insulin-dependent) in DM?
Intracellular glucose deficiency
| ↑ protein catabolism
212
What happens to insulin actions on GLUT1 (insulin-independent) in DM?
Intracellular hyperglycemia
| Non-enzymatic glycosylation
213
Effects of hyperglycemia
High intracellular glucose levels → Aldose reductase (enzyme) activation → Sorbitol formation → ↓ Na+/K+ ATPase activity
Glucose attaches (non-enzymatically) to the protein amino groups → amadori products → Advanced glycosylation end products (AGEs) → cause cross-linkage of matrix proteins → Damage to blood vessels
↑ Sorbitol and fructose in Schwann cells → disruption in their structure and function
214
What is the renal threshold for glucose?
180 mg/dL
215
What happens if plasma glucose exceeds threshold?
Glucose appears in the urine
| Polyuria, polydipsia
216
What is the effect of insulin on lipid metabolism?
↓ FFA conc in plasma
- Stimulates synthesis of triglycerides in the liver & adipose tissue
- Stimulates lipoprotein lipase – Increased uptake of FFA into the adipose tissue
- Inhibits hormone-sensitive lipase
217
What happens to lipid metabolism during insulin deficiency (DM)?
Causes lipolysis of storage fat and release of FFA
- bc hormone-sensitive lipase strongly activated
218
What happens with excess FFA during DM?
FFA are catabolized to acetyl CoA → excess acetyl CoA → ketone bodies
219
Diabetic ketoacidosis
When there's excess ketone bodies in blood causing acidosis
220
Kussmaul breathing
Rapid, deep breathing caused by metabolic acidosis
221
Effects of insulin on protein metabolism
- Stimulates transport of FAA across the plasma membrane in liver and muscle.
- Stimulates protein synthesis and reduces release of a.a. from muscle
222
Consequences of disturbed protein metabolism
- ↑ protein breakdown → muscle wasting
- ↓ protein synthesis
- ↑ plasma amino acids and nitrogen loss in urine → negative nitrogen balance and protein depletion.
- Protein depletion is associated with poor resistance to infections.
223
Signs of diabetes mellitus
```
Hyperglycemia
Glucosuria
Polydipsia
Polyuria
Polyphagia
Ketosis, acidosis, coma
```
224
Macrovascular & Microvascular complications of DM
Macrovascular:
- Stroke
- Peripheral vascular disease
- Myocardial infarction
Microvascular:
- Retinopathy
- Nephropathy
- Neuropathy
225
Cause of hypoglycemia
Drug overdose
Missing meals
Excercise
226
Adrenergic & Neuroglycopenic symptoms of hypoglycemia
Adrenergic symptom - palpitation, tremor, anxiety
Neuroglycopenic symptoms - confusion, fatigue, lethargy, loss of co-ordination, seizure, coma
227
Body response to hypoglycemia
1. Inhibition of insulin secretion
2. Secretion of glucagon, epinephrine & growth hormone
3. Secretion of cortisol
228
What controls growth?
Mainly hormones
Genetic factors
Environmental factors - nutrition
Involves cell division & protein synthesis
229
What is the bone matrix made up of?
Collagen, which is mostly calcium phosphate
230
How does elongation of bone occur?
1. On the epiphyseal growth plate, active proliferating cartilages are present
2. Osteoblasts convert the cartilage into bone, Chondrocytes produce cartilage
3. The simultaneous action causes growth plate widens
231
How does growth hormone work?
1. For the initial 1-2 years - GH ↑ cell division (mitogen); and ↑ maturation and cell division of chondrocytes
2. Causes widening of growth plate & lengthening of the bone
232
How does IGF-1 work with growth hormone?
1. GH acts on growth plate & converts prechondrocytes into chondrocytes
2. Mature cells secrete IGF-1 & produce receptors for IGF-1
3. IGF-1 undergo autocrine/paracrine action to stimulate cell division
233
Hormonal pathway controlling GH & IGF-1 secretions
Stimulus
→ Hypothalamus - ↑ GHRH & ↓ SST
→ Anterior pituitary - ↑ GH
→ Liver & others - ↑ IGF-1 secretion
234
When does GH cause greatest growth?
Adolescence
235
Role of IGF-1 in foetal growth
Important for pre-natal growth, esp nervous growth
Stimuli for secretion: placental lactogen
236
List the hormones that affect growth
```
Growth Hormone & IGF-1
Thyroxine
Insulin
Sex hormones
Cortisol
```
237
How is thyroid hormone involved in growth?
Facilitates synthesis of growth hormone
Stimulates chondrocyte differentiation
Stimulates growth of new blood vessels in developing bone
↑ responsiveness of bone to fibroblast-derived growth factor
238
Cretinism
Physical deformity & learning disabilities that is caused by congenital thyroid deficiency.
239
How is insulin involved in growth?
Stimulates cell division & differentiation during fetal period & childhood
Anabolic effect of insulin
↑ glucose & a.a. uptake by insulin-sensitive cells
↑ fat storage
↑ protein synthesis & ↓ protein breakdown
240
How are sex hormones involved in growth?
Testosterone & oestrogen
↑ growth of long bones & vertebrae
Stimulate secretion of GH & IGF-1
Stop growth by causing epiphyseal closure
241
How is cortisol involved in growth?
↑ protein catabolism
Inhibits bone growth & ↑ bone breakdown
↓ DNA synthesis
↓ secretion of GH & IGF-1
242
How is testosterone involved in growth?
Causes protein synthesis in non-productive organs & tissue
| ↑ muscle mass
