Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology 2nd Semester > PHS204 Thyroid And Reproductive Hormone > Flashcards

PHS204 Thyroid And Reproductive Hormone Flashcards

1
Q

What is the gross/functional anatomy of the thyroid gland?

A

Largest endocrine gland
15-25g
2 lobes joined by a narrow isthmus
highly vascularised and highly perfused

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the functional unit of the thyroid?

A

Thyroid follicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the principle thyroid hormones?

A

Tri-iodothyronine T3 10% Responsible for most tissue action
Thyroxine T4 90%
NB: T4 must be conveted to T3 to be active

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Cells and structures of the thyroid gland include…

A

Follicular cells - secrete thyroid hormone
Parafollicular cells-between follicular cells
-secrete calcitonin (in vloved in calcium homeostasis)
- colloid: contains thryoglobulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Thyroid hormone biosynthesis and storage

A

Iodine trapping
Synthesis and secretion of thyroglobulin
oxidation of iodides
organification of thyroglobulins
couplinh reaction
storage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Iodine trapping

A

Iodide is actively transported from the blood into follicular cells, against an electrochemical gradient.
Iodide is transported into the follicular cell along with sodium by a sodium-iodide symporter
Thyroid stimulating hormones controls iodide uptake
Anti-thyroid agents: Thiocynate and perchlorate inhibit iodide transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Thyroglobulin Synthesis and Secretion

A

The rough endoplasmic reticulum and Golgi apparatus in the follicular cells of the thyroid gland synthesize and secrete thyroglobulin realising into the lumen.

The Thyroglobulin molecule is a large glycoprotein containing 140 molecules of tyrosine residue (substrate for iodine for thyroid hormone synthesis). After synthesis, thyroglobulin is stored in the follicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Oxidation of iodides

A

Iodide must be oxidized to elementary iodine because only iodine is capable of combining with tyrosine to form thyroid hormones
Taken into lumen by transporter -pendrin.
The oxidation of iodide into iodine occurs inside the follicular cells in the presence of thyroid peroxidase. Absence or inactivity of this enzyme stops the synthesis of thyroid hormones.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Organification of thryoglobulins

A

First, iodine is transported from follicular cells into the follicular cavity, where it binds with thyroglobulin. This process is called the organification of thyroglobulin. Then, iodine (I) combines with tyrosine, which is already present in thyroglobulin

The iodination process is accelerated by the
enzyme iodinase, which is secreted by follicular cells.
Iodination of tyrosine occurs in several stages.

Tyrosine is iodized first (at position 3) into monoiodotyrosine (MIT) and later (at position 5) into di-iodotyrosine (DIT). MIT and DIT are called iodotyrosine residues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

coupling reaction

A

One molecule of DIT and one molecule of MIT
combine to form tri-iodothyronine (T3)

Two molecules of DIT combine to form tetraiodothyronine (T4), which is thyroxine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Storage of thyroglubulin

A

After synthesis, the thyroid hormones remain in the form of vesicles within thyroglobulin and are stored and can meet body requirements for 1-3 motnhs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Thyroid hormone is hydrophobic T/F

A

TRUE
It along with steroid hormones are not water soluble and therefore typically found bound with a plasma protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are C cells?

A

Parafollicular cells that make calcitonin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Examples of non-regenerative cells

A

neurons
neprons
cardiac myocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is transcription?

A

Transcription, is the process of making an RNA copy of a gene’s DNA sequence. This copy, called messenger RNA (mRNA), carries the gene’s protein information encoded in DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is translation?

A

Translation is the process in which ribosomes in the cytoplasm or endoplasmic reticulum synthesize proteins after the process of transcription of DNA to RNA in the cell’s nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Difference between lipophlic and lipophobic hormones

A

Lipophilic: can diffuse through the cell membrane
Liphophobic: needs transporters to pass through the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Thyroid hormone secretion is regulated by

A

Negative feedback
Auto Regulation of the thyroid gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Regulation of thyroid hormone by negative feedback

A

When levels of T3 and T4 decrease below normal, the hypothalamus releases thyroid regulating hormone (TRH), stimulating the anterior pituitary gland to produce thyroid stimulating hormone (TSH), which acts on the thyroid gland to produce more hormones and raise the blood levels. Once the levels rise, the hypothalamus “shuts off” and stops secreting TRH, which in turn inhibits the anterior pituitary gland release of TSH.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Regulation of thyroid hormone by autoregulation

A

Thyroid gland secretion is regulated by iodine in food
Iodine content in food and iodide trapping are inversely proportional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Action of thyroid hormone

A

Effects on growth and tissue development
effects on metabolic rates in general
effect on metabolism of carbohydrates fats protein vitamins
respiratory effects
cardiovascular effects
effects on nervous system development functioning of nervous tissue
effects on GIT
effects on reproductive system
Effects on other endocrine glands
effects on kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe the pancreas and why it is considered a dual-purpose organ

A

A triangular gland, which has both exocrine and endocrine cells.
• Located behind the stomach, closed to the duodenum.
•Exocrine cells-produce an enzyme-rich juice used for digestion.
•Endocrine cells- pancreatic islets (islets of Langerhans)-produce hormones involved in regulating fuel storage and utilisation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the islets of Langerhans?

A

The islets of Langerhans are small clusters of cells located in the pancreas and arranged as acinar cells that secrete hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Secretions from the islets of Langerhans includes

A

Alpha cells secrete glucagon- facilitates the breakdown of glycogen to glucose. This elevates the blood sugar.

Beta cells secrete the hormone insulin, which is essential for the maintenance of normal blood glucose levels.

Delta cells-secrete somatostatin, suppresses the release of glucagon and insulin.

F cell secretes pancreatic polypeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is insulin?

A

Hormone of nutrient abundance
•A protein hormone consisting of two amino acid chains linked by disulfide bonds
•Synthesized as part of proinsulin and then excised by enzymes, releasing functional insulin and C peptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Describe Insulin synthesis

A
  1. Preproinsulin is transcribes and translated in beta cells
  2. During translation, the signal peptide is cleaved to form proinsulin
  3. During packaging in granules by Golgi, proinsulin is cleaved (by endopetidases) into insulin and C peptide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Describe the regulation of Insulin synthesis

A

No insulin is produced when plasma glucose below 50 mg/dl
•Half-maximal insulin response occurs at 150 mg/dl
•A maximum insulin response occurs at 300 mg/dl
•Insulin secretion is biphasic:
–Upon glucose stimulation– an initial burst of secretion (5-15 min.)
–Then a second phase of gradual increment that lasts as long as blood glucose is high

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

The major targets for insulin are

A

–liver
–Skeletal muscle
–adipose tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe Incident action of insulin on carbohydrates metabolism

A

Liver:
•Stimulates glucose oxidation
•Promotes glucose storage as glycogen
•Inhibits glycogenolysis
•Inhibits gluconeogenesis

Muscle:
•Stimulates glucose uptake (GLUT4)
•Promotes glucose storage as glycogen

Adipose Tissue:
•Stimulates glucose transport into adipocytes
•Promotes the conversion of glucose into triglycerides and fatty acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Types of glucose transporters

A

GLUT2 (liver, pancreas)
•GLUT4, insulin sensitive transporter (muscle, adipose tissue)
•GLUT3 (brain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Function of glycogen

A

Short term storage of glucose
•Activates glycogen synthase
•Inhibit glycogen phosphorylase
•Glycolysis is also stimulated by insulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Lipogenic and anti-lipolitic function of pancreas

A

Insulin promotes lipogenesis and inhibits lipolysis
–Promotes formation of α-glycerol phosphate and fatty acid synthesis
–Stimulates fatty acid synthase (FAS)
–Inhibits hormone sensitive lipase (HSL)
–Activates lipoprotein lipase (LPL)

33
Q

The effects of the pancreas on protein synthesis

A

Insulin promotes protein accumulation:
1.Stimulates amino acid uptake
2.Increases the activity of protein synthesis
3.Inhibits protein degradation

34
Q

Describe action of insulin on the liver

A

Increase Glucose uptake (if blood glucose level is high)
Increase Glucose use
Increase Glycogenesis,
decrease glycogenolysis
Increase Glycolysis
decrease gluconeogenesis
Increase Fatty acid synthesis and very-low-density lipoprotein formation, decrease ketogenesis
decrease Urea cycle activity

35
Q

Describe the action of insulin on adipose tissue

A

Increase Glucose uptake by increasing GLUT-4 availability
Increase Glucose use
Increase Glycolysis
Increase Production of -glycerol phosphate
Increase Esterification of fats
Decrease Lipolysis

36
Q

Describe the action of insulin on muscle

A

Increase Glucose uptake by increasing GLUT-4 availability
Increase Glucose use
Increase Glycogenesis, decrease glycogenolysis
Increase Glycolysis
Increase Amino acid uptake (particularly branched-
chain amino acids)
Increase Protein synthesis, & decrease proteolysis

37
Q

What is glucagon

A

A 29-amino-acid polypeptide hormone that is a potent hyperglycemic agent
•Produced by α cells in the pancreas
•Its major target is the liver, where it promotes:
–Glycogenolysis
–Gluconeogenesis
–Release of glucose to the blood from liver cells

38
Q

What is glycogenolysis

A

the breakdown of glycogen to glucose

39
Q

What is gluconeogenesis

A

synthesis of glucose from lactic acid and non-carbohydrates

40
Q

How is glucogen regulated

A

Stimuli for Glucagon Secretion
Decrease Blood glucose
Increase Serum amino acids (arginine, alanine)
Sympathetic nervous system stimulation
Stress
Exercise

Inhibitors of Glucagon Secretion
Somatostatin
Insulin
Increase Blood glucose

41
Q

Symptoms of diabetes mellitus

A

Hyperglycemia
Polyuria
Polydipsia
Polyphagia
Ketoacidosis (IDDM)
Hyperlipidemia
Muscle wasting
Electrolyte depletion

42
Q

Where are reproductive hormone secreted from

A

Hypothalamus, anterior pituitary, posterior pituitary, ovary, testis and uterus

43
Q

What are the male reproductive organs and accessory organs

A

Main: testes and penis
Accessory: Prostate gland bubo urethral gland and seminal vesicle

44
Q

What are the female reproductive organs?

A

Ovary, uterus and placenta

45
Q

What are tropic hormones?

A

a group of hormones that stimulate other endocrine glands so as to produce their particular hormones. They are produced and secreted by the anterior pituitary gland.

46
Q

What are the reproductive tropic hormones?

A

GnRH - Gonadotropin releasing hormone
PRF - Prolactin-releasing factor
PIF - Prolactin- inhibiting factor
CRH - Corticotropin-releasing hormone

All peptide hormones

47
Q

The tropic hormones stimulate the production of

A

1.FSH & LH
2. Prolactin release
3. prolactin retention
4. Adrenocorticotropic hormone

48
Q

All hormones of the pituitary gland and hypothalamus are peptides true or false

A

TRUE

49
Q

Function of FSH

A

Estrogen release
follicle growth
Controls menstrual cycle
spermatogenesis

  • Protein hormone
50
Q

Function of LH

A

Regulation of ovulation
Sexual development and functioning controls the menstrual cycle
testosterone release

  • Protein hormone
51
Q

Function of prolactin

A

Milk synthesis

  • Protein hormone
52
Q

Function of ACTH

A

Release of glucocorticoid e.g. cortisol

-Poly peptide hormone

53
Q

Function of oxytocin

A

Parturition
milk ejection
Stimulates uterine contractions in labor and childbirth
It facilitates ejaculation of semen
it facilities sperm transports in the uterus

-Peptide hormone

54
Q

What’s hormones to the Ovaries secretes

A

Estrogen
progesterone

55
Q

Function of estrogen (Ovaries placenta and testis)

A

Regulation of the menstrual cycle

Regulates the development and functioning of the uterus.

It is mainly responsible for the changes that take place during pregnancy.

It is also responsible for secondary sexual characteristics and reproductive development during puberty.

-Steroid hormone

56
Q

Function of progesterone

A

Thickening the lining of your uterus for implantation.
Regulating bleeding during menstruation.
Supporting a pregnancy once conception occurs

poly peptide hormone

57
Q

Function of relaxin (secreted by the placenta And ovaries)

A

It loosens and relaxes your muscles, joints and ligaments during pregnancy to help your body stretch.

Relaxin also helps your body prepare for delivery by loosening the muscles and ligaments in your pelvis

-Polypeptide hormone

58
Q

Function of inhibin(secreted by the placenta And ovaries)

A

prevents FSH release
-Protein hormone

59
Q

Source of estrogen

A

Ovary placenta and testis

60
Q

Types of estrogen

A

Estrone (E1) is the primary form of estrogen that your body makes after menopause.

Estradiol (E2) is the primary form of estrogen in your body during your reproductive years. It’s the most potent form of estrogen.

Estriol (E3) is the primary form of estrogen during pregnancy.

61
Q

Insulin is stimulated and inhibited by what?

A

Insulin synthesis is stimulated by glucose or feeding and decreased by fasting

62
Q

What is the threshold of glucose-stimulated insulin secretion?

A

*Threshold of glucose-stimulated insulin secretion is 100 mg/dl.

63
Q

Effect of glucose on translation and transcription of insulin

A

*Glucose rapidly increase the translation of the insulin mRNA and slowly increases transcription of the insulin gene

64
Q

Is insulin lipophobic or lipophilic?

A

Lipophobic

65
Q

Is steroid lipophobic or lipophilic?

A

Lipophilic

66
Q

Is steroid lipophobic or lipophilic?

A

Lipophilic

67
Q

The following is true when beta cell is at rest, except
a. glucose transporter is closed
b. K atpase pump is opened
c. Ca2+ gated channel is closed
d. No insulin production
e. The cell is at a depolarised state

A

e. The cell is at a depolarised state

68
Q

When Beta cells secrete insulin (active) which one of these statements is not true?
a. glucose transporter is opened
b. Ca2+ gated channel is opened
c. cell becomes depolarised
d. there is an increase in glycolysis
e. K+ channel is open

A

e. K+ channel is open

69
Q

When Beta cells secrete insulin (active) which one of these statements is not true?
a. glucose transporter is opened
b. Ca2+ gated channel is opened
c. cell becomes depolarised
d. there is an increase in glycolysis
e. K+ channel is open

A

e. K+ channel is open

70
Q

Describe thyroid hormone metabolism

A

Deiodination: About 40% T4 deiodinated into T3 by enzyme 5’ deiodinase (type 1)

Decarboxylation: very few decarboxylated to form tetraiodithyroacetic acid and triiodothyroacetic acid

Conjugation 15% T3 anti-for conjugated in liver to form glucorinides and sulfates

71
Q

What is hyper thyroidism

A

Increased secretion of thyroid hormone causes are Graves’ disease and toxic nodular goiter

72
Q

What is Graves’ disease thyrotoxicosis

A

Aetiology
Auto immune disease
Thyroid stimulating antibodies against TSH receptors bind with receptors and mimic TSH affect
thyroid hyperplasia

73
Q

Signs and symptoms of Graves’ disease

A

Weight-loss heat intolerance
goiter

Cardiovascular features
sinus tachycardia
arrhythmia

Neuromuscular features
nervousness
irritability
restlessness
psychosis
tremors
muscle weakness

Gastrointestinal diarrhea steatorrhea and vomiting

Dermatological perspiration perspiration lots of hair redness of palm

Male: Impotence
females: amenorrhea

74
Q

What is hypothyroidism

A

Syndrome by low levels of thyroid hormone
primary thyroid disorder
secondary hypothalamus or anteriorpituitary disorder

75
Q

Clinical features of hypothyroidism

A

Infantile hypothyroidism (cretinism)
adults hypothyroidism

76
Q

Describe Infantile hypothyroidism cretinism

A

Hypothyroidism in first of life
mental retardation
Marked retardation of growth
Delayed milestone developments potbelly, protruding tongue, flat nose, dry skin and sparse hair 

77
Q

What is hypothyroidism myxodema

A

Due to infiltration of skin by myxodematous tissue

General
Tiredness, weights gain, cold intolerance decrease sweating

CVS bradycardia anemia

Neurological features
lethargy
slow movements
speech
sleepiness
delayed reflexes

skin
Toad skin
Sparse hair
Myxoedema 

reproduction
Menorrhagia
infertility
galactorrhea and impotence
adynamic ileus

78
Q

What is goitre

A

Abnormal increase in the thyroid gland

Physiology 2nd Semester (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions