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Human Physiology > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

Explain the difference between glands, exocrine glands and endocrine glands

A

Glands - Organs derived from epithelial cells, specialised in the synthesis and secretion of a product.

Exocrine Glands - Secrete their products into ducts which lead into the external environment (skin, lumen)

Endocrine Glands - Secrete hormone into interstitial fluid, then diffuse into the blood stream (internal environment)

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2
Q

Name the 2 major system that regulate cell communication

A

Nervous System - Autonomic and Somatic

Endocrine System

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3
Q

Explain the structure of the endocrine system: endocrine glands, hormones, target cells ad receptors

A

Endocrine System consists of all endocrine glands, that secrete hormones; plays a key role in the adaptation of the human organism to changes in the internal and external environment (homeostasis)

Hormone - A chemical substance secreted Into the bloodstream in very small amounts from specialised cells or organs

Target cells - The cells respond to a particular hormone

Receptor - Certain proteins in a target cell that specifically recognise and bind the messenger

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4
Q

Explain the role of neurohormones in the endocrine system

A

Messenger hormones

Released from neuron into blood

Transported in blood to target

Acts in manner similar to hormones

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5
Q

Explain what Autocrine and Paracrine is

A

Autocrine - acts through diffusion onto the same cells which produce it

Paracrine - move by diffusion, act on adjacent cells

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6
Q

Name the primary and secondary gland

A

Primary:

Pineal -

Hypothalamus

Pituitary gland

Thyroid gland

Parathyroid gland

Thymus gland

Adrenal gland

Pancreases

Ovaries (F)

Testes (M)

Secondary:

Heart

Stomach

Liver

Kidneys

Small intestines

Skin

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7
Q

Name the 3 types of hormones

A

Amine hormones

Peptide hormones

Steroid hormones

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8
Q

Explain and give examples of amine hormones

A

Mostly hydrophilic except thyroid Hs

Simplest, small molecules, structurally similar to amino acids

Catecholamines: dopamine, noradrenaline and adrenaline

Thyroid horomones: thyroid hormones (T4 and T3) (lipophilic)

Both derived from amino acid tyrosine

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9
Q

Explain and give examples of peptide hormones

A

Hydrophilic

Peptides are proteins; the majority of hormones

Examples - from pancreases: insulin and from anterior pituitary growth hormone

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10
Q

Explain and give examples of steroid hormones

A

Lipophilic

Lipids, constructed from cholesterol

Examples - from adrenal cortex: aldosterone, cortisol and androgens. From gonads: testosterone

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11
Q

How are hormones secreted and transported in the blood?

A

Hydrophilic messenger - peptide hormones, catecholamine

Hydrophobic messenger - steroid hormones and thyroid hormones

Peptides + catecholamine - secretion by exocytosis, free in plasma

Steroid + thyroid hormones - secretion by simple diffusion, protein-bound in plasma

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12
Q

Explain the action of hydrophilic hormones

A

Channel-linked receptors (ligand-gated ion channels)

Enzyme-linked receptors

G-protein linked receptors

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13
Q

Explain the action of lipophilic hormones

A

Bind to receptors intracellular:

Receptors located in the cytosol or nucleus

Synthesis of a specific protein is altered

1) 1A/1B receptor combined by hormones (HRE)

2) HRE binds to DNA

3) Gene transcription altered (mRNA)

4) mRNA moves into cytosol

5) mRNA translated by ribosome to yield proteins

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14
Q

Explain the role of antidiuretic hormone (ADH) and Oxytocin

A

ADH

Decrease water loss from kidneys (osmoreceptors)

Constriction of peripheral blood vessels

Secretion stimulated by - water deficit, decrease in blood pressure

Oxytocin

Acts on smooth muscle cells in the breasts and uterus

Stimulated by ‘sucking’ and uterine contractions

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15
Q

Name the hormones from the anterior pituitary

A

Growth hormone (GH)

Thyroid-stimulating hormone (TSH)

Adrenocorticotropic hormone (ACTH)

Prolactin

Gonadotropin hormone

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16
Q

Name the hypothalamus hormones

A

Growth hormone Releasing Hormone (GHRH)

Thyrotrophin Releasing Hormone (TRH)

Corticotrophin Releasing Hormone (CRH)

Gonadotrophin Releasing Hormone (GnRH)

Prolactin releasing Factor (PRF)

Somatostatin (SS)

Dopamine (DA)

17
Q

What are growth hormones also called?

A

Somatotrophic hormones, somatotrophin

18
Q

How is secretion of GH stimulated and regulated?

A

Secretion of GH is stimulated by GHRH and inhibited by SS from hypothalamus (SS also blocks GHRH stimulation non-competitively)

Synthesis increased by thyroid hormone and cortisol

Stimulated by sleep (REM phase), exercise and stress

19
Q

Explain the function of GH

A

The overall effect of GH are anabolic

Causes growth of all tissues of the body capable of growing; promotes an increase in cell size and rate of mitosis

Increases rate of protein synthesis

20
Q

Nam the hormones released by the thyroid gland

A

The thyroid gland procures 3 hormones:

Tetraiodothyronine, thyroxine (T4)

Triiodothyronine (T3)

Calcitonin, concerned with regulation of (Ca2+)

T3 and T4 are collectively knows as thyroid hormones, (TH)

21
Q

Give the effects of thyroid hormone

A

Regulating the body’s overall level of cellular metabolic activity and energy expenditure

T3 binds to a nuclear receptor interacting with DNA to alter gene transcription

22
Q

What is the effect of T3 on the synthesis of Growth Hormone?

A

Increases nuclear content of the mRNA transcription of the GH gene, directs synthesis of GH increases

23
Q

Explain what hypothyroidism is

A

Deficiency in T3 and T4 secreation, may be due to autoimmune or lack of iodine in the diet

Symptoms included low metabolic rate, lethargy (inactivity), bradycardia, cold intolerance and increased weight gain despite a decreased appetite

24
Q
A
25
Q

Explain what hyperthyroidism is

A

Over production of endogenous Heat or ingestion of exogenous Heat
Symptoms include high metabolic rate, restless, tachycardia, heat intolerance and weigh loss despite an increase appetite

26
Q

Explain the structure of the pancreas

A

Islets of langerhans

Group of cells make up 1-2% of pancreas tissue

Alpha cells secrete glucagon

Beta cells secrete insulin

Somatic cells secrete somatostatin

Synthesis and secretion - all hormones are peptides

Glucagon - increases breakdown of glycogen and increased blood sugar

Insulin - increases glucose uptake and decreases blood sugar

Somatostatin - helps in GI function and regulation of other pancreases hormones (GH)

27
Q

Define the terms glycolysis, glycogenolysis and gluconeogenesis

A

Glycolysis - glucose breakdown to lactate

Glycogenolysis - glycogen breakdown to glucose

Gluconeogenesis - conversion to glucose via Peru ate

28
Q

Explain the structure of the adrenal glands

A

Adrenal glands are situated above each kidney; two distinct parts:

Adrenal cortex (>80% mass), steroid hormones:

corticosteroids (glucocorticoids, e.g. cortisol & corticosterone;

mineralocorticoids, e.g. aldosterone)

androgens (sex hormones)

Adrenal medulla (<20% mass), catecholamine H

epinephrine secreting cells (80%)

norepinephrine secreting cells (20%)

dopamine (<1%)

29
Q

Explain the role of the adrenal medulla

A

Develops from an outgrowth of nervous tissue

Surrounded by the adrenal cortex
Cell bodies do not have axons, but instead, release their secretions into the blood

Functionally part of the sympathetic nervous system

Stimulation of the SNS followed by hormone secretion as the stimulus continues

Not essential to life - but without it the body is less able to face emergencies and stress

30
Q

Explain the role of the adrenal cortex

A

Mineralocorticoids – aldosterone (zona glomerulus)

Glucocorticoids - cortisol and corticosterone (zona fasciculata)

Androgens - dehydroepiandrosterone (DHEA) and androstenedione (zona reticularis)

The adrenal cortex is essential to life

31
Q

Explain the action or cortisol

A

Modulation of gene expression via a cytoplasmic-nuclear protein receptor;

Permissive to GH, glucagon; maintenance of normal function inc. [glucose]plasma

Catabolic in peripheral tissues (break down of proteins and fats)

Anabolic in the liver (gluconeogenesis)
In peripheral tissues, antagonism of insulin (decreased glucose utilization, increased blood sugar level)

inflammatory & immune responses; used for the treatment of autoimmune diseases, hypersensitivity, and transplantation

32
Q

Explain the action of aldosterone in the adrenal glands

A

Secretion stimulated by ACTH (but not directly gives feedback to ACTH and CRH)

Chief effects on salt (mineral) balance, mainly on kidney tubules

Promotes retention of Na+ and water (secretion stimulated by a fall in plasma volume via the renin-angiotensin system)

Increases excretion of K+ (secretion stimulated by high plasma [K+])

33
Q

What is Gametogenesis?

A

Gametes generation (meiosis)

34
Q

Explain the steps involved in reproduction

A

Gametogenesis – gametes generation (meiosis)

Fertilization – gametes fuse to produce a new cell

Implantation – 6 days post fertilization

Pregnancy – fetus development

Parturition – labor

Lactation

35
Q

Explain the components and functions of the gonad

A

The primary reproductive organs are known as the gonads: the testes in the male and the ovaries in the female.

Dual functions of the gonads:

Gametogenesis: the production of the reproductive cells, or gametes
spermatozoon (spermatozoa, sperm) - by males
ovum (ova, egg) - by females

Secretion of particular steroid hormones, often called sex hormones

36
Q

Explain the sex hormones produced

A

Testes: testosterone

Ovaries: estrogens and progesterone
Although males have more androgens and females have more estrogens and progesterone, all of these hormones are found in both sexes

Adrenal cortex also produces sex hormones androgen

37
Q

Explain how hormones are regulated

A

FSH (follicle stimulating hormone) and LH (luteinizing hormone) from the anterior pituitary

Same molecular structures in both sexes; together they are called gonadotropins

Gonadotropins (FSH and LH) are stimulated by GnRH (gonadotropin releasing hormone) from the hypothalamus

Human Physiology (9 decks)

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