Lesson 6: The Endocrine System Flashcards
1
Q
The Endocrine System
A
- Messages that travel via hormones, chemicals secreted into the bloodstream by endocrine glands
- Sends messages slowly, tend to be long-lasting signals
- Maintain homeostasis
2
Q
Target Cells
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- Hormones work by bonding to the receptors on a cell that’s sensitive to the effects of a specific hormone
3
Q
Endocrine Glands
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- Ductless glands, they excrete hormones into the spaces between cells, and from those spaces these chemical messengers diffuse into the bloodstream and are carried throughout the body by the cardiovascular system
4
Q
Exocrine Glands
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- Have ducts, and they excrete the substances that they produce into those ducts
- Examples are salivary glands, sweat glands, sebaceous glands and mammary glands
5
Q
Hypersecretion
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- Diseases of the endocrine system that results from secretion of too much of one or more hormones
6
Q
Hyposecretion
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- Diseases of the endocrine system that results from secretions of too little of one or more hormones
7
Q
Pituitary Gland
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- Located within the brain
- Not entirely composed of endocrine tissue; like the brain, it’s nervous tissue as well
- Small size, has a quite significant influence on overall functioning of the body
8
Q
Adenohypophysis
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- Portion composed of endocrine tissue
- Adeno refers to glandular tissue
9
Q
Neurohypophysis
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- Part made of nervous tissue
- Neuro refers to nervous tissue
10
Q
Pituitary Stalk
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- Attaches the pituitary gland to the underside of the brain and anchors it to the hypothalamus
11
Q
Adrenocorticotropic Hormone (ACTH)
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- This hormone makes the adrenal cortex increase in size and excrete more cortisol
12
Q
Luteinizing Hormone (LH)
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- In females, this hormone stimulates ovulation, in the male it stimulates testosterone production in the testes
13
Q
Thyroid-stimulating Hormone (TSH)
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- This hormone stimulates the production of thyroid hormones
14
Q
Growth Hormone (GH)
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- This hormone stimulates the development of tissue proteins, and the breakdown of fat
- Too much GH can cause high blood glucose levels
- Hypersecretion during development can cause the condition gigantism, involves growth to a gigantic size
- After growth years, excessive GH causes acromegaly, a condition involving overgrowth of bone in the hands, feet, cheeks and jaw
- Hyposecretion can lead to dwarfism, involves growth to a smaller than normal size
15
Q
Follicle-stimulating Hormone (FSH)
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- This hormone promotes the development of ova in females, and the production of sperm in males
16
Q
Prolactin (PRL)
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- This hormone stimulates breast development and milk secretion
17
Q
Antidiuretic Hormone (ADH)
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- This hormone acts against the creation of urine, so it plays an important role in fluid balance
- Hyposecretion of ADH can cause diabetes insipidus, which involves an acutely-elevated production of urine
18
Q
Oxytocin (OT)
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- This hormone plays a role in social bonding, milk letdown and labour
19
Q
Hypothalamus
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- Where the hormones antidiuretic hormone (AHD) and oxytocin (OT), both of which are released by the pituitary gland, are produced.
- Also produces hormones that mediate the secretory function of the pituitary
20
Q
Thyroid Gland
A
- Located at approximately the junction between the larynx and the trachea
- It produces two thyroid hormones (triiodothyronine and thyroxine) and a third hormone (calcitonin (CT))
21
Q
Triiodothyronine and Thryoxine
A
- Influence cellular metabolism
- Speed up the release of energy from nutrients
- Important hormones for normal day-to-day function
- Play a critical role in growth and development
- Too much hormone means to much energy released such as people suffering from hyperthyroidism can be restless, nervous, irritable, and experience weight loss . An inherited autoimmune condition called Grave’s disease involves hyperthyroidism.
- Too little hormone is called hypothyroidism. Iodine deficient diets can cause enlargement of the thyroid gland (called goiter) which is an attempt to increase secretion (why table salt has iodine)
22
Q
Cretinism
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- A developmental condition affecting mental and sexual development due to hyposecretion of thyroid hormones early in life
23
Q
Myxedema
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- A condition involving decreased physical and mental capacity, weight gain, and skin and hair changes occurring later in life
24
Q
Calcitonin
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- Hormone that causes calcium levels to drop by reducing absorption of calcium from the food we eat
- It acts on the kidneys to increase the concentration of calcium in urine and maintain calcium in our bones
- It also prevents hypercalcemia- an excess of calcium in the blood
25
Q
Parathyroid Glands
A
- Attached to the surface of the thyroid glands
- These glands excrete parathyroid hormone (PTH)
- Opposite effect of calcitonin: it increases blood calcium levels by promoting the breakdown of bone tissue
- It’s the dance between calcitonin and PTH that keeps blood calcium levels in a homeostatic state
26
Q
Adrenal Glands
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- Sit atop the kidneys
- It’s a two-in-one structure as it’s divided into two discrete endocrine glands: the adrenal cortex and the adrenal medulla
27
Q
Adrenal Cortex
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- The outer portion of an adrenal gland, secretes three different types of hormone: mineralocorticoids, glucocorticoids, and sex hormones
28
Q
Aldosterone
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- Primary mineralocorticoid
- Influences the sodium-potassium balance by promoting the reabsorption of sodium, and the excretion of potassium
29
Q
Cortisol
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- Main glucocorticoid excreted by the adrenal cortex
- Influences blood glucose and blood pressure levels and it has anti-inflammatory effect
- It is excreted in higher than normal levels as part of our stress response
30
Q
Androgens
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- Male sex hormones that are secreted by the adrenal cortex, similar to testosterone. In males they’re of little consequence because of the overwhelming amount of testosterone produced in the testes
- Female, androgens influence the sex drive
31
Q
Adrenal Medulla
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- Produces epinephrine ( as a drug its called adrenalin) and norepinephrine (noradrenaline)
32
Q
Epinephrine and Norepinephrine
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- Are produced as part of our stress reaction, specifically the “fight or flight” response
- These hormones increase blood pressure and glucose levels, which intensify our ability to fight or flee
33
Q
Pancreatic Islets
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- Tiny glands, small clusters of cells, scattered about the pancreas
- Two types of cells involved Alpha cells and Beta cells
34
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Alpha Cells
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- Produce the hormone glucagon
35
Q
Beta Cells
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- Produce the hormone insulin
36
Q
Glucagon and Insulin
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- Both play a role in maintaining blood glucose levels but they have opposite (antagonistic) effects
37
Q
Glucagon
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- Converts glycogen a substance stored in the liver into glucose.
- This increases blood glucose levels
38
Q
Insulin
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- Moves blood glucose into cells, promoting its metabolism by those cells
39
Q
Type 1 Diabetes Mellitus
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- When pancreatic islets hyposecrete insulin, less blood glucose moves into the cells
40
Q
Type 2 Diabetes Mellitus
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- There is adequate insulin, but the receptors upon which the hormone acts are impaired (they are less sensitive)
41
Q
Pineal Gland
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- Sometimes referred to as the “third eye” because its activity responds to sensory information related to cycles of light and dark
- Produces the hormone melatonin. It’s important for the regulation of sleep and may influence menstruation and the onset of puberty
42
Q
Seasonal Affective Disorder
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- A seasonal form of depression
- Even when it doesn’t cause depression, an excess in this melatonin hormone can make you feel groggy and cause difficulty waking up in the morning
- Too little melatonin can be the root cause of some cases of insomnia
