The Endocrine System

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  • Created by: Jade
  • Created on: 08-01-21 12:37
Define the endocrine system
One of the body's major information systems which instructs glands to release hormones directly into the bloodstream. These hormones are carried towards target organs in the body.
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What is the relationship between the endocrine system and the nervous system?
The endocrine system works alongside the nervous system to govern vital functions in the body.
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What is a "gland"?
An organ in the body that synthesises substances such as hormones.
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What are "hormones"?
Chemical substances that circulate the bloodstream and only affect target organs.
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What are the main endocrine glands in the human body?
Hypothalamus
Pituitary
Thyroid
Parathyroid
Adrenals
Pancreas
Ovaries (female)
Testes (male)
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What is the major endocrine gland?
The pituitary gland - located in the brain, and controls the release of hormones from all other endocrine glands in the body.
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What are the effects of the hormone "thyroxine" produced by the thyroid gland?
This hormone affects cells in the heart (increases heart rate). It also affects cells throughout the body increasing metabolic rates; in turn affecting growth rates.
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What are the two classifications of hormones?
Amino acid based molecules

Steroids
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How do the endocrine system and the autonomic nervous system work together to trigger the "fight or flight" response?
When a stressor is perceived, the hypothalamus triggers activity in the sympathetic branch of the ANS. The ANS changes from its resting state (parasympathetic), to the physiologically aroused (sympathetic) state.
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"Fight or flight" continued...
The stress hormone adrenaline is released from the adrenal medulla (part of the adrenal gland). Adrenaline triggers physiological changes (e.g. increased heart rate), creating the physiological arousal necessary for the "fight or flight" response.
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What is direct gene activation?
The method by which steroid hormones affect the activity of target cells. The hormones attach onto specific receptors on the cell surface membrane to form a hormone-receptor complex, which enters into the nucleus and activates certain genes.
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What is the second-messenger system?
The indirect pathway of activating a second messenger, used when hormones are unable to enter target cells directly.
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What are second messengers?
Molecules that relay signals from receptors on the cell surface, to target molecules inside the cell.
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What are the two functional lobes of the pituitary gland?
The anterior pituitary (glandular tissue) - acts of the master endocrine gland.

The posterior pituitary (nervous tissue) - acts as a storehouse for hormones.
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Which hormones are produced by the anterior pituitary?
Growth hormone
Prolactin
Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH)
Thyrotropic hormone
Adrenocorticotropic hormone
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What is the growth hormone and what does it affect?
An anabolic and protein-conserving hormone that promotes total body growth.Its most important effect is on skeletal muscles and bones.
Untreated hyposecretion during childhood results in pituitary dwarfism; hypersecretion produces gigantism and acromegaly
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What is the function of Prolactin?
Stimulates production of breast milk.
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What is the function of the thyrotropic hormone?
Influences the growth and activity of the thyroid gland.
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What is the function of the Adrenocorticotropic hormone (ACTH)?
Stimulates the adrenal cortex to release its hormones (mainly glucocorticoids).
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What are the gonadotropic hormones?
Follicle-stimulating hormone (FSH)

Luteinizing hormone (LH)
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What is the function of the follicle-stimulating hormone (FSH)?
Causes an egg to mature in an ovary; stimulates the ovaries to release oestrogen.

Promotes sperm production in the testes.
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What is the function of the luteinizing hormone (LH)?
Triggers ovulation (the release of a mature egg) and stimulates production of progesterone.

Stimulates testes to produce testosterone.
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Which hypothalamic hormones are stored and released by the posterior pituitary stores on command?
Oxytocin

The antidiuretic hormone (ADH)
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What is the function of oxytocin?
Stimulates powerful uterine contractions and causes milk ejection in nursing women.
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What is the function of the antidiuretic hormone (ADH)?
Causes kidney tubule cells to reabsorb and conserve body water and increases blood pressure by constricting blood vessels.

Hyposecretion leads to diabetes insipidus (extreme thirst and peeing a lot).
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What is the main hormone secreted by the pineal gland?
Melatonin - plays a major role in the sleep/wake cycle (increased amounts make us drowsy).
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Which two hormones are made by the thyroid gland?
The thyroid hormone

Calcitonin
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What are the two forms of the thyroid hormone?
Thyroxine

Triiodothyronine
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What are the functions of the thyroid hormone?
Controls the rate at which glucose is oxidized, and converted to body heat and chemical energy (ATP).
The thyroid hormone is also important for normal tissue growth and development, especially in the reproductive and nervous systems.
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What can abnormal levels of secretion of thyroxine result in?
Hyposecretion of thyroxine results in cretinism in children and ­ myxedema in adults.

Hypersecretion results from Graves’ disease or other forms of­ hyperthyroidism.
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What is the function of the parathyroid hormone?
It is the most important regulator of calcium ion (Ca 2+ ) homeostasis of the blood.
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What are the three types of adrenal cortex hormones?
Mineralocorticoids

Glucocorticoids

Sex hormones
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What is the function of mineralocorticoids?
To regulate sodium ion (Na + ) reabsorption and potassium ion (K + ) secretion by the kidneys.
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What is the function of glucocorticoids?
Enable the body to resist long-term stress by increasing the blood glucose level and depressing the inflammatory response.
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What can generalised hypoactivity of the adrenal cortex result in?
Addison’s disease

Symptoms include fatigue, muscle weakness and low mood.
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What can hypersecretion in the adrenal cortex result in?
Hyperaldosteronism - main symptom = high blood pressure

Cushing’s syndrome - main symptom = weight gain

Masculinization - abnormal development of male characteristics
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When is insulin released by pancreatic islets?
When the blood level of glucose is high. It increases the rate of glucose uptake and metabolism by body cells.
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When is glucagon released by pancreatic islets?
When the blood level of glucose is low. It stimulates the liver to release glucose to blood, thus increasing the blood glucose level.
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Card 2

Front

What is the relationship between the endocrine system and the nervous system?

Back

The endocrine system works alongside the nervous system to govern vital functions in the body.

Card 3

Front

What is a "gland"?

Back

Preview of the front of card 3

Card 4

Front

What are "hormones"?

Back

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Card 5

Front

What are the main endocrine glands in the human body?

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