Term
1. What is the thyroid gland?
2. What is its composition? |
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Definition
1. The thyroid gland is one of the largest endocrine glands. It is the only gland that stores hormone and it is highly vascularized.
2. The thyroid gland is composed of follicle cells and parafollicular cells. |
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Term
| What hormones are within the thyroid gland? Where are they located? |
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Definition
| Thyroid hormone (TH) and calcitonin are hormones within the thyroid gland. TH is produced in follicular cells and calcitonin is produced within parafollicular cells. |
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Term
| Explain the biosynthesis of thyroid hormone pathway. |
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Definition
1. Iodide is actively transported into a thyroid follicular cell by a Na+/I- symporter (moves two diff molecules opposite directions).
2. Thyroglobulin (Tg) is synthesized in the thyroid follicular cell.
3. Thyroglobulin is iodinated by thyroid peroxidase which is embedded in the follicular membrane.
4. Tg is exocytosed into the follicle lumen.
5. Two iodinated Tg's combine to form T4 or T3.
6. Endocytosis of Tg back into thyroid follicle cell occurs.
7. Tg is broken down by lysosomal enzymes into amino acids.
8. T3 and T4 diffuse out of the thyroid follicle and enter into the blood. |
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Term
| What does thyroid hormone do? |
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Definition
| Thyroid hormone is secreted by the thyroid gland. It serves to increase protein, fat, and glucose metabolism. This produces body heat and assists in the normal growth of tissues. |
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Term
What is calcitonin?
What is its purpose? |
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Definition
| Calcitonin is a hormone produced by parafollicular cells. Its purpose is to decrease blood calcium levels by preventing bone degradation by osteoclasts and by preventing calcium reabsorption through the kidneys and small intestine (vita D release). |
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Term
Where is the parathyroid gland located?
What does it secrete?
What does this hormone do? |
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Definition
| The parathyroid gland is embedded behind the thyroid gland. It releases parathyroid hormone (PTH). Its purpose is to increase blood-calcium levels by increasing bone degradation via osteoclasts, and stimulating calcium reabsorption in the kidneys and small intestine. |
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Term
| What happens when calcium levels in the blood increase? (step-wise pathway) |
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Definition
When blood-calcium levels increase...
1) stimulates the release of calcitonin from the thyroid hormone. Inhibits the release of PTH from the parathyroid gland.
2) Response decreases the levels of calcium in the blood as calcitonin decreases the amount of calcium reabsorption from bone, kidney, and small intestine.
3) homeostasis is restored. |
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Term
Where are the adrenal glands located?
What 2 types of tissue are they composed of?
What is significant about the medulla?
What does the medulla secrete?
How is the cortex divided? |
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Definition
The adrenal glands are located on top of the kidneys. They are composed of medulla (inner tissue) and cortex (outer tissue).
The medulla is significant because it is formed embryologically (from neural crest cells) The medulla secretes epinephrine and norepinephrine. The cortex is divided into 3 layers (superficial to innermost layer). The 3 layers are zona glomerulosa, zona fasciculate, and zona reticularis. |
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Term
What are the two hormones of the adrenal medulla?
What is the mechanism behind them?
What do they do? |
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Definition
| The two hormones of the adrenal medulla are epinephrine and norepinephrine. They are water-soluble hormones so they must induce a response by binding to extracellular adrenergic receptors to initiate g-protein response mechanisms. These hormones prepare the body for physical activity by increasing blood pressure to skeletal and cardiac muscle by dilating blood vessels, reducing blood pressure to visceral organs by constricting blood vessels, and increasing the breakdown of fat, as well as blood glucose levels. |
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Term
| What are the hormones of the adrenal cortex? Explain the type, example, and function of these hormones. |
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Definition
Hormones of the adrenal cortex...
1) Mineralcorticoids: aldosterone is secreted by the zona glomerulosa; serves to increase sodium reabsorption by the kidneys to ultimately, increase blood-sodium levels in the body.
2) Glucocorticoids: cortisol is secreted by the zona fasciculate; serves to increase the synthesis of glucose, breakdown of fat and protein, and decrease the body's inflammatory response.
2) Androgens: androgens are secreted by the zona reticularis; serve to convert into testosterone and stimulate pubic hair growth and increase female sex drive. |
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Term
| How is cortisol release regulated? |
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Definition
1. Stress, physical activity, and low blood-glucose levels stimulate the hypothalamus to release CRH (corticotropin-releasing hormone).
2. CRH stimulates the pituitary gland to release ACTH (adrenocorticotropic hormone)
3. ACTH binds to receptors on the adrenal cortex - zona glomerulosa to cause the release of cortisol.
4. Cortisol acts on effector tissues.
5. Cortisol release is regulated by the negative feedback mechanisms cortisol has on the hypothalamus and the pituitary gland. |
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Term
Where is the pancreas located?
What is it composed of? |
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Definition
| The pancreas is located along the small intestine and the stomach. It is composed of exocrine and endocrine glands. The exocrine gland is responsible for producing pancreatic digestive jucies. The endocrine gland is composed of alpha cells (secrete glucagon), beta cells (secrete insulin), and delta cells (secrete somatostatin). |
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Term
| Define the differences between the Somatic and Autonomic nervous system in terms of what neurotransmitters they release, what type of motor movement occurs, and how many synapses occur. |
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Definition
Autonomic Nervous System
- involuntary movement of cardiac muscle, smooth muscle, and glands.
- two synapses occur.
- preganglionic neuron releases ONLY acetylcholine, postganglionic neuron releases acetylcholine or norepinephrine.
Somatic Nervous System
- voluntary movement of skeletal muscle.
- single synapse occurs.
- release of acetylcholine to nicotinic receptors. |
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Term
| Where is the ganglia located in the sympathetic nervous system and parasympathetic? |
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Definition
| The ganglia are located along the spinal cord in the sympathetic nervous system and near effector organs in the parasympathetic nervous system. |
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Term
| What are the relative lengths of the neurons in the sympathetic nervous system and parasympathetic nervous system? |
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Definition
Short preganglionic neurons and long postganglionic neurons in the sympathetic nervous system.
Long preganglionic and short postganglionic neurons in the parasympathetic nervous system. |
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Term
What types of neurons release acetylcholine?
What types of receptors bind to acetylcholine?
Where are these |
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Definition
Cholinergic neurons release acetylcholine.
Acetylcholine binds to either nicotinic or muscarinic receptors. Nicotinic receptors are located on ALL postganglionic neurons, skeletal muscle, and adrenal glands. |
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Term
What types of neurons release norepinephrine?
What types of receptors bind to norepi and epi? |
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Definition
| The type of neurons that release norepinephrine are adrenergic neurons. The types of receptors that bind to norepi and epi are alpha and beta adrenergic receptors. |
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Term
Where are nicotinic receptors located?
Where are muscarinic receptors located? |
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Definition
Nicotinic receptors are located on ALL postganglionic neurons, skeletal muscle, and adrenal glands.
Muscarinic receptors are located on parasympathetic effectors. |
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Term
| Where are adrenergic receptors located? State whether adrenergic, nicotinic, and muscarinic receptors have an excitatory or inhibitory effect. |
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Definition
Adrenergic receptors are located on sympathetic effectors.
Adrenergic receptors and muscarinic receptors can have either an excitatory or inhibitory effect. Nicotinic receptors always have an excitatory effect. |
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Term
What do autonomic reflexes do?
What part of the brain are the autonomic reflexes heavily influenced by? |
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Definition
| Autonomic reflexes control most of the activity of the visceral organs, glands, and blood vessels. The part of the brain that heavily influences the autonomic reflexes is the hypothalamus. |
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Term
| How are the autonomic reflexes divided? |
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Definition
| The autonomic reflexes are divided into the sympathetic reflexes and parasympathetic reflexes. The sympathetic reflexes are responsible for increasing the heart rate via the cardiac accelerator nerve whereas the parasympathetic reflexes are responsible for decreasing the heart rate via the vagus nerve. |
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Term
| Do the parasympathetic and sympathetic nervous system work together? What is the role of the parasympathetic AND sympathetic nervous system? |
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Definition
| Yes, they work together to maintain coordination of activities of organs. The role of the sympathetic nervous system is to control activities of rest (SLUDD, salivation, lacrimation, urination, digestion, defection). The role of the sympathetic nervous system is to prepare the body for fight or flight. |
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Term
| State the functions of the body during activity. |
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Definition
1) Heart rate increases.
2) Blood vessels dilate in skeletal in cardiac muscle.
3) Respiratory passageway dilates.
4) Sweat gland activity increases.
5) Body temperature increases due to increased muscle activity.
6) Decreased activity of inessential organs.
7) Increased energy availability due to breakdown of glycogen into glucose and fat into triglycerides. |
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Term
What is hyperhidrosis?
What is Raynaud's disease? |
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Definition
Hyperhidrosis is an autonomic nervous system condition where the patient endures excessive sweating caused by an exaggerated sympathetic stimulation of the sweat glands.
Raynaud's disease is an autonomic nervous system condition where patients endure spasmodic contractions of blood vessels and poor circulation (cold hands/feet) caused by exaggerated sympathetic sensitivity of blood vessels; treated by preganglionic denervation. |
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Term
| What is FNDC5 and what is its role in exercise? |
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Definition
| FNDC5 is a muscle myokine that is released by muscles during exercise. FNDC5 cleaves into IRISIN, a molecule that converts white adipose tissue into brown adipose tissue. |
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Term
| State the benefits of exercise in a pathway (include PGC1a and FNDC5) |
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Definition
| Physical activity = increased PGC1a = increased FNDC5 = increased IRISIN = neuronal development, increased insulin activity, increased brown adipose tissue development. |
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Term
| Explain the PGC1a-FNDC5-IRISIN pathway |
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Definition
1. A person will undergo exercise.
2. Exercise increases intracellular calcium in a muscle cell.
3. Increased calcium will increase calcineuron/CaMK activity.
4. Increased calcineuron/CaMK activity will increase downstream transcription programs that will begin transcription of PGC1a in the nucleus.
5. PGC1a secretes into the cytosol, is phosphorylated by AMPK.
6. Phosphorylated PGC1a will induce transcription of FNDC5 in the nucleus.
7. FNDC5 will secrete into the cytosol and be cleaved into IRISIN.
8. IRISIN will secrete into the bloodstream. |
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Term
| Why is IRISIN a controversy? |
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Definition
| The Harvard lab released statements about how IRISIN was detectible in serum (blood) but many other labs could not reproduce these results, therefore, most concluded that IRISIN was a myth. |
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