anatomy 2, exam 1

Distinguish between an exocrine and endocrine gland?

An endocrine gland is where products are secreted directly into the bloodstream while exocrine gland products are secreted from a duct out of the body or into a hollow space.

What are the general characteristics of hormones

it is a chemical substance that must be released in the blood

it must bind to a specific receptor and result in a physiological response

hormones have a half life

hormones are not food so they can not be used for energy

describe cellular mechanisms of action in protein v steroid

For steroids they use the transcription factor where they can go directly though the lipid bilayer and bind to receptor on nucleus or cytoplasm and go to nucleus to alter transcription then affect translation and affect protein synthesis that may affect the receptor, ribosome, enzyme, etc

For proteins they use the second messenger system where they bind to the receptor on the plasma membrane that have an effect on the G protein then the cyclic messenger changes and this causes second messenger signaling that causes physiological changes.

What are the three chemical classification of hormones and compare and contrast them

Steroid hormone- it is lipid soluble, derived from cholesterol, orally active, have lasting residual effects

amine/proteins- water soluble (proteins), orally inactive, species specific

eicosanoids- act in a paracrine manner, use second messenger system, derived from arachidonic acid, rapidly degraded

Describe the mechanisms of control of hormonal secretion (humoral, neural, and hormonal)

Humoral secretion is changing the concentration of ions using negative feedback loops

neural is release from axons due to an action potential

Hormonal is one hormone stimulating the release of another hormone

Describe how hormones interact with their target cell receptor

Paracrine manner- act on neighboring cells

autocrine manner- act on same cells that secreted them

Identify the cells of the pancreas associated with insulin and glucagon secretion and describe what conditions need to be met that result in their synthesis and secretion.

Alpha cells secrete glucagon when glucose is low

Beta cells secrete insulin when glucose is high

Describe the physiological mechanism that occurs within target cells that impact the 4 Gs when insulin and glucagon bind, including what type of receptors are used and what type of cellular signaling occurs.

When insulin binds it is a protein hormone so second messenger signaling. It uses glut4 and glut1 transport to help entry of glucose into the b cells. Since glucose is high, we want to store the glucose into glycogen by transporting it to the liver for it to be stored. So, we inhibit glycolysis, decrease gluconeogenesis, increase glycogenesis, and decrease glycogenolysis.

When glucagon binds that means the glucose levels in the blood are low. It is a protein which uses second messenger signaling. The glucagon is released from the alpha cells. This causes glycogenesis to increase, gluconeogenesis to decrease, and glycogenolysis to increase.

Explain how glucose homeostasis is controlled through a negative feedback loop with insulin and glucagon secretion.

When glucose levels are low alphas cells secrete insulin that stimulates the liver to break down glycogen into glucose and form glucose from amino acids.This raises blood glucose levels to normal but if it rises to high then hyperglycemia inhibits the release of glycogen. High glucose levels causes the beta cells to release insulin which accelerates diffusion of glucose into the cell and speed conversion of glucose into glycogen which make the glucose levels fall.

Identify sources of glucose and discuss the pattern of glucose maintenance in the bloodstream when fasting occurs / dietary glucose is no longer present (timing and the 4Gs, especially glycogenolysis vs gluconeogenesis).

refer to chart

Compare and contrast the causes of Type I and II Diabetes Mellitus and how each condition affects glucose and insulin concentrations in the blood.

Type 1 diabetes is an insulin deficiency so this is an autoimmune disorder where the beta cells are being attacked causing low insulin levels which causes hypoinsulinemia and since there is low insulin hyperglycemia meaning glucose is high due to pancreas not producing enough insulin. Alpha cells might be destroyed too due to the hyperglycemia causing alteration to the glucagon

Type 2 diabetes is insulin resistance and is multifactoral meaning that there could be many reasons but mainly obesity but can be genetic. This causes hyperinsulinema and hyperglycemia because the insulin is not being recognized and used the glucose is not entering the cell

Identify three areas of the body where calcium is pooled

It is stored in the bone calcium, calcium in the blood or extracellular fluid, and intracellular calcium

Describe pathological conditions that may occur as a result of hypo or hyper-calcemia

hypocalcemia causes altered neuromuscular excitability, muscle spasms, cardiac dysfunction

Hypercalcemia - may lead to precipitation of calcium phosphate in tissues. Widespread organ dysfuction and damage

Describe Calcitriol synthesis and the physiological changes it brings about in target tissues to result in changes in blood calcium concentrations.

UV radiation hits the skin causing the keratinocytes that make 7 dehydrocholesterol to synthesize cholecalciferol (Vitamin D). It goes to the liver to make calcidiol (adding a hydroxyl group) and then to the kidneys to make calcitriol (adding a hydroxyl group).

Calcitriol causes increased absorption of calcium in the small intestine, promotes osteoclast differentiation (pulling calcium from bone), promotes calcium reabsorption by kidneys,

Describe the conditions that result in PTH and Calcitonin secretion and

explain physiological changes seen in their target cells upon binding that

result in changes in Calcium concentrations in the blood.

The secretion of PTH is a result of the calcium blood levels being too low. The secretion of Calcitonin is due to calcium blood levels being too high

PTH increases osteoclast activity promoting calcium release, reduce osteoblast activity, urinary phosphate excretion because you are taking away phosphate so calcium can’t bind and form hydroxyapatite, less urinary calcium excretion, promotes final step of calcitriol synthesis in kidneys

Illustrate examples of negative feedback loops involved in Calcium

homeostasis.

Calcium homeostasis is a negative feedback loop because when calcium blood levels get too high then calcitonin acts on certain tissues to lower it and when calcium blood levels get too low calcitriol and parathyroid hormone act on certain tissues to put calcium back into the blood and increase it.

Reiterate the mechanisms in which hormones activate second messenger systems or serve as transcription factors to result in physiological change in cells

Protein hormones use second messenger signaling to bind to receptors on the cell membrane to communicate inside the tissue. Steroid hormones go right through the cell membrane and bind to receptors in the cytoplasm or nucleus to alter transcription and cause changes. Calcitonin and Parathyroid hormone are protein hormones. Calcitriol binds to an intracellular receptor to bind to intracellular receptors and serves as a transcription factor like a steroid.

Identify the location of the hypothalamus and describe the role of hypothamic nuclei

The hypothalamus is superior to the pituitary gland, it is at the base of the diencephalon, and made up of neural tissue. The hypothalamic nuclei is a cluster of cell bodies that have a unique function

Describe the location and early development of the adeno and neurohypophysis.

The adenohypophysis is in the front of the pituitary gland and originated from the epithelial cells of the mouth. The neurohypophysis is the back of the pituitary gland and originated from the hypothalamus containing nervous tissue

Compare and contrast the physiological mechanisms that lead to hormone synthesis and secretion from the adenohypophysis from the neurohypophysis

For the adenohypophysis a stimulus creates an action potential that travels down the neuron to the terminal to release a releasing hormone that goes through capillary bed 1 and down the portal veins into capillary bed #2 that then finds and binds to receptors on the cell that then use second messenger signaling to release the hormone that travels in capillary bed #2 into the main circulation.

For the neurohypophysis a stimulus causes an action potential that travels down the axon to the terminal to release a hormone that travels through a capillary bed into the main circulation

Describe the role of the hypothalamus plays with secretion of hormone from the adenohypophysis vs the neurohypophysis

The hypothalamus is made up of nervous tissue causing an action potential to slide down the axon terminal to either release a releasing hormone (adenohypophysis) or hormone (neurohypophysis)

Identify examples of hormones that are released from the hypothalamus and adeno and neurohypophysis.

For the hypothalamus there could be GHRH (growth hormone releasing hormone), GnRH (gonadotropin releasing hormone) PRH (prolactin releasing hormone) in adenohypophysis, corticotropin releasing hormone, thyroid releasing hormone

For the hypothalamus there could be oxytocin, antidiuretic hormone