Study Guide A ( Test 1)

What do Endocrine glands produce?

hormones

What type of physician treats hormone imbalances?

endocrinologist

What are Target Cells?

cells that have specific receptors for a hormone

How are hormones moved between endocrine glands and target organs?

“ by blood”

1. endocrine system → hormones secreted by endocrine cells into interstitial fluid and enter the blood within capillaries

2. travel through cardiovascular system

3. hormones leave the blood and enter interstitial fluid to have the hormones molecules available to entire body

4. hormone bind to target cell receptor either in cell or plasma

What are two central features of the nervous system and endocrine system?

1. response to stimuli → release of ligands (hormone/neurotransmitter)

2. binding of ligand receptor cell in target cell to create cellular change

What are noticeable differences between the Nervous system and the Endocrine system?

Endocrine system:

• secretes hormones

• target = any cell

• slow reaction time

• long-lasting duration of response

Nervous system:

• neurotransmitter release

• target= neuron, muscle cells, gland cells

• rapid reaction time

• localized range of effect

• short-term duration to response

What are the four broad categories of hormone function?

regulation

homeostasis

digestive processes

reproductive activities

What are the Endocrine Glands?

Pituitary, pineal, thyroid, parathyroid, adrenal

What is Hormonal Stimulation?

What 2 hormones are examples of this?

1. release of another hormone triggers release of the hormone

ex:

Anterior pituitary releases TSH → TSH stimulates thyroid gland to release TH

What is Humoral Stimulation?

What is an example of this?

1. changes in level of nutrient or ion in the blood triggers release of the hormone

ex:

blood glucose lev. increase → increased blood glucose stim. pancreas to release insulin

What is Nervous system Stimulation?

What is an example of this?

1. stimulation by the nervous system triggers release of hormone

ex:

sympathetic division is activated → sympathetic preganglionic axons stim. adrenal medulla to release Epinephrine/norepinephrine

What are the 3 categories of circulating hormones?

Steroids, biogenic amines, proteins

What is the precursor for Steroids?

cholesterol

What is the precursor for biogenic amines?

amino acids

What is the precursor of proteins?

amino acid chains

Which two circulating hormones are water-soluble?

biogenic amines and proteins

Which circulating hormone is lipid-soluble?

steroids

What hormones fall into the category of Steroids?

estrogen, progesterone, testosterone, cortisol, aldosterone

What hormones fall into the category of Biogenic amines?

Epinephrine/Norepinephrine

What hormones fall into the category of proteins?

insulin, glucagon, GH

What is a local hormones?

short-lived signaling molecules that do not circulate within the blood

note: they influence changes in the tissues

ex: influencing diameter of blood vessels and pain perception

What is Autocrine Stimulation?

binding of signaling molecules with either the same cell that produced it

What is Paracrine Stimulation?

binding of signaling molecule to a neighboring cell

How would u classify Eicosanoids?

primary type of local hormones

How would you classify Prostaglandins?

most diverse eicosanoids

What type of hormones require a transport protein and why?

Lipid-soluble hormones do not dissolve readily within the blood plasma so they need a carrier protein.

What is another benefit of transport proteins?

they can prolong the life of the hormone and prevent early destruction of hormones

What is a bound hormone?

any hormone attached to a carrier protein

What is an unbound hormone?

unattached hormone = free hormone

What types of hormones do not require a transport protein and why?

water-soluble hormones readily dissolve within aqueous environment so, these hormones are generally releases directly into the blood and transported to target cells

Why is it important to maintain hormone levels within homeostatic limits?

to maintain balance of rate released by its elimination

What are the key ways to achieve hormone levels within homeostatic limits?

through negative feedback and sometimes positive feedback

What is the half-life of a hormone?

amount of time necessary to reduce hormone concentration within the blood to ½ of what had been originally secreted

What class of hormones have a longer half-life?

steroids

If a cell lacks a receptor for a hormone, will it have any impact on the cell?

no, b/c the hormone will not interact with the receptor

How does the type/distribution of target cells impact the influence of a particular hormone?

the greater the number of different target cells, the wider the potential influence that may be exhibited by a given hormone

Where are the receptors for lipid-soluble hormones located and why?

cytosol or nucleus b/c lipid-soluble hormones can diffuse across the plasma membrane

The hormone-receptor complex stimulates ______________ of DNA leading to protein synthesis.

mRNA

Where are the receptors for water-soluble hormones located and why?

outside the plasma membrane by receptor to allow passage b/c water-soluble hormones are unable to pass through plasma

What is the first messenger for water-soluble hormones?

signaling molecule

What is the second-messenger for water-soluble hormones?

receptor

Second messenger systems involve activation of ____________ proteins. This often results in the activation or inhibition of _________.

1. g-protein

2. enzymes

What are some things that influence the extent of a cell’s response to a hormone?

a single target cell can

• display differing numbers of receptors for the same hormone = binding varying amounts of hormone

• possess receptors for many hormones = respond to many at the same time

What is up-regulation?

target cells increase number of receptor = increase cell sensitivity to a hormone

What is down-regulation?

target cell decreases number of receptors = reduce target cell’s sensitivity to hormone

How does the number of receptors on a target cell influence the response of a cell to a hormone?

the greater number of receptors to more likely the hormone will respond and vice versa

sensitivity vs. decrease of sensitivity

Under what conditions does up-regulation typically occur?

when there is lower than normal hormone concentration

Under what conditions does down-regulation typically occur?

when there is elevated hormone concentration

How does up/down regulation help maintain homeostasis?

by helping to prevent either under or overstimulation of the target cell to promote normal level cellular response

What is synergistic hormone interaction?

hormones work together to produce greater effect

ex: estrogen + progesterone

What is permissive hormone interaction?

first hormone allows action of second hormone

ex: prolactin → oxytocin

What is antagonistic hormone interaction?

one hormone causes opposite effect of another hormone

ex: insulin vs. glucagon

Name two important hormones produced by the pancreas?

insulin + glucagon

Describe the shape and location of the pancreas.

shape: elongated organ

location: btwn duodenum of small intestine and the spleen and posterior to the stomach

99% of the pancreas has what function?

exocrine gland function → producing digestive enzymes

What cells help carry out the function of the pancreas?

pancreatic acinus

(modified simple cuboidal epithelial cells)

1% of the pancreas has what function?

to secrete glucagon or insulin

What is the name for the cluster of cells that help carry out the 1% function of the pancreas?

pancreatic islets or islets of langerhans

What cells produce insulin?

beta cells

What cells produce glucagon?

alpha cells

What is the Endocrine Function of the pancreas?

maintain concentration of glucose in the blood withtin normal range by secretion of insulin and glucagon into blood

What happens if hyperglycemia occurs?

excess glucose must be transported into other body cells that can use or store this resource

What happens if hypoglycemia occurs?

lethargy can occur

When is insulin released?

When blood glucose is high

How are carbohydrates stored and what organ stores them?

stored as: glycogen

in the: skeletal muscle or liver

How are lipids stored and what cells store them?

stored: fatty acids

in the: adipose tissue

Amino acids are taken up and may be converted into what form?

protein

Glucose is transported into cells via __________ transport proteins.

glucose

Do all cells require insulin for glucose transport?

no

What happens to insulin release as blood glucose levels drop?

less insulin is released from the pancreas

What stimulates the release of glucagon?

When there is low levels of blood glucose

How do hepatocytes (liver cells) respond to glucagon?

glycogenolysis (break down of glycogen)

gluconeogenesis ( forming of glucose )

How do adipocytes respond to glucagon?

lipolysis ( breakdown of fats to release fatty acids)

What is diabetes mellitus?

reduced insulin release or response to insulin

elevated blood/urine glucose levels

What are the 3 classic signs of diabetes?

increased hunger (polyphagia)

increased urination (polyuria)

increased thirst (polydipsia)

What is the reason for polyphagia?

cells are unable to normally absorb glucose from the blood into their cells

What is the reason for polyuria?

glucose lost in urine and pulls fluid into urine by osmosis

What is the reason for polydipsia?

abnormal loss of fluid in urine = dehydration

What type of diabetes is known as insulin-dependent diabetes?

type 1

What cells are destroyed in type 1 diabetes?

beta cells

What destroys the cells in type 1 diabetes?

viral infection

How is type 1 diabetes treated?

regular injections of insulin

What type of diabetes is known as insulin-independent?

type 2

What causes type 2 diabetes?

decreased insulin release or decreased insulin effectiveness on target cells

obesity

How is type 2 diabetes treated?

diet, exercise, medications

What is gestational diabetes?

diabetes in pregnant women

What System

• communicates by hormones

• adapts realtively slowly

• reacts slowly to stimuli

• may contin. responding long after stimuli stops

Endocrine System

What system

• communicates by electrical impulses

• adapts quickly to continual stimulation

Nervous System

The Endocrine System…

releases hormones into the bloodstream for general distribution

sometimes has very general effects

The Nervous System…

releases neurotransmitters at synapses

relatively local (specific effects)

reacts quickly to stim.

stops quickly when stim. stops

A hormone is a ________________________ and the target cell is ___________________________

1. molecule that has a metabolic effect on another cell

2. a cell that has receptors for specific hormones

a) Pineal gland

b) Pituitary gland

c) Thyroid gland

d) Thymus

e) Pancreas

a) hypothalamus

b) parathyroid gland

c) adrenal gland

d) ovaries

e) testes

What are examples of Up-Regulation?

increased # of testosterone receptors in skeletal muscle following resistance training

In response to a chronic lack of a hormones, the target cell increases that concentration of receptors

greater response to the same magnitude of hormone release

What are examples of Down-Regulation?

decreased hormone receptors resulting from chronically high insulin levels

decreased response to an increase in hormone

in response to a chronic abundance of hormone, the target cell reduces the concentration of receptors

decreased sensitivity

a)bound hormone

b)unbound hormone

c)hormone

d)hormone-receptor complex

e)hormone-response element

f)hormone receptor

Two or more hormones work together to produce a result is?

Synergistic effect

A hormone enhances an organ’s response to a second hormone, or increases the activity of the second hormone is?

permissive effect

One hormone inhibits the secretion and action of another hormone, or has an opposite effect is?

antagonistic effect

Testosterone is an example of which type of hormone?

steroid hormone