Exam one

What is the endocrine system made up of ?

Various glands and glandular cells, hormones, and some organs that release hormones

What does the endocrine system do?

Internal communication, control of growth/development, homeostasis, and metabolism response to environment

Speed of nervous system vs endocrine system internal communication

Nervous system communicates very fast while the endocrine system communicates slow

Targets of internal communication in nervous system vs endocrine

Nervous system has specific targets while the endocrine has general targets

Internal communication signals in nervous vs endocrine system

Nervous system sends electrical signals (NTs) while the endocrine system sends hormones

What does thyrotropin-releasing hormone (TRH) do?

Promotes secretion of thyroid-stimulating hormone and prolactin

Sourced from the hypothalamus and targets the anterior pituitary

What does croticotropin-releasing hormone (CRH) do?

Promotes secretion of adrenocorticotropic hormone (ACTH)

Sourced from the hypothalamus and targets the anterior pituitary

What does gonadotropin-releasing hormone (GnRH) do?

Promotes secretion of follicle-stimulating hormone and luteinizing hormone

Sourced from the hypothalamus and targets the anterior pituitary

What does growth hormone-release hormone (GHRH) do?

Promotes secretion of growth hormone

Sourced from the hypothalamus and targets the anterior pituitary

What does prolactin-inhibiting hormone (PIH) do?

Inhibits secretion of prolactin

Sourced from the hypothalamus and targets the anterior pituitary

What does somatostatin do?

Inhibits secretion of growth hormone and thyroid-stimulating hormone

What does parathyroid hormone (PTH) do?

Regulates calcium and phosphorus metabolism

Sourced from the parathyroid gland and targets the kidneys and bones

What is norepinephrine (NE)?

A hormone synthesized by the adrenal medulla; it stimulates the fight or flight response; also a neurotransmitter in the sympathetic nervous system

Follicle-stimulating hormone (FSH)- what does it stimulate and where is it secreted?

It is sourced in the anterior pituitary and targets the ovaries and testes- stimulates the secretion of estrogen, growth of ovarian follicles, and stimulates sperm production

Luteinizing hormone (LH)- what does it do?

Sourced by the anterior pituitary and targets the ovaries and testes; it stimulates ovulation and maintenance of the corpus luteum and testosterone secretion

Thyroid-stimulating hormone (TSH)

Sourced from the anterior pituitary and targets thyroid follicular cells

Stimulates increased cell division/ growth of the thyroid gland and secretion of T3/T4

Adrenocorticotropic hormone (ACTH)

Sourced in the anterior pituitary and targets adrenal glands

Stimulates the release of glucocorticoids (cortisol) and mineralocorticoids

What do glucocorticoids (cortisol) do?

Regulate glucose, protein and fat metabolism

Prolaction (PRL)

Sourced in the anterior pituitary and targets the mammary glands

Stimulates the production of milk

Types of signaling in the endocrine system

Cell to cell and tissue to tissue

Difference between exocrine and endocrine glands?

Exocrine: release secretory product via ducts that open on body surfaces in contact with external world

Endocrine: release secretory product (hormones) into spaces between secretory cells and it enters bloodstream

What is a chemical synapse?

A type of synapse at which a chemical (NTs) is released from the axon of a neuron into the synaptic cleft, where it binds to receptors on the next structure (either another neuron or an organ)

Electrical synapse

A type of synapse in which the cells are connected by gap junctions, allowing ions (and APs) to spread easily from cell to cell

Paracrine and autocrine signaling

Secrete molecules, local regulators that act over short distances, reach target cell by diffusion

What does paracrine signaling target?

Cell to cell- it’s neighbors

What does autocrine signaling target?

It targets itself

T/F: autocrine and paracrine signaling can happen at the same time?

True

Antiduretic hormone (ADH)

Sourced in the posterior pituitary and targets the kidney

It stimulates increased reabsorption of water from urine; helps prevent dehydration

Oxytocin (OT)

Sourced in the posterior pituitary; targets mammary glands (my-epithelial cells) and uterine muscle

Stimulates ejection of milk and contractions during childbirth

What is endocrine signaling?

Hormones carried long distances by blood or other fluids

Target cells must have …?

Specific receptors

T/F: There are usually multiple target cell types per hormone?

True

Exocrine glands do not ____, they ____

They do not signal, they secrete

Exocrine glands secrete products where?

Into duct or directly onto body surface

Endocrine glands are closely associated with what?

Blood vessels

What are the 2 antagonist hormones in glucose homeostasis?

Insulin and glucagon

What secretes insulin and glucagon?

The pancreas

Does insulin raise or lower blood glucose levels?

Lower

Does glucagon raise or lower blood glucose levels?

Raise

What is the normal blood glucose level?

70-110 mg/dL

mg of glucose per dL of blood

Insulin makes the liver uptake ____ glucose from the blood?

More

What is glycogenesis?

Converting glucose to glycogen

What is the difference between glucose and glycogen?

Glucose is the sugar in our bloodstream that the body uses for energy

Glycogen is a stored form of energy

Example: after eating, when there is too much glucose to be used then the extra is converted to glycogen to be stored

Insulin causes the liver to have ____ glycogenesis

Increased

Fatty acid synthesis

Occurs in the liver as a result from insulin- after glycogenesis

Turns glucose into fatty acids

Stores glucose as fat

Adipose turns glucose into triglycerides

Gluconeogenesis

Formation of new glucose from amino acids

Increases when glucagon is secreted in liver

Insulin causes the liver to ____ gluconeogenesis

Decrease

Insulin causes adipose to _____ glucose uptake from blood

Increase

In adipose, insulin …

Inhibits triglyceride breakdown which promotes energy storage and fat accumulation

Insulin causes skeletal muscle to …

Increase glucose uptake from the blood

What 2 things do glucagon cause to happen in the liver?

Increased glycogenolysis and gluconeogenesis

What is glycogenolysis?

Glycogen breakdown

Glucagon causes an ____ triglyceride breakdown in adipose

Increased

The hypothalamus and pituitary are in the …?

Diencephalon region

What connects the hypothalamus to the pituitary?

Infundibulum

What is the anterior lobe of the pituitary gland?

Adenohypophysis

What is the posterior lobe of the pituitary gland?

Neurohypophysis

What cells have properties of both the pituitary gland and hypothalamus?

Neuroendocrine cells

What do neuroendocrine cells do?

Produce action potentials and secrete hormones into bloodstream

The anterior pituitary is controlled by …

Neuroendocrine cells in the hypothalamus

Growth hormone (GH) target and response

Most cells in body → leads to growth and increased protein synthesis and decreased protein breakdown

Liver → release of insulin-like growth factors (IGF-I & IGF-II)

Adipocytes → triglyceride breakdown & release of free fatty acids into blood

Hypophyseal portal system

Blood travels from the hypothalamus to the anterior pituitary using 2 capillary beds

How many hormones are produced in the hypothalamus?

8

6 to regulate the anterior pituitary

2 stored in posterior pituitary

released on demand

What is the effect of IGF 1 (insulin like growth factor)

Prolong the effects of GH

What is involution?

Shrinking of tissue or organ

At night, the ____ gland synthesizes melatonin

Pineal gland

Thymus

A bilobed gland in the mediastinum superior to the heart

An immune organ that is a site for the maturation of T cells

What is the largest adult gland to have purely endocrine function?

Thyroid gland

What is the effects of thyroid hormone (T3/T4)?

Increase body’s metabolic rate, increase body heat, increase expression of Na+/K+ pumps, increased expression of aerobic respiration enzymes, increased number and activity of mitochondria and increased heart rate

What organs secrete steroid hormones?

Adrenal cortex, ovary, testes

Releasing and inhibiting hormones are produced in the _____ and sent to the _____?

Hypothalamus; anterior pituitary

If the hypothalamus controls the anterior pituitary, what controls the hypothalamus?

Other neurons in the hypothalamus stimulated by internal conditions or other parts of the brain stimulated by external sensory info

What is cortisol?

Stress hormone released by the adrenal cortex

What is feedback inhibition?

When product inhibits its own production

What can cause increased ADH?

High osmolarity or low BP

Is the thyroid gland an endocrine or exocrine gland?

Endocrine

What hormones are released from the thyroid gland?

T3/T4 and calcitonin

Follicles of the thyroid gland contain ____?

Colloid- a viscous liquid of iodinated proteins

What are the follicle cells that make colloid?

Cuboidal epithelium

What are C cells?

They are between follicles and they produce calcitonin

T3 and T4 contain ____ and are derived from ____?

Iodine; tyrosine

Follicle cells trap iodine from …?

Blood

Follicle cells make …, which is then transported into the …?

Thyroglobulin; colloid

In the colloid, tyrosine side chains in thyroglobulin are ____?

Iodinated

2 iodinated tyrosine side chains make …?

T3/T4

What is thyroglobulin?

Protein made with tyrosines and other amino acids, by follicle cells

Iodine trapping

Uptake of iodide from the blood by thyroid gland by sodium-iodide supporter

What does thyroid peroxidase do?

Converts iodide to elemental iodine then attaches to tyrosines on thyroglobulin

Iodinated thyroglobulin is stored in …?

Colloid

Proteolysis

Protein digestion (thyroglobulin → free amino acids)

Are T3 and T4 lipid or water soluble?

Lipid soluble

What is the main carrier of T3 and T4 in the bloodstream?

Thyroxine-binding globulin (TBG) made by the liver

What percent of T3 and T4 is free in the blood?

Less than 1%

Which is more active: T3 or T4?

T3 is 5x more active than T4

Where is T4 converted to T3?

In the liver and kidneys

What is hypothyroidism?

Low levels of T3 and T4 in early childhood; leads to stunted bones and mental disability

Another name for thyroid stimulating hormone

Thyrotropin

Thyroid stimulating hormone stimulates the production and release of…?

T3 and T4

TSH causes increased production of ____ in follicle cells

Iodine transporter, thyroglobulin, thyroid peroxidase

TSH causes ____ endocytosis and digestion of colloid in follicle cells

Increased