Chapter 16 Endocrine system

What characteristic do molecules need to be called hormone?

It must be able to travel through blood

What is the difference between endocrine, paracrine and autocrine signaling?

Endocrine travels through blood/entire body and acts on distant target cells. Paracrine uses chemical signaling to act on nearby cells (do not travel through blood). Autocrine releases a cell to act on itself, altering its own function.

In what ways do the endocrine system and the nervous system regulate the body differently?

Endocrine system primary messenger are hormones while nervous system primary messenger are neurotransmitters. Nervous system is also faster than endocrine system (m/s > sec)

In what ways do the endocrine system and the nervous system regulate the body similarly?

Both use chemical ligands that bind to specific receptors in on target cells to initiate cellular response

In what type of blood vessel are hormones released into and out of the cell?

Capillaries

What about Capillaries makes the exchange of hormones possible?

It’s a single cell thick

To be affected by a given hormone, what must a target cell possess for that hormone?

Target cell must possess a specific receptor protein made for hormones molecular structure

What’s the difference between a Primary and Secondary endocrine organ?

Primary endocrine organ’s main function is to produce hormones whereas secondary endocrine organs can produce hormones, but it is not the main function

Where are the receptors for Hydrophilic hormones typically found?

On the plasma cell membrane

Why cant Hydrophilic hormones pass through the plasma membrane?

Because Hydrophilic hormones are polar

Where are the receptors for Hydrophobic hormones found?

The receptors are located inside the cell, within the cytoplasm or nucleus

Why are Hydrophobic hormones located within the cell but not Hydrophilic?

Hydrophobic hormones can pass through because they’re nonpolar while Hydrophilic hormones are polar

What’s the difference between hormonal, humoral and neural regulation of hormone secretion

Hormone secretion - hormone from one gland stimulates or inhibits secretion from another gland. Humoral secretion - Changes in ECF and ion/nutrient concentration directly stimulate endocrine cells. Neural regulation - Nerve fibers directly synapse with endocrine gland and stimulate release through action potentials.

What is Hormone secretion?

Hormone from one gland stimulates or inhibits secretion from another gland.

What is Humoral secretion?

Changes in ECF and ion/nutrient concentration directly stimulate endocrine cells.

What is Neural regulation?

Nerve fibers directly synapse with endocrine gland and stimulate release through action potentials.

What is a Negative feedback loop?

Regulatory mechanism that inhibits initial stimulus to bring it back to baseline(normal) to maintain homeostasis

Where in the body would you find the pituitary gland? (Hypophysis)

Sits securely within Sella Turcica of Sphenoid bone at the base of brain

To which portion of the brain is the pituitary gland physically attached?

Hypothalamus and attached via infundibulum

Two types of hormones released by the Posterior pituitary gland are?

Oxytocin and Antidiuretic hormone (ADH)

What is the Hypophyseal portal system?

The hypophyseal portal system is a specialized vascular network consisting of two capillary beds connected in series by portal veins.

How many Capillary beds are in the Hypophyseal portal system?

2

How does the structure of the hypophyseal portal system aid in its function?

The use of two capillary beds connected by portal veins allows for travel directly to anterior pituitary quickly and allows for hormones to stay in high concentration and not get diluted

What type of hormones are released from hypothalamus in the hypophyseal portal system?

Releasing and inhibiting hormones into this portal network

What are the 6 types of hormones released by the anterior pituitary gland?

Growth hormone (GH), Thyroid stimulating hormone (TSH), Adrenocorticotropic hormone (ACTH), Follicle stimulating hormone (FSH), Luteinizing hormone (LH) and Prolactin (PRL)

Targets of each anterior pituitary gland hormone?

TSH targets thyroid gland, ACTH targets Adrenal cortex, GH targets liver and other tissue, FSH targets gonad (sperm production), LH targets gonad (trigger ovulation and sex hormones), PRL targets mammary glands to stimulate milk production

Target for Thyroid gland (TSH?)

Thyroid gland

Target for Adrenocorticotropic hormone? (ACTH)

Adrenal cortex

Target for Growth hormone?

Liver and other tissue

What is a tropic hormone?

A tropic hormone is a hormone that stimulates other glands or targets to release its own hormone.

How does growth hormones affect the human body?

Grows bone length/ muscle mass and helps body have available nutrition to grow (Glucose and Fat in blood)

Which hormones are generated by each cell type of the Thyroid?

Follicular cells generate Triiodothyronine (T3) and Thyroxine (T4) . Parafollicular cells generate Calcitonin.

What is the difference between Triiodothyronine (T3) and Thyroxine (T4)?

T3 has 3 iodine atoms meanwhile T4 has 4 iodine atoms. T3 is faster but T4 is released in larger amounts

Major effects of Thyroid hormone on human body?

Raises baseline metabolic rate by increasing cellular oxygen and heat production. Promotes normal skeleton, muscular and nervous system development

Where are Parathyroid glands located?

Embedded on posterior surface of thyroid gland lobes (in neck)