ASCI 1101 - Animal Physiology Exam 2

What does the endocrine system do?

It produces hormones that regulate growth, metabolism, sexual development, and sexual function.

What are the two ways the endocrine system communicates between cells?

Endocrine communication and paracrine/autocrine communication.

What is endocrine communication?

Hormones enter the bloodstream and affect many tissues or organs at the same time.

What is paracrine/autocrine communication?

Local chemical signals transfer information between cells in the same tissue.

What are the three groups of hormones based on chemical composition?

Amino acid derivatives, peptide hormones, and lipid derivatives.

What are examples of amino acid derivative hormones?

Thyroid hormones, epinephrine, norepinephrine, dopamine, serotonin, and melatonin.

What are examples of peptide hormones?

ADH, oxytocin, insulin, growth hormone, prolactin, TSH, LH, and FSH.

What are the two major lipid derivative hormone groups?

Eicosanoids and steroid hormones.

What are examples of steroid hormones?

Androgens, estrogens, progestins, corticosteroids, and calcitriol.

What do eicosanoids do?

They act as local factors that coordinate local cellular activities. Prostaglandins are eicosanoids.

How do amino acid derivative and peptide hormones act on target cells?

They are not lipid soluble, so they bind to receptors on the outside of the plasma membrane.

How long do amino acid derivative and peptide hormones remain functional?

Usually less than one hour because they are quickly broken down.

How do steroid hormones and eicosanoids act on target cells?

They are lipid soluble, diffuse through the plasma membrane, and bind to intracellular receptors.

How do steroid hormones affect cells?

They directly change the rate of DNA transcription in the nucleus.

Why do steroid hormones remain in circulation longer than peptide hormones?

They are bound to transport proteins in plasma.

Where is the hypothalamus located?

It extends from above the optic chiasm to the thalamus.

What does the hypothalamus do for the autonomic nervous system?

It adjusts and coordinates autonomic centers in the pons and medulla oblongata.

How does the hypothalamus regulate the anterior pituitary?

It stimulates or inhibits endocrine cells using regulatory hormones sent through the hypophyseal portal system.

Which two hormones are made in the hypothalamus and released from the posterior pituitary?

Antidiuretic hormone, or ADH, and oxytocin.

What connects the hypothalamus to the pituitary gland?

The infundibulum, or pituitary stalk.

Which hypothalamic nuclei produce ADH and oxytocin?

The paraventricular and supraoptic nuclei.

What does oxytocin do?

It stimulates uterine contractions during childbirth and triggers milk ejection.

What does ADH do?

It causes the kidneys to reabsorb more water and decreases urine formation.

What do hypothalamic osmoreceptors monitor?

Solute concentration in body fluids.

What does thyrotropin-releasing hormone, or TRH, stimulate?

The release of thyroid-stimulating hormone, or TSH, from the anterior pituitary.

Where is the pituitary gland located?

Below the hypothalamus in the sella turcica.

What are the two main pituitary lobes?

The anterior lobe, or adenohypophysis, and the posterior lobe, or neurohypophysis.

What does the anterior pituitary do?

It releases hormones that activate endocrine glands or support other organs.

What are the divisions of the anterior pituitary?

Pars distalis, pars tuberalis, and pars intermedia.

What is found in the posterior pituitary?

Unmyelinated axons from hypothalamic nuclei.

Where is the thyroid gland located?

Inferior to the thyroid cartilage of the larynx.

What is the basic structure of the thyroid gland?

Two lobes connected by an isthmus.

What are thyroid follicles?

Hollow spheres lined with cuboidal epithelium and filled with viscous colloid.

What hormones do thyroid follicles produce?

Thyroxine, or T4, and triiodothyronine, or T3.

What mineral is needed to make thyroid hormones?

Iodine ions.

What are C cells, or parafollicular cells?

Thyroid cells that produce calcitonin.

What does calcitonin do?

It decreases calcium concentration in body fluids.

What regulates T3 and T4 production?

The hypothalamus and thyroid-stimulating hormone, or TSH.

What does TSH do at the thyroid gland?

It activates enzymes needed to synthesize T3 and T4.

What is the calorigenic effect of thyroid hormones?

They raise cellular metabolic rate by increasing energy transformation and use.

How do thyroid hormones affect the cardiovascular system?

They increase heart rate, force of contraction, blood pressure, and sensitivity to sympathetic stimulation.

How do thyroid hormones affect red blood cells?

They stimulate red blood cell formation and improve oxygen delivery.

Where are the parathyroid glands located?

Usually four glands on the posterior surface of the thyroid gland.

What hormone do parathyroid glands produce?

Parathyroid hormone, or PTH.

What causes PTH release?

Low calcium concentration in body fluids.

How does PTH relate to calcitonin?

PTH is calcitonin’s antagonist because PTH raises blood calcium.

How does PTH raise blood calcium?

It stimulates osteoclasts, increases calcium reabsorption by the kidneys, and increases intestinal calcium absorption through active vitamin D.

Where are the adrenal glands located?

Along the superior border of each kidney.

What are the three zones of the adrenal cortex?

Zona glomerulosa, zona fasciculata, and zona reticularis.

What does the zona glomerulosa produce?

Mineralocorticoids, mainly aldosterone.

What does aldosterone do?

It causes kidneys to conserve sodium and reabsorb more water.

What stimulates aldosterone secretion?

A drop in blood sodium, blood volume, or blood pressure.

What does the zona fasciculata produce?

Glucocorticoids, mainly cortisol.

What are glucocorticoids known for?

They are stress hormones that prepare the body for fight or flight.

What are major effects of cortisol?

It speeds protein breakdown, inhibits white blood cell activity, and slows wound healing.

What does the zona reticularis produce?

Sex hormones.

Why are adrenal sex hormones usually less noticeable?

Their effects are overshadowed by larger amounts of estrogen and testosterone from the ovaries or testes.

What hormones are made by the adrenal medulla?

Epinephrine and norepinephrine.

How do adrenal medulla hormones affect skeletal muscle?

They mobilize glycogen, speed glucose breakdown for ATP, and increase strength and endurance.

How do adrenal medulla hormones affect adipose tissue?

They break down stored fats into fatty acids for ATP production.

How do adrenal medulla hormones affect the liver?

They break down glycogen and release glucose into the blood.

How do adrenal medulla hormones affect the heart?

They increase heart rate and force of cardiac muscle contraction.

Which endocrine hormones are produced by the intestines?

Gastrin, GIP, secretin, CCK, and VIP.

Which endocrine hormones are produced by the kidneys?

Calcitriol, erythropoietin, or EPO, and renin.

Which hormones are produced by the pancreas?

Insulin and glucagon.

What does testosterone support?

Differentiation and physical maturation of sperm.

What does estradiol support?

Follicular growth and ovulation.

What does leptin do?

It regulates energy balance by inhibiting hunger.

Where is leptin made and where does it act?

It is made by adipose cells and acts on the arcuate nucleus of the hypothalamus.

Where is the pancreas located?

Behind the stomach, extending from the duodenum toward the spleen.

What are the three main regions of the pancreas?

The head, body, and tail.

Where is the head of the pancreas located?

In the loop of the duodenum.

What is the pancreatic duct, or duct of Wirsung?

A duct that joins the common bile duct and empties into the duodenum.

What regulates flow through the pancreatic duct?

The hepatopancreatic sphincter.

Why is the pancreas called a mixed gland?

It has both exocrine and endocrine functions.

What is the exocrine function of the pancreas?

It releases pancreatic juice with digestive enzymes.

Which enzymes are in pancreatic juice?

Pancreatic alpha-amylase, pancreatic lipase, nucleases, and proteolytic enzymes.

What is the endocrine function of the pancreas?

It releases hormones that regulate metabolism and homeostasis.

What cells release insulin?

Beta cells of the endocrine pancreas.

What tissues are major targets of insulin?

Muscle, liver, and adipose tissue.

What is insulin’s overall role?

It helps the body use or store glucose and helps prevent blood sugar from becoming too high or too low.

What does insulin do in muscle and liver?

It increases glucose use and ATP production and stimulates glycogen formation.

What does insulin do for protein synthesis?

It stimulates amino acid absorption and protein synthesis.

What does insulin do in adipose tissue and the liver?

It stimulates triglyceride formation and storage.

What cells release glucagon?

Alpha cells of the endocrine pancreas.

What is glucagon’s main role?

It mobilizes energy reserves.

What does glucagon do to glycogen?

It stimulates glycogen breakdown in skeletal muscle and liver cells.

What does glucagon do to fats and glucose production?

It stimulates triglyceride breakdown and glucose production in the liver through gluconeogenesis.

Which pituitary hormones control both ovaries and testes?

Luteinizing hormone, or LH, and follicle-stimulating hormone, or FSH.

Which pituitary cells release LH and FSH?

Gonadotrophs in the anterior pituitary gland.

What do LH and FSH do in females?

They stimulate the ovaries.

What do LH and FSH do in males?

LH stimulates Leydig cells to secrete testosterone, while FSH stimulates Sertoli cells to secrete inhibin.

Where do gonadal steroids come from?

The ovaries, testes, and adrenal glands.

How are gonadal steroids transported in blood?

Bound to transport proteins.

What are the major types of gonadal steroids?

Androgens such as testosterone, estrogens such as estradiol, and progestins such as progesterone.

What are prostaglandins?

Locally acting hormones made by many tissues and degraded in the lungs.

What is melatonin and what does it do?

A modified amino acid hormone from the pineal gland that helps regulate light effects and reproductive processes.

What is human menopausal gonadotropin, or hMG?

A hormone with FSH-like activity that can be used for superovulation.

What does equine chorionic gonadotropin, or eCG, do?

It helps form accessory corpora lutea and maintains pregnancy.

What does human chorionic gonadotropin, or hCG, do?

It maintains the primate corpus luteum and pregnancy.