Unit One

What is the primary communication system of the body along with the nervous system?

The endocrine system

What is the difference between exocrine and endocrine glands?

Exocrine glands secrete substances into ducts; endocrine glands are ductless and secrete hormones directly into circulation.

What happens when there is too much hormone in the body?

Hypersecretion

What happens when there is too little hormone in the body?

Hyposecretion

How do steroid and thyroid hormones enter cells?

They are lipid soluble and can pass directly through the cell membrane.

What is the role of the second messenger in protein hormone action?

It modifies cell activity after the first messenger (the protein hormone) binds to a receptor on the cell membrane.

What is a common example of a second messenger?

Cyclic adenosine monophosphate (cAMP)

What connects the pituitary gland to the hypothalamus?

The infundibulum

What are the two parts of the pituitary gland?

Anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis)

What is the function of releasing hormones from the hypothalamus?

They signal the anterior pituitary to either inhibit or increase the release of hormones.

What hormone does the anterior pituitary release in response to Thyroid Releasing Hormone (TRH)?

T3/T4 from the thyroid gland

What condition results from hyposecretion of growth hormone during childhood?

Dwarfism

What condition results from hypersecretion of growth hormone during adulthood?

Acromegaly

What hormone is produced by the posterior pituitary in response to dehydration?

Antidiuretic hormone (ADH) or vasopressin

What are the effects of oxytocin (OT)?

It has various effects including stimulating uterine contractions and milk ejection.

Where is the thyroid gland located?

In the neck below the larynx (Adams apple)

What do follicular cells of the thyroid gland secrete?

Triiodothyronine (T3) and thyroxine (T4)

What is the effect of T3 and T4 on the basal metabolic rate (BMR)?

They increase the basal metabolic rate.

What is the role of calcitonin?

It decreases blood calcium levels by increasing osteoblast activity and inhibiting osteoclast activity.

What condition can arise from iodine deficiency?

Hypothyroidism

What is congenital hypothyroidism in children?

A condition leading to dwarfism and mental retardation due to insufficient thyroid hormones.

What is hyperthyroidism, and name a common cause?

An overproduction of thyroid hormones; a common cause is Graves' disease.

What is exophthalmos?

A condition characterized by protruding eyes, often associated with hyperthyroidism.

What are the parathyroid glands responsible for?

Releasing parathyroid hormone (PTH) to increase blood calcium levels.

How does parathyroid hormone (PTH) increase blood calcium levels?

By increasing osteoclast activity, reabsorbing calcium in the kidneys, and stimulating calcitriol production.

Where are the adrenal glands located?

On top of the kidneys.

What are the two major components of the adrenal glands?

The adrenal cortex and the adrenal medulla.

What hormone is primarily secreted by the adrenal cortex's outer zone?

Mineralcorticoids, primarily aldosterone.

What triggers the secretion of aldosterone?

Low vascular volume, low blood pressure, or low blood sodium.

What is the function of cortisol?

To maintain normal blood glucose levels during stress or low blood glucose situations.

What are the effects of glucocorticoids on the body?

They stimulate protein breakdown, lipolysis, and have anti-inflammatory effects.

What do the inner zone of the adrenal cortex produce?

Androgens, which are male hormones important for sex drive in females.

What hormones does the adrenal medulla produce?

Norepinephrine (NE) and epinephrine (E).

What is the role of the pancreas in hormone secretion?

It contains pancreatic islets that secrete hormones like glucagon and insulin.

What do alpha cells in the pancreas secrete?

Glucagon, which increases blood glucose levels.

What do beta cells in the pancreas secrete?

Insulin, which decreases blood glucose levels.

How does insulin facilitate glucose uptake?

By increasing the number of glucose transporters in the cell membrane.

What are the symptoms of untreated diabetes mellitus?

Increased thirst, frequent urination, and unexplained weight loss.

What hormones do the ovaries secrete?

Estrogen and progesterone.

What is the function of estrogen in females?

To prepare the uterine lining for fertilized egg implantation and develop secondary sex characteristics.

What is the function of testosterone in males?

To develop secondary sex characteristics and support sperm production.

What is the role of the thymus gland?

To mature certain types of white blood cells and secrete thymosin, which stimulates the immune system.

What does the pineal gland produce?

Melatonin, which regulates sleep cycles and mating cycles.

What triggers the release of gonadotropin releasing hormone (GnRH) in males?

Puberty.

Where are sperm produced?

In the seminiferous tubules of the testes.

What is the function of the epididymis?

To mature sperm and allow them to gain motility.

What is the role of the bulbourethral glands?

To produce a lubricating fluid that is alkaline.

What is the significance of nitric oxide (NO) in the penis?

It causes arterioles to dilate, increasing blood flow and leading to an erection.

What is the typical volume of semen during ejaculation?

Approximately 5 mL, containing 100-300 million sperm.

What triggers the release of GnRH in the ovaries?

Body weight, approximately 100 lbs.

Where does fertilization normally occur?

In the fallopian tubes.

What is the role of the fimbriae in the female reproductive system?

They sweep the egg into the fallopian tubes.

What is the function of the uterus?

It is where the fertilized egg implants and develops.

What is the primary function of the vagina?

It serves as the birth canal and where sperm is deposited during intercourse.

What hormonal changes occur during the preovulatory phase of the menstrual cycle?

FSH and LH stimulate follicle growth, and granulosa cells secrete estrogen.

What happens during ovulation?

The oocyte is released from the follicle due to an LH/FSH surge.

What is the corpus luteum?

The ruptured follicle that secretes estrogen and progesterone after ovulation.

What hormone does a fertilized oocyte secrete to maintain the corpus luteum?

Human chorionic gonadotropin (hCG).

What is the purpose of birth control pills?

They keep estrogen and progesterone levels elevated to prevent ovulation.

What is meiosis?

A type of cell division that generates 4 non-identical daughter cells to create gametes.

How many pairs of homologous chromosomes do humans have?

23 pairs in somatic cells.

What is the difference between somatic cells and gametes?

Somatic cells are diploid (2n) while gametes are haploid (1n).

What is spermatogenesis?

The process of sperm cell development occurring in the seminiferous tubules.

What occurs during prophase of Meiosis I?

Chromatin condenses into chromosomes, and homologous chromosomes pair up to form tetrads.

What is crossing over?

The exchange of genetic material between homologous chromosomes during prophase I.

What is the outcome of Meiosis II?

Four unique haploid daughter cells called spermatids.

What is oogenesis?

The process of egg cell development in females, resulting in one functional haploid cell.

What is nondisjunction?

The failure of homologous chromosomes or sister chromatids to separate during meiosis.

What is an example of an autosomal recessive disorder?

Tay Sachs disease.

What is an example of an autosomal dominant disorder?

Huntington Disease.

What does the term 'genotype' refer to?

The actual genetic make-up of an organism.

What does the term 'phenotype' refer to?

The trait that is expressed in an organism.

What is the difference between heterozygous and homozygous?

Heterozygous has two different alleles, while homozygous has two of the same alleles.

What is the significance of the first and second polar bodies in oogenesis?

They are byproducts of meiosis that disintegrate and do not contribute to the embryo.

Why is nondisjunction of sex chromosomes more viable than that of autosomes?

Sex chromosome abnormalities often result in conditions that can be tolerated better than autosomal abnormalities.

What are chorionic villi sampling and amniocentesis used for?

They are tests used to detect genetic abnormalities during pregnancy.