Anatomy and Phisiology II Exam 1

what is physiology

The function of the body and how body parts work.

Define homeostasis.

The condition of maintaining the body's internal environment in a relatively constant state.

What is homeostatic imbalance?

Anything that disturbs or alters the balance of the internal environment.

What are homeostatic control mechanisms?

Self-regulating mechanisms that maintain the homeostatic steady state.

What are the three components of homeostatic control mechanisms?

Receptor, control center, and effector.

What is negative feedback?

The output shuts off the original effect of the stimulus or reduces its intensity.

How does negative feedback function?

A change in one direction results in a feedback that causes a change or adjustment in the opposite direction.

What is positive feedback?

The result enhances the original stimulus so that the response is accelerated.

Give an example of positive feedback.

Blood clotting, labor contractions, or orgasm.

What are the two regulatory systems involved in feedback mechanisms?

Nervous system and endocrine system.

How does the nervous system communicate?

Uses electrical impulses delivered by neurons to specific target cells.

What is the role of the endocrine system?

Affects cell activity by releasing hormones directly into the bloodstream.

What are hormones?

Chemical messengers produced by one type of cell that alter the physiological activity of another type of cell.

What are the two main classes of hormones?

Amino acid-based hormones and steroids.

What are amino acid-based hormones?

Water-soluble molecules ranging from small amino acids to large proteins.

What is the characteristic of steroid hormones?

They are lipid-soluble and can cross the plasma membrane.

Why do only specific cells respond to certain hormones?

Because they have specific receptors for that hormone.

What happens when a hormone binds to its receptor?

It causes a chain of events within the cell resulting in physiological change.

What are the effects of hormones on target cells?

They can alter membrane potential, stimulate synthesis of enzymes, induce secretory activity, and stimulate mitosis.

How do water-soluble hormones act?

They act on plasma membrane receptors and use G protein second messengers.

What is the primary function of the endocrine system?

To coordinate and integrate the activity of body cells through hormones.

What is the difference between endocrine and exocrine glands?

Endocrine glands secrete hormones into the bloodstream; exocrine glands secrete non-hormonal products via ducts.

What is the role of target cells in hormonal action?

They are the cells that hormones specifically affect.

What is the significance of receptor quantity in hormonal effects?

Different quantities of receptors can produce varying magnitudes of an effect.

What is the relationship between hormones and their receptors?

Hormones bind to specific receptors like a lock and key.

What is the effect of hormonal control on the body?

It influences metabolic activities and maintains homeostasis.

What type of hormones act on intracellular receptors to activate genes?

Lipid-soluble hormones

What is the primary mechanism of action for amino acid-based hormones?

They exert effects through second-messenger systems.

Name the two main second-messenger systems used by amino acid-based hormones.

Cyclic AMP and PIP-calcium.

What happens when lipid-soluble steroid hormones enter a target cell?

They bind with intracellular receptors and form a receptor-hormone complex that enters the nucleus.

What is the role of the receptor-hormone complex in the nucleus?

It binds to a specific region of DNA to initiate DNA transcription to produce mRNA.

What are the three stimuli that can trigger endocrine glands to release hormones?

Humoral stimuli, neural stimuli, and hormonal stimuli.

What is an example of humoral stimuli in hormone secretion?

Declining blood calcium concentration stimulates parathyroid glands to secrete parathyroid hormone (PTH).

How do neural stimuli affect hormone release?

Nerve fibers stimulate hormone release, such as sympathetic nervous system fibers stimulating the adrenal medulla.

What is hormonal stimuli?

Hormones stimulate another endocrine gland to release its hormones.

What is the feedback loop involving hypothalamic hormones and anterior pituitary hormones?

Hormones from final target organs inhibit the release of anterior pituitary hormones.

How can the nervous system modulate hormone levels?

The nervous system can override normal endocrine controls and adjust hormone levels as needed.

What is the half-life of a hormone?

The time required for the level of hormone in blood to decrease by half.

What factors influence the concentration of circulating hormones?

The rate of release, speed of inactivation, and removal from the body.

What are the three types of hormone interactions at target cells?

Permissiveness, synergism, and antagonism.

What is permissiveness in hormone interactions?

It is when one hormone cannot exert its full effects without another hormone being present.

What is synergism in hormone interactions?

It occurs when more than one hormone produces the same effects at the target cell, amplifying their combined effects.

What is antagonism in hormone interactions?

It occurs when one hormone opposes the action of another hormone.

What connects the hypothalamus to the pituitary gland?

The infundibulum.

What are the two major lobes of the pituitary gland?

The posterior pituitary (neurohypophysis) and anterior pituitary (adenohypophysis).

What hormones are produced by the hypothalamus and stored in the posterior pituitary?

Oxytocin and antidiuretic hormone (ADH).

What is the function of oxytocin during childbirth?

It is a strong stimulant of uterine contractions.

What triggers the milk ejection reflex in breastfeeding?

Oxytocin acts as a hormonal trigger for the letdown reflex.

What type of tissue makes up the posterior pituitary?

Neural tissue.

What is the role of the anterior pituitary?

It consists of glandular tissue that secretes various hormones.

What is the duration of hormonal response typically limited to?

Ranges from 10 seconds to several hours.

How can hormones be removed from the blood?

Through degrading enzymes, kidneys, or liver.

What hormone is released during suckling that helps with milk ejection?

Oxytocin

What type of feedback mechanism is involved in the release of oxytocin during suckling?

Positive feedback

What does ADH stand for?

Antidiuretic hormone

What triggers the secretion of ADH?

High solute concentration in the blood

What is one result of ADH action in the kidneys?

Increased water reabsorption in the collecting ducts

What condition is characterized by intense thirst and excessive urine output due to ADH deficiency?

Diabetes Insipidus

What can inhibit the release of ADH?

Alcohol and diuretics

What is the syndrome characterized by excessive retention of fluid and headache due to inappropriate ADH secretion?

Syndrome of inappropriate ADH secretion (SIADH)

What is the anterior pituitary also known as?

Adenohypophysis

How does the hypothalamus communicate with the anterior pituitary?

Through the hypophyseal portal system

What are the six hormones secreted by the anterior pituitary?

GH, TSH, ACTH, FSH, LH, PRL

What is the primary function of Growth Hormone (GH)?

To promote growth and metabolism

What is IGF and its role in relation to GH?

Insulin-like growth factor; it promotes growth stimulated by GH

What condition results from hypersecretion of GH in children?

Gigantism

What condition results from hypersecretion of GH in adults?

Acromegaly

What is the effect of GH on glucose metabolism?

It causes glycogen breakdown and raises blood glucose levels

What hormone stimulates the release of thyroid hormones?

Thyroid-stimulating hormone (TSH)

What does ACTH stimulate?

The adrenal cortex to release corticosteroids

What triggers the release of ACTH?

Hypothalamic corticotropin-releasing hormone (CRH)

What is the primary target tissue for Growth Hormone?

Bone and skeletal muscle

What hormone inhibits the release of Growth Hormone?

Growth hormone-inhibiting hormone (GHIH) or somatostatin

What is the role of gonadotropins like FSH and LH?

They regulate reproductive processes, including egg release

What hormones are secreted by gonadotropic cells of the anterior pituitary?

Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)

What is the function of Follicle Stimulating Hormone (FSH)?

Stimulates production of gametes (egg or sperm)

What does Luteinizing Hormone (LH) promote in females?

Production of gonadal hormones, maturation of follicles, triggers ovulation, and release of estrogen and progesterone

What does Luteinizing Hormone (LH) stimulate in males?

Production of testosterone

What triggers the release of gonadotropins during and after puberty?

Gonadotropin Releasing Hormone (GnRH)

What hormone suppresses the release of gonadotropins?

Prolactin (PRL)

What is the primary function of Prolactin (PRL)?

Stimulates milk production in females

What regulates the release of Prolactin (PRL)?

Primarily controlled by Prolactin-Inhibiting Hormone (PIH), which is dopamine

What is the structure of the thyroid gland?

Butterfly-shaped gland in the anterior neck on the trachea, consisting of follicles and parafollicular cells

What do follicular cells in the thyroid gland produce?

Thyroglobulin

What is the function of the thyroid hormone (TH)?

Major metabolic hormone affecting virtually every cell in the body

What are the two forms of thyroid hormone?

T4 (thyroxine) and T3 (triiodothyronine)

What condition can result from hypersecretion of thyroid hormone in adults?

Myxedema

What is a goiter and what causes it?

Enlargement of the thyroid gland due to lack of iodine, leading to decreased TH levels and increased TSH secretion

What is the primary hormone secreted by the parathyroid glands?

Parathyroid Hormone (PTH)

What triggers the secretion of Parathyroid Hormone (PTH)?

Low blood levels of calcium (Ca2+)

What are the effects of Parathyroid Hormone (PTH)?

Stimulates osteoclasts to release calcium into the blood, enhances reabsorption of calcium by kidneys, and promotes activation of vitamin D

What are the two parts of the adrenal gland?

Adrenal Cortex and Adrenal Medulla

What hormones are produced by the adrenal cortex?

Corticosteroids, including mineralocorticoids, glucocorticoids, and gonadocorticoids

What is the primary mineralocorticoid produced by the adrenal cortex?

Aldosterone

What is the function of glucocorticoids?

Influence metabolism of most cells and help resist stressors

What is the main glucocorticoid in humans?

Cortisol

What is the role of catecholamines produced by the adrenal medulla?

Increase heart rate, vasoconstriction, and blood glucose levels

What hormone is secreted by the pineal gland?

Melatonin

What is the potential effect of melatonin?

May affect the timing of sexual maturation

What physiological processes show rhythmic variations?

Day/night cycles, body temperature, sleep, and appetite.