42 Questions
What stimulates the release of TSH?
Low blood levels of T3 and T4
Where is the thyroid gland located?
Inferior to the larynx
What is the function of glucagon?
Increases blood glucose levels
Which hormone stimulates the secretion of pancreatic juices rich in HCO3-?
Secretin
Which hormone inhibits the release of GH and TSH?
Somatostatin
What does the thymus secrete?
Thymosin
What triggers the secretion of glucagon?
Low blood glucose
What is the role of parathyroid hormone (PTH)?
Increases blood calcium levels
Where do endocrine glands secrete their contents?
Directly into the blood
Which of the following hormones is both a hormone and a neurotransmitter?
Nitric oxide
What is one of the functions of transport proteins for lipid-soluble hormones?
To increase hormone solubility in blood
Which gland is NOT part of the endocrine system?
Sebaceous gland
Which type of hormone binds to receptors within the cytoplasm or nucleus of a cell?
Lipid-soluble hormones
Which is a function of hormones?
Regulate extracellular fluid homeostasis
How do paracrine hormones function?
Bind to nearby cells in the interstitial fluid
Which hormone is categorized as a steroid hormone?
Testosterone
Which hormone is classified as an amine hormone derived from histidine?
Histamine
Which hormone increases the levels of cAMP in cells?
Thyroid stimulating hormone (TSH)
Which of the following is a second messenger used by water-soluble hormones?
Diacylglycerol (DAG)
What effect does serotonin have on hormone activity?
No effect
Which hormone interaction requires simultaneous exposure to a second hormone?
Permissive effect
During childbirth, which hormone increases uterine contractions?
Oxytocin
How is hormone secretion generally controlled?
Negative or positive feedback
What stimulates the release of parathyroid hormone (PTH)?
Low blood Ca2+ levels
Which hormone increases flexibility of the pubic symphysis during pregnancy?
Relaxin
What is the main hormone produced and secreted by the testes?
Testosterone
Which hormone is involved in regulating blood calcium levels?
Parathyroid hormone
What is the function of inhibin in both males and females?
Inhibits the secretion of FSH
What hormone does the pineal gland secrete?
Melatonin
Which hormone secreted by the kidneys increases red blood cell production?
Erythropoietin
Which of the following is NOT a function of estrogens and progesterone?
Stimulate descent of testes before birth
Which gland secretes atrial natriuretic peptide (ANP)?
Heart
Which gland is the major link between the nervous and endocrine systems?
Hypothalamus
What hormone is released by the posterior pituitary in response to elevated blood osmotic pressure?
Antidiuretic hormone (ADH)
Which hormone stimulates the liver to secrete insulinlike growth factors (IGFs)?
Human growth hormone (HGH)
What hormone is secreted in darkness by the pineal gland?
Melatonin
What principal actions does oxytocin (OT) perform?
Stimulates contraction of smooth muscle cells of the uterus during childbirth
What hormone inhibits the release of corticotropin by anterior pituitary corticotrophs?
Cortisol
Which hormone is involved in elevating blood glucose concentration?
Human growth hormone (HGH)
What is the function of follicle-stimulating hormone (FSH) in males?
Stimulates sperm production
The pineal gland secretes a hormone important for what function?
Regulation of the biological clock
What does the anterior pituitary do in response to hypothalamic inhibiting hormones?
Reduces corticotropin secretion
Study Notes
Endocrine System
- Coordinates all body systems with the nervous system
- Uses hormones produced by endocrine structures to produce effects
Endocrine Glands
- Secrete contents directly into the blood
- Include: pituitary, thyroid, parathyroid, adrenal, and pineal glands
Exocrine Glands
- Secrete contents into a lumen or duct
- Include: sudoriferous, sebaceous, mucous, and digestive glands
Hormone Functions
- Regulate:
- Extracellular fluid homeostasis
- Metabolism
- Muscle contraction
- Glandular secretions
- Some immune functions
- Involved in:
- Growth and development
- Reproduction
- Establishing circadian rhythms
Endocrine Hormones
- Secreted into interstitial fluid and then absorbed into the bloodstream
- Can act on any cell with the appropriate receptor
Local Hormones
- Autocrine hormones: act on the same cell that secretes them
- Paracrine hormones: act on nearby cells
- Examples: IL-2, NO
Lipid-Soluble Hormones
- Bind to receptors in the cytoplasm or nucleus of a cell
- Examples: steroid hormones (aldosterone, cortisol, testosterone, oestrogen), thyroid hormones (T3, T4), and gases (nitric oxide)
Thyroid Gland
- Located inferior to the larynx and anterior to the trachea
- Triggers growth of the nervous and skeletal systems
Thyroid Hormones
- Actions:
- Regulate metabolism
- Involved in growth and development
- Establish circadian rhythms
- Regulated by:
- Thyroid-stimulating hormone (TSH)
- Thyrotropin-releasing hormone (TRH)
Parathyroid Glands
- Located on the posterior surface of the thyroid gland
- Secrete parathyroid hormone (PTH) in response to low blood calcium levels
- Actions:
- Regulate blood calcium levels
Pancreatic Hormones
- Include:
- Glucagon
- Insulin
- Somatostatin
- Gastrin
- Secretin
- Cholecystokinin (CCK)
- Glucose-dependent insulinotropic polypeptide (GIP)
- Actions:
- Regulate blood glucose levels
- Involved in digestion and absorption of nutrients
Thymus
- Located superior to the heart
- Secretes thymosin
- Actions:
- Promotes proliferation and maturation of T cells
Ovaries
- Produce several steroid hormones:
- Estrogens and progesterone
- Relaxin
- Inhibin
- Actions:
- Regulate female reproductive cycle and oogenesis
- Maintain pregnancy
- Prepare mammary glands for lactation
Testes
- Produce testosterone
- Actions:
- Regulate male reproductive cycle and spermatogenesis
- Involved in development and maintenance of male secondary sex characteristics
Other Endocrine Tissues
- Include:
- Pineal gland
- Hypothalamus
- Pituitary gland
- Heart
- Stomach
- Kidney
- Adrenal glands
- Pancreas
- Small intestine
- Skin
- Liver
Water-Soluble Hormones
- Bind to receptors on the plasma membrane of a cell
- Include:
- Amine hormones
- Peptide hormones
- Eicosanoid hormones
Hormone Interactions
- Responsiveness of target cells depends on:
- Hormone concentration in blood
- Number of hormone receptors on target cells
- Influences of other hormones
- Types of interactions:
- Permissive
- Synergistic
- Antagonistic
Control of Hormone Secretion
- Regulated by:
- Signals from the nervous system
- Chemical changes in the blood
- Other hormones
- Types of control:
- Negative feedback
- Positive feedback
Hypothalamus and Pituitary Gland
- Hypothalamus: major link between the nervous and endocrine systems
- Pituitary gland: regulates other endocrine glands
- Anterior pituitary: stimulated by releasing hormones from the hypothalamus
- Posterior pituitary: stores and releases hormones produced by the hypothalamus
Pineal Gland
- Secretes melatonin
- Involved in maintaining the biological clock (seasonal and daily cycles)
Learn about the nervous and endocrine systems, their functions, and the types of glands involved. Understand how they coordinate body systems and produce effects.
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