BMS Exam 2 Flashcards
What type of intracellular communication?
- Exchange of ions & molecules between adjacent cells across gap junctions.
- Occurs between 2 cells of the same type
- Highly specialized and relatively RARE
Direct Communication
What type of intracellular communication?
- Chemical signals transfer information from cell to cell within a single tissue.
- Transmission via extracellular fluid specific receptors on target cells
- Example: Blood Clot Formation
Paracrine Communication
What type of intracellular communication?
- Messages affect the same cells that secrete them
- Chemicals involved are autocrine agents
- Example: prostaglandins secreted by smooth muscle cells cause the same cells to contract
Autocrine Communication
What type of intracellular communication?
- Endocrine cells release chemicals (hormones) that are transported in the bloodstream
- Alters metabolic activities of many organs
- Target Cells - Have receptors needed to bind and “read” hormonal messages
Endocrine Communication
Similarity in BOTH Endocrine & Exocrine Glands
Both made up of glandular epithelium
Endocrine or Exocrine?
Release their contents through a duct that leads to the epithelial surface.
Exocrine Glands
3 types of exocrine glands
Merocrine, Apocrine, and Holocrine
Type of Exocrine Gland:
- Release by exocytosis
- Part
Merocrine
Examples of Merocrine
Sweat & Salivary Glands
Type of Exocrine Gland:
- Away
- Release by part of the cell being pinched off
Apocrine
Examples of Apocrine
Mammary & Odorous Sweat Glands
Type of Exocrine Gland:
- Whole
- Release by entire cell rupturing
Holocrine
Example of Holocrine
Sebaceous Glands
3 Classes of Hormones
Amino Acid Derivatives, Peptide Hormones, Lipid Derivatives
Class of Hormone:
- Small molecules structurally related to amino acids
- Derivates of tyrosine
- Derivatives of tryptophan
Amino Acid Derivatives
Derivates of Tyrosine
Thyroid Hormones, Catecholamines
Catecholamines
Epinephrine, norepinephrine, and dopamine
Derivatives of Tryptophan
Serotonin and Melatonin
Class of Hormone:
- Chains of amino acids
- Most are synthesized as prohormones
- Glycoproteins
- Short Polypeptides
- Small Proteins
- Includes ALL hormones secreted by hypothalamus, heart, thymus, digestive tract, pancreas, posterior lobe of the pituitary gland, etc.
Peptide Hormones
Inactive molecules converted to active hormone before or after they are secreted
Prohormones
Examples of Short-Chain Polypeptides
ADH and OXT
How many amino acids are in ADH and OXT?
9
Examples of Small Proteins in Peptide Hormones
Insulin, Growth Hormones, Prolactin
Derived from arachidonic acid, 20-cacrbon fatty acid molecules that coordinate cellular activities and affect enzymatic processes
Example?
Eicosanoids
Ex: Blood Clotting
What 2 examples have contrasting effects on blood clotting?
Omega 3 and Omega 6
Which class of hormone?
Eicosanoids
Steroid Hormones – derived from cholesterol
Bound to specific transport proteins in the plasma. Retain in circulation longer than peptide hormones.
Lipid Derivatives
Examples of steroid hormones:
Androgens from testes, estrogen and progesterone from ovaries, corticosteroids from adrenal cortex, and calcitriol from kidneys
What is a major difference between Peptide hormones and lipid derived hormones?
Lipid derived stay in circulation longer
Properties of Catecholamines and Peptide Hormones (4)
Not Lipid Soluble
Hydrophilic
Can’t penetrate plasma membrane
Bind to extracellular receptor proteins
Properties of Steroid & Thyroid Hormones
Lipid Soluble
Can diffuse across plasma membrane & bind to intracellular receptors
Under what conditions are free hormones inactivated? (3)
- Diffuse out of bloodstream & bind to receptors on target cells
- Are absorbed and broken down by liver or kidneys
- Are broken down by enzymes in blood or interstitial fluid
What 2 ways can hormones exist?
Circulate freely or bound to special carrier proteins
Do catecholamines & peptide hormones or steroid & thyroid hormones remain functional for longer?
Steroid and Thyroid
Presence of a hormone triggers a decrease in the number of hormone receptors.
When levels of a particular hormone become high, cells become less sensitive to it.
Down-Regulation
Absence of a hormone triggers an increase in the number of hormone receptors.
When levels of a particular hormone are low, cells become more sensitive to it.
Up-Regulation
Steroid Hormones can alter rate of DNA transcription in nucleus
Alterations in synthesis of enzymes or structural proteins -> directly affect activity & structure of target cell
Genomic Effect
Thyroid Hormones bind to receptors within the nucleus and on mitochondria.
- Activated genes or change rate of
transcription
- Increases rate of ATP production
Non-Genomic Effects
How many hormones does the anterior pituitary produce/secrete?
7
What class of hormones are the hormones that come from the pituitary gland?
Peptide Hormones
How many hormones does the posterior pituitary release?
2
2 facts about pituitary hormone transport/binding
Bind to extracellular receptors
Use cAMP as second messenger
Location of the pituitary gland in terms of the hypothalamus?
Hangs inferior, connected by infundibulum
Neural Stimuli
Stimulates uterine contractions and dilation of the cervix.
Positive Feedback Mechanism
Responsible for milk “let down”
Contribute to parent-newborn bonding
Oxytocin (OXT)
Ensures regulatory hormones reach cells in anterior pituitary before entering general circulation.
Blood flow is unidirectional.
Hypophyseal Portal System
Humoral Stimuli
Osmoreceptors in hypothalamus trigger release when blood osmolarity increases.
Negative Feedback Mechanism
Causes blood vessels to contract and increase blood pressure
Diabetes insipidus
Antidiuretic Hormone (ADH)
Released by GnRH
Stimulates male spermatogenesis and female oocyte maturation
production is inhibited by inhibin
Follicle Stimulating Hormone (FSH)
A peptide hormone released by cells in the testes and ovaries that inhibits production of FSH
Inhibin
Stimulates testes to produce testosterone and ovaries to produce estrogen.
Lead to secondary sexual development.
A surge of this causes ovulation.
Luteinizing Hormone (LH)
