Chapter 5 - Endocrinology and Immunology Flashcards
What role do phagocytes play in the immune response?
They leave the blood through pores in the blood vessels and enter the tissues to attack and destroy forein bacteria and viruses by phagocytosis.
What six hormones are secreted by the anterior pituitary?
- prolactin (PRL)
- growth hormone (GH)
- luteinizing hormone (LH)
- follicule stimulating hormone (FSH)
- thyroid stimulating hormone (TSH)
- adrenocorticotropic hormone (ACTH)
What two hormones are secreted by the posterior pituitary and where are they synthesized?
- oxytocin
- antidiuretic hormone (ADH)/vasopressin
They are synthesized in the hypothalamus.
Which class of antibody binds to mast cells and is involved in the allergic reaction?
IgE
When a peptide hormone binds a cell surface receptor, what is the first step of its second-messenger cascade?
The hormone-receptor complex activates a G protein.
Which class of antibody is produced a few days after the IgM is secreted?
IgG
What do monocytes become in the immune response?
macrophages
Which class of antibody is able to cross the placenta?
IgG
Describe insulin’s second-messenger cascade.
It binds to a specific transmembrane receptor. The cytoplasmic portion of that receptor is converted into a tyrosine kinase that autophosphorylates the amino acid tyrosine, which enhances the activity of the tyrosine kinase.
The insulin receptor can also internalize and act as a second messenger itself.
What is the general role of T lymphocytes in the immune response?
They are responsible for cell-mediated immunity.
Which class of antibody is produced a few days after detection of an antigen?
IgM
What two types of cells make up blood?
- erythrocytes (red blood cells)
- leukocytes (white blood cells)
Where are Class I MHC protein receptors found?
on almost every one of our cells
Which class of antibody is most abundant?
IgG
Define humoral mediated immunity
immune response mediated by macromolecules in the extracellular fluids such as antibodies
What does IP3 typically interact with and cause?
It interacts with the endoplasmic reticulum to stimulate the release of Ca2+ into the cytoplasm
Where are red blood cells produced?
in the marrow of the sternum, ribs, and vertebrae
What role does histamine play in the immune response?
It acts on endothelial cells, causing an increased permeability to cells like neutrophils.
What recognizes an antigen on a macrophage’s MHC protein and what happens when it binds the antigen?
Receptors on a cytotoxic T cell recognize the antigen-Class I MHC protein complex and bind. The macrophage releases the growth factor interleukin-1 and the cytotoxic T cell releases the growth factor interleukin-2 causing the proliferation of more cytotoxic T cells.
What three ways do antibodies work against foreign invaders?
- Directy Block: bind antigens, physically blocking invader’s access to host cell
- Complement: bind antigens, allow a complement protein to recognize the antigen-antibody complex and trigger an immune response: membrane attack complex (MAC) lets water into the bacterial cell and it lyses
- Cell Surface Coating: bind antigens and coat invader’s cell surface, “tagging” it to be recognized by phagocytes or cytotoxic T cells
What are the three types of T lymphocytes?
- cytotoxic T cells (kill T cells)
- helper T cells
- suppressor T cells
Which cells secrete glucagon?
α cells
What hormone is released and from where when the metabolic rate of the body is too low?
thyroxine from the thyroid
In the catecholamine second-messenger cascade, what does the G protein do to inactivate?
It hydrolyzes the bound GTP to GDP and Pi.
What does a protein kinase do?
It transfers the end phosphate (gamma phosphate) of ATP to a specific amino acid residue of a substrate protein (phosphorylates).
What is an antigen?
It is a foreign substance (protein or polysaccharide) which has a high molecular weight that has entered the body and induces a particular immune response. It is located on the surface of an invader.
In the catecholamine second-messenger cascade, what does the G-protein-GTP complex do?
The G protein-GTP complex diffuses through the membrane to activate membrane-bound adenylate cyclase enzymes.
In the catecholamine second-messenger cascade, what is the second-messenger?
cyclic adenosine monophosphate (cAMP)
What general role do B lymphocytes play in the immune response?
They circulate in the blood and to lymph organs and are responsible for humoral mediated immunity. They can differentiate into plasma cells.
What connects the four chains (2 heavy, 2 light) in an antibody?
disulfide bonds
Where are white blood cells produced?
in the tissues of the lymph and partly in bone marrow
What does DAG typically interact with and cause?
It interacts with membrane-bound protein kinase C (PKC), stimulating it with the help of Ca2+ to phosphorylate and activate another enzyme.
What specifically does cholera do to affect the second-messenger cascade?
It binds to active G protein, preventing it from inactivating, so cAMP is continually synthesized. cAMP causes the intestinal cells to secrete digestive fluids ► diarrhea.
What is the role of memory B and memory T cells?
They “remember” antigens and proliferate faster during the same invasion of a foreign body.
What differs between classes of antibodies?
composition of their heavy chains
In the peptide hormone second-messenger cascade, what is the second-messenger?
IP3
What are antibodies/immuniglobulins (Ig)?
proteins that are synthesized in response to an antigen that has been introduced to the body
What happens when a macrophage engulfes an antigen?
It breaks it into fragments which are released into the macrophage’s cytosol and transported to its membrane where they bind to the Class I major histocompatibility complex (MHC) protein.
What is paracrine regulation?
A signalling chemical is released from a cell to influence its direct neighbors.
What are the clusters of cells called in the pancreas that secrete hormones?
Islets of Langerhans
Define cell-mediated immunity
An immune response that does not involve antibodies, but phagocytes and cytotoxic T cells
Where do T cells originate?
thymus gland
Which class of antibody is the first to be produced in response to an antigen?
IgM
What are the two types of lymphocytes?
- T lymphocytes (T cells)
- B lymphocytes (B cells)
What enzyme does PKA stimulate to perform glycogenolysis? In which cell does this take place?
PKA phosphorylates glycogen phosphorylase which catalyzes the conversion of glycogen to glucose. This takes place in hepatic liver cells.
What is meant by amplification of a hormone signal?
Each enzyme in the cascade activates many more molecules in the next step of the sequence.
What do plasma cells do?
synthesize and secrete antibodies
What is the precursor molecule to steroid hormones?
cholesterol
After a catecholamine binds its receptor, what is the next step in the second-messenger cascade?
The hormone-receptor complex interacts with a membrane-bound G protein, which exchanges GDP for GTP.
Which class of antibody is found in milk and helps protect nursing infants?
IgA
Describe the detailed role of B lymphocytes when it comes across an antigen.
They have Class II major histocompatibility complex (MHC) protein on their surface, along with antibodies. When an antigen binds its antibodies, the B lymphocyte engulfs that antigen-antibody complex, degrades it, and releases antigen fragments to its Class II MHC protein to “display” the antigen.
What are the three classes of hormones?
- peptide
- amine
- steroid
Which class of antibody has an unknown function?
IgD
What recognizes an antigen on a B lymphocyte’s MHC protein, and what happens when it binds the antigen?
Receptors on helper T cells bind the B lymphocyte’s antigen-Class II MHC protein complex and release growth factor interleukins causing the proliferation of B lymphocytes.
What role do mast cells play in the immune response? What are they derived from?
Derived from white blood cells, they reside in the tissues and release histamine when stimulated.
What is a major example of catecholamine hormones?
epinephrine (adrenaline)
What four regions make up an antibody in order from the lower portions to the terminal ends of the heavy and light chains? How do these fit into domains?
Constant Domain:
- constant (C)
Variable Domain:
- joining (J)
- diversity (D)
- variable (V)
Define diuresis
excessive loss of urine
How do steroid hormones interact with target cell receptors
They pass through the cell’s plasma membrane and interact with a receptor in the cytosol or in the nucleus.
What major enzyme does cAMP typically interact with?
protein kinase A (PKA)
How does T cells structure differ from antibody structure?
They are very similar in regards to domains and regions, but rather than 4 polypeptide chains, it only has two.
In a peptide hormone second-messenger cascade, what is the role of activated G protein?
The G protein interacts with the membrane-bound enzyme phospholipase C (PLC), inducing it to hyrolyze phosphatidyl-inositol-4,5-bisphosphate (PIP2) to inositol-1,4,5-triphosphate (IP3) and 1,2-diacylglycerol (DAG).
What cell-surface receptor binds catecholamines?
β-adrenergic receptors
Where is the antigen binding site of an antibody located?
at the end of the variable regions of the heavy and light chains.
Which cells secrete insulin?
β cells
In animals, what is the stored form of glucose?
glycogen
What two types of cells are phagocytes?
- monocytes
- neutrophils
What is autocrine regulation?
Cells release certain chemicals they can respond to themselves.
What level of the immune response does HIV affect?
It infects helper T cells.
Where do thyroid hormones bind and cause?
They bind in the nucleus to activate transcription for certain metabolic processes.
What do interleukin-1, interleukin-2, and other interleukins do?
They stimulate the proliferation of more cytotoxic T cells which can bind invading foreign cells’ antigens, inducing them to lyse.
They also stimulate B lymphocytes to proliferate and form plasma cells that will produce many antibodies which tag antigens, signaling phagocytes to destroy them.
What do the adenylate cyclase enzymes do?
Adenylate cyclase catalyzes the conversion of ATP to cAMP + PPi.
