Virology Lecture 2

Front 1

Autocrine

Back 1

Means that the cell secretes a chemical that affects activity in the same cell

Front 2

Paracrine

Back 2

means that the cell secretes a chemical that affects activity in adjacent cells

Front 3

Endocrine

Back 3

means that the cell secretes a chemical that affects activity in distant cells

Front 4

Ectocrine

Back 4

means that the organism secretes a chemical that affects another organism

Front 5

Definition of Endocrine Gland

Back 5

A ductless gland ...

1. From which hormones are released
2. Into the bloodstream
3. In response to physiological signals

Front 6

Definition of Hormone

Back 6

A chemical that...

1. Is effective in minute quantities
2. is released from endocrine cells
3. is secreted into the circulatory system
4. interacts with specific target cells some distance away
5. exerts a specific regulatory action on the target cell

Front 7

Definition of a Receptor

Back 7

A chemical structure that...

1. Is on the surface of the cell or inside it
2. has affinity for a specific chemical compound

Front 8

What are the classes of hormones?

Back 8

1. Peptide
2. Steroids
3. Amines
a. Catecholarmines
b. Indoleamines
c. Thyroid hormones

Front 9

Structure of Peptide hormones

Back 9

1. Water soluble
2. 3 - 40 amino acids
3. Polypeptide = 50 - 200 amino acids

Front 10

Action and Metabolism of Peptide Hormones

Back 10

1. Modify existing proteins
2. Affects synthesis of new proteins

Front 11

Structure of Steroids

Back 11

1. Three 6C rings + 1 conjugated 5C ring

Front 12

Steroid Hormone Synthesis

Back 12

1. Made from cholesterol by tissue-specific enzymes
2. synthesized in smooth endoplasmic reticulum
3. Cholesterol is present in tissue or taken up from the blood

Front 13

Steroid hormone secretion

Back 13

1. Secretion is coupled with synthesis
2. Secretion happens in pulses because pituitary hormones that activate it are pulsatile

Front 14

Steroid Transport

Back 14

1. Inactive while bound to CPs
2. At target tissues, dissociate from CPs and diffuse into cells

Front 15

General Features of Hormone Receptors

Back 15

1. Proteins or glycoproteins
2. Lock and key analogy
3. High affinity
4. High specificity
5. Embedded in cell membrane, cytosol, or nucleus
6. Undergo conformational change when bound to hormone
7. Receptor number and affinity are critical determinants of hormone effects
8. Receptor numbers are dynamic

Front 16

Peptide Hormone Receptors

Back 16

1. Embedded in plasma membrane
2. 3 major domains: extracellular, transmembrane, and cytoplasmic domain
3. two major types: intrinsic enzymatic activity
act via a G protein and an intracellular 2nd messenger

Front 17

G protein sample pathway

Back 17

1. signal molecule binds to G-protein linked receptor
2. G protein turns on adenylyl cyclase
3. Adenylyl cyclase converts ATP to cAMP
4. cAMP activates protein kinase A
5. Protein kinase A phosphorylates other proteins

Front 18

Steroid Hormone Receptors sample pathway

Back 18

1. Hormone receptor located in cell nucleus or cytoplasm
2. Hormone-Receptor complex translocates to nucleus
3. H-R binds to hormone response elements to stimulate or inhibit transcription

Front 19

What are the actual effects of hormones on cells?

Back 19

1. Change the rate of normal cellular functions
2. Affects size or morphology of cells
3. Affect growth, development, and death of cells
4. Alter sensitivity to other chemical messengers

Front 20

What does the posterior pituitary store and secrete?

Back 20

Vasopressin and Oxytocin

Front 21

Vasopressin effect

Back 21

1. Acts on kidney to reabsorb water
2. Acts on blood vessels to tighten tone
3. released in response to increased blood osmolarity, decreased blood volume, or decreased blood pressure

Front 22

Oxytocin effect

Back 22

1. Acts on uterus to increase contractions
2. Acts on breast to release milk