EXAM 2 extra study material

Cells that respond to signals are usually called?

Targets

Which is NOT a basic method of cell-to-cell communication?

Mechanical Signals

The most significant difference between a paracrine and an autocrine is

the cell that responds to it

Neurotranmitters and neurohormones both

are released by neurons and affect only cells with specific receptors

Why do some normal cells fail to respond to a chemical signal?

some cells lack the necessary receptors

Receptor molecules on the surface of a cell

determine that cell's response and may allow a particular ligand to bind

Receptor molecules are located

outer membrane, cytosol, nucleus, and cells surface

Down-regulation may allow a target cell to

only decrease its number of receptors for a ligand

Lipophilic hormones

bind to receptors inside the cytoplasm or nucleus

When adenylyl cyclase is activated,

cAMP is formed

Second messenger molecules directly

change the regulation of ion channels, increase intracellular calcium concentration, change enzyme activity, and change regulation of gene expression

An integrating center

evaluates incoming signals and compared it with the setpoint

Which of the following are considered differences between endocrine and neural control systems?

specificity, nature of the signal, speed, and duration of action

The desired target value for a parameter

setpoint

Receives information about the regulated variable and initiates a response

integrating center

The minimum stimulus to trigger a response

thershold

The organ or gland that performs the change

effector

Continuously moniters its environment for a specific variable

sensory receptor

Peripheral cells sensitive to the presence of hormones are called

targets

\____________________ can be caused by alterations in receptors or by problems with G protein or second

messenger pathways

\_________________ is a process by which an extracellular signal molecule, called the \____________, activates a membrane receptor that in turn alters intracellular molecules, called the \__________ to create a response

signal transduction, first messenger, second messenger

A chemical that is secreted by a cell to act on cells in its immediate vicinity is called a(n)

paracrine

If the signal molecule acts on the cell that secreted it, the chemical is called a(n)

autocrine

All molecules secreted by nerve cells (neuromodulators, neurotransmitters, and neurohormones) are known as

neurocrines

\_______________ are molecules that bind to the receptor in such a way that they block the normal ligand from binding and turning the receptor on. As a result, the signal pathway remains inactive.

antagonists

The nervous system has a role in preserving the "fitness" of the \________________________.

internal environment

The \____________ link membrane receptors to either ion channels or to membrane enzymes located on the cytoplasmic face of the membrane.

g proteins

Many second messenger systems activate \____________, enzymes that transfer a phosphate group from ATP to a protein. The phosphorylation of proteins sets off a series of intracellular events that lead to the ultimate cellular response.

protein kinases

To maintain \_______________, the body uses a combination of simple diffusion across small distances; wide spread distribution of molecules through the circulatory system and rapid, specific delivery of messages by the nervous system.

homeostasis

Most long-distance communication between cells takes place through the \___________ and \____________ systems with their combination of chemical and electrical signals.

nervous, endocrine

An intracellular signal molecule that translates a signal from a neurotransmitter or hormone into an intracellular response is called a \_______________________.

second messenger

The secretion of the hormone insulin in response to changes in blood glucose level is an example of a(n) \_____________ reflex.

simple endocrine

Homeostatic regulation usually involves a(n) \_____________ that is sensitive to a particular stimulus (variable) and a(n) whose activity has an effect on the same stimulus.

receptor, effector

What us the half-life of a signal?

the time required for a signal to lose half its activity

The intracellular effector in chemical signaling is often

a protein kinase

The most important factor determining which type of receptor a signal molecule will bind to is

the lipid solubility of the ligand

An ion widely important in intracellular signaling is

calcium

When calcium becomes available inside a cell, it comes from

extracellular fluid and intracellular storage

One intracellular calcium-binding protein is

calmodulin

Signal molecule receptors exhibit

specificity, competition, and saturation

The binding of lipophilic messengers, such as steroid hormones, to their receptors triggers

gene expression

Both insulin and glucagon are peptide hormones that target liver cells. The response of the target cells to each of these two hormones is opposite. This information implies that

the two hormones bind to different receptors and use a different second messenger

Homeostatic control that takes place at the tissue or cell by using paracrine or autocrine signals is called

local control

What general action is shared by about half of the medical drugs currently in use?

these drugs act on membrane receptor proteins

The link between a first messenger and a second messenger in a cell that responds to peptide hormones is usually

g protein

When adenylyl cyclase is activated

cAMP is formed

Typically, when steroid hormones bind to their receptors,

gene transcription may increase or decrease

Each of the following hormones is an amino acid derivative EXCEPT one. Identify the exception

thyroid-stimulating hormone

The majority of hormones in the body are

peptide hormones

The most complex endocrine responses involve the

hypothalamus

The posterior pituitary gland secretes

ADH

The pituitary hormone that controls the release of glucocorticoids from the adrenal cortex is

ACTH

The pituitary hormone that controls hormone synthesis and release from the thyroid gland is

TSH

The pituitary hormone that stimulates milk production by the mammary gland is

prolactin

Lipophobic molecule that interacts with receptors on cell surface

peptide hormone

Site of vasopressin synthesis

hypothalamus

True endocrine gland of epithelial origin

anterior pituitary

Cannot be stored in secretory vesicles

steroid hormone

Storage and release site for oxytocin

posterior pituitary

Primary source of adrenal medulla

epinephrine

Primary source of pancreas

insulin

Primary source of anterior pituitary

prolactin

Primary source of pineal

melatonin

The \____________________ of a hormone is an indicator of how long a hormone is active in the body,

half-life

A circulatory route that has two sets of capillaries is known as \___________________.

portal system

The \_______________ gland sits along the superior border of the kidney

adrenal

The outer layer of the adrenal gland is called the \___________.

adrenal cortex

The adrenal cortex produces a steroid hormone called \____________ that controls Na+ and K+ homeostasis and another steroid hormone called \_____________ that controls blood glucose levels.

aldosterone, cortisol

The term for two hormones that have additive effect is

synergists

The term that describes the need for one hormone to be present for a second hormone to produce a full effect is called \__________.

permissive

Two hormones that have opposing effects are called

antagonists

Chemical signals released into the blood by neurons are called \______________.

neurohormones

When stimulated by a particular hormone, there is marked increase in the activity of G proteins in the membrane. The hormone is probably

a steroid

In a simple endocrine reflex, the endocrine cell is the

sensor and integrating center

Synergism occurs when

hormones working together produce a larger effect than predicted

Hormones acting through signal transduction pathways elicit a \________________ response compared to hormones that produce genomic effects.

faster

A cell's or tissue's response to a hormone primarily depends on \______________ and \___________________.

cell receptors, signal transduction pathways

The signal molecule produced by one animal that may affect the behavior of another animal of the same species is the \________________.

pheromone

A signal molecule that is secreted into the external environment, instead of into the blood, is called a(n) \___________.

pheromone

The portions of a neuron that extend off of the roughly spherical cell body are usually collectively called

processes

Information coming into the central nervous system is transmitted along\_____________ neurons.

afferent and sensory

The afferent and efferent axons together form the

peripheral nervous system

The brain and spinal cord together compose the

central nervous system

Exocrine glands, smooth muscles, and cardiac muscles are controlled by the

autonomic nervous system

autonomic motor neurons are subdivided into the

sympathetic and parasympathetic divisions

In general, the nervous system is composed of which two types of cells

neurons and glial

Interneurons are found

only in the CNS

The multi thin, branched structures on a neuron whose main function is to receive incoming signals are the

dendrites

The collection of axons that carries information between the central nervous system and the peripheral effector is called

nerve

The region where the axon terminal meets it target call is called the

synapse

The axon is connected to the cell body by the

axon hillock

Clusters of nerve cell bodies in the peripheral nervous system are called

ganglia

Glial cell communicate primarily using

chemical signals only

Myelin is formed by

schwann cells and oligodendrocytes

These glial cells act as scavengers

microglia

Which ions is/are higher in concentration inside the cell compared to outside

potassium

Ion channel inactivation is

closing of the channel even when the stimulus continues

Which of the following is the most common location where action potentials originate

axon hillock

The rising phase of the action potential is due to

Na+ flows into the cell body

The falling phase of the action potential is primarily due to

K+ flow out of the cell