Unit 1 Lecture

Typically, an adult's body contains _______ of blood.

5 liters

The term down-regulation refers to the process by which

A cell decreases the number of receptors it has for a hormone

A G protein is

A molecule that binds a guanine nucleotide and helps transduce a signal inside a target cell.

Excessive secretion of growth hormone in adults can cause

Acromegaly

An autorhythmic heart cell is one in which

Action potentials fire spontaneously

Glucagon works by

Activating second messengers and stimulating glycogenolysis and gluconeogenesis

The release of hormones from the adrenal cortex is stimulated by

Adrenocorticotropic hormone

Metabolically, cardiac muscle relies on

Aerobic metabolism using many mitochondria and a rich supply of myoglobin.

How does aging affect the endocrine system?

All of the choices are correct

Endocrine Glands

All of the choices are correct: are ductless goands, are the organs of the endocrine system, secrete hormones directly into the bloodstream, help maintain homeostasis

An individual's hematocrit would vary with

All of these choices are correct

The plateau phase of an action potential

Allows cardiac muscle cells to contract and then relax without locking up

Norepinephrine is considered a positive chronotropic agent because it causes

An increase in the firing rate of SA node cells

Glucagon and insulin work _________ on blood glucose levels

Antagonistically

Which lobe of the pituitary is larger and secretes more hormones?

Anterior pituitary

Thyroid-stimulating hormone (TSH) is secreted by the

Anterior pituitary, and it targets follicular cells of the thyroid gland.

Eicosanoids are synthesized from

Arachidonic Acid

According to the Frank-Starling law

As the volume of blood entering the heart increases, ventricular contractions become more forceful.

In an ECG, the P wave is generated when the

Atria depolarize

Blood plasma is slightly _______; if pH drifts out of the normal range, dire consequences can result from alterations in the structure of _______ .

Basic, proteins

Lipid-soluble hormones, such as progesterone, excert their effects by forming hormone-receptor complexes that

Bind to DNA and initiate transcription

To initiate a cardiac muscle cell contraction, calcium

Binds to troponin

During thyroid surgery, a surgeon mistakenly removes the parathyroid glands from his patient. Which of the following is a likely outcome in the patient?

Blood calcium lvels will drop

Aldosterone release can be triggered by the presence of blood-borne messenger angiotensin II or by low levels of sodium, and so its secretion regulation is said to be

Both hormonal and humoral

Cardiac output is the amount of blood that is pumped

By a single ventricle in one minute

What is the sequence of events in the transmission of an impulse through the heart muscle? a: AV node b: AV bundle c: SA node d: Through the atria e: Through the ventricles f: Bundle branches g: Purkinje fibers

C, D, A, B, F, G, E

For the repolarization phase of an SA nodal cell action potential,

Calcium channels close and potassium channels open

Once an SA nodal cell reaches threshold, the depolarization phase occurs during which

Calcium comes in through fast voltage-gated channels.

Which type of muscle cell exhibits a longer refractory period?

Cardiac muscle cell

Steroid hormones are lipids, derived from

Cholesterol

The disease called ___________ is caused by excessive secretion of glucocorticoids, and is characterized by redistribution of body fat to produce characteristic features such as "moon face."

Cushing syndrome

One of the functions of blood is to regulate fluid levels in the body. If too much fluid escapes from the bloodstream and enters the tissues, blood pressure will

Decrease

A malnourished person might have abnormally low levels of plasma proteins. As a result, colloid osmotic pressure

Decreases, and there is fluid retention in the interstitial space

At the AV node of the conduction system, the action potential is

Delayed due to the cells being small and having few gap junctions.

During the plateau phase of a cardiac muscle cell's action potential, the membrane stays

Depolarized as potassium exits and calcium enters

Once a structure is fully grown and mature, it will probably

Down-regulate its receptors for growth hormone, as it no longer needs to continue to grow at a fast rate.

In response to excessive amounts of hormone, a target cell may reduce its number of receptors for that hormone. This is an example of

Down-regulation

Intracellular signaling pathways within target cells are organized such that

Each step allows for amplification of the signal where one molecule can activate many

As with action potentials in other types of cells, the repolarization of cardiac muscle cells involves the

Exit of potassium through voltage-gated channels

The membrane of a contractile cardiac muscle cell contains

Fast voltage-gated sodium channels and slow voltage-gated calcium channels

Which hormones are collectively called the gonadotropins?

Follicle-stimulating hormone and luteinizing hormone

Most of the calcium that triggers contraction of cardiac muscle comes

From the sacroplasmic reticulum of the cell

Which is NOT correct regarding growth hormone (GH)?

GH stimulates the kidney to secrete somatomedin

The hormone that increases the rate of glycogen breakdown and glucose release by the liver is

Glucagon

Follicle-stimulating hormone is a

Glycoprotein

Cardiac output equals the

Heart rate multiplied by stroke volume

Parathyroid hormone release depends on blood levels of calcium. Such as an endocrine reflex is said to be initiated by

Humoral stimulation

You are "shadowing" an endocrinologist who is examining a patient complaining of weakness, weight loss, and heat intolerance. The doctor points out the patient's obvious exophthalmos and asks for your diagnosis. What would you speculate is the patient's problem?

Hypersecretion of thyroid hormone

The part of the brain that functions as a "master control center" of the endocrine system is the

Hypothalamus

Thyrotropin-releasing hormone is secreted by the

Hypothalamus and it increases release of thyroid-stimulating hormone from the anterior pituitary.

Damage to the liver might impair enzymatic degradation of some hormones. The levels of such hormones in the blood would therefore be expected to

Increase

Thyroid hormone's effects are to

Increase metabolic rate and body temperature by increasing protein synthesis in target cells.

Which hormone induces its target cells to take up glucose, thereby lowering blood glucose levels?

Insulin

Which hormone is secreted by the beta cells of the pancreas?

Insulin

Lipophilic hormones bind to ___________ receptors of target cells.

Intracellular

The reason it is more appropriate to call an erythrocyte a "formed element" rather than a "cell" is that erythrocytes

Lack a nucleus and organelles

The hormones and neurotransmitters released by the endocrine and nervous systems are chemical substances referred to as _________.

Ligands

Which type of hormone requires a carrier protein in the blood?

Lipid-soluble hormone

Compared to young adults, the elderly usually have ______ levels of circulating growth hormone and _____ levels of circulating sex hormones

Lower, lower

Which hormone is secreted by the pineal gland?

Melatonin

Which of the following is false?

Melatonin makes us feel alert and awake

As someone starts to develop in puberty, most cells in their reproductive organs are probably starting to express

More receptors for sex hormones

In response to high blood glucose, the pancreas releases insulin to enable glucose to enter body cells. When the blood glucose level returns to normal, insulin release stops. This is an example of regulation by

Negative feedback

A drug that decreased calcium levels in a muscle cell and thereby lowered the number of crossbridges formed during the heart's contractions would be a

Negative inotropic agent

Which hormone group is not secreted by the adrenal cortex?

No exceptions; all choices are secreted by the adrenal cortex

Where are the target cells for follicle-stimulating hormone?

Ovaries and testes

The two hormones released from the posterior pituitary are

Oxytocin and antidiuretic hormone

In addition to secreting hormones, the pancreas also produces

Pancreatic juice

When a chemical messenger helps initiate an inflammatory response by causing cellular changes in neighboring cells, it is demonstrating ___________ signaling.

Paracrine

The heart valves

Permit the passage of blood in one direction

The "buffy coat" in a centrifuged blood sample is composed of

Platelets and leukocytes

Glucose is a

Polar molecule, and therefore it dissolves readily in plasma.

Large doses of certain stimulants can lead to dangerous increases in heart rates. Such a stimulant is a

Positive chronotropic agent

Which term best describes the function of blood when considering the presence of leukocytes and antibodies?

Protection

Within the adenylate cyclase signal transduction pathways of target cells, cAMP activates

Protein kinase

What is the function of the mineralocorticoids secreted by the adrenal gland?

Regulate electrolyte concentration in body fluids

In an ECG, what does the T wave represent?

Repolarization of ventricles

The primary function of adrenocorticotropic hormone (ACTH) is to

Stimulate glucocorticoid release from the adrenal glands.

Growth hormone

Stimulates gluconeogenesis

Calcitonin

Stimulates osteoblast activity

When the effects of one hormone reinforce the activity of another hormone on the same target cell, the interaction is said to be

Synergistic

When the effects of water-soluble hormones on their target cells are considered, the hormone itself is

The first messenger

Generally, the shorter the half-life of a hormone

The more frequently it must be replaced

The release of hormones from the adrenal medulla is stimulated by

The sympathetic division of the autonomic system.

The half-life of a hormone is

The time necessary to reduce the hormone concentration in the blood to half of what had been secreted.

Thyroid hormone synthesis involves secretion of a glycoprotein called ___________ by the follicular cells.

Thyroglobulin

Blood is correctly classified as a(n)

Tissue

Which term best describes the function of blood when considering the presence of carbon dioxide and endocrine hormones?

Transportation

The metabolic condition called ___________ results from the destruction of the beta cells in the pancreas due to an autoimmune response

Type 1 diabetes

Reduced hormone concentration in the blood often causes target cells to

Up-regulate receptors in order to increase cell sensitivity

Which of the following does not have an endocrine function?

Urinary bladder

Protein hormones are

Water-soluble

A lack of dietary iodine can render the thyroid gland unable to synthesize TH. Without the negative feedback of TH, the anterior pituitary ____________, ultimately resulting in the development of a goiter

Will increase the release of TSH

Which region of the adrenal cortex synthesizes glucocorticoids?

Zona fasciculata

The smallest and most abundant plasma proteins are the

albumins

The membrane of a contractile cardiac muscle cell contains

calcium pumps that move calcium out of the cell.

Sodium, calcium, and bicarbonate are all described as plasma

electrolytes

The most numerous of the formed elements are the

erythrocytes

As growth hormone levels in the blood increase

glycogenolysis increases

One of the unhealthy effects of blood doping is to

increase the viscosity of the blood