Travismulthaupt.com Chapter 45 Hormones and the Endocrine System.

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Hormones and the Endocrine System

Hormones and the Endocrine System

Internal CommunicationInternal Communication

Animals have 2 systems of internal communication and regulation:1. The nervous system.2. The endocrine system.

Animals have 2 systems of internal communication and regulation:1. The nervous system.2. The endocrine system.

1. The Nervous System1. The Nervous System

The nervous system is the pathway of communication involving high speed electrical signals.

There are two portions to it:CNSPNS

The nervous system is the pathway of communication involving high speed electrical signals.

There are two portions to it:CNSPNS

Nervous TissueNervous Tissue

Senses stimuli and transmits nerve impulses from one part of the body to the next.

The neuron is the functional unit.AxonDendrite

Senses stimuli and transmits nerve impulses from one part of the body to the next.

The neuron is the functional unit.AxonDendrite

Near its end, an axon divides into several branches, each ending in a synaptic terminal.

Near its end, an axon divides into several branches, each ending in a synaptic terminal.

Copyright ©2005 Pearson Education, Inc. Publishing as Pearson Benjamin Cummings. All rights reserved.

What is a nerve?—Form Fitting Function

http://biologyclass.neurobio.arizona.edu/images/synapse2.jpg



The synapse is the site of communication between one nerve and another.

The synapse is the site of communication between one nerve and another.




Neurotransmitters transmit the signal from a pre-synaptic cell to a post-synaptic neuron.

Neurotransmitters transmit the signal from a pre-synaptic cell to a post-synaptic neuron.

Synaptic Transmission

Synaptic Transmission

The transmission of information from the presynaptic neuron to the postsynaptic neuron due to an action potential can trigger short and long term changes—membrane potential or signal cascades.

The transmission of information from the presynaptic neuron to the postsynaptic neuron due to an action potential can trigger short and long term changes—membrane potential or signal cascades.


How Do Nerve Systems Work?How Do Nerve Systems Work?

Information processing by the nervous system consisting of 3 stages:1. Sensory input2. Integration3. Motor output

Information processing by the nervous system consisting of 3 stages:1. Sensory input2. Integration3. Motor output

How Do Nerve Systems Work?


These three stages are handled by specialized neurons.

These three stages are handled by specialized neurons.


How Do Nerve Systems Work? 1. Sensory

neurons transmit information from sensors that detect external stimuli and internal conditions.These receptors are

usually specialized neurons or epithelial cells.

1. Sensory neurons transmit information from sensors that detect external stimuli and internal conditions.These receptors are

usually specialized neurons or epithelial cells.



2. Interneurons integrate and analyze sensory input. They allow the spinal cord to work independently of the brain and provide reflexes.

2. Interneurons integrate and analyze sensory input. They allow the spinal cord to work independently of the brain and provide reflexes.



This reflex is an automatic response to certain stimuli and acts to protect the body from harm—think about touching something hot.

This reflex is an automatic response to certain stimuli and acts to protect the body from harm—think about touching something hot.



2. These interneurons provide inhibitory signals to opposing muscles allowing the reflex to produce the desired result.

2. These interneurons provide inhibitory signals to opposing muscles allowing the reflex to produce the desired result.



The CNS also provides the integrative power for the organism—specifically the brain.

The CNS also provides the integrative power for the organism—specifically the brain.



3. Motor output leaves the CNS via motor neurons which communicate with effector cells eliciting a change.

3. Motor output leaves the CNS via motor neurons which communicate with effector cells eliciting a change.



These motor neurons can be due to voluntary control, or involuntary control.

These motor neurons can be due to voluntary control, or involuntary control.

2. The Endocrine System2. The Endocrine System

The endocrine system is all of the animal’s hormone secreting cells.

The endocrine system coordinates a slow, long-lasting response.

The endocrine system is all of the animal’s hormone secreting cells.

The endocrine system coordinates a slow, long-lasting response.

Endocrine GlandsEndocrine Glands

Endocrine glands are hormone secreting organs.

They are ductless glands.Their product is secreted into

extracellular fluid and diffuses into circulation.

Endocrine glands are hormone secreting organs.

They are ductless glands.Their product is secreted into

extracellular fluid and diffuses into circulation.

Endocrine and Nervous Systems

Endocrine and Nervous Systems

It is convenient to think of the nervous system and the endocrine as separate.

They are actually very closely linked.Neurosecretory cells are specialized

nerve cells that release hormones into the blood. They have characteristics of both nerves and

endocrine cells.

It is convenient to think of the nervous system and the endocrine as separate.

They are actually very closely linked.Neurosecretory cells are specialized

nerve cells that release hormones into the blood. They have characteristics of both nerves and

endocrine cells.

Neurosecretory CellsNeurosecretory Cells

The hypothalamus and the posterior pituitary gland contains neurosecretory cells.

These produce neurohormones which are distinguishable from endocrine hormones.

Some hormones serve as both endocrine hormones and neurotransmitters.

The hypothalamus and the posterior pituitary gland contains neurosecretory cells.

These produce neurohormones which are distinguishable from endocrine hormones.

Some hormones serve as both endocrine hormones and neurotransmitters.

Neurosecretory CellsNeurosecretory Cells

They can stimulate a response, or they can induce a target cell to elicit a response.For example, a suckling infant and

oxytocin release is an example.

They can stimulate a response, or they can induce a target cell to elicit a response.For example, a suckling infant and

oxytocin release is an example.

Biological Control SystemsBiological Control Systems

Recall, These are comprised of a receptor/sensor

which detects a stimulus and sends information to a control center that controls an effector.

The control center processes the information and compares it to a set point.

The control center sends out processed information and directs the response of the effector.

Recall, These are comprised of a receptor/sensor

which detects a stimulus and sends information to a control center that controls an effector.

The control center processes the information and compares it to a set point.

The control center sends out processed information and directs the response of the effector.

3 General Hormonal Pathways

3 General Hormonal Pathways

1. A simple endocrine pathway.2. A simple neurohormone

pathway.3. A simple neuroendocrine

pathway.

1. A simple endocrine pathway.2. A simple neurohormone

pathway.3. A simple neuroendocrine

pathway.

1. A Simple Endocrine Pathway


A stimulus elicits a response on an endocrine cell causing a hormone release.

The hormone diffuses into the blood where it reaches a target effector eliciting a response.

A stimulus elicits a response on an endocrine cell causing a hormone release.

The hormone diffuses into the blood where it reaches a target effector eliciting a response. Copyright ©2005 Pearson Education, Inc. Publishing as Pearson Benjamin Cummings. All rights reserved.



For example: A low glucose level in the

blood stimulates the pancreas to release glucagon.

Glucagon acts on liver cells to release glycogen.

Glycogen breaks down into glucose and gets into the blood.

For example: A low glucose level in the

blood stimulates the pancreas to release glucagon.

Glucagon acts on liver cells to release glycogen.

Glycogen breaks down into glucose and gets into the blood.


2. Simple Neurohormone Pathway


In the simple neurohormone pathway, a stimulus travels via a sensory neuron to the hypothalamus/posterior pituitary gland.

Neurosecretory cells here release hormones into the blood.

These hormones travel to the target cells and elicit a response.

In the simple neurohormone pathway, a stimulus travels via a sensory neuron to the hypothalamus/posterior pituitary gland.

Neurosecretory cells here release hormones into the blood.

These hormones travel to the target cells and elicit a response. Copyright ©2005 Pearson Education, Inc. Publishing as Pearson Benjamin Cummings. All rights reserved.



For example: A suckling infant’s

stimulation is sent via a sensory neuron to the hypothalamus/posterior pituitary where oxytocin is made and released into the blood.

The hormones travel to the smooth muscle in the breast which responds by contracting and releasing milk.

For example: A suckling infant’s

stimulation is sent via a sensory neuron to the hypothalamus/posterior pituitary where oxytocin is made and released into the blood.

The hormones travel to the smooth muscle in the breast which responds by contracting and releasing milk.


3. A Simple Neuroendocrine Pathway


A stimulus sends the signal to the hypothalamus via a sensory neuron.

The neurosecretory cells of the hypothalamus release hormones into the blood.

These act on endocrine cells to release different hormones into the blood.

These hormones have an effect on target cells and elicit a response.

A stimulus sends the signal to the hypothalamus via a sensory neuron.

The neurosecretory cells of the hypothalamus release hormones into the blood.

These act on endocrine cells to release different hormones into the blood.

These hormones have an effect on target cells and elicit a response. Copyright ©2005 Pearson Education, Inc. Publishing as Pearson Benjamin Cummings. All rights reserved.



For example: Neural and hormonal signals tell

the hypothalamus to secrete prolactin releasing hormone.

This hormone travels through the blood to the anterior pituitary which releases prolactin.

Prolactin travels through the blood to the mammary glands stimulating milk production.

For example: Neural and hormonal signals tell

the hypothalamus to secrete prolactin releasing hormone.

This hormone travels through the blood to the anterior pituitary which releases prolactin.

Prolactin travels through the blood to the mammary glands stimulating milk production.


Positive and Negative Feedback

Positive and Negative Feedback

Recall,Positive feedback acts to reinforce

the stimulus. It leads to a greater response.

Negative feedback acts to reduce the response of the stimulus.

Recall,Positive feedback acts to reinforce

the stimulus. It leads to a greater response.

Negative feedback acts to reduce the response of the stimulus.

Molecules Functioning as Hormones

Molecules Functioning as Hormones

There are 3 major classes of molecules that function as hormones:1. Proteins/peptides-water soluble.2. Amines-water soluble.3. Steroids-not water soluble.

There are 3 major classes of molecules that function as hormones:1. Proteins/peptides-water soluble.2. Amines-water soluble.3. Steroids-not water soluble.

Key EventsKey Events

There are 3 key events involved in signaling: 1. Reception-is when the signal binds to the

receptor protein in or on the target cell. Receptors can be inside or outside the cell.

2. Signal transduction-signal binds and triggers events within the cell (cascade events).

3. Response-changes a cell’s behavior.

There are 3 key events involved in signaling: 1. Reception-is when the signal binds to the

receptor protein in or on the target cell. Receptors can be inside or outside the cell.

2. Signal transduction-signal binds and triggers events within the cell (cascade events).

3. Response-changes a cell’s behavior.

Signal TransductionSignal Transduction

Receptors for most water soluble proteins are embedded in the plasma membrane.

Binding of a hormone initiates a signal transduction pathway.

Receptors for most water soluble proteins are embedded in the plasma membrane.

Binding of a hormone initiates a signal transduction pathway.

Signal TransductionSignal Transduction

The pathway is a series of changes where cellular proteins convert an extracellular chemical signal into an intracellular response.

Examples: Activation of an enzyme Uptake or secretion of a specific molecule Rearrangement of a cytoskeleton

The pathway is a series of changes where cellular proteins convert an extracellular chemical signal into an intracellular response.

Examples: Activation of an enzyme Uptake or secretion of a specific molecule Rearrangement of a cytoskeleton

Signal TransductionSignal TransductionThe signals can activate

proteins that can act to directly or indirectly regulate transcription of certain genes.

Hormones can cause a variety of responses in target cells with different receptors.

These responses are types of signal transductions.

The signals can activate proteins that can act to directly or indirectly regulate transcription of certain genes.

Hormones can cause a variety of responses in target cells with different receptors.

These responses are types of signal transductions.

Water Soluble HormonesWater Soluble Hormones

Most water soluble hormones have receptors embedded in the membrane.

Surface receptor proteins activate proteins in the cytoplasm which then move into the nucleus and regulate transcription.

Most water soluble hormones have receptors embedded in the membrane.

Surface receptor proteins activate proteins in the cytoplasm which then move into the nucleus and regulate transcription.

Epinephrine Example-Water Soluble HormoneEpinephrine Example-

Water Soluble HormoneLiver cells and smooth muscle of

blood vessels supplying skeletal muscle contain β-type epinephrine receptors.

Liver cells and smooth muscle of blood vessels supplying skeletal muscle contain β-type epinephrine receptors.

Epinephrine Example-Water Soluble HormoneEpinephrine Example-

Water Soluble HormoneSmooth muscle of

intestinal blood vessels contain α-type receptors.

The tissues respond differently to epinephrine. Increased blood flow

and glucose to the skeletal muscles.

Decreased blood flow to the digestive tract.

Smooth muscle of intestinal blood vessels contain α-type receptors.

The tissues respond differently to epinephrine. Increased blood flow

and glucose to the skeletal muscles.

Decreased blood flow to the digestive tract.

Lipid Soluble HormoneLipid Soluble HormoneLipid soluble hormones

have their receptors located inside of the cell. Either in the cytoplasm or the nucleus.

Entrance of the signal and binding of the signal to the receptor initiates the signal transduction pathway. Binding to DNA stimulates

transcription of genes. mRNA produced is translated into

protein within the cytoplasm.

Lipid soluble hormones have their receptors located inside of the cell. Either in the cytoplasm or the nucleus.

Entrance of the signal and binding of the signal to the receptor initiates the signal transduction pathway. Binding to DNA stimulates

transcription of genes. mRNA produced is translated into

protein within the cytoplasm.

Estrogen Example-Lipid Soluble Hormone

Estrogen Example-Lipid Soluble Hormone

Estrogen induces cells within the female bird’s reproductive system to make large amounts of ovalbumin.

Estrogen induces cells within the female bird’s reproductive system to make large amounts of ovalbumin.

Paracrine SignalingParacrine SignalingNeighboring cells signal local

regulators to convey signals between these neighboring cells.

Neurotransmitters, cytokines, and growth factors are all examples of local regulators.

Neighboring cells signal local regulators to convey signals between these neighboring cells.

Neurotransmitters, cytokines, and growth factors are all examples of local regulators.

Paracrine Signaling-Example

Paracrine Signaling-Example

Nitric oxide (NO).When blood O2 levels fall,

endothelial cells in the blood vessel walls synthesize and release NO.

NO activates an enzyme that relaxes neighboring smooth muscle.

This results in the dilation of blood vessels and improves blood flow.

Nitric oxide (NO).When blood O2 levels fall,

endothelial cells in the blood vessel walls synthesize and release NO.

NO activates an enzyme that relaxes neighboring smooth muscle.

This results in the dilation of blood vessels and improves blood flow.

Endocrine ControlEndocrine Control

The hypothalamus integrates the vertebrates’ nervous and endocrine systems.

It is found on the underside of the brain.

It receives information from nerves throughout the body and brain.

It initiates the appropriate endocrine signals for varying conditions.

The hypothalamus integrates the vertebrates’ nervous and endocrine systems.

It is found on the underside of the brain.

It receives information from nerves throughout the body and brain.

It initiates the appropriate endocrine signals for varying conditions.

The HypothalamusThe Hypothalamus

Contains 2 sets of neurosecretory cells.

The secretions from these cells are stored in or regulate the activity of the pituitary gland.

Contains 2 sets of neurosecretory cells.

The secretions from these cells are stored in or regulate the activity of the pituitary gland.

The PituitaryThe Pituitary

The pituitary gland has 2 parts: the anterior and the posterior.

The pituitary gland has 2 parts: the anterior and the posterior.

The Anterior Pituitary Gland


It is regulated by hormones produced by neurosecretory cells in the hypothalamus.

Some inhibit hormone release, others stimulate it. The adenohypophysis consists of endocrince cells

that make and secrete at least 6 different hormones. Many of them target and stimulate endocrine glands.

It is regulated by hormones produced by neurosecretory cells in the hypothalamus.

Some inhibit hormone release, others stimulate it. The adenohypophysis consists of endocrince cells

that make and secrete at least 6 different hormones. Many of them target and stimulate endocrine glands.



FSH-stimulates production of ova and sperm.

LH-stimulates ovaries and testes.TSH-stimulates the thyroid gland.ACTH-stimulates production and

secretion of the hormones of the adrenal cortex.

MSH-stimulates concentration of melanin in skin.

Prolactin-stimulates mammary gland growth and milk synthesis.

FSH-stimulates production of ova and sperm.

LH-stimulates ovaries and testes.TSH-stimulates the thyroid gland.ACTH-stimulates production and

secretion of the hormones of the adrenal cortex.

MSH-stimulates concentration of melanin in skin.

Prolactin-stimulates mammary gland growth and milk synthesis.

The Posterior Pituitary Gland

The Posterior Pituitary Gland

The neurohypophysis is an extension of the hypothalamus.

It stores and secretes 2 hormones: ADH and oxytocin. ADH acts on the kidneys

increasing H2O retention. Oxytocin signals uterine

muscle contraction and mammary gland excretion of milk.

The neurohypophysis is an extension of the hypothalamus.

It stores and secretes 2 hormones: ADH and oxytocin. ADH acts on the kidneys

increasing H2O retention. Oxytocin signals uterine

muscle contraction and mammary gland excretion of milk.

The Thyroid GlandThe Thyroid Gland

The thyroid produces 2 hormones.Triiodothyroxine (T3)Thyroxin (T4)

In mammals, T4 is converted to T3 by target cells.

T3 is mostly responsible for the cellular response.

The thyroid produces 2 hormones.Triiodothyroxine (T3)Thyroxin (T4)

In mammals, T4 is converted to T3 by target cells.

T3 is mostly responsible for the cellular response.


The thyroid is crucial to development. It is required for normal functioning of

bone-forming cells. It promotes branching of nerves in utero. It helps skeletal growth and mental

development. It helps maintain muscle tone, digestion,

reproductive functions, b.p., h.r.

The thyroid is crucial to development. It is required for normal functioning of

bone-forming cells. It promotes branching of nerves in utero. It helps skeletal growth and mental

development. It helps maintain muscle tone, digestion,

reproductive functions, b.p., h.r.


The thyroid creates calcitonin.

It works in conjunction with the parathyroid to maintain calcium homeostasis.

The thyroid creates calcitonin.

It works in conjunction with the parathyroid to maintain calcium homeostasis.

Parathyroid HormoneParathyroid HormoneReleased by the

parathyroid gland in response to low blood calcium levels.

PTH induces the breakdown of osteoclasts.

Ca2+ is then released into the blood.

PTH stimulates Ca2+ uptake by the renal tubules.

Released by the parathyroid gland in response to low blood calcium levels.

PTH induces the breakdown of osteoclasts.

Ca2+ is then released into the blood.

PTH stimulates Ca2+ uptake by the renal tubules.

Parathyroid HormoneParathyroid HormonePTH also promotes the conversion

of vitamin D into its active form.The active form of vitamin D acts

on the intestines stimulating the uptake of Ca2+ from food.

When Ca2+ gets above a certain setpoint, it promotes the release of calcitonin which opposes the effects of PTH lowering blood Ca2+ levels.

PTH also promotes the conversion of vitamin D into its active form.

The active form of vitamin D acts on the intestines stimulating the uptake of Ca2+ from food.

When Ca2+ gets above a certain setpoint, it promotes the release of calcitonin which opposes the effects of PTH lowering blood Ca2+ levels.

HomeostasisHomeostasis

Homeostatic mechanisms moderate changes in internal environments and have 3 functional components:1. A receptor2. A control center3. An effector

Homeostatic mechanisms moderate changes in internal environments and have 3 functional components:1. A receptor2. A control center3. An effector

The ReceptorThe Receptor

Detects a change in the internal environment of an animal.Example: Body temperature.

Detects a change in the internal environment of an animal.Example: Body temperature.

The Control CenterThe Control Center

Processes the information it receives and directs an appropriate response.Example: Brain.

Processes the information it receives and directs an appropriate response.Example: Brain.

The EffectorThe Effector

The effector displays the appropriate response.Example: Shivering, dilation or

constriction of blood vessels.

The effector displays the appropriate response.Example: Shivering, dilation or

constriction of blood vessels.

For Example:For Example:The regulation of room temperature.The control center is the thermostat

and it contains a receptor called the thermometer.

When the temp falls below a set point, it switches the heater (the effector) on.

When the thermometer senses the temp is above the set point, it switches the heat off--negative feedback.

The regulation of room temperature.The control center is the thermostat

and it contains a receptor called the thermometer.

When the temp falls below a set point, it switches the heater (the effector) on.

When the thermometer senses the temp is above the set point, it switches the heat off--negative feedback.

Negative FeedbackNegative Feedback

Occurs when the variable being monitored counteracts any further change in the same direction.

There are only slight variations above and below the set point in a negative feedback system.

Most homeostatic mechanisms in an animal operate under this principle.

Occurs when the variable being monitored counteracts any further change in the same direction.

There are only slight variations above and below the set point in a negative feedback system.

Most homeostatic mechanisms in an animal operate under this principle.

Positive FeedbackPositive Feedback

On the other hand, positive feedback occurs when a change in an environmental variable triggers mechanisms that amplify the change.

For example:During childbirth, the head against the

uterine wall stimulates more contractions in the uterus.

Positive feedback completes childbirth.

On the other hand, positive feedback occurs when a change in an environmental variable triggers mechanisms that amplify the change.

For example:During childbirth, the head against the

uterine wall stimulates more contractions in the uterus.

Positive feedback completes childbirth.

ThermoregulationThermoregulation

This is the process by which animals maintain an internal temperature within a tolerable range.

This ability is critical to survival because enzyme function and membrane permeability is dramatically affected by large changes in temperature.

This is the process by which animals maintain an internal temperature within a tolerable range.

This ability is critical to survival because enzyme function and membrane permeability is dramatically affected by large changes in temperature.

Heat ExchangeHeat Exchange

Endotherms and ectotherms use 4 modes of heat exchange:1. Conduction2. Convection3. Radiation4. Evaporation

Endotherms and ectotherms use 4 modes of heat exchange:1. Conduction2. Convection3. Radiation4. Evaporation

Thermoregulatory Functions

Thermoregulatory Functions

Thermoregulators function by balancing heat loss with heat gain.

There are 5 general categories to assist with this:1. Insulation2. Circulatory Adaptation3. Evaporative Cooling4. Behavioral Responses5. Adjusting Metabolism

Thermoregulators function by balancing heat loss with heat gain.

There are 5 general categories to assist with this:1. Insulation2. Circulatory Adaptation3. Evaporative Cooling4. Behavioral Responses5. Adjusting Metabolism

1. Insulation1. Insulation

Fat, hair, and/or feathers help to reduce heat flow between the organism and the surroundings.

The integumentary system in mammals acts as this insulating layer.

Fat, hair, and/or feathers help to reduce heat flow between the organism and the surroundings.

The integumentary system in mammals acts as this insulating layer.

2. Circulatory Adaptations2. Circulatory Adaptations

Vasodilation and vasoconstriction work together to transfer body heat form the core to the surroundings.Vasodilation--vessels get larger.Vasoconstriciton--vessels get smaller.

Vasodilation and vasoconstriction work together to transfer body heat form the core to the surroundings.Vasodilation--vessels get larger.Vasoconstriciton--vessels get smaller.

3. Evaporative Cooling3. Evaporative Cooling

Many animals have structural adaptations that enable them to take advantage of evaporation as a way of controlling body temperature.For Example: Sweat glands, panting,

and mucous secretions.

Many animals have structural adaptations that enable them to take advantage of evaporation as a way of controlling body temperature.For Example: Sweat glands, panting,

and mucous secretions.

4. Behavioral Adaptations4. Behavioral Adaptations

Behavioral responses are used by endotherms and ectotherms as a means to control body temperature.Basking in the sunMigrationHibernation

Behavioral responses are used by endotherms and ectotherms as a means to control body temperature.Basking in the sunMigrationHibernation

5. Adjusting Metabolism 5. Adjusting Metabolism

There are a variety of ways by which animals can control their body temperature by changing their metabolic activity.

In some mammals, hormones can stimulate mitochondria to generate heat instead of ATP--non-shivering thermogenesis.

There are a variety of ways by which animals can control their body temperature by changing their metabolic activity.

In some mammals, hormones can stimulate mitochondria to generate heat instead of ATP--non-shivering thermogenesis.

5. Adjusting Metabolism5. Adjusting Metabolism

In other mammals, a layer of brown fat is found in the neck region and is specialized in rapid heat production.

Some female pythons can increase their body temperature when incubating eggs.

In other mammals, a layer of brown fat is found in the neck region and is specialized in rapid heat production.

Some female pythons can increase their body temperature when incubating eggs.

5. Adjusting Metabolism5. Adjusting Metabolism

Humans have nerve cells concentrated in the hypothalamus to control thermoregulation.

These nerve cells are grouped together and function as a thermostat regulating mechanisms that increase or decrease heat loss.

Humans have nerve cells concentrated in the hypothalamus to control thermoregulation.

These nerve cells are grouped together and function as a thermostat regulating mechanisms that increase or decrease heat loss.

PancreasPancreas

The pancreas is both an endocrine and a exocrine gland.Exocrine-releases secretions into

ducts.Endocrine-secretions diffuse into

bloodstream. Islets of Langerhans are scattered

throughout the exocrine portion of the pancreas.

The pancreas is both an endocrine and a exocrine gland.Exocrine-releases secretions into

ducts.Endocrine-secretions diffuse into

bloodstream. Islets of Langerhans are scattered

throughout the exocrine portion of the pancreas.

PancreasPancreas

Each islet contains α-cells and β-cells.

α-cells produce glucagon. β-cells produce insulin. Insulin and glucagon oppose each

other and regulate the concentration of glucose in the blood.

Each islet contains α-cells and β-cells.

α-cells produce glucagon. β-cells produce insulin. Insulin and glucagon oppose each

other and regulate the concentration of glucose in the blood.

Blood GlucoseBlood GlucoseGlucagon gets

released when blood glucose falls below a setpoint.

Insulin gets released when blood glucose is elevated.

Insulin stimulates most cells to take up glucose from the blood.

It also acts to slow glycogen breakdown in the liver.

Glucagon gets released when blood glucose falls below a setpoint.

Insulin gets released when blood glucose is elevated.

Insulin stimulates most cells to take up glucose from the blood.

It also acts to slow glycogen breakdown in the liver.

Diabetes MellitusDiabetes Mellitus

Diabetes is an endocrine disorder caused by a deficiency in insulin or decreased response to insulin.There are 2 types:

Type I-insulin dependent.Type II-non-insulin dependent.

Diabetes is an endocrine disorder caused by a deficiency in insulin or decreased response to insulin.There are 2 types:

Type I-insulin dependent.Type II-non-insulin dependent.

Type I DiabetesType I Diabetes

Insulin dependent. It’s an autoimmune disease resulting in the destruction of the body’s β-cells.

The pancreas can’t produce insulin and the person requires insulin injections.

Insulin dependent. It’s an autoimmune disease resulting in the destruction of the body’s β-cells.

The pancreas can’t produce insulin and the person requires insulin injections.

Type II DiabetesType II Diabetes

Non-insulin dependent. It is caused by a reduced

responsiveness of the cells to insulin.

Non-insulin dependent. It is caused by a reduced

responsiveness of the cells to insulin.

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Travismulthaupt.com Chapter 45 Hormones and the Endocrine System.

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