Hormone and Nervous system Biolove

7/29/2019 Hormone and Nervous system Biolove

1/28

M.I/ASASI/2013 Page 1

BIOLOVE

ENDOCRINE SYSTEM AND NERVOUS SYSTEM


2/28


HORMONE CLASSES

steroidglucocortisoids

mineralcortisoids

Fatty acids

derivatives

prostaglandin

juvenile hormone

amino acid

derivatives

noradrenaline

adrenaline

thyroxine

protein

and

peptide

peptide

- oxytocin

-PTH

-calcitonin

-ADH

proteins

-insulin

-glucagon

-FSH

-LH

-prolactin

Peptide hormones are shorter than proteins

Protein hormone consist of one or more polypeptide

These hormones released by endocrine glands into

blood and from blood to target cell where response

occur.

Endocrine glandbloodtarget cellresponse

Adrenaline, noradrenaline and thyroxine are from amino

acid thyrosine

Adrenaline, noradrenaline = epinephrine/norepinephrine

Prostaglandins in human

Juvenile hormone in insects

Bothe derived from arachidonic acid (20 C fatty acids)


3/28


Neurosecretory cell

- Neuron/nerve cell- Translate neural signal into chemical stimuli

Type of hormonal control pathways

Mechanism of Hormone Actions

mechanisms ofactions

steroid

(lipid soluble)

non-steroid

(water soluble)


4/28


Steroid hormones are able to enter the cell

Why?

- Because lipid portion of the PM does not act as a barrier for lipophilic regulators-

Steroid is lipophilic

Steroid hormones

- Cannot dissolve in blood plasma- Need transport protein- Always attach to protein carrier

Mechanism of steroid hormones

Flow

BindHRCactivated HRCbind on gene

regiontranscription into mRNAtranslation of mRNA

New protein and enzyme

1. Hormone combine with receptorprotein (at cytoplasm or in

nucleus)

2. Form Hormone receptor complex(HCR)

3. Activated hormone receptorcomplex will bin to specific region

in DNA

4. Results in transcription of generegion into mRNA

5. Translation mRNA transcripthappen outside the nucleus

6. Results in formation of enzymeand other protein


5/28


Mechanism of non-steroid hormones

This kind of mechanism is enzyme mediated

Signaling by any of these molecules(steroid and non-steroid) involves three key events Reception

Bind to receptor Signal transduction Response

Action of enzyme Reactant to product

The same hormone may have different effects on target cells that have

Different receptors for the hormone Different signal transduction pathways Different proteins for carrying out the response

Non-steroid hormone cannot pass

the PM

1. Hormone bind to receptor atcells surface

2. Trigger activation of 2messenger, cAMP by cAMP

synthesizing enzyme with the

help of ATP

3. cAMP activate inactiveenzyme

4. enzyme catalysed conversionof reactant to products

Flow

BindcAMPactivate enzymeconversion


6/28


The hormone epinephrine Has multiple effects in mediating the bodys response to short-term stress

The hypothalamus and pituitary integrate many functions of the vertebrate endocrinesystem

The hypothalamus and the pituitary gland Control much of the endocrine system

Pituitary gland is regulated by:1. Nervous system2. Endocrine system

Pituitary gland called as MASTER GLAND

- Because control activity of other glandsSome of these cells in hypothalamus produce direct-acting hormones

- That are stored in and released from the posterior pituitary, or neurohypophysis

Neuroendocrine s stem

The two hormones released from the posterior pituitary Act directly on nonendocrine tissues Oxytocin

o Induces uterine contractions and milkejection

Antidiuretic hormone (ADH)o Enhances water reabsorption in the

kidneys


7/28


Other hypothalamic cells produce tropic hormonesThat are secreted into the blood and transported to the anterior pituitary or adenohypophysis

The anterior pituitary Is a true-endocrine gland

The tropic hormones of the hypothalamus Control release of hormones from the anterior pituitary

The anterior pituitary Produces both tropic and nontropic hormones The four strictly tropic hormones are

o Follicle-stimulating hormone (FSH)o Luteinizing hormone (LH)o Thyroid-stimulating hormone (TSH)o Adrenocorticotropic hormone (ACTH)

Each tropic hormone acts on its target endocrine tissueo To stimulate release of hormone(s) with direct metabolic or developmental

effects


8/28


The nontropic hormones produced by the anterior pituitary includeo Prolactin

Prolactin stimulates lactation in mammalso But has diverse effects in different vertebrates

Growth hormone (GH)/somatotropin

o Promotes tissue growth directly and has diverse metabolic effectso Promote protein synthesiso Stimulates the production of growth factors by other tissues

Liver to produce insulin-like growth factors(IGFs) IGFs promotes tissues and skeletal growth

The pineal gland, located within the brain

o Secretes melatonin

Figure 1: Pineal Gland

The thyroid gland Consists of two lobes located on the ventral surface of the trachea Produces two iodine-containing hormones, triiodothyronine (T3) and thyroxine (T4)

Release of melatonin Is controlled by light/dark cycles

The primary functions of melatonin- Influence and control onset of sexual

maturity and biological clock

- Control circadian rythm (24 hour cycle)

The thyroid hormones Play crucial roles in stimulating

metabolism and influencing

development and maturation

The thyroid gland also produces calcitonin Which functions in calcium

homeostasis


9/28


Two antagonistic hormones, parathyroid hormone (PTH) and calcitonin Play the major role in calcium (Ca2+) homeostasis in mammals

PTH secrete by parathyroid gland at the surface of thyroid gland

Insulin and Glucagon: Control of Blood Glucose

Two types of cells in the pancreas Secrete insulin and glucagon, antagonistic hormones that help maintain glucose

homeostasis and are found in clusters in the islets of Langerhans

Glucagon Is produced by alpha cells

Insulin Is produced by beta cells

Calcitonin, secreted by the thyroidgland

Stimulates Ca2+ depositionin the bones and secretion

by the kidneys, thus

lowering blood Ca2+

levels

PTH, secreted by the parathyroidglands

Has the opposite effects onthe bones and kidneys, and

therefore raises Ca2+

levels

Also has an indirect effect,stimulating the kidneys to

activate vitamin D, which

promotes intestinal uptake

of Ca2+

from food


10/28


Type I diabetes mellitus (insulin-dependent diabetes) Is an autoimmune disorder in which the immune system destroys the beta cells of

the pancreas

Type II diabetes mellitus (non-insulin-dependent diabetes) Is characterized either by a deficiency of insulin or, more commonly, by reduced

responsiveness of target cells due to some change in insulin receptors

Adrenal Glands

The adrenal glands Are adjacent to the kidneys Are actually made up of two glands: the adrenal

medulla and the adrenal cortex

Insulin reduces blood glucoselevels by

Promoting the cellularuptake of glucose

Slowing glycogenbreakdown in the liver

Promoting fat storage Glucagon increases blood glucose

levels by

Stimulating theconversion of glycogen to

glucose in the liver

Stimulating thebreakdown of fat and

protein into glucose

Diabetes mellitus, perhaps thebest-known endocrine disorder

Is caused by a deficiencyof insulin or a decreasedresponse to insulin in

target tissues

Is marked by elevatedblood glucose levels


11/28


The adrenal medulla secretes epinephrine and norepinephrine (a.k.a adrenaline andnoradrenaline)

Hormones which are members of a class of compounds called catecholamines

These hormones epinephrine and norepinephrine:

Are secreted in response to stress-activated impulses from the nervous system Mediate various fight-or-flight responses

Fight-Or-Flight Responses

Catecholamine hormones, such as adrenaline or noradrenaline, facilitate immediate physical

reactions associated with a preparation for violent muscular action. These include the

following

1. Acceleration of heart and lung action2. Paling or flushing, or alternating between both3. Inhibition of stomach and upper-intestinal action to the point where digestion slows

down or stops

4. General effect on the sphincters of the body5. Constriction of blood vessels in many parts of the body6. Liberation of nutrients (particularly fat and glucose) for muscular action7. Dilation of blood vessels for muscles8. Inhibition of the lacrimal gland (responsible for tear production) and salivation9. Dilation of pupil (mydriasis)10.Relaxation of bladder11.Inhibition of erection12.Auditory exclusion (loss of

hearing)

13.Tunnel vision (loss of peripheralvision)

14.Disinhibition of spinal reflexes15.Shaking


12/28


Hormones from the adrenal cortex Also function in the bodys response to stress

Adrenal cortex secrete: Glucocorticoids, such as cortisol

Influence glucose metabolism and the immune system Promotes the liver to undergo gluconeogenesis to convert amino acid to

glucose

Mineralocorticoids, such as aldosterone Affect salt and water balance Maintain proper balance of sodium and potassium ion in kidney tubules

The gonadstestes and ovaries

Produce most of the bodys sex hormones:androgens, estrogens, and progestins


13/28


Androgen: testosterone

Which stimulate the development and maintenance of the male reproductivesystem

Testosterone causes an increase in muscle and bone mass And is often taken as a supplement to cause muscle growth, which carries

many health risks

Estrogens, the most important of which is estradiol Are responsible for the maintenance of the female reproductive system and

the development of female secondary sex characteristics

In mammals, progestins, which include progesterone Are primarily involved in preparing and maintaining the uterus

Molting and Metamorphosis

In insects Molting and development are controlled by three main hormones

- Metamorphosis is a development from egg to adult in which there is a series ofdistinct stages.

- Molting is a process to shed periodically part or all of a coat or an outer covering,such as feathers, cuticle, or skin, which is then replaced by a new growth.


14/28


Nervous System

- All animals except sponges has nervous system- What differentiate between animals is how the nervous system is organized

Flatworm has small brain composed of Ganglia

Has 2 parallel nerve cords

These 2 are CNS while the others is PNS

Have neurons arranged in nerve nets Has Radial nerve. Nerve net

connect to nerve ring by radial

nerve (uncentralized)

Leech, insect and flatworm has

bilateral nervous system

Bilateral nervous system has:

1. Cephalization nervoussystem concentrated at head

end

2. Centralization Has centralnervous system(CNS) and

peripheral nervous

system(PNS). But CNS is

different from PNS.


15/28


Nervous systems in molluscs Correlate with the animals lifestyles

Sessile molluscs have simple systems While more complex molluscs have more sophisticated systems

Squid has high degree of

cephalization (many nerve at the

head)

Give intelligence

In vertebrates The central nervous system

consists of a brain and dorsal

spinal cord

- The PNS connects to the CNS

Nervous systems process information in three stages Sensory input, integration, and motor output(motor function)

photo 1: Neural Signaling


16/28


1 Sensory(afferent) neurons transmit information from sensorsa. That detect external stimuli and internal conditions

2 Sensory information is sent to the CNSa. Where interneurons integrate the information

3 Motor output(motor function) leaves the CNS via motor(efferent) neuronsa. Which communicate with effector cells(muscles, glands) for response

Example:

Knee-Jerk Reflex

Integration takes place in the CNS (brain and spinal cord)

- Brain and spinal cord:a. Receive sensory informationb. Make decisions from the information obtained

Motor output(motor function) is the stimulation of effectors


17/28


Neurons

- Make up nervous tissue- Also called nerve cells

What is neurons?

1. Functional units of nervous system2. Function to receive and send information3. Information is in form of electrical signals called nerve impulse

Most of a neurons organelles are located in the cell body

Types of neurons


18/28


Differences between Sensory neuron and Motor neuron

Sensory neuron Motor neuron

Dendrites shorter Dendrite longer

Cell body located in the middle of axon Cell body located at upper axon

Transmit message from sensoryreceptors to CNS

Transport message from CNS to effectors

- Interneurons connect neuron to neuron Most neurons have dendrites

Highly branched extensions that receive signals from other neurons The axon is typically a much longer extension

That transmits signals to other cells at synapses That may be covered with a myelin sheath

Glia are supporting cells That are essential for the structural integrity of the nervous system and for

the normal functioning of neurons

Oligodendrocytes (in the CNS) and Schwann cells (in the PNS) Are glia that form the myelin sheaths around the axons of many vertebrate

neurons

Glia alson known as Neuroglia

Functions:

1. Supplies nutrients to neurons2. Remove waste3. Provide immune function


19/28


Neurons Transmission of Impulse

Across its plasma membrane, every cell has a voltage Called a membrane potential

The inside of a cell is negative Relative to the outside

The unequal distribution of charge is called as Electrical Gradient Electrical gradient is called as potential difference

The membrane potential of a cell can be measured

In all neurons, the differences in charge depends on:1. Ionic concentration2. Sodium-potassium pump3. Ion leak channel

Ionic concentration

- Molecules such as carbohydrate, protein and nucleic acid are negative charged- Cannot pass the PM- Called fixed anions


20/28


Sodium potassium pump

The concentration of Na+ is higher in theextracellular fluid than in the cytosol

While the opposite is true for K

+

Pumps out three Na+ and pump out two K+ Help to maintain concentration gradient

Ion leak channels

Membrane protein that is more numerous for K+ than Na+ Allows little Na+ to diffuse in Allows more K+ to diffuse out So more negative ions will remained in the cytoplasm

The resting potential

Is the membrane potential when a cell at restOR

The resting potential Is the membrane potential of a neuron that is not transmitting signals

Voltage: -65mV to -70mV

Why negative: inside cell more negative charge

Treshold potential

When stimulus id applied, voltage rise to point called as treshold potential

- About -50mV- Only about 2 to 3 seconds

What is treshold potential?

- Membrane potential that must be reached before all membrane channel can openWhat membrane channel?

- Sodium ion and potassium ion channels


21/28


Action potential

- Change in membrane potential occuring in nerve, muscleor other excitable tissues whenexcitation occurs

oIs a brief all-or-none depolarization of a neurons plasma membrane

o Is the type of signal that carries information along axons Both voltage-gated Na+ channels and voltage-gated K+ channels

o Are involved in the production of an action potential When a stimulus depolarizes the membrane

o Na+ channels open, allowing Na+ to diffuse into the cell As the action potential subsides

o K+ channels open, and K+ flows out of the cell A refractory period follows the action potential

o During which a second action potential cannot be initiated


22/28


An action potential can travel long distances By regenerating itself along the axon

At the site where the action potential is generated, usually the axon hillock An electrical current depolarizes the neighboring region of the axon membrane


23/28


The speed of an action potential Increases with the diameter of an axon

In vertebrates, axons are myelinated(has myelin sheath) Also causing the speed of an action potential to increase

Action potentials in myelinated axons Jump between the nodes of Ranvier in a process called saltatory conduction

Action potential is all-or-none event. Whether treshold is reach to produce action potential or

treshold is not reached causing no action potential at all.

Neurons Communication

Neurons communicate with other cells at synapses

In an electrical synapse Electrical current flows directly from

one cell to another via a gap junction

The vast majority of synapses Are chemical synapses

In a chemical synapse, a presynaptic neuron Releases chemical

neurotransmitters, which are stored

in the synaptic terminal


24/28


When an action potential reaches a terminal The final result is the release of neurotransmitters into the synaptic cleft

The process of direct synaptic transmission Involves the binding of neurotransmitters to ligand-gated ion channels

Neurotransmitter binding Causes the ion channels to open, generating a postsynaptic potential

After its release, the neurotransmitter Diffuses out of the synaptic cleft May be taken up by surrounding cells and degraded by enzymes

Summary of the process:

1. Action potential arrived at synaptic cleft will trigger the opening of Ca2+ channel.2. Ca2+ enter the channel rapidly.3. The fusion of Ca2+ will act as stimulus for the presynaptic neuron vesicles to fuse within its

own outer membrane(presynaptic membrane).

4. The vesicle content(neurotransmitter) will be released by exocytosis into synaptic cleft.5. Neurotransmitter will bind to receptor protein on the surface of postsynaptic membrane.6. The binding will cause ion channel to open and ion diffuse into receiving cell. The diffusion

will trigger new action potential.


25/28


Neurotransmitter

Acetylcholine Is one of the most common neurotransmitters in both vertebrates and invertebrates Can be inhibitory or excitatory

Inhibitory neurotransmitter- Open channel for another ion such as Cl- .- No action potential.- Triggering hyperpolarization. Excitatory neurotransmitter- Open Na+ channel. Thus triggering action potential- Promotes depolarization

The vertebrate nervous system is regionally

specialized

- In all vertebrates, the nervous systemo Shows a high degree of cephalization and

distinct CNS and PNS components


26/28


CNS consist of Cranial nerve and Spinal nerve

The cranial nerves originate in the brain And terminate mostly in organs of the head and upper body

The spinal nerves originate in the spinal cord And extend to parts of the body below the head

The PNS can be divided into two functional components

Motor division can be divided into The somatic nervous system and the autonomic nervous system

The somatic nervous system (allows us to control voluntary) Carries signals to skeletal muscles

The autonomic nervous system (system control involuntary) Regulates the internal environment, in an involuntary manner Is divided into the sympathetic, parasympathetic, and enteric divisions

The sympathetic and parasympathetic divisions Have antagonistic effects on target organs

PNS

sensory(afferent)pathways

from sensoryreceptor of all

body to the CNS

motor(efferent)pathways

carry impulse fromCNS to effector

Motor pathways

efferent

Not in syllabus


27/28


The sympathetic division Correlates with the fight-or-flight response

The parasympathetic division Promotes a return to self-maintenance functions Slows body functions, thus conserving energy

The enteric division Controls the activity of the digestive tract, pancreas, and gallbladder speeds body functions, thus increasing energy use.

This two system has opposite effect- If one is activated, another one is inhibited

Endocrine VS Nervous system

Categories Endocrine system Nervous system

Nature of messages Chemical signals Electrical signals

Speed of message quite slow because it needs to

be transported by blood to

specific target sites

really fast due to saltatory

conduction

Speed of response Slower speed Rapid speed

Duration of effect Longer duration of effect Shorter duration of effect

Accuarcy of message Precise Diffuse


28/28

References

BIOL2060: Cell Biology. (n.d.). Memorial University. Retrieved from

http://www.mun.ca/biology/desmid/brian/BIOL2060/CBhome.html

Campbell, N. A., Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., &

Jackson, R. (2008). Biology. San Francisco: Pearson, Benjamin Cummings.

Hormone and Nervous system Biolove

Documents

Transcript of Hormone and Nervous system Biolove