Nervous and Endocrine

System

How do humans carry out the life process, regulation?

How do the nervous and endocrine systems help to maintain homeostasis in the body?

A network of nerve cells that carry messages or impulses throughout the organism.

Impulses- the effect of an action

Receptors- binding sites on target cells

Effectors- A muscle, gland, or organ capable of responding to a stimulus

Stimulus – anything in an organism internal or external environment that causes a reaction

1) Stimulus activates a receptor

2) Impulses are started in nerve pathways

3) Effector responds to an impulse

Involves the two systems!• Nervous- nerve control• Endocrine- chemical/ hormone control

• Starting with the Nervous system 2 components of the nervous system

1. Central nervous - Made up only of the brain

and spinal cord

2. Peripheral Nervous system

- all the other nerves

Peripheral Nervous-

Nerves that branch off the

brain and spinal cord

Somatic nerves-

movement and skeletal muscles/ skin/ sense

organs- What you consciously

control

Autonomic nerves- in charge of autonomic things

like heart beat, peristalsis, breathing,

blood flow

The nervous system is made up of “ nerve” cells called

3 Types of Neurons:

Sensory-

Motor-

Interneurons-

Sensory, Motor, Interneurons

Carry impulses from receptors to the spinal cord and brain

Carry impulses from the brain and spinal cord to effectors, usually muscles

relay impulses from one neuron to another in the brain/ spinal cord

Cell body

node

dendrite

Myelin sheath

Nucleus

axon

Cell body- contains the cell’s nucleus

Dendrite- receive signals and carry them towards the cell body

Axon- carries electrical impulses away from the cell body

Myelin sheath- axons of the neurons are insulated by the thick coat

Nodes- signals must “jump” from node to node where it is uninsulated

A synapse:

Nerve transmission at the synapse- Excitatory neurotransmitters:

- Inhibitory neurotransmitters

The place between the end of one neuron and the membrane of another neuron

AcetylcholineHistamineNorepinephrine

Serotoninepinephrine

a path that a nerve impulse travels along when you carry out a reflex

Reflexes are not under conscious control- they are

Dealt with by the spinal cord

They start with a stimulus and end with a response

Stimulus- causes the receptors to start impulses in a nerve pathway

Involuntary

Neuron clip

What is a hormone?- is a chemical released by a gland in that

sends out messages that affect cells

What common things are controlled by hormones?

• Metabolism, growth & development, behavior

How do hormones travel around the body?

In the bloodstream, attach to specific binding sites- target cells to receptors

The major parts of the Endocrine System

glands

hormones

1. Insulin2. Growth

hormone3. Glucagon4. Cortisol5. Follicle

Stimulating6. Luteinizing

which secrete

Some examples:

1. Overall Metabolism2. Growth and Reproduction

3. Chemical messengers

hypothalamus: Controls the pituitary gland, synthesizes antidiuretic, oxytocin during contractions at birth

pituitary gland: Secretes growth hormone , controls adrenal, thyroid, ovary, and testes (glands).

thyroid gland: to stimulate growth, metabolism and secretes calcitonin.

Calcitonin- regulate calcium levels/ process of bone building.

Insulin- regulate blood sugar

Growth hormone- stimulates growth cell reproduction /regeneration in humans/other animals

Glucagon- raises blood sugar levels

Cortisol- increase blood sugar, suppress immunity

Follicle Stimulating- regulates the development, growth, pubertal maturation, and reproductive processes of the body

Luteinizing- development of the corpus luteum, ovulation

Adrenal medulla: (amino acid hormone). Secretes epinephrine (also known as adrenaline- increase heart rate)

& norepinephrine (stress, fight or flight).

Ovaries: (steroid hormone) secretes female sex hormones

Testes: (steroid homone). secretes male sex hormones

Adrenal cortex: (steroid hormone). Secretes glucocorticoid (metabolism of glucose/immunity) and aldosterone (aids in the increase of blood pressure).

What do they do• Prepare your body for stressful situations

Where are they located?-on top of the kidneys

The outer portion? Raise available glucose levels and blood

pressure. This helps to “fight” , temp extremes, infection, disease

The inner portion? “flight or fight”- increase heart rate, blood pressure, resp rate, muscle contractions

An example from your body:

An example from outside of your body:

To maintain homeostasis :- regulate temperature- (**set

point**) - secretion of hormones

• Home thermostat: when temperature rises above the set point, the heat will “turn off” – allowing the house to cool.• If the temperature drops below the set point, the heat will turn back on

Thyroxine is secreted by the thyroid gland regulated by Thyroid Stimulating

Hormone (TSH) When Thyroxine is low TSH is secreted to signal to produce more

thyroxine Thyroxine reaches a certain point; TSH

stops being secreted TSH is reduced, therefore thyroxine stops

being secreted.

Negative Feedback of Hormones

Body stops secreting

hormone B

Levels of Hormone A are low This

triggers the release

of Hormone B

This stimulates the body to

release Hormone A

Levels of hormone

A are now high

You eat causing your blood sugar

levels to

This triggers the release

of the hormone

___________By your

pancreas

Insulin helps your cells

absorb glucose so

your glucose levels

Now you are tired & hungry your _________ secretes the hormones

glucagon to raise your blood

sugar level

increase

insulin

Pancreas

Will decrease

What organ secretes hormones that control blood sugar levels?• Pancreas

What hormone is releases when blood sugar is too high? Insulin

Too low? glucagon