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 Acetylcholine Histamine Norepinephrine Serotonin epinephrine

 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 NeuronNeuron 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.Insulin 2.Growth hormone 3.Glucagon 4.Cortisol 5.Follicle Stimulating 6.Luteinizing which secrete Some examples:

1. Overall Metabolism 2. 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