The Nervous System and the Endocrine System

Nervous System

* Consists of the central nervous system and the peripheral - nervous system


* Communicates using electrical signals.

Nervous System Functions

To collect, process and respond to information in the environment and to co-ordinate the working of different organs and cells in the body

Central Nervous System (CNS)

Consists of the brain and the spinal chord and is the origin of all complex commands and decisions

Cerebral Cortex

The brains outer layer, 3mm thick and covers the brain like a peel, it is only found in mammals

Peripheral Nervous System (PNS)

Sends information to the CNS from the outside world, and transmits messages from the CNS to muscles and glands

Somatic Nervous System (SNS)

Transmits information from receptor cells in the sense organs to the CNS. It also receives information from the CNS that directs muscles to act.

Autonomic Nervous System (ANS)

* Transmits information to and from internal bodily organs
* Governs functions such as breathing, heart rate and digestion.
* System operates involuntarily
* Two main divisions: the sympathetic and parasympathetic nervous system.

Endocrine System

* One of the body’s major information systems that instruct glands to release hormones directly into the bloodstream.
* These hormones are carried towards target organs in the body.
* Communicates via chemicals but slower than the nervous system.

Thyroxines Purpose

The thyroid gland releases thyroxine to increase heart rate and increases metabolic rate in cells

Pituitary Gland

The ‘master' gland, located in the brain which controls the release of hormones from all other endocrine glands in the body

Gland

An organ in the body that synthesised substances such as hormones

Hormones

* Chemical substances that circulate in the bloodstream and only target organs
* They are produced in large quantities but disappear quickly
* Effects are very powerful.

Fight or Flight Response

* The way an animal responds when stressed
* Body becomes physiologically aroused in readiness to fight an aggressor or, in some cases, flee
* First, the hypothalamus is alerted and activates the pituitary gland which triggers activity in the sympathetic part of the autonomic nervous system.

Adrenaline

* A hormone produced by the adrenal glands which are part of the human body’s immediate stress response system


* Adrenaline has a strong effect on the cells of the cardiovascular system - stimulating heart rate, contracting blood vessels and dilating air passages.

Adrenalin’s effect

Stimulating heart rate, contracting blood vessels and dilating air passages

Parasympathetic Action

* Once the threat has passed, the parasympathetic nervous system returns the body to its resting state


* Acts as a ‘brake’ and reduces the activities of the body that were increased by the actions of the sympathetic branch.
* Rest and digest.