There are many different types of coordination and response and on this page we'll explore them all:
What is the nervous system?
The nervous system is the system in the body which controls your nerves and feelings. To do this, we have three types of specialised cells:
Sensory neurone
Relay neurone
Motor neurone
These neurones all work in conjunction with the CNS - the Central Nervous System - and control things from muscle movements to reflex responses.
Neurones connect to each other with synapses - a synapse is a gap between neurones, across which neurotransmitters (which transport nerve impulses from one cell to another) are released from a cells' dendrons to the next cells' dendrites/dendrons
All three of these cells are made up of the same organelles:
- Dendrons: The dendrons are an extension of the cytoplasm of a neurone that carries impulses towards the cell body. (Another name for dendrite.)
- Axon: long extension of a neurone that carries nerve impulses in a direction away from the cell body
- Myelin sheath: covering made of a lipid material that surrounds an axon. Nerve cells that have a myelin sheath are described as myelinated. Made up of Schwann cells.
- Dendrites: a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.
- all other normal animal cell organelles: you should know all of these already!
These are the neurones:
(photo by https://www.tutor2u.net/psychology/reference/biopsychology-sensory-relay-and-motor-neurons)
Sensory neurone
Relay neurone
Motor neurone
These neurones all work in conjunction with the CNS - the Central Nervous System - and control things from muscle movements to reflex responses.
Neurones connect to each other with synapses - a synapse is a gap between neurones, across which neurotransmitters (which transport nerve impulses from one cell to another) are released from a cells' dendrons to the next cells' dendrites/dendrons
All three of these cells are made up of the same organelles:
- Dendrons: The dendrons are an extension of the cytoplasm of a neurone that carries impulses towards the cell body. (Another name for dendrite.)
- Axon: long extension of a neurone that carries nerve impulses in a direction away from the cell body
- Myelin sheath: covering made of a lipid material that surrounds an axon. Nerve cells that have a myelin sheath are described as myelinated. Made up of Schwann cells.
- Dendrites: a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.
- all other normal animal cell organelles: you should know all of these already!
These are the neurones:
(photo by https://www.tutor2u.net/psychology/reference/biopsychology-sensory-relay-and-motor-neurons)
Sensory neurons have specialised receptors on them (depending on where the sensory neurone is located in the body such as photoreceptors in the retina) which will react to its specific stimulus and send an electrical impulse down the sensory neurone, which will then reach a synapse where neurotransmitters will diffuse across the gap of the synapse until it reaches a relay neurone.
Relay neurones are the next type of neurones an impulse will travel too. They are found in the CNS (brain and spinal cord.). There really isn't much to say about the relay neurone, though they are important and you'll see why in a bit.
The motor neurone is the final neurone of the three. It connects to the relay neurone, and when it receives an impulse via neurotransmitters diffusing across its synapse, it will cause its effector (muscle or gland) to contract or relax depending on what its currently doing: if it's relaxing it will contract and vice versa.
There are two types of reactions to stimuli; conscious and unconscious reactions. For example, accidentally placing your hand on a board pin and quickly retracting it is an unconscious action, or reflex, while picking up said board pin is a conscious action.
The reflex arc:
The reflex arc is something you need to know like the back of your hand, but luckily it is quite easy to learn and remember. Here's a diagram of what happens:
(Photo by https://moodle.beverleyhigh.net/mod/resource/view.php?id=6124)
The reflex arc:
The reflex arc is something you need to know like the back of your hand, but luckily it is quite easy to learn and remember. Here's a diagram of what happens:
(Photo by https://moodle.beverleyhigh.net/mod/resource/view.php?id=6124)
What's basically happening here is that:
- The pain receptors in the finger detected a stimulus;
- The receptor on the end of the sensory neurone sent an impulse across the sensory neurone;
- Neurotransmitters are released when the impulse reaches the synapse to the relay neurone in the spinal cord;
- The neurotransmitters diffuse across the synapse where they are broken down by enzymes in the relay neurone;
- The impulse then carries on across the relay neurone until it reaches the next synapse;
- The neurotransmitters once again diffuse across the synapse;
What is the endocrine system?
The endocrine system is the term given to parts of the body which secrete hormones into the blood.
Parts of the endocrine system and their functions
Pituitary gland - the pituitary gland secretes many different hormones. Among these are ADH, LH, FSH, TSH, and HGH.
ADH: Antidiuretic Hormone, the hormone which controls the solubility of cells in the collecting duct of the urinary system.
LH - Luteinising Hormone, stimulates ovulation in females and testosterone production in males.
FSH - Follicle Stimulating Hormone, stimulates egg development and oestrogen secretion in females and sperm production in males.
TSH - Thyroid Stimulating Hormone, stimulates the Thyroid glands to produce thyroxine.
HGH - Human Growth Hormone, maintains growth and health in children. In adults it aids healthy bone and muss;e mass, and affects fat distribution.
Thyroid gland - the thyroid gland releases thyroxine
Thyroxine - controls the body's metabolic rate (how fast chemical reactions take place in cells)
Pancreas - produces insulin and glucagon
Insulin - lowers blood glucose levels
Glucagon - raises blood glucose levels
Adrenal glands - produces adrenaline
Adrenaline - prepares the body for physical activity. Often called the "fight or flight" response
Ovary - produce oestrogen and progesterone (more detail in inheritance topic here)
Oestrogen - part of the menstrual cycle, secreted during ovulation, controls development of females during puberty
Progesterone - helps regulate the menstrual cycle, secreted after the egg is released
Testes - releases testosterone
Testosterone - controls development of males during puberty
ADH: Antidiuretic Hormone, the hormone which controls the solubility of cells in the collecting duct of the urinary system.
LH - Luteinising Hormone, stimulates ovulation in females and testosterone production in males.
FSH - Follicle Stimulating Hormone, stimulates egg development and oestrogen secretion in females and sperm production in males.
TSH - Thyroid Stimulating Hormone, stimulates the Thyroid glands to produce thyroxine.
HGH - Human Growth Hormone, maintains growth and health in children. In adults it aids healthy bone and muss;e mass, and affects fat distribution.
Thyroid gland - the thyroid gland releases thyroxine
Thyroxine - controls the body's metabolic rate (how fast chemical reactions take place in cells)
Pancreas - produces insulin and glucagon
Insulin - lowers blood glucose levels
Glucagon - raises blood glucose levels
Adrenal glands - produces adrenaline
Adrenaline - prepares the body for physical activity. Often called the "fight or flight" response
Ovary - produce oestrogen and progesterone (more detail in inheritance topic here)
Oestrogen - part of the menstrual cycle, secreted during ovulation, controls development of females during puberty
Progesterone - helps regulate the menstrual cycle, secreted after the egg is released
Testes - releases testosterone
Testosterone - controls development of males during puberty
Glucoregulation
Glucoregulation is the body's way of regulating blood glucose levels.