domingo, 27 de marzo de 2011
Here you have a link to an interesting brain atlas of Lundbeck Institute.
- Voluntary actions,
- Involuntary actions or reflex actions.
A voluntary action is basically an action which you yourself initiate by your own conscious. Your cerebral cortex (brain) sends impulses from it to the effectors (muscles or glands) via the spinal cord with relay neurons and finally a motor neurons. This action is under the control of the will thus is known as a voluntary action.
Involuntary Actions (Reflex Actions):
Involuntary actions as their name suggest, are total opposites of voluntary actions, a reflex action is not under the control of the will. In this case, your spinal cord takes total control, without your own conscious. Reflex actions controlled by the spinal cord, example scratching, are called spinal reflexes. There are also cranial reflexes, example blinking, that are controled by de brain but not by the cerebral cortex. Brushing, sneezing and salivation are also reflex actions however, salivation is also known an conditioned reflex action which we will be discussing later. In this webpage Kidshealth you can read and listen to a explanation of different reflex actions.
This table compares the two types of actions:
|Voluntary actions||Reflex actions|
|Iniated in cerebral cortex of brain - due to though||Iniated by stimulation of receptor|
|Impulses passes from the motor area in cerebral cortes down spinal cord to:||Impules pases sensory neuorns and relay neurone in grey matter of spinal cord which passes impulse to:|
|Motor neurone carries impulse to effector (muscle) with contracts and produces action||Motor neurone carries impulse to effector (muscle) with contracts and produces action|
|Impulses passes over to oppsite side of the body||Stimulus, neurones,|
actions all on same side of body
|Many cells and synapses, and longer pathway – therefore slow.||Only 3 cells, 2 synapses – therefore quicker.|
Secondary information passes up spinal cord to brain, so subject is aware after event.
viernes, 25 de marzo de 2011
The peripheral nervous system is divided into two parts: the sensory division and the motor division. How these divisions of the peripheral nervous system are related to the rest of the nervous system is shown in Figure. Refer to the figure as you read more about the peripheral nervous system below.
The sensory division carries messages from sense organs and internal organs to the central nervous system. Human beings have several senses. They include sight, hearing, balance, touch, taste, and smell. We have special sense organs for each of these senses. Sensory neurons in each sense organ detect a certain type of stimulus, or input. For example, sensory neurons in the eyes detect light, and sensory neurons in the skin detect touch.
Our sense organs detect sensations, but they don’t tell us what we are sensing. That’s your brain’s job. The sense organs send messages about sights, smells, and other stimuli to the brain. The brain then interprets the messages. A particular area of the brain interprets information from each sense organ. For example, information from the nose is interpreted by the temporal lobe of the cerebrum.
The motor division of the peripheral system carries messages from the central nervous system to internal organs and muscles. As shown in Figure, the motor division is also divided into two parts:
The somatic nervous system
The autonomic nervous system.
The somatic nervous system carries messages that control the muscles and so the body movements.
The autonomic nervous system carries nerve impulses to internal organs. It is responsible for activities that are not under your control, such as sweating and digesting food. The autonomic nervous system has two divisions:
The sympathetic division of the autonomic nervous system is the division that prepares the body for stressful situations. It is often referred to as the "fight or flight" system. The effects of this system are numerous, but generally include increasing heart rate, constricting blood vessels to the skin and viscera (thereby increasing blood flow to muscles), increasing pupil size and decreasing salivation. These responses all promote survival in a dangerous situation.
The parasympathetic division of the autonomic nervous system prepares the body for restful situations and is often called the "rest and digest" system. Effects of the parasympathetic nervous system include slowing heart rate, increasing gastric motility, and increasing salivation. These responses help the body to recover as well as prepare for stressful situations by storing nutrients.
In this link you can find how acts each division.
In this post we are going to study the cerebrum. As it have a los of difficult names maybe this funny video can help you to remember them.
The cerebrum is what most people would think of as the "brain." Mammals (including humans), have the largest and most well-developed cerebrum among all species.
The cerebrum lies on top of the brainstem. It’s divided into a right and left half. Each half of the cerebrum is called a hemisphere. Each of these hemispheres has an outer layer of grey matter (body cells of neurons) called the cerebral cortex that is supported by an inner layer of white matter (myelinated axons). The two cerebral hemispheres are connected to each other at the corpus callosum. It lies deep inside the brain and carries messages back and forth between the two hemispheres. The right hemisphere controls the left side of the body, and the left hemisphere controls the right side of the body.
The cerebral cortex is the highly-folded outer layer of the cerebrum that is between 2 mm and 4 mm thick. The lobes that make up the cerebral cortex, shown in Figure, are named after the skull bones that cover those areas of the brain. Each hemisphere of the cerebrum is divided into four parts called lobes. The four lobes are the frontal, parietal, temporal, and occipital lobes. Each lobe has different functions. Some of the functions are listed in Table:
Cerebral Lobes and Their Functions
|Frontal||Speech, thinking, touch|
|Parietal||Speech, taste, reading|
The cerebral cortex controls higher functions, such as consciousness, reasoning, emotions, and language. It also controls sensory functions such as touch, taste, smell, and responses to external stimuli.
Magnetic resonance imaging
The brain consists of gray matter and white matter. Grey matter contains neural cell bodies, in contrast to white matter, which does not and mostly contains myelinated axons.
The brain can be classified by the processes its different parts control:
- The cerebrum is the largest part of the brain. It lies on top of the brainstem. The cerebrum controls functions that we are aware of, such as problem-solving and speech. It also controls voluntary movements.
- The cerebellum is the next largest part of the brain. It lies under the cerebrum and behind the brain stem. The cerebellum is involved in coordination and control of body movement.
- The brain stem is the smallest of the three main parts of the brain. It lies directly under the cerebrum. It controls basic body functions such as breathing, heartbeat, and temperature regulation.
In this link you can go over the brain partsThe Spinal Cord
In this cross-section a spinal cord is the grey matter in the centre, in those funny shaped structures with horns and the white matter outside of the horns. (Remember white matter is formed by nerves travelling up and down your spinal cord and grey matter is formed by the cell bodies of the neurons).
The brain and spinal cord are quite fragile. They are protected by a series of bone, membrane, and fluid. The bones are the skull that protected the brain and the vertebrae that protected the spinal cord. Then, there are three membranes called meninges. In these meniges there is a clear liquid called cerebroespinal fluid (CSF). This liquids forms a cushion between the soft brain tissue and the hard cranial bones.
lunes, 21 de marzo de 2011
Earth Hour, was first started in Australia (2007) as a way to bring community together to acknowledge the importance of reducing consumption of earths natural resources. Turning off the lights for an hour helps us see the impact we have on the environment..
Just one year after the first "Earth Hour" in Sydney Australia it became a viral phenonemon. Now spreading globally with a movement reaching more than 50 million people that participate in more than 35 countries.
Earth Hour hopes to encourage consumers, businesses, and governments to be thoughtful in action plans to caryy out practical ways to reduce emmissions.
In Spain it will be next saturday from 20.30 to 21.30. Pocoyo is going to be one of the main protagonist of the third edition of the Earth Hour.
If you have more interest about the activities of this day you can go to http://www.horadelplaneta.es/
I encourage you to participate. You are the future and there is only one EARTH
The brain accounts for a mere two percent of our body weight, but consumes 20 percent of the oxygen we breathe and 20 percent of the energy we take in. Our brains are what set us apart from every other species on Earth.
Disorders of the brain are a major cause of death and disability worldwide. As the world population ages the problem will grow, because many brain disorders disproportionately affect older people. Finding ways to prevent, treat, and cure the disorders of the nervous system is a primary goal of neuroscience research.Now we are going to see some interesting questions:
how does the brain accomplish multiple tasks at once?
The brain needs to attend to one task at a time; it can't just double or triple its processing power in line with how many things we're trying to do at once. That's not to say that walking and chewing gum isn't possible. But in general, tasks that require mental processing seem to be handled sequentially by the brain, not simultaneously.
What happens to the brain as we age?
Not all brains age the same, just as not all bodies age the same. In other words, everyone's brain ages differently.
The good news is that the braín is adaptable at any age. It continues to add and modify its synapses and neural pathways throughout Iífe, in an experience-dependent manner.
That means "use it or lose it." Brain pathways that are inactive are eventually lost, while an enriching and stimulating life creates a richer network of synapses.
How can I keep my brain young?
Converging evidence from multiple areas of brain research is beginning to point to a number of factors that seem to contribute to a brain-healthy lifestyle, including:
• Stimulating our mind with mental activities and novel experiences that challenge the brain and activate new neural pathways.
• Incorporating physical activity -especially aerobic exercise- into our daily schedule, even if only for 10 minutes at a time.
• Interacting with other people and engaging in social activities.
• Having a sense of self-worth and self-efficacy, the feeling that what we do matters.
• Reducing cardiovascular risk factors such as high blood pressure and high cholesterol.
• Eating a healthful diet that includes plenty of colorful fruits and vegetables (for antioxidants and other vitamins and minerals) and fatty fish or nuts (sources of Omega-3 fatty acids), and that limits trans fat and saturated fats.
• Managing stress and finding healthful ways to cope with high-stress periods.
• Getting adequate amounts of sleep¬about 8 hours for most adults.
Think about how you can work brain-friendly activities into your day in each of these areas. It's never too late (or too early) to start.
How does the brain develop from birth to adulthood?
The development ot the human brain is a complex, dynamic process that untolds over the course ot two decades or so. It is driven partly by genetic programming and partly by interactions with the environment, both ot which conspire to shape the "wiring diagram" ot the brain.
At birth, the human brain is equipped with only a small proportion ot the synapses it will eventually have. In early development, synaptic connections are added primarily through synapse overproduction and loss-essentially, genetic programming sets up a large number ot connections, then experience plays upon this network to strengthen some synapses and eliminate others. The timing ot this process varies by brain region
This is why neuroscientists talk about "critical periods" or "sensitive periods" for learning certain skills such as language.
Around adolescence, the brain undergoes a second burst of synapse overproduction, followed by another dramatic "pruning" period during which underused synapses wither and die back. This final developmental wave of synaptic fine-tuning proceeds from the back of the brain to the front, making the prefrontal cortex the last area of the brain to develop. This region is associated with advanced cognitive functions such as planning, reasoning, and inhibiting impulsive behavior.
The teenage years represent one of the most dynamic phases of brain development,
a period during which the brain is "hyper-plastic" -highly adaptable- as it shapes and refines the neural pathways that will support it through adulthood. This can be a double-edged sword, for the same mechanisms that appear to make the teen brain exquisitely primed for learning also make it vulnerable. Drugs of abuse, for example, seem to have longer-term effects on the brain when they are used during adolescence than at other ages.
domingo, 20 de marzo de 2011
The explanation is with drawings and texts that you can be listening at the same time. So it's not difficult to understand and if you don't know a word you can look it up in the diccionary.
We can difference three components
The presynaptic neuron is the transmitting cell, its axon terminal has a lot of vesicles full of neurotransmiters. A neurotransmitter is a chemical message that is used to relay electrical signals between a neuron and another cell
The possinaptic neuron is the receiving cell, It has a lot the neurotransmiter receptor in ist membrane.
The synaptic cleft is the gap between both. (about 20 nm wide)
When a nerve impulse reaches the axon terminal, it causes the neurotransmitter vesicles to fuse with the terminal membrane, and the neurotransmitter is released into the synaptic cleft.When the neurotransmitters diffuse across the synaptic cleft they bind to receptor proteins on the membrane of the postsynaptic cell and causes a nerve impulse to start on the membrane of this neuron.
This video can help to understand the process (action potential is as nerve impulse is transmitted)
viernes, 18 de marzo de 2011
This is known as lunar perigee by astronomer but astrologer call it supermoon and one astrologer believes it could inflict massive damage on the planet. I think that is false and we don’t have to worry about it. Otherwise it's true that we will be able to enjoy looking at the full moon after the sunset. The best moment is the moonrise. Enjoy yourself
When the perigee moon lies close to the horizon, it can appear absolutely enormous. That is when the famous “moon illusion” combines with reality to produce a truly stunning view.
For reasons not fully understood by astronomers or psychologists, a low-hanging moon looks incredibly large when hovering near trees, buildings and other foreground objects. The fact that the moon will be much closer than usual this weekend will only serve to amplify this strange effect.
In this video it is explained all about this phenomenon
Speaking of moons, the song “blue moon” has come to my mind. So
miércoles, 16 de marzo de 2011
The neuron is the structural unit of the nervous system that transmits electrical signals.
The glial cells that provide a support system for the neurons.
Structure of a Neuron : Neurons are typically made up of a cell body (or soma), dendrites, and an axon, as shown in Figure
The cell body contains the nucleus and other organelles similar to other body cells.
The dendrites extend from the cell body and receive a nerve impulse from another cell. Some neurons can have over 1000 dendrite branches other neurons have only 1 or 2 dendrites
The axon is a long, membrane-bound extension of the cell body that passes the nerve impulse onto the next cell. In general, neurons have only one axon and the longest axon of a human neuron can be over a meter long.
The end of the axon is called the axon terminal. The axon terminal is the point at which the neuron communicates with the next cell.
The axons of many neurons are covered with an electrically insulating phospholipid layer called a myelin sheath. The myelin speeds up the transmission of a nerve impulse along the axon. It acts like a layer of insulation, like the plastic you would see around an electrical cord.
Types of Neurons Neurons are highly specialized for the processing and transmission of cellular signals and can be classified by their structure or function. Structural classification is based on the number of dendrites and axons that a cell has. Functional classification groups neurons according to the direction in which the nerve impulse is moving in relation to the CNS.
Thre are three functional groups:
• Sensory neurons carry signals from tissues and organs to the central nervous system and are sometimes also called afferent neurons.
• Motor neurons carry signals from the central nervous system to muscles and glands and are sometimes called efferent neurons.
• Interneurons connect sensory and motor neurons in neural pathways that go through the central nervous system. Interneurons are found only in the central nervous system where they connect neuron to neuron.
The endocrine system is a system of glands around the body that release chemical signal molecules into the bloodstream. The electrical signals of the nervous system move very rapidly along nervous tissue, while the chemical signals of the endocrine system act slowly in comparison and over a longer period of time. Working together, the nervous and endocrine systems allow your body to respond to short or long term changes in your environment.Your nervous system mostly through your eyes and ears constantly monitors your surroundings, alerting you instantly at any sign of change or danger.
|Nervous System||Endocrine System|
|* Means of transmision||nerve impulses by nerves||hormones in blood|
|* Speed of response||rapid||slow|
|* Duration of response||brief||long|
* Regulation and coordination functions
rapid responses such as locomotion
maintained responses such as growth and metabolism
martes, 15 de marzo de 2011
We start with interaction functions remembering what you studied last year and I guess you have already known
What is interaction ?
All living beings interact with their environment and with other living beings to survive. lnteraction enables living beings to receive and respond to a stimulus.
Stimuli. These are detectable changes in the internal or external environment. They provoke responses. Stimuli can be:
Physical: light, sound, temperature, pressure, etc.
Chemical: the presence or absence of chemical substances
Biotic: changes caused by the presence of other living beings
• Receptors. These are structures which receive stimuli from the external or internal environment. In animals, the receptors are the sense organs.
• Coordination systems. These consist of organs which process information received by the receptors and produce a response.
• Responsive organs, also called effectors. These are structures which produce responses, such as muscles and glands in animals.
Coordination systems work together to process information received from stimuli and to produce appropriate responses. Human being as most animals have two coordination systems: the nervous system and the endocrine system.
• The nervous system regulates the body's activities and responses. lt works by means of specialised cells called neurons which transmit information in the form of nerve impulses.
• The endocrine system regulates and coordinates the body functions by means of chemical substances called hormones.
In animals, stimuli are processed and analysed quickly. Responses are immediate.
viernes, 4 de marzo de 2011
First, it's sure that one question is a drawing of an organ system. you will have to label the different names of the organs (Drawings are like in activities). Here I put an example
Second, another question will consist in matching different concepts with their definitions. You did quite a lot of this kind of exercise in your homework. From these activities I will choose most of the concepts for your exam.
Third, you will have a question of define concepts. There are several post in the blog with concepts and their definitions. Maybe they are too many concepts, so I have chosen only a few from all the concepts ( There will be 4 concepts):
constipation / anemia / bladder / digestion / homeostasis / urine / duodenum /
systemic circulation / nephrons / enzyme / pulmonary circulation /
excretion /gall bladder / plasma / epiglottis / peristalsis / diaphragm / larynx
Fourth, there will be another question of “fill in the gaps”. I am going to copy some parragraphs from the “mini” textbook, but without some keywords that you will have to figure out.
Fifth, you should study each different organs of all the organ systems and which happen in each of them. A good example is activity 22 about digestive system ( I am not saying this activity is going to be in the exam, there will be something similar about all the systems).
Sixth, there will be another question with differents sentences about the organ systems and you will have to decide if the sentence is true or false, as you did in the activities. ( This question is not absolutly sure)
Seventh, it could appear one text with questions. In this case it would be one of the text you have worked in class.
Finally, I like the questions of describing paths of cells or molecules through our body. It could be the path of some component of the foods (glucose, ...) through the digestive system ( from the mouth to the small intestine and blood) It could be the path of a red blood cell from one part of the heart to different place (This post could help you to learn the path ). It could be the path of the oxygen outside in the air to the cells. It colud be the path of urea trough the kidney (nephrons) and urinary system,..........Of course these question are for getting good marks in the exam.
Please, study quite a lot. If you have any doubt or question. in the blog you have my e-mail to ask me about them.