B10 - The Human Nervous System (Y11 - Autumn 1) Flashcards
❌ What Is The Brain?
The brain controls complex behaviour. It is made of billions of interconnected neurones and has different regions that carry out different functions.
❌ The Structure Of The Brain
Your brain is kept protected inside the bones of your skull, and is encased in protective membranes called the meningles. The brain itself has a textire rather like set yoghurt. It is made up of billions of interconnected neurones that form
different regions. The different regions of the brain carry out
different functions. For example:
- The celebral cortex is concerned with consciousness, intelligence, memory,and language
- The cerebellum is concerned mainly with coordinating muscular activity and balance.
- The medulla is concerned with unconscious activities, such as controlling the heartbeat, the movements of the gut, and breathing.
The brain has many other specialises areas. For example, the hypothalamus is involved in controlling body temperature, while the pituitary gland produces many different chemicals (hormones) which play a big part in coordinating and controlling body systems.
❌ How Do Neuroscientists Study The Brain
Neuroscientists have been able to map the regions of the brain to particular functions by studying patients with brain damage, electrically stimulating different parts of the brain and using MRI scanning techniques. The complexity and delicacy of the brain makes investigating and treating brain disorders very difficult.
❌ How Have Scientsits Studied People With Brain Damage
Over many years, it has been possible to discover the role different areas of the brain when people suffer from brain damage. Matching changes in behaviour or memory with the damaged area has helped scientists map the functions of some parts of the brain. For example in 1848 an explosives accideng blew an iron rod through the skull of 25 year old Phineas Gage. Amazingly, he survived for 13 years but the polite, hardworking, young man became wild, rude, and unreliable. Modern scans show the accident removed part of Gage’s cerebral cortex, including the area that controls social inhibitions. Modern scientists can explain the changes observed almost two centuries ago.
❌ Why Do Scientists Electrically Stimulate Different Parts Of The Brain
If scientists expose the brain by removing the top of the skull, they can stimulate different areas and see what effect this has. As there are no sensory nerve endings in the brain, brain surgery is sually done on conscious patients. People can experience hunger, anger, fear, or thirst, simply because the relevant area of their brain is stimulated.
❌ How Are MRI Scans Used To Research The Brain
In recent years, scientists have been able to develop a much better understanding of how the brain works as a result of new ways of taking images of the brain in living people. For example, if someone develops a tumour in their brain, or has a stroke, this will show exactly which area of the brain is affected. This enables scientists to link the loss of a certain function, such as speech or control of movement on one side of the body, with damage to a particular region of the brian. The most recent MRI scanners can take images as someone carries out a simple task.
❌ What Problems Are There With Investiagting The Brain
The brain is very complex and very delicate. Many of the process that take place involve many different neurones in different areas. There is also a range of different chemicals released in the synapses in the brain. It is easily damaged and destroyed. As a result it is very difficult to treat them. Drugs do not always reach the brain through the membranes which surround it. Surgery is difficult because it is not fully understood what each area of the brain actually does. It is easy to cause unintended damage.
🟠 Homeostasis Definition
Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
🟠 What Is Homeostasis
The conditions inside your body are known as its internal enviornment. Your organs cannot work properly if this keeps changing. Many of the processes that go inside your body aim to keep everything as constant as possible. As well as the body as a whole, this includes the regulation of the internal conditions of cells to maintain optimum conditions for functioning, in response to internal and external changes. This balancing act is called homeostasis.
🟠 What Things In The Body Need To Be Regulated By Homestasis
Homeostasis maintains optimal conditions for enzyme action and all cell functions. In the human body, these include control of:
- Blood Glucose Concentration
- Body temperature
- Water Levels
(Others can include:
- pH
- Osmotic Potential
- Ion Concentration, e.g Na+
- Toxins, e.g Urea)
🟠 What 3 Main Things Need To Be Maintained In The Body And How/Why
Enzymes can function at their optimum in humans at 37°C, so there are homeostatic mechanisms to maintain this core body temperature.
The blood pH must stay within 7.2 and 7.4, so acidic CO2 made by respiring cells is removed by breathing out.
Toxic urea from the breakdown of excess proteins is removed by the kidneys, along with excess water and ions, e.g Na+, Cl-. The fluid excreted from the bladder is called urine.
🟠 How Does Homeostasis Work (How Does The Body Need To Work Together)
Homestasis involves coordination and control. Organisms need to be aware of changes in the world around them, such as changes in temperature or levels of sunlight. They also need to respond to changes in the internal environment. When you exercise your muscles get hotter, when you have eaten a meal your blood sugar levels go up, and in hot weather you lose water and salt through sweating. Detecting changes and responding to them involves automatic control systems. These automatic systems include nervous responses in your nervous system and chemical responses in your hormone system. They also involve many of your body organs.
🟠 What Key Features Does The Control Systems In The Body Need To Function?
All control systems in the body need certain key features to function:
- Receptors: Cells that detect changes in the internal or external environment. These changes are known as stimuli. Receptors may be part of the nervous or the hormonal control systems of the body.
- Coordination Centres: Areas that recieve and process the information from the receptors. They send out signals and coordinate the response of the body. They include the brain, which acts as a coordination centre for both the nervous system and parts of the hormonal system, the spinal chord, and some organs such as the pancreas.
- Effectors: Muscles or glands that bring about responses to the stimulus that has been recieved. These resources restore conditions in the body to the opimum levels.
❌ What Part of the Brain Are Reflex Actions Controlled By (Conscious Part or Unconscious Part)
Reflex actions are automatic and rapid; they do not involve the conscious part of the brain.
❌ What Does The Nervous System Do
- The nervous system enables humans to react to their surroundings and to coordinate their behaviour.*
- Organisms must be aware of what is happening around them, as this affects their survival chances
- Co-ordination of an organism’s activities is carried out by the nervous system and the endocrine system
- A nervous system allows an organism to detect and respond to stimuli in its internal or external environment
- A stimulus is any change in your environment, e,g the flash of a light, a noise, a fly landing on your nose, e.c.t
❌ What Are The Two Parts The Nervous System Is Divided Into
The nervous system is divided into two parts:
- Central Nervous System (CNS)
- Periphery Nervous System (PNS)
❌ What Does The Central Nervous System (CNS) and Periphery Neevous System (PNS) Consist Of?
- The Central Nervous System (CNS) consists of the brain and spinal chord
- The Peripheral Nervous System (PNS) consists of a vast network of nerves that carry messages between the CNS and the rest of the body
- All of the nerves are made up of bundles of tiny nerve cells called neurones
❌ What Is The CNS, What Does It Do And What Does It Consist Of?
The nervous system enables humans to react to their surroundings and to coordinate their behaviour.
Information from receptors passes along cells (neurones) as electrical impulses to the central nervous system (CNS). The CNS is the brain and spinal cord. The CNS coordinates the response of effectors which may be muscles contracting or glands secreting hormones.
❌ What Is The Process Of The Nervous System’s Response (What Are The Structures Found In A Reflex Arc And At What Point Do They Act)
(+ Life Example of Each Part)
Refelx Arc Example:
Stimulus (Red Light)
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Receptor (Eye)
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Coordinator (Brain)
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Effector (Muscle)
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Response (Brake)
❌ Summary Of How The Nervous System Works/What It Does
The receptor sends an impulse along a sensory neurone, carrying information about a change in the environment to the coordinator (CNS). Once all of the incoming information has been processed, the coordinator sends impulses down motor neurones. These motor inpulses stimulate the effectors to bring about the responses needed in any particular situation.
❌ What Are Neurones And What Do They Do in the Nervous System
Once a sensory receptor detects a stimulus, the information is sent as an electrical impulse that passes along cells called neurones. These are usually found in bundles of hundreds or even thousands of neurones known as nerves.
❌ What Are Sensory Neurones And What Do They Do in the Nervous System
The impulse travels along the neurone until it reaches the central nervous system (CNS). The CNS is made up of the brain and the spinal cord. The cells that carry impulses from your sense organs to your CNS are called sensory neurones.
