Science Biology Test 2- Body Systems

Memorise Diagram 5.26

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Occipital Lobe

• The occipital lobe is at the very back of the brain. It is responsible for various aspects of vision.

Homeostasis Examples

•Some of the environmental changes that homeostasis can correct are: •Temperature •Blood sugar levels •Blood pressure •pH levels •Oxygen and carbon dioxide levels •Nutrient levels •Water balance •If there is a change in any of these factors, homeostasis comes into effect and will send messages to other structures to bring that factor back to normal

Pathogen

pathogen is a substance or organism that is capable of causing disease or sickness

Phagocyte

phagocyte white blood cell that destroys pathogens and deals with a non-immune response

Receptor

A receptor is an organ or cell able to respond to light, heat, or other external stimulus and transmit a signal to a sensory nerve.

Location of nervous system

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What is a Reflex?

A reflex, or reflex action, is an involuntary and nearly instantaneous movement in response to a stimulus. During a reflex action, an impulse is passed along a sensory neuron to the spinal cord, where it crosses a synapse to a motor neuron. This allows reflex actions to occur quickly by activating motor neurons without having to wait for signals to pass through the brain. Of course, the message is eventually sent on to the brain so the brain can record what has happened. So a fraction of a second after you pull your hand away from a hot stove, you feel the pain in your hand.

Stimuli

A stimulus is any information that your body receives that might cause it to respond. A stimulus is a thing or event, a piece of information, that evokes a specific functional reaction in an organ or tissue.

Antigen

An antigen is any substance that causes the body's immune system to make antibodies; may be a pathogen or a marker molecule found on the surface of a pathogen

What makes up nerve cell structures?

Cell body Dendrites Axon Myelin sheath Axon terminals Synapse

Diabeties

Diabetes is one of the more serious and common results of hormone imbalance. Left untreated it can result in blindness, kidney failure, heart disease or death. Diabetes occurs when the pancreas either produces too little insulin or doesn't properly use the insulin it does produce. Insulin is the hormone that assists the body to process sugar in the bloodstream. A message that blood sugar is low results in less insulin being produced. The opposite happens when blood sugar is high.

When things go wrong in the endocrine system

Disorders and diseases of the endocrine system are fairly common and are often due to imbalances in feedback mechanisms within hormonal systems. Diabetes, thyroid goitre and obesity are all caused by imbalances in the endocrine system.

Endocrine System involved in Homeostasis

ENDOCRINE SYSTEM •Involves glands which secrete hormones into the blood to regulate the body •Hormones attach to certain tissues and allow communication between cells •Can regulate moods, growth and development and metabolism •Major endocrine glands include the pituitary, hypothalamus, adrenal, pancreas, ovaries and testes

Types of Radiation

Exposure to radiation can fall into one of two categories; it can either be intentional, such as medical treatment, or unintentional, such as everyday exposure or accidents. But what does it actually do to us?

Homeostasis

Homeostasis is your body's ability to regulate and maintain a stable condition inside your body, regardless of changes to the external environment. To maintain homeostasis your body uses two very important body systems to sense and respond to change: the nervous and endocrine systems. They have a big job due to the huge number of changes and threats your body encounters.

Why is Homeostasis important in the body?

Homeostasis keeps the body environment under control and keeps the conditions right for cells to live and function. Without the right body conditions, certain processes (eg osmosis) and proteins (eg enzymes) will not function properly.

Feedback mechanisms

Hormonal effects are often controlled by feedback mechanisms. This means that when a hormone— a messenger—is sent out into the body, information is received back about what is going on. This then affects other responses by the body. The rate of hormone production and secretion is often regulated by a negative feedback mechanism. This means that if a stimulus is received indicating that something in the body is happening 'too much', the response would be to produce less of that hormone to reduce the effects.

Types of Hormones

Hormones are classi ed into two types based on their chemical structure: peptide hormones and steroid hormones. Peptide hormones are made from proteins and produced by the anterior pituitary, parathyroid gland, placenta, thyroid gland and pancreas. Most hormones are peptides. Peptides travel through the bloodstream until they nd and interact with speci c receptors on the surface of their target cells. Steroid hormones include those hormones secreted by the adrenal glands and the ovaries (women) or testes (men). Steroid hormones are produced from cholesterol.

Immunity

Immunity is the ability to resist and overcome infection, disease or other unwanted invasion of the body

Interneurons

Interneurons link sensory and motor neurons, as well as other interneurons. Interneurons only make connections with other neurons. They are also known as connector neurons.

Insulin

Is also produced by the pancreas and acts on the liver When blood glucose is too high, insulin is released to convert glucose into glycogen to be stored in the liver

Motor neurons

Motor neurons carry messages from the central nervous system to muscle cells throughout the body, which then carry out the response. Motor neurons are also known as effector cells.

What are the three types of neutrons?

Motor, sensory and interneuron

Nervous System involved in Homeostasis

NERVOUS SYSTEM •Contains a network of neurons that coordinate the actions of an animal and transmit signals between different parts of the body •Main organs of the nervous system are the brain, spinal cord and nerves •Receives messages when body temperature, sugar levels or water content changes and sends messages to organs to react to these changes •Eg. Sending a message to the sweat glands to activate when it is hot

Sensory Neurons

Sensory neurons are sensitive to various stimuli, collecting information either from the body's internal environment or the outside world. Sensory neurons send the information they have collected to the central nervous system for processing.

Vaccination

One other way to acquire immunity is by ingestion or injection with speci c antigens. This is called vaccination, or inoculation. Vaccination is an example of acquired active immunity. Natural passive immunity is obtained by a baby from its mother. The mother's antibodies are passed onto the child through the placenta and are in the mother's breast milk. A vaccine can be given that is: • • • the dead pathogen an alive but non-virulent (weakened) form of the pathogen antigens of the pathogen that have been separated from it. Through vaccination, a person receives antibodies, which usually leads to immunity. Vaccinations are often given as a preventive measure. For instance, the in uenza vaccine is recommended for people over 65 years of age because complications from in uenza can be life-threatening in older people. Vaccination can also be given when there is an urgent need to provide immunity. Tetanus vaccine is often given for this reason after a tetanus-prone injury, for example for an open wound caused by a rusty or dirty object, because tetanus can be fatal.

Disease

Pathogen: Disease Features: Unicellular organism; cell wall but no nucleus Example of Disease: Chlamydia (a sexually transmitted infection)

Virus

Pathogen: Virus Features: Not a cell: contains genetic material surrounded by a protein coat; not considered living Example of Disease: Hepatitis (inflammation of the liver)

Glucagon

Produced by the pancreas and acts on the liver When blood glucose (blood sugar) is too low, glucagon is released to convert glycogen (which is stored in the liver) into glucose

Thyroxine

Produced by the thyroid gland and acts on body cells. •Its role is to regulate the rate of metabolism and physical and mental development •Metabolism refers to all the chemical reactions that occur in your body -Eg cellular respiration (converting glucose into energy)

Radiation

Radiation is energy. Energy is required to make and break chemical bonds, which means radiation can interfere with the molecules in your body's cells.

Draw a simple feedback loop (low and high)

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Memorise Table 5.2 pg 145

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Label a reflex arc

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Label the following parts of a brain

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Autonomic nervous system

The autonomic nervous system also has two parts: the sympathetic division and the parasympathetic division. These two divisions often have opposite effects. For example, the parasympathetic division slows down the heart rate, whereas the sympathetic division speeds up the heart rate. The systems work together to maintain a balance in the body.

Brain

The brain is the processing centre of the body and is mainly concerned with our survival. The brain is a soft, heavy organ that is surrounded by a tough skull. The brain gathers information about what is going on inside and outside the body. It then makes decisions about things like internal changes and movements. It is also home to your memories, personality and thought processes.

Medulla

The medulla is at the bottom of the brain stem and controls automatic functions, like respiration (breathing) and digestive system activities. The pons assists in some automatic functions, like breathing, and also controls sleep and arousal. The midbrain contains areas that receive and process sensory information, such as movement and vision

Central Nervous system

The central nervous system is the control centre of the body. All incoming messages from your environment and your responses to them are processed through the central nervous system. The two main features of the central nervous system are the brain and the spinal cord.

Cerebellum

The cerebellum is like a smaller version of the cerebrum and is responsible for movement, balance and coordination

Stimuli Example

The easiest stimuli to identify are those that we respond to physically: • Temperature changes cause us to shiver, put on or remove clothing, sweat, or feel pain (if the changes are extreme or for long periods). • Pressure on a part of our body might be light and ticklish, strong and painful, it might reduce blood circulation or simply make us look at what is causing it. • Light might make us squint, close our eyes or look towards its source. • Sound might makes us look towards its source, follow an instruction or cover our ears.

What is the difference between the endocrine and nervous systems?

The endocrine and nervous systems are the systems largely responsible for sensing and responding to the environment. Part of this important job is communication: once a change or threat has been received, messages must be sent around the body to coordinate a response. The nervous system sends very fast electrical messages, and the endocrine system is a much slower system that uses chemical messengers called hormones to maintain homeostasis and to regulate growth.

Endocrine system

The endocrine system is a collection of glands that secrete (release) hormones. These hormones are secreted directly into the bloodstream and then travel through the blood to arrive at a target organ. How does the hormone know where to go? Hormones bind to a matching receptor, working like a lock and key mechanism. The glands and organs of the endocrine system are spread throughout the body (Table 5.2).

Frontal Lobe

The frontal lobe is located at the front of the brain. Its functions include emotions, reasoning, movement and problem solving.

Hypothalamus

The hypothalamus is primarily responsible for homeostasis. This includes maintaining a constant heart rate, body temperature and sleep pattern. The hypothalamus is also involved in hormone production by control of the pituitary gland

Cerebrum

The largest part of the brain is the cerebrum. It is divided into two paired cerebral hemispheres, joined by the corpus callosum. All of our conscious activities are controlled by the cerebrum. The outer layer of the cerebrum is called the cerebral cortex (also known as grey matter)

Effects of radiation

The nucleus of each of your cells contains the instructions for every task and substance required for healthy functioning. The instructions take the form of the molecule DNA. Any change to these instructions can result in damage, which may be major or minor depending on where the change occurs. We often think of DNA as most important for reproduction. However, DNA is vital for the reproduction of all cells, not just the ones that make new organisms. Many of your other cells need to be regularly replaced and cells need to be reproduced for healing to occur.

Parietal Lobe

The parietal lobe manages the perception of senses, including taste, pain, pressure, temperature and touch.

The peripheral nervous system

The peripheral nervous system The peripheral nervous system is a large system made up of all the nerves outside the central nervous system. The peripheral nervous system carries information to and from the central nervous system to the rest of the body, such as the limbs and organs. The peripheral nervous system is divided into two parts: • The somatic nervous system controls voluntary skeletal muscle movements, such as waving or reaching out to take something. • The autonomic nervous system controls involuntary actions, which happen without our conscious control.

Pituitary Gland

The pituitary gland is the major endocrine gland, a pea-sized body attached to the base of the brain that is important in controlling growth and development and the functioning of the other endocrine glands.

Immune system

The role of your immune system is to protect you against foreign invaders by physically stopping them from entering your body, and identifying and attacking them if they manage to enter. Your immune system has three lines of defence against disease, each with a different role.

First line of defence

The rst line of defence against pathogens is to stop the pathogens from getting inside our bodies (Fig. 5.39). ➔ Fig 5.39 The skin and mucous membranes are the rst line of defence against pathogens. Tears wash pathogens out of our eyes Ear wax has a role in capturing pathogens trying to enter the body through our ears The eyes, ears, nose, mouth and genitals are usually exposed to the air and/or environment and so pathogens can easily enter. Mucous membranes are the thin skin-like linings of these entry points. Chemical barriers are present here to assist in defence. Slimy mucus can capture and kill some of the bacteria Urine is slightly acidic, which makes the growth of bacteria more dif cult The skin acts as the rst line of protection. Skin is a great barrier. It is thick, waterproof and dif cult to damage. Helping protect the skin are the oils and sweat released from the skin. In dry conditions, bacteria are damaged and destroyed by the salt and antimicrobial chemicals in these secretions

Temporal Lobe

The temporal lobe is located in the region near your ears. It deals with the recognition of sounds and smells.

Thalamus

The thalamus processes and carries messages for sensory information, such as information sent from the ears, nose, eyes and skin, to the cortex

Phagocytosis

These are called phagocytes, and the word comes from Greek words meaning 'cells that eat'. A pathogen can be enveloped by a phagocyte, and when inside the phagocyte it is destroyed. This process is called phagocytosis.

Third line of Defence

Third line of defence Any pathogens that remain after a non-speci c response are targeted according to their type. This is called a speci c immune response. The speci c immune response creates antibodies. Antibodies are protein molecules that bind speci cally to a target called an antigen. Antigens may be the pathogen itself or even marker molecules on the surface of a pathogen.

Tumours

Tumours are faulty cells that continue to multiply, replicating the fault with each cell division. These tumours can cause physical blockages in the body or interfere with certain chemical processes. Location, size and type determines whether a particular tumour is considered malignant (cancerous) or benign (not cancerous). Tumours that continue to grow and spread, forming new tumours, are considered to be cancers.

Vaccination

Vaccination is the administration of antigenic material (a vaccine) to stimulate an individual's immune system to develop adaptive immunity to a pathogen.

Second line of defence

Viruses, unlike bacteria, contain a protective coating that allows them to more easily slip through the rst line of defence. If a pathogen gets inside the body, the body tries to remove it in one of two ways. First, a general 'seek and destroy' approach is taken. This occurs regardless of the type or structure of the pathogen. This is called a general or non-speci c immune response. The key parts of the non-speci c immune response are: • blood clotting, to stop additional infection through skin damage • in ammation, to increase the amount of blood reaching an infected area • fever—some pathogens cannot survive in extreme heat conditions, so heating up the body is one way to destroy them. Second, white blood cells are produced by the body to destroy pathogens. An increase in the amount of blood reaching an infected area of the body as a result of in ammation means that more white blood cells are available to attack the pathogen. The white blood cells may also release substances that increase the amount of uid in the infected area, causing swelling. There are a few different types of white blood cell. Each type does its own job but they all work together. Only some white blood cell types deal with the non-speci c immune response. These are called phagocytes, and the word comes from Greek words meaning 'cells that eat'. A pathogen can be enveloped by a phagocyte, and when inside the phagocyte it is destroyed. This process is called phagocytosis.

What happens if I have too little thyroxine

What happens if I have too little thyroxine? This is known as hypothyroidism It can cause a decreased metabolic rate which may result in fatigue, inability to withstand cold temperatures, low heart rate, weight gain, reduced appetite and poor memory It can be caused by autoimmune diseases or poor iodine intake

What happens if I have too much thyroxine

What happens if I have too much thyroxine? This is known as hyperthyroidism Symptoms include the development of a goitre which is a swelling of the neck due to the enlargement of the thyroid gland. Other symptoms include intolerance to heat, weight loss, increased appetite, increased bowel movements and palpitations

Active and passive immunity

When a person is infected with a pathogen, speci c antibodies are produced to combat the pathogen. If the person is infected with the same pathogen again, the antibodies react immediately to attack and destroy it. This is called natural active immunity. The body may take up to a week to make the antibodies needed to combat a new antigen. This is why recovering from an illness takes time. Once the body has learned how to make the particular antibody, it will be protected from re-infection in the future. The person is now said to be immune. Unborn babies obtain some natural immunity by receiving antibodies across the placenta. Antibodies are also passed to babies who drink breast milk. This is called natural passive immunity.

Uses for radiation

When radiation is used to treat tumours, high doses of radiation are focused solely on the cells making up the tumour. Not all tumours are caused by radiation; some may be caused by chemicals or genetic factors.

Receptor Example

Your ears, eyes, nose and mouth are an example of receptors as they all receive information from a stimulus.

Mid Brain

a small central part of the brainstem, developing from the middle of the primitive or embryonic brain.

Antibody

antibody is a protein molecule produced in the body that binds to a specific target called an antigen.

Disease

disease is an unhealthy impairment of the body that stops it from functioning as it should

What is a hormone?

the endocrine system is a much slower system that uses chemical messengers called hormones to maintain homeostasis and to regulate growth. These chemical messengers act more slowly than the nerve impulses sent around by the nervous system, but their effects often last for a lot longer.