Human Biology Notes PDF

**Human Biology Notes** **Definitions:** +-----------------------------------+-----------------------------------+ | Term | Meaning | +===================================+===================================+ | Neuron...

**Human Biology Notes** **Definitions:** +-----------------------------------+-----------------------------------+ | Term | Meaning | +===================================+===================================+ | Neuron | A type of cell that receives and | | | sends messages from the body to | | | the brain and back to the body | +-----------------------------------+-----------------------------------+ | Cell Body | The compact section of the nerve | | | cell that contains the nucleus | | | and the cytoplasm | +-----------------------------------+-----------------------------------+ | Axon | A portion of a nerve cell that | | | carries nerve impulses away from | | | the cell body | +-----------------------------------+-----------------------------------+ | Myelin Sheath | An insulating layer that forms | | | around the nerves including those | | | in the brain and spinal cord | +-----------------------------------+-----------------------------------+ | Dendrites | Projections from the cell body or | | | soma of the neuron the cells of | | | the nervous system | +-----------------------------------+-----------------------------------+ | Stimulus | Any information that the body | | | receives causing a response | +-----------------------------------+-----------------------------------+ | Receptor | A receptor is a structure that | | | detects a stimulus or change in | | | the normal functioning of the | | | body and sends information to the | | | brain | +-----------------------------------+-----------------------------------+ | Glands | An organ that makes hormones and | | | releases into the bloodstream | +-----------------------------------+-----------------------------------+ | Hormones | A chemical messenger that brings | | | about a response in the body | +-----------------------------------+-----------------------------------+ | Target Cells | A cell in the body that is acted | | | on selectively by a hormone | +-----------------------------------+-----------------------------------+ | Circulatory System | The system that moves substances | | | around the body, including | | | hormones | +-----------------------------------+-----------------------------------+ | Homeostasis | The process of maintain a stable | | | internal environment (withing a | | | healthy normal range) | | | | | | [Examples Include:] | | | | | | Glucose, pH, water and oxygen | | | levels, temperature and sleep | | | cycles. | +-----------------------------------+-----------------------------------+ | Negative Feedback | The responsible for maintaining | | | homeostasis. Act in the opposite | | | way to the original stimulus | +-----------------------------------+-----------------------------------+ | Hypothalamus | A part of the brain that produces | | | hormones to control your body | | | temperature, heart rate, hunger | | | and mood | +-----------------------------------+-----------------------------------+ | Pathogen | A micro-organism that can cause a | | | disease | +-----------------------------------+-----------------------------------+ | Disease | An abnormal condition that | | | affects the function of the body | +-----------------------------------+-----------------------------------+ **Lesson 2 -- Receptors Detect Stimuli** +-----------------+-----------------+-----------------+-----------------+ | Sense ​ | Stimuli​ | Organ ​ | Receptor type​ | +=================+=================+=================+=================+ | Taste | ​Chemicals in | ​Tongue | ​Chemo receptor | | | food | | | +-----------------+-----------------+-----------------+-----------------+ | Smell | ​Chemicals in | ​Nose | ​Chemo receptor | | | the air | | | +-----------------+-----------------+-----------------+-----------------+ | Sight | ​Light, colour | ​Eye | ​Photo receptor | +-----------------+-----------------+-----------------+-----------------+ | Touch | ​pressure | ​skin | ​Mechano-recept | | | | | or | | | temperature | | | | | | | Thermo-receptor | +-----------------+-----------------+-----------------+-----------------+ | Hear | ​movement of | ​Ear | ​Mechano-recept | | | air particles | | ors | +-----------------+-----------------+-----------------+-----------------+ **Lesson 13 -- The immune system line defence** **PowerPoint notes:** - The immune system prevents pathoens from entering the body and attacks them if they do enter - The Immune system has 3 lines of defence - The body uses physical barriers and chemicals to prevent pathogens from entering the body: - Skin is thick, waterproof and difficult to damage. It alsp produces oil and sweat which can destroy some types of bacteria - Mucous membranes line the opening to the body. The mucus in these areas can trap and kill pathogens - If the first line of defence fails the body launches a **non-specific immune response** - Blood clots to prevent additional infection through damage to the skin - Inflammation occurs to increase the number of blood celss reaching the effected area - Fevers damages pathogens that cannot survive at high temperatures - Some specialised white blood cells can engulf pathogens destroying them in a process called phagocytosis (which means eating cells) - These cells are often destroyed in this process and become the yellow pus that collects in wounds - If pathogens can survive through the body's first line of defence they are now targeted according to their type - This is a specific immune response, and has two forms of attack using lymphocytes (white blood cells) called B and T cells - The defence has a long-lasting effects, as the body is able to recognise the pathogen if it comes into contact with it again in the future and is able to destroy it much faster - Viruses can make it to the third line of defence, as they are coated in special proteins that protect them - B Cells: - Are specialised white blood cells that produce antibodies - They are produced in bone marrow - Antibodies are specific to particular pathogens and latch onto them as they git their shape - Each antibody fits onto a pathogen and collects them together so they do not function properly - T Cells: - Are another type of white blood cells that seeks out the antibody-pathogen complex and destroy the pathogen. The antibody is unharmed - They are produced in the thymus gland - It may take up to a week for b and t cells to recognise and destroy pathogen which is why recovering from a disease can take time **Lesson 14 -- Vaccines** **Immunity PowerPoint Notes:** - As a result of b and t cells destroying a pathogen in the body, memory cells are produced - Acquired immunity arises when antibodies are created without the body and experiencing the pathogen - Vaccinations also provide immunity against diseases as the body creates memory cells for the specific pathogen of the vaccine **Lesson 15 -- Revision** **Neurons:** - Has 5 main parts - A cell body which contains the nucleus - Dendrites that branch out from the cell body and receive messages from other nerve cells - An axon which sends nerve impulse away from the body - Synaptic terminals which pass the nerve impulse on - A myelin sheath that electrically insulates the neurons from each other and maintains the speed of the nerve impulse - There are 3 types of neurons - Sensory neurons are found in the sense organs and carry messages towards the central nervous system - Motor neurons carry messages away from the central and connect to muscles and glands. - Interneurons link sensory and motor neuron. They only exist in the central nervous systems (the brain and the spinal chord) - Any information that the body receives, causing a response - Stimuli can be external or internal - A receptor is a structure that detects a stimulus or change in the normal functioning of the body, and sends information to the brain +-----------------+-----------------+-----------------+-----------------+ | Sense | Stimuli | Organ | Receptor | +=================+=================+=================+=================+ | Sight | Light | Eye | Photoreceptors | +-----------------+-----------------+-----------------+-----------------+ | Hearing | Sound-movements | Ear | Mechanoreceptor | | | of air | | s | | | particles | | | +-----------------+-----------------+-----------------+-----------------+ | Taste | Chemicals in | Tongue | Chemoreceptors | | | food | | | +-----------------+-----------------+-----------------+-----------------+ | Smell | Chemicals in | Nose | Chemoreceptors | | | air | | | +-----------------+-----------------+-----------------+-----------------+ | Touch | Pressure, | Skin | Mechanoreceptor | | | temperature, | | s | | | pain | | | | | | | Thermoreceptors | +-----------------+-----------------+-----------------+-----------------+ **The nervous system:** - Nervous system is a communication system that controls all parts of the body - The human nervous system has 2 main parts: 1. It receives information from all over the body 2. Processes that information 3. Sends out messages telling the body how to respond - The somatic nervous system (SNS) collects information receptors from out sense organs - It then coordinates movement of the body in response, by controlling voluntary muscle movements - Example: taking a jumper off in hot weather, or drinking water to cool down - The autonomic nervous system (ANS) controls involuntary actions of the body - These include - Heartbeat - Digestion - Respiration - Salivation - Pupil size - Perspiration **Diversions of the nervous system:** - The central nervous system is composed of the brain and spinal cord - The peripheral nervous system is composed of the nerves in the limbs and organs - The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system - Each of these divisions controls different important functions of the body - The somatic nervous system (SNS) collects information receptors from our sense organs - It then coordinates movement of the body in the response, by controlling voluntary muscle movements - Example: taking a jumper off in hot weather, or drinking water to cool down - The autonomic nervous system (ANS) controls involuntary actions of the body - These include: - Heart beat - Digestion - Respiration - Salivation - Pupil size - Perspiration - The Autonomic Nervous System is responsible for maintaining the body's internal environment **Stimulus-Response Model** 1. Stimuli in the environment are detected by receptors in our sense organs 2. Sensory neurons then pass nerve impulses to the CNS where interneurons gather and process the information 3. The nerve impulses are then sent to the muscles and organs via motor neurons in the peripheral nervous system 4. Muscles / organs then work to create a response from the body **Reflexes:** - A reflex action is an involuntary, almost instantaneous movement in response to a stimulus - During a reflex action, the sensory neuron carries the message from the receptor to the spinal cord as usual - The interneuron in the spinal cord then sends 2 messages at the same time: - One to the brain, which is processed normally - One to the motor neuron and muscles, resulting in a immediate, involuntary response - The brain is decided into 3 parts: - Cerebrum: - Frontal lobe - Temporal lobe - Parietal lobe - occipital lobe - Cerebellum - Brain stem **The Endocrine System** - The endocrine system is a collection of glands and organs that secret hormones - Its function is to maintain the body's internal environment - Hormones are secreted into the blood and travel around the body via the circulatory system - Glands and organs of the endocrine system are located all throughout the body - The endocrine system acts much slower than the nervous system, however it effects las longer - There are several glands that make up the endocrine system - They are referred to as ductless glands because they secrete hormones straight into the bloodstream - Many hormones are released from the hypothalamus and the pituitary gland in the brain - The hypothalamus is a bundle of nerves that links the nervous and endocrine systems - It monitors the body's internal environment - The hypothalamus secretes hormones to the pituitary gland, which then secretes more, or less, hormones itself **Hormones:** - Hormones are a type of protein chemical messenger that work to maintain control and growth of the body - Hormones are produced in very small amounts and travel through the blood, reaching all body cells - Hormones are specific -- they do not affect all the cells - This means that they only act on particular cells in the body. These are target cells - Different hormones have different chemical structures. This means that their shape varies - It is the shape of the hormone that makes it specific - A hormone is only active in cells that have receptors that fir the shape of the hormone - Target cells and hormones fit together like a lokc and key or pieces of a jigsaw - It only takes on hormone to cause a change in the target cell's activity **Homeostasis Revision:** Homeostasis is the process of regulating the internal conditions of the body - Regulation happens through the coordination of the nervous system, endocrine system and various organs - The conditions that are regulated are - Temperature - Water and salt content - Available energy - Available oxygen - Concentration of wastes in the blood - Homeostasis involves receptors that are sensitive to a particular stimulus, and effectors that have an effect on the same stimulus (stimulus response model) - Negative feedback occurs when the body responds to remove a stimulus - Example: consider a reverse-cycle air conditioner - A sensor called a thermostat is set at a particular temperature range, such as 21-23 degrees - If the temperature of the room goes above 23 degrees, the air conditioner switches on and cools the room until the required temperature is reached - It then switches off. - Blood glucose levels are controlled by the pancreas - When blood glucose is high (stimulus) the pancreas secretes insulin - Insulin causes muscle and liver cells to store glucose, removing the glucose from the blood - The stimulus is corrected through negative feedback - When blood glucose is low (stimulus) pancreas secrets glucagon - Glucagon causes muscle and liver cells to release glucose into the blood, removing the stimulus - Glucagon has the opposite effect to insulin - By controlled release of the two hormones, glucose levels are kept fairly constant