Homeostasis

Homeostasis

1. Nervous System

   • Central Nervous System (CNS)
     • Brain
       • Parts of the brain
         • Hypothalamus
           • Helps regulate body temperature
           • Helps the body realise hunger and thirst
           • Plays a role in emotions
           • Releases and controls many hormones that the body needs to function
         • Pituitary gland
           • Regulates and releases important hormones to our body
           • Plays a big part in the body's overall wellbeing
         • Brain stem
           • Breathing
           • Heart rate
           • Blood pressure
           • Swallowing
           • PLays a role in alertness and sensation
         • Cerebrum
           • Divided into two hemishperes
           • Largest part of the brain
           • Controls all conscience activities
         • Cerebellum
           • Responsibles for movement, balance and coordination
           • Allows us to stand upright, keep our balance and move around
         • Frontal Lobe
           • Planning and organising
           • Problem solving and decision making
           • Memory and attention
           • Controlling behaviour, emtions and impulses
           • Left frontal lobe plays a large role in speech and language
         • Temporal Lobe
           • Recognizing and processing sound
           • Understanding and producing speech
           • Various aspects of memory
         • Occipital Lobe
           • Receives and processes visual information
           • Contains areas that help in perceiving shapes and colours
         • Parietal Lobe
           • Intergrate sensory information from various parts of the body and contains primary sensory cortex, which controls sensation (hot, touch, cold, pain)
           • Tells us which way is up and helps keeping us from bumping into things when we walk
     • Spinal cord
   • Peripheral Nervous System
     • Somatic Nervous System
       • Controls voluntary muscle movements
         • e.g. waving, chewing, swallowing, movement
         • Coordinates movements of the body
       • Deals with external stimulus
       • Collects information from sensory organs
     • Autonomic Nervous System
       • Sympathetic Nervous System
         • Fight or flight
         • Speeds up body functions and makes them work more efficiently - its in control when you are active
       • Parasympathetic Nervous System
         • Rest and digest
         • Slows down body functions - is in control when you're resting
       • Controls involuntary action which maintain homeostasis e.g. digestion, heartbeat
     • Makes up all nerves outside the CNS
     • Carries information to and from CNS to the rest of the body
   • Neurons
     • Different types of neurons
       • Motor Neurons
         • Carries messages to the effector (glands and muscles) which creates the response
       • Sensory Neurons
         • Carries messages from the sense organs to the brain and spinal cord.
       • Inter/ connector neurons
         • Makes connections in nerve pathways
     • Parts of a neuron
       • Dendrites
         • Receives information from other cells
       • Cell body
         • Contains nucleus, vacuole, mitochondria etc.
       • Axon
         • Transfers the electrical messages
       • Myelin Sheath
         • Insulates the electrical signal in the axon and protects the nerve cells in the axon - it is made of fat and increases the speed of the nerve impulse
       • Axon terminal
         • Passes the message/ signal onto the synaptic cleft
       • Synaptic cleft
         • Neurotransmitters transmit the electrical signal across the gap
     • Neurons have a fast electrical signal called a "nerve impulse"

2. Endocrine System

   • Bloodstream
   • Produces hormones in endocrine glands
     • Hormones bind to specific receptors on cells
       • Those cells are called target cells

3. Immunity

   • Pathogens
     • Types of pathogens
       • Bacteria
       • Fungi
       • Viruses
       • Protozoa
       • Worms/ parasites
     • Cause sickness - are infectious
     • Transmission
       • Direct contact
         • e.g. Coughing/ sneezing/touching someone when you are sick
       • Indirect contact
         • e.g. Sick person touching a door handle and then someone else touching the handle
       • Contamination
         • Food poisoning
         • Contaminated water
   • Immunisations
     • People get injections that hold deformed or dead pathogens
     • The immune response to pathogens is faster after immunisations
   • The three lines of defense
     • Third line (specific)
       • Specific
       • Lymphadic system
       • Lymphocytes (T and B cells)
         • Located in lymph nodes
       • T and B cells are activated by an antigen
         • T cells kill the infection
         • B cells release antibodies
         • The T and B cells clone themselves to help kill the infection - thus the lymph nodes becoming swollen
         • Antibodies are released
           • The antibodies stick to the antigens and clump bacteria together for the macrophages to eat
             • After this the T and B cells form memory cells - these remember how to fight the pathogen the next time it infects the body
     • Second line (innate)
       • Non - specific
       • Inflammation
       • Neutrophils and macrophages
         • They form pus when they die
         • They engulf bacteria, break them down and kill them
     • First line
       • Purpose is to stop pathogens getting into the body
       • Non - specific
       • Parts of the body in the first line
         • Saliva
         • Skin
         • Eyelashes
         • Mucus
         • Stomach acid
         • Tears

4. Respiratory System

   • Diffusion
     • The movement of particles from a high concentration to a low concentration.
   • Breathing
   • Gas exchange
     • Alveoli - they are located on the lungs and have many features that help with diffusion
       • Only one cell thick
       • Covered in capillaries
       • Moist membranes so gases can dissolve more easily
       • Moves oxygen into the blood and takes CO2 (carbon dioxide) out of the blood

5. Digestive System

   • Includes breakdown of lipids and fats
   • The characteristics and features of villi help with efficient diffusion of nutrients
     • The nutrients - proteins, glucose and lipids - then go to the bloodstream
     • Only one cell thick
     • Surrounded by blood capillaries
     • They are located in the small intestine
     • Villi have micro- projections on them that allow a bigger surface area
   • Breaking down foods
     • Mechanical Breakdown
       • Chewing
     • Chemical Breakdown
       • Enzymes

6. Metabolism

   • Chemical processes
   • Cellular respiration
   • Glucose + oxygen (O2) = carbon dioxide (CO2) + energy + water (H2O)