Coordination + Control

Definitions

Homeostasis - A state of balance among all body systems needed for the body to survive and function correctly

Negative Feedback - A regulatory mechanism in which the body produces a response opposite to a change that is opposite to the change

Receptors - Specialised cells and organs that detect change

Effector - A muscle, gland, or organ that responds to a message sent by the nervous or endocrine system

Gland - Tissues that secrete hormones

Hormone - A chemical secreted by a gland that triggers a response in certain cells

Neuron - A specialised cell that makes up the nervous system

Synapse - The gap between the axon and the dendrite of two neighbouring neurons

Cellular Respiration - The process that all living things use to produce cellular energy from glucose and oxygen

Diffuse - To move from an area of high concentration to an area of low concentration

Gas Exchange - The exchange of oxygen and carbon dioxide between an organism and the environment

Receptors

  • When receptors respond to stimuli, they send messages to different body systems to trigger changes

  • These messages are chemical and electrical signals brought about by the endocrine and nervous systems

The nervous system transmits signals across the body

  • The nervous system transmits fast messages across the body

  • It consists of billions of nerve cells called neurons, which form long nerve fibres

  • Messages are sent throughout the nervous system via electrical nerve impulses

The nervous system consists of two parts

  • CNS - Central Nervous System

  • The CNS consists of the brain and spinal cord

  • PNS - Peripheral Nervous System

  • The PNS consists of the nerves running through the rest of the body, connecting to the CNS

Neurons

  • Sensory neurons lead away from the receptor, while motor neurons lead towards muscles, glands, and other effector organs that respond to signals

  • Neurons do not connect together; there are gaps between them called synapses

  • When all electrical impulses reach a synapses, it triggers the neuron chemicals called neuotransmitters, these cross the synapses and stimulate the next neuron, continuing the message

Stimulus Response Model

The steps in the stimulus-response pathway when someone touches a hot flame

  • Stimulus - Hot flame

  • Receptor - Thermoreceptor

  • Sensory Neuron - The message travels along an alternate pathway to the CNS/spinal cord

  • Motor Neuron - Message travels away from CNS

  • Effector - Message reaches muscle in arm

  • Response - Jerk hand away

Endocrine System

  • The endocrine system releases hormones

  • The endocrine system consists of multiple glands - groups of cells that produce molecules called hormones

  • Once the gland is triggered, it secretes hormones into the bloodstream that travel to the target cells and trigger a response

  • Endocrine responses are much slower than neuron system responses

  • The pituitary gland is the ‘master gland’, secreting hormones that control other endocrine glands

Hormones are often produced in pairs

  • When blood sugar levels are too high, the pancreas produces insulin, which tells the liver to remove blood glucose and store it

  • When blood sugar levels are too low, the pancreas releases glucagon, which tells the liver to return glucose into the blood

Cellular Respiration

Worded Equation - glucose + oxygen = carbon dioxide + water + energy

Respiratory System

  • The respiratory system is required for gas exchange

  • The function of the respiratory system is to conduct gas exchange

  • The structure of the respiratory system allows for this exchange to occur efficiently

  • When you inhale, your diaphragm flattens and moves downwards while your ribs move upwards and outwards, drawing in air

Air Flows

  • Nostrils/mouth - trachea - bronchi (x2) - bronchioles - alveoli

Alveoli

  • At the end of the bronchioles are tiny sacs called alveoli, which are surrounded by capillaries (blood vessels)

  • Gas exchange occurs at the alveoli, where oxygen diffuses through the alveoli wall and into the capillaries. Oxygen will then bond to haemoglobin in red blood cells

  • Carbon dioxide will diffuse from the blood plasma in the capillaries into the alveoli

  • When you breathe out, your diaphragm becomes dome-shaped and moves upwards to your ribs, and your ribs move downwards and inwards, causing the air in your lungs to move back out

Types of Neurons

Sensory Neurons

  • Transit neural information from the sensory receptor sites in the PNS to the CNS

  • The sensory information being transmitted could be from any of your five senses

Interneurons

  • Transmit neural information within the spinal cord and brain

  • Interneurons connect the sensory and motor neurons and can only be found in the CNS

Motor Neurons

  • Transmit neural information from the CNS to the PNS

  • This information is designed to initiate a response in the effector, which could be muscles, organs, or glands

Structure of the Brain

  • Cerebellum - Located at the back of the head, beneath the cerebrum and above the brainstem. It is primarily responsible for coordinating voluntary movements like balance, coordination, and posture

  • Cerebrum - The largest part of the brain, responsible for high-level functions like conscious thought, memory, voluntary movement, and sensory processing

  • Brain Stem - The connection of the spinal cord to the brain. It is responsible for unconscious body function

Lobes of the Brain

  • Frontal Lobe - Located at the front of the brain, and is responsible for higher-order thinking

  • Parietal Lobe - On the top of the brain, and is responsible for major sensory input from the skin

  • Occipital Lobe - At the back of the brain, and is responsible for visual processing

  • Temporal Lobe - On the side of the brain, and is primarily responsible for auditory processing, but also some areas of visual processing