Musculoskeletal system & Emergencies Biology – Premed Windsor University School of Medicine and Health Sciences Dr. Uche Amaefuna

Musculoskeletal system & Emergencies Pre Med – Biology Chapter 13 The Nervous System There is more to lectures than the power point slides! There is more to lectures than the power point slides! Engage your mind Engage your mind

Musculoskeletal system & Emergencies KEYWORDS Gland, Hormone, Impulse, Nervous system, Effector, Stimulus, Receptor, Neuron, Synapse

Musculoskeletal system & Emergencies Name the hormones –write down the names of the hormones secreted by the glands. Name the hormones – Have you thought of any others? Time: 10 minutes Working Groups: Your choice of 1, 2 or 3 STARTER

Musculoskeletal system & Emergencies STARTER answers Pituitary gland – FSH, LH (stimulates the release and maturity of follicles during menstruation) Thyroid gland – Thyroxine (regulates the rate of metabolism) Adrenal gland - corticosteroids and catecholamines including cortisol and adrenaline and small amounts of testosterone (regulates stress levels) Pancreas – peptides (regulates the production of shorter active digestive enzymes) Ovary – oestrogen, progesterone and small amounts of testosterone (regulates the growth of eggs and stabilises the growing foetus during pregnancy) Testis – testosterone (plays a key role in the health and well- being of the man)

Musculoskeletal system & Emergencies CONTROL SYSTEMS There are two main control systems in your body. 1. Nervous system – which has two main sections l central or CNS that is made up of the spinal cord and brain and functions to coordinate all actions of the body l peripheral or PNS that is made up of the bodies nerves and functions to connect the CNS to the rest of the body through neurones. PNS is further divided into – somatic or SNS which is associated with the voluntary control of body movements and is made up of all neurones, sense organs, skin, skeletal muscles – Autonomic or ANS which is associated with the involuntary control of body movements such as reflex and controls such things as heart rate, body temperature, digestion etc. The ANS is further divided into Parasympathetic nervous system works in actions that do not require a fast response (rest and digest response) Parasympathetic nervous system works in actions that do not require a fast response (rest and digest response) Sympathetic nervous system works in actions that do require a fast response (fight or flight response) Sympathetic nervous system works in actions that do require a fast response (fight or flight response) 2. Endocrine system – which is a system of glands that release a number of signalling chemicals known as hormones.

Musculoskeletal system & Emergencies NERVOUS SYSTEM CNS PNS ANS SNS ParasympatheticSympathetic Nervous system releases electrical impulses that are quick but the effects are short lived and it involves the CNS (either just spinal cord or both spinal cord and brain) messages are carried by neurons Endocrine system releases chemical signals that are slow to react but the effects are long lasting. This does not involve the CNS. Messages are carried by the blood.

Musculoskeletal system & Emergencies

Parts of the nervous system The nervous system is made up of three main parts; l The brain l The spinal cord l Nerve fibres It detects stimuli such as light, sounds, temperature, pressure, pain and co- ordinates the bodies response.

Musculoskeletal system & Emergencies Parts of the nervous system For example; If you smell something burning… l Your nose ( receptor ) detects the stimulus (smell) l Nerve fibres send the message to the brain l Your brain then sends a message to move your body away or to put out the fire! SIMPLE RIGHT! SIMPLE RIGHT!

Musculoskeletal system & Emergencies Lets look at some bits more closely RECEPTORS l Receptors are sensors on the body that detect stimuli l They convert stimuli into electrical signals (messages) called impulses.

Musculoskeletal system & Emergencies EFFECTORS An effector is any part of the body that produces the response. Here are some examples of effectors: l a muscle contracting to move the arm l a muscle squeezing saliva from the salivary gland l a gland releasing a hormone into the blood

Musculoskeletal system & Emergencies NERVE FIBRES l Nerve fibres are bundles of nerve cells (neurons) that pass on electrical signals (impulses) to the brain. l From the brain, nerve fibres send impulses to effectors (muscles).

Musculoskeletal system & Emergencies NEURONS There are three types of neurons 1. Sensory neuron – carries impulses from the receptors to the spinal cord. 2. Relay Neuron – carries impulses to and from the spinal cord and the brain 3. Motor Neuron – carries impulses from the brain to the effector

Musculoskeletal system & Emergencies Multiple-choice quiz

Musculoskeletal system & Emergencies SYNAPSES Where two neurons meet, there is a tiny gap called a synapse. Signals cross this gap using chemicals. One neuron releases the chemical into the gap. The chemical diffuses across the gap and makes the next neuron transmit an electrical signal.

Musculoskeletal system & Emergencies What is a synapse? A synapse is a junction between two neurons across which electrical signals pass. The human body contains up to 500 trillion synapses. presynaptic cell postsynaptic cell

Musculoskeletal system & Emergencies The release of neurotransmitters When a nerve impulse arrives at the end of one neuron it triggers the release of neurotransmitter molecules from synaptic vesicles. synaptic vesicle neurotransmitter molecules

Musculoskeletal system & Emergencies Continuing the impulse The neurotransmitters diffuse across the synaptic cleft and bind with receptors on the next neurone, triggering another impulse. nerve impulse receptor synaptic cleft

Musculoskeletal system & Emergencies REFLEX ARC l When your body needs to react to something very quickly (to protect itself) it uses a reflex arc (spinal reflex). l Instead of sending impulses from the receptor Spinal cordbrainspinal cord effector l It sends impulses from the receptor spinal cordeffector…Yup it bypasses the brain!

Musculoskeletal system & Emergencies ANSWERS l Electrical impulses along neurons, chemical (neurotransmitters) across the synapse. l The microscopic gap between two neurones. l By chemicals called neurotransmitters. l To pass the impulse onto the correct motor neurone. l Glands or muscle that produce the effect or make a response.

Musculoskeletal system & Emergencies The sequence of a reflex arc

Musculoskeletal system & Emergencies REFLEX ACTION The way the iris in our eye adjusts the size of the pupil in response to bright or dim light is also a reflex action. In bright light In dim light Radial muscles of the iris relax. Circular muscles of the iris contract. Less light enters the eye through the contracted pupil. Radial muscles of the iris contract. Circular muscles of the iris relax. More light enters the eye through the dilated pupil.

Musculoskeletal system & Emergencies The iris reflex

Musculoskeletal system & Emergencies Inside the eye lens focuses light on retina iris regulates amount of light entering eye ciliary muscles change shape of the lens optic nerve transmits impulses to the brain cornea protects eye surface and focuses light rays retina senses light hold lens in place suspensory ligaments

Musculoskeletal system & Emergencies REFLEX ACTION

Musculoskeletal system & Emergencies NERVE PATHWAY… Have a go at completing this worksheet

Musculoskeletal system & Emergencies NERVE PATHWAY… answers SENSORY NEURON Takes impulses from the sense organ to the relay neuron. RELAY NEURON Takes impulses to the brain and from the brain. MOTOR NEURON Takes impulses from the relay neuron to the effector. BRAIN Receives impulses from the spinal cord and sends out new impulses. SENSE ORGAN/ RECEPTOR Senses stimuli from our surroundings. EFFECTOR The muscle that receives the impulse from motor neuron. SPINAL CORD Where the relay neurones are found.

Musculoskeletal system & Emergencies Summary/Terms (1/2) accommodation – The reflex reaction that keeps the lens the right shape to focus light on the retina. accommodation – The reflex reaction that keeps the lens the right shape to focus light on the retina. CNS – The central nervous system, consisting of the brain and spinal cord. CNS – The central nervous system, consisting of the brain and spinal cord. iris – The part of the eye that limits the amount of light entering the eye. iris – The part of the eye that limits the amount of light entering the eye. lens – The part of the eye that focuses light on the retina. lens – The part of the eye that focuses light on the retina. motor neuron – A neuron that carries electrical impulses from the CNS to muscles and glands. motor neuron – A neuron that carries electrical impulses from the CNS to muscles and glands. neuron – A specialized cell that carries electrical impulses. neuron – A specialized cell that carries electrical impulses.

Musculoskeletal system & Emergencies Summary/Terms (2/2) neurotransmitter – A chemical that diffuses across synapses to continue an impulse in a connecting neurone. neurotransmitter – A chemical that diffuses across synapses to continue an impulse in a connecting neurone. reaction time – The time taken to respond to a stimulus. reaction time – The time taken to respond to a stimulus. reflex – A fast, automatic protective response. reflex – A fast, automatic protective response. retina – The part of the eye that contains light receptors. retina – The part of the eye that contains light receptors. sensory neuron – A neuron that carries electrical impulses from sense organs to the CNS. sensory neuron – A neuron that carries electrical impulses from sense organs to the CNS. synapse – The gap between two connecting neurons. synapse – The gap between two connecting neurons.