The Nervous System
Nervous System The control system that enables animals to detect a stimulus and coordinate a response
Stimulus and Response Stimulus: change in the environment that is detected by your body Response: Your body’s reaction to this stimulus
Stimuli and Responses Eg. Stimulus: you are in a sauna…it’s very hot! Stimulus: someone yawns in front of you Stimulus: someone is about to poke you in the eye Reponse:
Structural Features Central Nervous System Peripheral Nervous System Brain and Spinal Cord Peripheral Nervous System Carries signals between the CNS and the Body Relays information about the internal and external environments to the brain Relays instructions from the brain to other parts of the body
Parts of the Human Nervous System Central nervous system made up of the brain and spine coordinates all components of the nervous system
Parts of the Human Nervous System Peripheral nervous system All other nerves Relays information between central nervous system and other body parts
Parts of the Peripheral Nervous System Somatic nervous system Nerves that control voluntary muscles Nerves that carry information from the sensory organs (eyes, ears, taste buds, touch receptors) Autonomic Nervous system Motor neurons that are unconsciously controlled Eg. Heart, body temp, blood pressure, pupil dilation, gland secretions
Nervous System Central Nervous System Peripheral Nervous System Brain Spinal Cord Somatic Nerves Somatic Nervous System Autonomic Nerves Autonomic Nervous System Voluntary Involuntary Sensory Motor Sympathetic Parasympathetic
Parts of the Autonomic Nervous System Sympathetic nerve Prepares body for danger Parasympathetic nerve Returns body to normal relaxed state after stress Sympathetic nerves counteract the effect of parasympathetic nerves
Sympathetic and Parasympathetic Nerves
Parts of the Nervous System
Nerve Tissue Nerve tissue is made up of special cells called neurons Functional unit of the nervous system. Uses electrical signals called impulses to communicate with other cells
Parts of a Neuron Dentrites Axon Myelin sheath carry impulses from outside the cell into the cell body Axon carries the impulse away from the cell body towards neighbouring cells conducting wire Myelin sheath sometimes covers the axon, speeds up transmission of the nerve impulse
Parts of a Neuron Terminal knobs attach the neuron to other cells (other neurons or target cells) Neurotransmitters Chemical released by the terminal knobs that carries the impulse from 1 neuron to another Synapse Space between the axon of one neuron and dentrites of an adjacent neuron Direction of impulse is always from the dentrites to the terminal knobs
Synapse
Nerve Nerves are bundles of neurons that are surrounded by connective tissue
Did you know? Average number of neurons human brain= 100 billion octopus brain= 300 billion Longest axon of a neuron = around 15 feet (Giraffe primary afferent axon from toe to neck) Velocity of a signal transmitted through a neuron= 1.2 to 250 miles/hour adult brain: Human = 3 pounds (1,300-1,400 g) elephant = 6,000 g longest axon of a human neuron can be over a meter long, reaching from the base of the spine to the toes
Types of Neurons Sensory neurons Motor neurons Interneurons carry impulses from sensory receptors (eye, ear, nose, skin, tongue) to the brain Motor neurons carry impulses from the brain or spinal cord to muscles for movement or glands for hormone secretion Interneurons link the sensory and motor neurons in the brain and spinal cord
Types of Neurons
The Human Endocrine System
The Human Endocrine System The organ system that regulates the internal environment by releasing hormones into the bloodstream.
Hormone chemical released into the bloodstream by one type of cell that has an effect on another type of cell in a different location help regulate and coordinate the functions of almost all organ systems important in maintaining a constant internal environment control many developmental changes
Gland Organ that manufactures and secretes hormones Pituitary gland and Hypothalamus control the hormone secretions of several other glands in the body Pituitary gland secretes the most hormones in the body
Glands of the Endocrine System
Homework Activity: Mapping Sensory Receptors p.105 Equipment & Materials: paper clip and ruler p. 107 # 1, 2, 4, 5