Coordination and Control Human Regulation Coordination and Control

Regulation in Humans Controlled by 2 systems Nervous System - electrical Endocrine System – chemical Both systems respond to and send messages throughout the body

Central and Peripheral Human Nervous System Central and Peripheral

A General Sense…

An Overview of the Nervous System: Peripheral Nervous System Central Nervous System -Brain -Spinal Cord Sensory Neurons -carry messages towards spinal cord from sensory receptors Motor Neurons -carry signals away from CNS Somatic System: Voluntary Nerves --neurons control skeletal muscles Autonomic System: Visceral, Involuntary --heart, blood vessels, digestive organs, smooth muscle Sympathetic Division --“fight or flight” --activated by stress Parasympathetic Division: --Routine

Nervous System Cells Called neurons Neurons have long axons that enable them to transmit signals. Many neurons together are called a nerve. Each nerve has a dorsal root (info coming into the CNS) and a ventral root (info going out from CNS to body).

Anatomy of a Neuron Cell body – main part Dendrite – receives stimulus from other neurons Axon – branches from cell body, sends the signal out Myelin sheath – lipid layer for protection over neurons that allows for increase in speed of signal transmission Synapse – gap between neurons; between the axon terminal of 1 neuron and the dendrite of a 2nd neuron

Anatomy of a Neuron

Central Nervous System (CNS) BRAIN About 1.4 kg, 2% of body weight About 100 billion neurons 12 pairs of cranial nerves are connected to the human brain Example: Pupil reflex in response to bright light, to avoid damage to retina. Nerves that control this reflex are connected to the brain.

Spinal Cord Starts at the medulla oblongata (in the brain) 31 pairs of spinal nerves branch out to the body Spinal Reflexes: these don’t go to the brain, instead they go to the spinal cord— Ex. patellar reflex Spinal Cord

Reflexes An automatic reaction to some sense message, like pain Don’t need to think or make decisions about something The information gets processed in your spinal cord Your muscles begin to react immediately even before your brain gets the news of what’s happening. This is called a reflex arc

Reflex Arc Begins at a receptor Sensory neurons in the skin receive a stimulus Travels to the reflex center (spinal cord) Ends at an effector A muscle or gland that reacts to the stimulus

Reflex Arc A pathway of nerve impulses Stimulus – a change in the environment that causes a change in the body Receptor – specialized organ that receives the stimulus Sensory neuron – brings the stimulus to the spinal cord Synapse – space between neurons Interneuron – neurons in the spinal cord Motor neuron – brings the stimulus from the spinal cord to the correct part of the body Effector – muscle or gland that reacts to the stimulus

The Patellar Reflex

Peripheral Nervous System (Motor and Sensory) Motor Division: signals away from CNS Somatic nervous system is for voluntary muscle control. These neurons control the skeletal muscles…. Autonomic nervous system is automatic or involuntary Control of heart rate, respiration, blood pressure, smooth muscle, etc. This has 2 separate divisions: sympathetic and parasympathetic

Autonomic: Sympathetic Division & Parasympathetic Division Sympathetic: Shunting of blood from one part of body (ex = stomach to heart) to another. Activated by physical or emotional stress. “Fight or Flight” response. Parasympathetic: Routine life, conserves energy, heart rate lowers, digestive organs back to normal. “Rest and Ruminate” response.

Autonomic NS: Parasympathetic and Sympathetic Controls

Peripheral Nervous System Sensory Division Sensory neurons carry messages toward the CNS from sensory receptors all over body. Sensory receptors are in sense organs, such as eyes, ears, mouth, nose, skin… and different regions of the brain respond to different signals.

Transmission of neural signals: How it Works… In general, the signaling activity of the nervous system is composed of electrical activity within neurons and chemical flow between neurons. Quite a complex network! 200 years ago… found out that a recently dead animal will still contract muscles if an electrical stimulation is sent through.

Human brain 2005-2006

Brainstem The “lower brain” Functions medulla oblongata midbrain homeostasis coordination of movement conduction of impulses to higher brain centers 2005-2006

Medulla oblongata Controls autonomic homeostatic functions breathing heart & blood vessel activity swallowing vomiting digestion Relays information to & from higher brain centers 2005-2006

Midbrain Involved in the integration of sensory information regulation of visual reflexes regulation of auditory reflexes 2005-2006

Cerebrum Most highly evolved structure of mammalian brain Cerebrum divided hemispheres left = right side of body right = left side of body Corpus callosum major connection between 2 hemispheres 2005-2006

Cerebrum specialization Regions of the cerebrum are specialized for different functions Lobes frontal temporal occipital parietal 2005-2006

The Endocrine System

Endocrine System A set of glands that produce hormones-- chemical messengers that circulate in the blood

Hormone Chemical messengers produced by the endocrine glands and circulated in the blood Similar to neurotransmitters in that they are also messengers Slower communication system, but with longer lasting effects

Endocrine System

Hypothalamus Brain region that controls the pituitary gland Controls homeostasis – the bodies ability to remain at a status quo level

Pituitary Gland The endocrine system’s gland that controls the other endocrine glands Called the “master gland” Located at the base of the brain and connects to the hypothalamus Controls thirst by controlling the amount of water in the body’s cells Controls female contractions, and tells the mammary glands to produce milk for newborns May control grooming habits, companionship, and sexual behavior Controls the flow of the human growth hormones – dwarfism and gigantism

Thyroid Gland Endocrine gland that helps regulate the energy level in the body Located in the neck controls body temperature Controls metabolism – our body’s ability to transform the food we eat into usable energy Overactive- Behaviors may include excitability, insomnia, ADD, agitation, difficulty focusing Reduced Activity- Behaviors may include sleepiness, reduced muscle tone, overweight

Adrenal Gland Endocrine glands that help to arouse the body in times of stress Located just above the kidneys Release epinephrine (adrenaline) and norepinephrine (noradrenaline) Increase heart rate, blood pressure, and blood sugar

Pancreatic Gland Regulates the level of blood sugar (insulin) in the blood Insulin is needed in the body to break down sugars in the body Too much insulin in the body devours all of the sugar in the blood. Behaviors exhibited include sluggishness and inattentiveness.

Too little insulin causes a buildup of sugar in the blood and makes the kidneys use a lot more water to flush it out of the body. The extra water needed to flush the sugar comes from surrounding cells, which in turn dehydrates them and leaves them vulnerable to infection and poisons.

Sex Glands Ovaries (females) and testes (males) are the glands that influence emotion and physical development. Testosterone – primary male hormone Estrogen – primary female hormone Males and females have both estrogen and testosterone in their systems.

Gonads Testicles – release androgens (male hormones) Ovaries – release estrogens (female hormones) The presence of these chemicals influence male and female reproductive characteristics.

Maintaining Homeostasis Homeostasis is the maintenance of a stable internal state within an organism. Organisms detect changes in their environment and respond to these changes in a variety of ways.  A feedback mechanism occurs when the level of one substance influences the level of another substance or activity of another organ.

Feedback Mechanisms Three parts of the mechanism Sensor – something that can detect a change Ex. Structures in the brain detect change in CO2 levels Control Unit – something that knows what the correct level should be Ex. Information in the brain is preset for the correct CO2 level Effector – something to take the instructions and make changes Ex. Muscles in the chest used for breathing

Feedback Mechanisms Positive feedback - designed to accelerate or enhance the output created by a stimulus that has already been activated. Designed to push levels out of normal ranges. Example is the release of oxytocin to intensify the contractions that take place during childbirth. The more oxytocin, the greater and more frequent the contractions, which in turn produces more oxytocin

Feedback Mechanisms Negative feedback – process in which a stimulus produces a response that opposes the original stimulus. Ex. Blood sugar regulation An increase in blood sugar level triggers the release of the hormone insulin by the pancreas the hormone insulin lowers blood sugar level restoring the body to its original blood glucose level in two major ways: it increases the ability of body cells to take in glucose from the blood it converts blood glucose to the compound glycogen -- this compound is also called animal starch and is stored in our liver and muscles A decrease in blood sugar levels triggers the release of the hormone glucagon by the pancreas It causes the liver to release glucose into the blood to regulate blood sugar levels

Regulation Disorders Nervous System Cerebral Palsy – affect the ability to control body movements Alzheimer’s – progressive degenerative disease; lose memory and ability to think, speak, etc. Multiple Sclerosis – cells in the brain and spinal cord do not function normally. Wide variety of symptoms

Regulation Disorders Endocrine System Diabetes – interruption of the feedback system that controls blood sugar. Type I – born with it Controlled by insulin injections Type II – acquired Usually occurs in older people May be controlled with diet