Nervous & Endocrine Systems Honors Biology Semester One Mrs. Williams
How Organ Systems Communicate Importance of cell membrane; what makes it up? Phospholipid bilayer Carbohydrates Proteins What serves as a cell identifier? Carbohydrates Read pg. 84…then think, pair, share the following question: HOW DOES THE CELL MEMBRANE HELP CELLS COMMUNICATE?
How Organ Systems Communicate We’ll look at the nervous and endocrine systems through the lens of cells communicating What is homeostasis? Maintenance of a stable internal environment For that maintenance to occur, the body must Generate, deliver, interpret, and act upon messages That’s the job of the nervous and endocrine systems
Nervous System Physically connected network of cells, tissues, and organs that controls thoughts, movements, and simpler life processes Works quickly and controls immediate processes such as heart rate and breathing Divided into two parts: Central nervous system (CNS) Peripheral nervous system (PNS)
Special Cells Neurons Store information and carry messages within the nervous system and between other body systems 3 parts to the neuron: 1. Cell body 2. Dendrites 3. Axon
Neuron Drawings You and your partner will draw a LARGE neuron on your table with chalk Label and be able to explain the function of the following parts of the neuron: 1. Cell body 2. Dendrites 3. Axon 4. Myelin Sheath (the function of this may take a little looking for…)
Three Types of Neurons 1. Sensory neurons Detect stimuli and transmit signals to the brain and spinal cord 2. Interneurons Compose the brain and spinal cord Receive signals from sensory neurons and relay them within the brain and spinal cord 3. Motor Neurons Pass messages from the nervous system to other tissues in the body, such as muscles
So… How does a neuron’s shape allow it to send signals across long distances?
How Signals are Sent Figure 29.4, page 878 Join with another table and use your neuron drawings to explain how a signal is transmitted between two neurons based on Fig Include the following terms in your explanation: Action potential, synapse, terminal, neurotransmitters
The Senses Your group will summarize – in 50 words or less – the following senses with regards to cell communication: 1’s: Vision (pg. 881) 2’s: Hearing (pg. 882) 3’s: Smell & Taste (pg. 882/883) 4’s: Touch, Temperature & Pain (Pg. 883)
Investigation… With your partner, quickly do the lab on pg. 884 in your textbook FOLLOW DIRECTIONS CAREFULLY When you’re done, answer questions 1 & 2 at the bottom of the page
Central and Peripheral Nervous Systems These systems work together to help you interpret stimuli and respond appropriately
Central Nervous System Includes the brain and the spinal cord Composed of interneurons that interact with other nerves in the body Receives, interprets, and sends signals to the peripheral nervous system
Peripheral Nervous System Collection of nerves that connect the CNS to all of the organ systems Uses sensory neurons to detect internal and external stimuli Uses motor neurons to carry signals from the CNS to other parts of the body
CNS – The Brain Has more than 100 billion neurons Protected by three layers of connective tissue called meninges with fluid in between each layer Composed of three main structures: Cerebrum Cerebellum Brain Stem
Cerebrum Interprets signals from the body and forms responses such as hunger, thirst, emotions, motion, and pain Divided into the right and left hemispheres Right hemisphere processes stimuli received by the left side of the body Left hemisphere processes stimuli received by the right side of the body
Cerebrum Outer layer is the cerebral cortex Interprets information from sensory organs and generates responses As thick as a pencil, but is folded to increase surface area Unfolded, it would cover the area of a typical classroom desk Can hold more than 10 billion neurons Divided into lobes See Fig on page 887
Cerebellum Coordinates movements Helps maintain posture and balance Automatically adjusts the body to help you move smoothly Positioned below and behind the cerebrum
Brain Stem Connects the brain to the spinal cord Controls the most basic activities required for life such as breathing and heartbeat Divided into three major parts Midbrain Controls some reflexes Pons Regulates breathing and passes signals between the brain and spinal cord Medulla Oblongata Connects the brain to the spinal cord and controls basic, life-sustaining functions
CNS – The Spinal Cord Spinal column consists of vertebrae, fluid, meninges, and spinal cord Spinal cord Ropelike bundle of neurons about as wide as your thumb All signals that go to or from the brain pass through the spinal cord (why spinal cord injuries often result in paralysis)
Reflex Arcs Spinal cord controls involuntary movements called reflexes Nerve pathways that only need to cross two synapses before producing a response Response is quick because the signal never has to travel up the spinal cord See Fig on page 889
Peripheral Nervous System Includes 12 pairs of nerves in the head and 31 pairs of spinal nerves Most nerves contain axons from both sensory and motor neurons that carry info to and from the CNS PNS made up of a sensory and motor system Sensory systems collects info about the body and its surroundings Motor system triggers voluntary and involuntary responses within the body
Peripheral Nervous System – Categories Somatic Nervous System Regulates all of the movements over which you have voluntary control Connects CNS to target organs Autonomic Nervous System Controls involuntary movement/ response Helps maintain homeostasis
Autonomic Nervous System - Categories Sympathetic Nervous System Prepares body for action and stress “Fight or flight” response Contracting and dilating blood vessels cause changes that improve your physical movement and abilities and allow you to think quickly Parasympathetic Nervous System Calms the body Helps body conserve energy Lowers blood pressure and heart rate Active when the body is relaxed
Endocrine System
Makes chemical signals – hormones - that help the body grow, develop, and maintain homeostasis Some of the chemicals control processes such as cell division, cell death, and sexual development Some chemicals help maintain homeostasis by affecting body temperature, alertness, or salt levels
Hormones Chemical signals made by the endocrine system in glands Glands are found throughout the body and release hormones into the bloodstream Hormones only interact with cells that have specific membrane receptors These are called the target cells Hormones belong to one of two categories Steroid hormones Nonsteroid hormones
Steroid vs. Nonsteroid Hormones Steroid hormones are: Made of cholesterol, a type of lipid Nonsteroid hormones are: Present in three different types Made up of one or more amino acids
Hormone Action Read Fig on page 897 Talk with your table partner about the differences between actions of steroid and nonsteroid hormones Be prepared to share…
Major Glands Hypothalamus Pituitary gland Thyroid gland Thymus Adrenal gland Pancreas Gonads Fig on page 899
Importance of the Hypothalamus The nervous and endocrine systems connect to each other at the base of the brain The hypothalamus acts as part of both systems As part of the CNS, it receives, sorts, and interprets information from sensory organs As part of the endocrine system, it produces releasing hormones that affect tissues and other endocrine glands What are ‘releasing hormones’? Hormones that stimulate other glands to release their hormones
Hypothalamus Many of the releasing hormones affect the pituitary gland The pituitary and hypothalamus are connected by a series of short blood vessels, so hormones can be passed quickly back and forth between the two Read the example on page 900 How does this relate to cell communication?
Illness Due to Hormonal Imbalance Read page 901 Why do hormonal imbalances affect the entire body? *You don’t need to know about specific illnesses caused by hormonal imbalances