Presentation on theme: "Human Body Systems Organization of the Body (Review) Cells"— Presentation transcript:
1 Human Body Systems Organization of the Body (Review) Cells Basic unit of structure and functionTissuesGroup of cells that perform a single function (e.g. epithelial, connective, nervous, muscle)OrgansDifferent types of tissues that work together to perform a closely related function (e.g. eye, liver, lungs)Organ SystemsGroup of organs that perform closely related functions (e.g. circulatory, respiratory, digestive)
2 HomeostasisDefinition: the process by which organisms keep internal conditions relatively constant despite changes in their external environmentsRequires the integration of all organ systems at the same timeNervous system in conjunction with the endocrine system (hormones) is responsible for this integration
3 III. Maintaining Homeostasis Examples of Feedback InhibitionIII. Maintaining HomeostasisNegative feedback – your body’s response results in decreasing the effect of the stimulus (e.g. body temperature)Section 35-1Sensed byRoom TemperatureDropsRoom temp. risesThermostatSignalsHeater to turn on
4 Positive feedback – your body’s response results in an increase in the effect of the stimulus, (e.g. the flight-fight response)
5 Nervous SystemRecognizes and coordinates the body’s response to changes in its internal and external environments.General Functions of the Nervous SystemSensory input – vision, hearing, balance, smell, taste, and touchMotor output – muscle contraction and movementMemory and integration of information
6 Organization of the NSCentral N.S.1. Brain2. Spinal CordB. Peripheral N.S.1. Somatic N.S.2. Autonomic N.S.a. Sympatheticb. Parasympathetic
7 Nervous System Division of Labor Central Nervous System (CNS) Control center of the body that relays messages, and processes and analyzes informationBrainCerebrum – largest region; right and left hemispheres that are connected by corpus callosum; voluntary activities and higher brain functionsCerebellum – located at the lower back part of brain; coordination and balanceCorpus callosum is how the left and right lobes communicate. Often cut to treat epilepsy. Left lobe is for right side of body and vise-versa.
8 Nervous SystemBrain stem – connects the brain and spinal chord; two regions: pons and medulla oblongata, control breathing, heart rate and swallowingThalamus and hypothalamus - between brain stem and cerebrumThalamus: relay station for sensory infoHypothalamus: most important homeostatic site; hormones, body’s thermostat, fight or flight, thirst, hunger, reproductionMedulla oblongata: lowest part of the brain,
10 Nervous System Spinal Cord Two main fxns: Processing of simple responses to certain stimuli (reflexes)Carries info to and from brain to body
11 Nervous System Peripheral Nervous System (PNS) Receives information from the environment and relays to and from CNS and sensory, motor and gland cells
12 Nervous System Two divisions: Sensory - Made of sensory neurons that bring info to the CNSMotor - Made of sensory neurons that convey info from the CNS; two subdivisionsSomatic (voluntary): respond to external stimuliAutonomic (involuntary): respond to internal stimuli w/the parasympathetic and sympathetic divisionsSympathetic ↑energy consumptionParasympathetic ↓energy consumptionParasympathetic center controls things like digestion and slowing heart to conserve energy. Sympathetic center controls accelerating HR, increasing metabolism, thus increasing energy consumption
14 Nervous System Neurons (Nerve Cells) Specialized cells that carry electrical signals called impulses (Draw Fig. 35-5; pg. 897)3 Types of Neurons:Sensory – carry impulses from the sense organs to the spinal cord and brainMotor – carry impulses from brain and spinal cord to muscles and glandsInterneurons – Connect sensory and motor neurons and carry impulses between them
15 Nervous System Anatomy of a Neuron Cell Body Largest part of the neuronContains the nucleus and most of the cytoplasmMetabolic activity takes place in the cell bodyCell Body
16 Nervous System Dendrites Carry impulses from the environment or other neurons to the cell body
17 Nervous SystemAxonLong fiber that carries impulses from the cell bodyEnds in axon terminals that contain vesicles for neurotransmitters
18 Nervous System Myelin Sheath Insulates the axon Gaps in the myelin sheath allow an impulse to jump from node to node, thus increasing its speed
19 Which part of the neuron is yellow? Which parts are blue?
20 The Nerve Impulse The Resting Neuron At rest, the outside of the cell has a net positive charge and the inside has a net negative charge. This charge difference is called the resting potential. (-70mVolts, about 5% of the voltage in AA battery)
21 The Resting Neuron (cont) The charge difference is created by active transport of ions across the cell membrane via the sodium-potassium pump.Sodium ions (Na+) are pumped outside the cell and potassium (K+) ions are pumped into the cell.
22 The Moving ImpulseAn impulse begins when a neuron is stimulated by the axon of another neuron or by the environment.Na+ pores open and the flood of Na+ ions makes the inside positive._++_
23 The Moving Impulse (cont) This reversal of charges, from negative to positive is called a nerve impulse, or an action potential.As the impulse passes, K+ pores open and K+ flows out which restores the resting potential (charge difference)+_+_
24 The Moving Impulse (cont) How do things get back to the original condition?The sodium potassium pump kicks in.The minimum level of a stimulus that is required to activate a neuron is called the threshold.
26 Nerve Impulse Pathway Overview Impulse is received by the dendrites from the environment or another neuron, then gets rapidly channeled through the cell body to the axonAxon branches out into axon terminals, which contain tiny vesicles filled with neurotransmitters, which are chemicals used by a neuron to transmit an impulse to another cell. (e.g. acetylcholine, serotonin, dopamine and adrenalin).Vesicles release neurotransmitters into the open space between neurons called the synapse.Talk about speed of impulse. Dopamine and serotonin and ecstasy: similar to meth, X damaged cells that release the neurotransmitter called serotonin. Damage to these cells could affect a person's abilities to remember and to learn. Same for dopamine. Death of dopamine cells causes Parkinson's disease
27 Nerve Impulse Pathway (cont) The neurotransmitters diffuse across the synapse and attach themselves to receptors on dendrite of neighboring cellDirection of ImpulseDendrite of adjacent neuronAxonReceptorVesicleAxon terminalSynaptic cleftNeurotransmitter
28 Nervous System Reflexes Reflexes are automatic responses to stimuli Controlled by 5-part reflex arc:Sensory receptors on finger reacts to stimulus (heat)Impulse is carried to the spinal cord by a sensory neuronIn the spinal cord, the impulse is transferred by an interneuron to motor neuronMotor neurons conducts the impulse to an effector (arm muscles)Effector responds to the impulses by contracting (hand gets pulled away from the heat)
29 Nervous System The Senses 5 General Sensory Receptors: pain, thermo-, mechano-, chemo- and photoreceptors.Where do you think these different types of receptors are found and what is their function?VisionHearing and BalanceSmell and TasteTouch
30 Nervous System Nervous System Disorders Migraine Headaches – caused by change in serotonin levels? (affected by caffeine, estrogen, certain foods)Parkinson’s –caused by damage to dopamine transmitters; causes uncontrollable shaking, no cureTay-Sachs –lack enzyme to break down fatty deposits in the brain; neurological deterioration; death by age 4-5Dementia - damaged brain cells caused by injury or disease (Alzheimer’s); memory loss and personality change.
31 Nervous System Accelerate HR, BP, and breathing rate Drugs and the Nervous SystemStimulantsAccelerate HR, BP, and breathing rateIncreases the release of neurotransmitters; leads to release of energy and feeling of well-beingWhen effect wears off, brain’s supply is depletedCaffeineCocaineMethamphetamines
32 Nervous System Depressants Slow down HR, lower BP and breathing rate, relax muscles and relieves anxietyAlcoholMarijuanaSleeping Pills
33 Commonly Abused Drugs Commonly Abused Drugs Section 35-5 Drug Type StimulantsDepressantsOpiatesUsed to increase alertness, relieve fatigueUsed to relieve anxiety, irritability, tensionUsed to relieve painMedical UseAmphetaminesBarbituratesTranquilizersMorphineCodeineExamplesEffects on the bodyIncrease heart and respiratory rates; elevate blood pressure; dilate pupils; decrease appetiteSlow down the actions of the central nervous system; small amounts cause calmness and relaxation; larger amounts cause slurred speech and impaired judgementAct as a depressant; cause drowsiness, restlessness, nausea