Five Levels of Organization Cell Tissue Organ Organ System Organism

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1 Levels Human of Body Organization Systems Five Levels of Organization Cell Tissue Organ Organ System Organism ORGANS ORGAN SYSTEM ORGANISM

2 Levels Human of Body Organization Systems KEY CONCEPT Homeostasis is the regulation and maintenance of the internal environment.

3 Levels Human of Body Organization Systems Conditions within the body must remain within a narrow range. Homeostasis involves keeping the internal environment within set ranges that support life pore ex: temperature, fluids, salt, ph sweat glands Control systems help maintain homeostasis. sensors gather data control center receives data, sends messages communication system delivers messages to target organs, tissues targets respond to change hair follicle muscle goose bump

4 Levels Human of Body Organization Systems Homeostasis is maintained by feedback loops. Feedback compares current conditions to set ranges. Two types of feedback loops: 1) Negative feedback= counteracts change; more common ex: temperature & O 2 /CO 2 regulation ( ) Negative Feedback Loop Holding breath, CO 2 levels rise, O 2 /CO 2 level returns to normal Control system forces exhale, inhale

5 Levels Human of Body Organization Systems 2) Positive feedback = increases change; less common ex - During childbirth, oxytocin enhances ( ) labor contraction - Torn vessel stimulates ( ) release of clotting factors - Growth hormones stimulate ( ) cell division fibrin platelets blood vessel clot red blood cell white blood cell

6 Levels Human of Body Organization Systems Feedback loop = Blood temperature regulation

7 Neurons The Nervous System KEY CONCEPT The nervous system controls and coordinates functions throughout the body and responds to internal and external stimuli.

8 Neurons The Nervous System A stimulus causes a response. ex: When you touch something hot (stimulus), you immediately pull your hand away (response). Messages carried by the nervous system are called impulses.

9 Neurons The Nervous System 1) electrical impulse = due to the differences in electrical charges across the nerve cell membrane; aka action potential

10 29.2 Neurons 2) chemical impulse = due to the move movement of chemical messengers between nerve cells

11 Neurons The Nervous System The nervous system is composed of highly specialized cells called neurons. A neuron has three parts. cell body has nucleus and organelles 1 Cell body

12 Neurons The Nervous System Neurons are highly specialized cells. A neuron has three parts. cell body has nucleus and organelles dendrites receive impulses 2 dendrites

13 Neurons The Nervous System Neurons are highly specialized cells. A neuron has three parts. cell body has nucleus and organelles dendrites receive impulses axon sends impulse to next cell through the axon terminal axon terminal 3 axon

14 Neurons The Nervous System The axon is wrapped in a myelin sheath Made up of Schwann cells insulated impulse cannot go through Gaps between are the nodes of Ranvier not insulated impulse can go through Schwann cell Nodes of Ranvier

15 Neurons The Nervous System The axon is wrapped in a myelin sheath Myelin sheath speeds up the impulse Impulse jumps from one node of Ranvier to the next signal direction 330 mph (myelinated) vs. 11 mph (unmyelinated)

16 Neurons The Nervous System Myelin sheath = jelly roll!!

17 Neurons The Nervous System Types of neurons 1.sensory neuron (from senses) 2. interneuron (brain & spinal chord) 3. motor neuron (to muscle) 17

18 Neurons The Nervous System Synaptic Transmission Neurotransmitters - chemical messengers that transmit impulse between nerve cells - contained in small vesicles in axon terminal Synapse - junction between two nerve cells

19 Neurons The Nervous System Synaptic Transmission 1) Impulse reaches axon terminal and vesicles fuse to presynaptic membrane release chemicals into synapse (exocytosis) 2) Neurotransmitters diffuse across the synapse (diffusion) 3) Neurotransmitters bind to receptors in postsynaptic membrane 4) Neurotransmitters are taken back up into vesicles (endocytosis)or destroyed by enzymes

20 Divisions Central and of Peripheral the Nervous Nervous SystemSystems KEY CONCEPT The central nervous system interprets information, and the peripheral nervous system gathers and transmits information.

21 Divisions Central and of Peripheral the Nervous Nervous SystemSystems The nervous system s two parts work together. The CNS includes -brain - spinal cord The PNS includes sensory receptors 12 cranial nerves 31 spinal nerves connects CNS to rest of the body

22 Divisions Central and of Peripheral the Nervous Nervous SystemSystems The PNS links the CNS to muscles and other organs. The somatic nervous system regulates voluntary movements. The autonomic nervous system controls involuntary, functions sympathetic nervous system: fight vs. flight parasympathetic nervous system: calms the body, conserves energy

23 Divisions Central and of Peripheral the Nervous Nervous SystemSystems The CNS and PNS pass signals between one another. Sensory receptor (PNS) generates impulse. PNS passes impulse to CNS through the sensory neurons Interneurons in CNS interpret impulse and make a decision. CNS passes the decision (impulse) to the motor neurons of the PNS. Motor neurons (PNS) stimulate a response by a muscle or gland (effectors).

24 Divisions Central and of Peripheral the Nervous Nervous SystemSystems The CNS processes information. The brain has three parts. cerebrum controls thought, memory, movement, emotion cerebellum allows for balance brain stem controls basic life functions Brain stem midbrain pons medulla oblongata

25 Divisions Central and of Peripheral the Nervous Nervous SystemSystems Cerebrum Largest part of brain Made up of right and left hemispheres connected by corpus callosum

26 Divisions Central and of Peripheral the Nervous Nervous SystemSystems Cerebrum Cerebral cortex gray matter highly folded outer layer of cerebrum Below the cerebral cortex - white matter - connects cortex to other parts of nervous system

27 Divisions Central and of Peripheral the Nervous Nervous SystemSystems Cerebrum Right hemisphere - controls verbal and nonverbal artistic abilities - creative side Left hemisphere - controls reading, writing, and analyzing - logic side

28 Divisions Central and of Peripheral the Nervous Nervous SystemSystems The brain stem has three parts. midbrain controls some reflexes pons regulates breathing and is the relay station between cerebrum and cerebellum medulla oblongata controls heart function, swallowing, coughing midbrain medulla oblongata pons

29 Divisions Central and of Peripheral the Nervous Nervous SystemSystems The spinal cord controls reflexes. sensory neuron sends impulse to interneuron in spinal cord spinal cord directs impulse to motor neuron does not involve the brain interneuron motor neurons sensory neuron

30 The Senses KEY CONCEPT The senses detect the internal and external environments.

31 The Senses The senses help to maintain homeostasis. Senses gather stimuli, and send it to the nervous system. Nervous system responds to stimuli. Pupils shrink when too much light enters the eyes. Goose bumps when cold air touches skin.

32 The Senses The senses detect physical and chemical stimuli. The eye contributes to vision. Photoreceptors sense light. Two photoreceptors work together: rod cells and cone cells.

33 The Senses The ear contributes to hearing. mechanoreceptors called hair cells bend in response to vibrations

34 The Senses Taste and smell use chemoreceptors. Taste uses tongue, and smell uses nose. Chemoreceptors detect chemicals dissolved in fluid.

35 The Senses The skin senses touch. Mechanoreceptors detect pressure. Pain receptors detect damaged tissue. Thermoreceptors detect temperature. pain receptor light pressure receptor hair follicle heavy pressure receptor saw_02/index.shtml?nervous

36 The Endocrine System and Hormones KEY CONCEPT The endocrine system produces hormones that affect growth, development, and homeostasis.

37 The Endocrine System and Hormones How does endocrine system work? Works closely with nervous system Nervous system detects changes sends signal to Endocrine gland secretes Hormone travels through bloodstream to Target cell Restores homeostasis

38 The Endocrine System and Hormones Endocrine glands are organs of the endocrine system Hormones are chemical signals that influence cell s activities. produced by glands travel through the circulatory system affects target cells with matching receptors target cell hormone bloodstream receptor not a target cell

39 The Endocrine System and Hormones Endocrine glands secrete hormones that act throughout the body. There are many glands located throughout the body. HYPOTHALAMUS PITUITARY THYROID THYMUS ADRENAL GLANDS PANCREAS FEMALE GONADS :OVARIES MALE GONADS : TESTES

40 The Endocrine System and Hormones Types of Endocrine glands Controls pituitary and other glands connects Nervous sys and Endocrine sys Makes hormones that control other glands Makes thyroxin to control metabolism Makes thymosin to help white blood cells to mature Make adrenaline to prepare body for emergencies Makes insulin and glucagon to control blood glucose levels Controls secondary sex characteristics Makes testosterone in men and estrogen and progesterone in women

41 The Endocrine System and Hormones Negative Feedback of Blood Glucose Blood Glucose Level (BGL) is regulated by 1) insulin = BGL 2) glucagon = BGL Both hormones are secreted by the pancreas insulin pancreas high body cells take up sugar from blood liver liver stores sugar reduces appetite blood sugar level (90mg/100ml) triggers hunger low liver releases sugar liver glucagon pancreas

42 The Endocrine System and Hormones Negative Feedback of Blood Glucose After Meal After Exercise BGL BGL Pancreas releases insulin Insulin pushes glucose into the target cells BGL Restores homeostasis Pancreas releases glucagon Glucagon binds to liver Liver releases glucose BGL Restores homeostasis