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35.1 Human Body Systems & Organization A. Levels of organization * body organized in levels from microscopic to the whole organism Cell Tissue Organ Organ system Organism
B. Body Tissues muscle tissue * most abundant tissue * controls internal movement digestion, blood through veins * external movement of body epithelial tissue * covering for body & organs * linings of organs & vessels connective tissue * holds organs in place ligaments, tendons, some keep organs in place nervous tissue * receives messages from body’s internal and external messages * analyze data & direct response
C. 11 Organ Systems 11 organ systems work together to help the body maintain HOMEOSTASIS. The ability of an organism to maintain a controlled, stable internal environment. temperature, sugars, blood pressure heart rate, salt, potassium, hormones Homeostasis of organisms is maintained through Feedback Inhibition: The product of a system shuts down the system or limits its function.
Non-living example of Feedback Inhibition: Heating a house thermostat senses temp and switches off heating system heating system room temp turns on decreases thermostat senses temp change and switches off heating system Living example of Feedback Inhibition: Heating a body hypothalamus nerve cells chemicals sent to cells senses temps at core body temp decreases make them speed up and stop cell temp activities and increase temp nerves in the hypothalamus sense the decrease in temp
Section 35-1 • 11 organ systems: Integumentary System Skeletal System Muscular System Circulatory System Nervous System Respiratory System Digestive System Excretory System Endocrine System Lymphatic/Immune Systems Reproductive System
Chapter 35.2 & 35.3 Nervous System 35.2 How nerves work…………….. Function: * coordinates functions throughout the body * responds to internal and external stimuli. 1. Neurons: Neurons are cells that transmit impulses (action potentials) from one neuron to the next, etc 3 types: a. sensory: from sensory organs to spinal cord/brain b. motor: from brain/spinal cord to muscles and glands c. interneurons: connect sensory and motor neurons
interneuron Make muscles move Senses stimuli
Dendrites Nucleus Direction of impulse • General shape of a neuron Cell body: cytoplasm, organelles and nucleus dendrites: carry impulses from environment to cell body axons: long fiber carries impulse away from cell body myelin sheath: insulates the axon smooth impulse Axon Axon Terminals node synapse Myelin sheath Cell body Axon – Away….both have A’s
Nodes: gaps in the myelin sheath called . Impulses jump from one node to the next Synaptic cleft: the space between two neurons
The Moving Impulse • An impulse begins when a neuron is stimulated by another neuron or by the environment. • The nerve impulse is a movement of positive charges through neuron from the dendrite through the end of the axon.
3. Synapse • The junction between 2 nerves or a nerve and muscle. • impulse travels away from cell body down the axon to the axon terminal • axon terminal contains vesicles that release neurotransmitters into the synaptic cleft towards the dendrites of the next neuron.
Section 35-2 Direction of Impulse Dendrite of adjacent neuron *. synapse Axon Receptor Vesicle Axon terminal Synaptic cleft Neurotransmitter The nerve junction
CNS relays messages, processes information, • and analyzes information. • brain & spinal cord • wrapped in three layers of connective tissue known • as meninges
The Brain • Parts of The Human Brain Cerebrum Thalamus Pineal gland Hypothalamus Cerebellum Pituitary gland Pons Brain stem Medulla oblongata Spinal cord
The Brain • The Cerebrum • The largest region of the brain. • controls the voluntary, or conscious, activities of the body. • site of intelligence, learning, and judgment. • mirror neurons
The Cerebellum • second largest part of the brain • It coordinates and balances the muscles so that the body can move gracefully and efficiently.
The Brain Stem • The brain stem connects the brain and spinal cord. • It has two regions: pons and the medulla oblongata. • Brain stem controls blood pressure, heart rate, breathing, and swallowing • Thalamus - receives messages from sensory receptors in body • Hypothalamus – control center for thirst, hunger, fatigue, hormones
The Brain Pons Brain stem Medulla oblongata
The Spinal Cord • Main communications link between the brain and the rest of the body. • Some kinds of reflexes, are processed directly in the spinal cord. • A reflex is a quick, automatic response to a stimulus. Reflex arc: Sensory Interneuron Motor
The Peripheral Nervous System • The Peripheral Nervous System • The PNS is all of the nerves that are not part of the brain and the spinal cord. • The peripheral nervous system includes cranial nerves, spinal nerves. • 2 divisions • Autonomic: nerves that control involuntary action – organs, glands • Somatic : nerves that control voluntary actions – movement of skeletal muscle