Nervous, Integumentary & Endocrine Systems Ch. 35-2, 35-3, 36-3, 39-1 & 39-2

I. Chapter 35-2 & 35-3: Nervous System B. FUNCTION: Coordinates & controls body’s response to internal/external environment A. STRUCTURES: Brain, spinal cord, nerves, sense organs, receptors

II. Nervous System – has 2 major divisions: A.Central Nervous System (CNS) analyzes & interprets messages received from neurons Brain & spinal cord

1. Brain FUNCTION: Oversees daily operation of body & interprets info it receives

1) Cerebrum – Largest, voluntary activities, senses, intelligence, learning & judgment. Consists of approx. 10 billion neurons! a. Parts

2) Cerebellum – 2nd largest. muscle coordination & balance

3) Brain stem – links the cerebrum w/ spinal cord. Breathing, swallowing controlled here

2. Spinal Cord – links brain to body. Reflexes are processed here Brain Spinal cordBody

B. Peripheral Nervous System (PNS)- has 2 parts nerves outside the brain and spinal cord. Send and receive messages with the CNS

1. Somatic Nervous System - VOLUNTARY Relays info. from senses CNS muscles Ex. Reach for a book

2. Autonomic Nervous System - INVOLUNTARY Relays info from CNS internal organs ex. Heart rate, breathing

-REFLEX ARC – rapid, involuntary muscle movement Involves only neurons & spinal cord Brain gets bypassed!!

III. Structure of a NEURON (nerve cell) 1. DENDRITES – 1 st to receive impulse 3. NUCLEUS 2. CELL BODY -surrounds nucleus

4. AXON – carries impulse away from cell body 5. MYELIN SHEATH – insulates/ prevents loss of impulse 6. AXON TERMINAL – end of neuron

IV. Types of Neurons A. SENSORY neuron – from body to CNS (sense stimuli) B. INTERNEURONS –from CNS to motor neurons (connect) C. MOTOR neuron – from CNS to muscle/gland (move)

V. Neuron Organization A. Neurons don’t touch! C. SYNAPSE = space between 2 neurons B. IMPULSE = electrochemical messages

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Receptors and Sense Organs Sensory receptors are neurons that are specialized to detect a stimulus. They are found in HIGH concentration in the sense organs (eyes, ears, nose, mouth & skin). They are found in LOW concentration throughout the rest of the body.

Types Types of Sensory Receptors 1. Mechanoreceptors: Respond to movement, pressure, tension 2. Photoreceptors: Respond to variations in light

3. Chemoreceptor: Respond to chemicals 4. Thermoreceptors: Respond to changes in temperature 5. Nociceptors: Respond to tissue damage &pain

Nervous system and drugs 1. Stimulants a. Cocaine, nicotine, caffeine, amphetamines

b. Increase the speed of messages being sent - Feeling of energy and wellness c. After effect wears off  fatigue & depression

2. Depressants a. Alcohol, Barbiturates, muscle relaxers, sleeping pills b. Slows down messages - Feeling of being relaxed, calm, sleepy

c. Can slow down the system too much  body stops breathing

Section 36-3: I. Integumentary System (Skin) A. Includes skin, hair & nails B. Skin is largest organ of human body

C. Functions of the Skin: 1. Regulate body temperature a. Blood vessels When hot, vessels dilate & release heat

When cold, vessels constrict & heat is conserved b. Sweat – released by glands to cool body

2. Senses – sensory neurons 3. Vitamins – when exposed to UV light, makes vitamin D detects hot/cold, pressure helps absorb calcium

4. Remove Wastes Sweat – releases excess water, salts & urea 5. Protection from… Physical & chemical damage Disease (1 st line of defense)

D. 3 Layers of Skin: 1.Epidermis – outermost layer made of dead cells & constantly replaced a. Keratin – protein that… makes nails gives tough texture “waterproof” quality

b. Melanin – pigment that… colors the skin protects cells from sun damage more sun exposure makes more melanin

2. Dermis – inner, thicker portion of skin Contains: Nerves Blood vessels Hair follicles (warmth & protects) Sweat glands Oil glands – soften skin

3. Subcutaneous Layer (Hypodermis) Mostly fat deposits Absorb impact Retain heat Store food/ energy

E. How Cuts Heal 1) Blood clots & cut closes 2) New cells push damaged cells to surface 3) Scab forms & WBC fight wound infection 4) New cells fill in gap of scab

Ch & 39-2: I. Endocrine System A. FUNCTION: Transmit chemical messages to control growth, development & metabolism

B. Hormones & Glands 1. Hormone = secreted chemical in blood stream or ducts that affects cells Ex: Human growth hormone (HGH), insulin 2. Gland = organ that releases hormones into body

C. Compared to nervous system 1. Message delivered throughout the body 2. Body’s response is slower than nerve impulse

1) EXOCRINE gland – secrete substance through ducts (Ex: sweat, tears) D. Two Gland Types: 2) ENDOCRINE gland – secretes hormones into bloodstream

E. Endocrine Glands: 1. Pituitary gland (in brain) regulates other glands most important (master gland) 2. Thyroid (in neck) makes thyroxine; regulates metabolism

3. Adrenal glands (above each kidney) makes epinephrine (adrenaline) ; response to stress (fight or flight) 4. Pancreas makes insulin; regulates glucose levels

F. Feedback Mechanism 1. adjusts to regulate amount hormone levels 2. maintains HOMEOSTASIS

Ex. Thyroid  thyroxine Thyroid gland controlled by hypothalamus & pituitary gland Hypothalamus sense low levels of thyroxine in blood & sends a message to pituitary releases hormone

Pituitary signals the thyroid to produce & release thyroxine Thyroxine sent to cells to speed metabolism

Low Hormone Level Increase Hormone Production High Hormone Level Decrease Hormone Production