Five Levels of Organization - 1.cdn.edl.io€¦ · system: “fight vs. flight” – parasympathetic nervous ... or gland (effectors). ... corpus callosum

28.1 Levels of Organization

Five Levels of Organization

Cell Tissue Organ Organ System Organism

ORGANS

ORGAN SYSTEM

ORGANISM

35.1 Human Body Systems


KEY CONCEPT Homeostasis is the regulation and maintenance of the internal environment.



pore

sweat glands

hairfolliclemuscle

goosebump

Conditions within the body must remain within a narrow range.• Homeostasis involves keeping the internal environment

within set ranges that support lifeex: temperature, fluids, salt, pH

• 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



Homeostasis is maintained by feedback loops. • Feedback compares current conditions to set ranges.• Two types of feedback loops:

1) Negative feedback= counteracts change; more commonex: temperature & O2/CO2 regulation (↓)

Negative Feedback Loop

Holding breath, CO2 levels rise,

Control system forces exhale, inhale

O2 / CO2 level returns to normal



2) Positive feedback = increases change; less commonex - During childbirth, oxytocin enhances (↑) labor

contraction - Torn vessel stimulates (↑) release of clotting factors- Growth hormones stimulate (↑) cell division

platelets

fibrin

white blood cellred blood cell

blood vessel

clot



Feedback loop = Blood temperature regulation


29.2 Neurons

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

35.2 The Nervous System

29.2 Neurons

• 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.


29.2 Neurons

1) electrical impulse = due to the differences in electricalcharges across the nerve cell membrane;aka “action potential”


29.2 Neurons

2) chemical impulse = due to the move movement ofchemical messengers between nerve cells

29.2 Neurons

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


29.2 Neurons

– dendrites receive impulses

Neurons are highly specialized cells.

• A neuron has three parts.– cell body has nucleus and organelles

2 dendrites


29.2 Neurons

– axon sends impulse to next cell through the axon terminal

3 axon

– dendrites receive impulses

Neurons are highly specialized cells.

• A neuron has three parts.– cell body has nucleus and organelles

axon terminal


29.2 Neurons

• The axon is wrapped in a myelin sheath

– Made up of Schwann cellsinsulated impulse cannot go through

– Gaps between are the nodes of Ranviernot insulated impulse can go through

Schwann cell Nodes of Ranvier


29.2 Neurons

signal

direction

• The axon is wrapped in a myelin sheath– Myelin sheath speeds up the impulse – Impulse “jumps” from one node of Ranvier to the next– 330 mph (myelinated) vs. 11 mph (unmyelinated)


29.2 Neurons

• Myelin sheath =jelly roll !!


29.2 Neurons

17

Types of neurons1.sensory neuron

(from senses)

2. interneuron(brain & spinal chord)

3. motor neuron(to muscle)


29.2 Neurons

Synaptic Transmission• Neurotransmitters

- chemical messengers that transmit impulse between nerve cells

- contained in small vesicles in axon terminal• Synapse

- junction between two nerve cells


29.2 Neurons

Synaptic Transmission1) 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


29.4 Central and Peripheral Nervous Systems

KEY CONCEPT The central nervous system interprets information, and the peripheral nervous system gathers and transmits information.

35.3 Divisions of the Nervous System


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



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



• 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).



The CNS processes information.

• The brain has three parts. – cerebrum controls

thought, memory, movement, emotion

– cerebellum allows for balance

midbrainpons

medulla oblongata

– brain stem controls basic life functions

Brainstem



Cerebrum• Largest part of brain• Made up of right and left hemispheres connected by

corpus callosum



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



Cerebrum• Right hemisphere

- controls verbal and nonverbal artistic abilities

- “creative side”• Left hemisphere

- controls reading, writing, and analyzing

- “logic side”



• 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



• 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


29.3 The Senses

KEY CONCEPT The senses detect the internal and external environments.

35.4 The Senses

29.3 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.

35.4 The Senses

29.3 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.

35.4 The Senses

29.3 The Senses

• The ear contributes to hearing.

– mechanoreceptors called hair cells – bend in response to vibrations

35.4 The Senses

29.3 The Senses

• Taste and smell use chemoreceptors.

– Taste uses tongue, and smell uses nose.– Chemoreceptors detect chemicals dissolved in fluid.

35.4 The Senses

29.3 The Senses

• The skin senses touch.

– Mechanoreceptors detect pressure.

pain receptor

light pressure receptor

hair follicle

heavy pressure receptor

– Pain receptors detect damaged tissue.– Thermoreceptors detect temperature.

35.4 The Senses

http://www.bbc.co.uk/science/humanbody/body/interactives/3djigsaw_02/index.shtml?nervous

29.6 The Endocrine System and Hormones

KEY CONCEPT The endocrine system produces hormones that affect growth, development, and homeostasis.

39.1 The Endocrine System


How does endocrine system work?• Works closely with nervous system• Nervous system detects changes

Endocrine gland

sends signal to

Hormonetravels through bloodstream to

Target cell

secretes

Restores homeostasis



• 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

receptornot a target cell

bloodstream



Endocrine glands secrete hormones that act throughout the body.

• There are many glands located throughout the body.

HYPOTHALAMUS

PITUITARY

THYROID

THYMUS

ADRENAL GLANDSPANCREASFEMALE GONADS :OVARIES

MALE GONADS : TESTES



Types of Endocrine glandsControls 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



Negative Feedback of Blood Glucose• Blood Glucose Level (BGL) is regulated by

1) insulin = ↓ BGL2) glucagon = ↑ BGL

• Both hormones are secreted by the pancreas

liverpancreas

liver

blood sugar level(90mg/100ml)

insulin

body cells takeup sugar

from blood

liver storessugar

reducesappetite

glucagonpancreas

liver releases

sugar

triggershunger

high

low



Negative Feedback of Blood GlucoseAfter Meal

Pancreas releases insulin

Insulin pushes glucose into the target cells


BGL ↑

BGL ↓

After Exercise

Pancreas releases glucagon

Glucagon binds to liver


BGL ↑

BGL ↓

Liver releases glucose


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Five Levels of Organization - 1.cdn.edl.io€¦ · system: “fight vs. flight” – parasympathetic nervous ... or gland (effectors). ... corpus callosum