Honors Bio - Unit 2B: Homeostasis & Human Body Systems

breathing

mechanical process by which O₂ is obtained

organs responsible are part of the respiratory system

epiglottis

small flap, closes over trachea while swallowing

trachea

windpipe

bronchi

2 short tubes that take air into right and left lungs

bronchioles

smaller air tubules within the lungs

diaphragm

sheet-like muscle that separates the thoracic cavity from the gut

alveoli

location of gas exchange

tiny air sacs found at the ends of the bronchioles

hemoglobin

protein molecule in red blood cells responsible for carrying oxygen

digestion

mechanical and chemical processes which break down food into simpler molecules

provides raw materials for synthesis of new molecules & energy production (cellular respiration)

mechanical digestion

mixing/chewing, increases surface area for chemical digestion to occur

chemical digestion

chemical processes which break down food particles into simpler molecules

requires enzymes and digestive agents

mouth (teeth, tongue, salivary glands)

food is broken into smaller pieces

saliva moistens food to form bolus

amylase enzyme promotes breakdown of starch to sugars

MECHANICAL & CHEMICAL

GI tract

pharynx

area behind uvula; bolus moves through here to esophagus

GI tract

esophagus

tube connecting pharynx to stomach

strong muscles propel bolus using peristalsis

GI tract

peristalsis

wavelike contraction propelling food and liquids through the digestive tract

involuntary process that propels the bolus (food) from the esophagus to the stomach, then to the small & large intestines, ultimately leading to the excretion of wastes

stomach

bolus mixed/grounded by strong muscles contractions; enzymes (pepsin) & HCl acid react to break down protein molecules

MECHANICAL & CHEMICAL

GI tract

liver

produces bile; bile emulsifies (separates into droplets) fats to promote digestion

MECHANICAL

Accessory

gallbladder

storage area for bile produced in liver; bile moves into small intestine via duct

MECHANICAL

Accessory

pancreas

produces digestive enzymes including amylase, lipase, nuclease, protease

enzymes enter small intestine through duct

CHEMICAL

Accessory

small intestine

first section (duodenum) completes most enzymatic digestion

middle section (jejunum) finalizes digestion & absorption begins

final section (ileum) is where absorption of nutrients is completed; aided by villi

MECHANICAL & CHEMICAL

GI tract

large intestine

water reabsorption occurs; feces formed

GI tract

circulatory system

transportation system of the body

heart

muscle used to pump blood throughout the body

blood

transports nutrients & wastes to & from all body tissues

red blood cells

made in the bone marrow

contain hemoglobin, protein that carries O₂

carries O₂ to body tissues

makes up 99% of all blood cells

white blood cells

made in bone marrow, spleen, & lymph nodes

larger/fewer than RBCs (1% of all blood cells)

some engulf microorganisms, others produce antibodies

defend the body against infection from microorganisms

platelets

help to form blood clots

fragments of cells produced in bone marrow

much smaller than RBCs

arteries

large, muscular blood vessels which carry blood away from the heart

very elastic to deal with high pressure of pumped blood

veins

carry blood back to the heart

much less muscular, blood is under low pressure

contains 1-way valves which keeps blood moving towards the heart

capillaries

smallest blood vessels

walls are only 1 cell layer thick

diffusion of O₂, CO₂, nutrients, wastes, etc.

regulation

process of controlling body systems to maintain ideal function & homeostasis

depends on nervous & endocrine systems

stimulus

detectable change (physical or chemical) in the environment (ext or int) or an organism that results in some activity in response

control center

brain/gland that senses a stimulus message & decides on a response

sends a response to an effector by nerve signal/hormone message

ex: brain sense temp increase, sends message to effector

effector

organ/gland/muscle that performs an action

ex: sweat glands begin secreting sweat due to increased temp

response

any behavior of a living organism that results from an int or ext stimulus

nervous system

short term

rapid response (0.1 seconds)

sends electrochemical signal along neurons

endocrine system

long term

slower response (many seconds to minutes)

hormone/chemical message that travels through blood

negative feedback loop

nerve or endocrine response that corrects or negates stimuli to help maintain homeostasis in the body

positive feedback mechanism

rare in humans!

stimulus causes a response that increases/reinforces the stimulus

ex: vomiting, childbirth

villi

tiny, finger-like projections that increase surface area in the walls of the small intestine for nutrient absorption

bile

greenish-yellow fluid in the liver that aid in fat digestion and absorption by breaking down fats into smaller droplets that are easier for enzymes to digest