bio exam 4

homeostasis

maintaining steady state of health

is the optimal range of physiological conditions

diffusion in single celled orgnaisms

depend on it for oxygen and nutrients

easy for aquatic organism

diffusion in multi-cellular organisms

it because a less effective method of getting oxygen and nutrients

movement becomes more complex and coordination even more so

three main types on neurons

sensory, interneurons, and motor neurons

sensory neurons

receive info and pass it along

Interneurons

act as intermediate by conducting a signal from sensory neurons

Motor neurons

Affect physiological change or movement in response to signal from sensory neurons

what each neuron has

dendrite, axon hillock, synaptic cleft, nucleus, neurotransmitters, receptors,

synapse

what do dendrites do

receive a signal

signal is summed at axon hillock

what does the axon hillock do

integrates incoming signals from dendrites and determines whether

to generate an action potential, sending it down the axon.

what does the axon do

it transmits a signal

what is a synaptic cleft

the narrow gas between an axon of one neuron and a dinitride of another

what is a synapse

the entire structure of the presynaptic axon terminal, synaptic cleft, and postsynaptic

dendrite

neurotransmitter

signaling molecules carried by vesicles that are released by the presynaptic cell at the axon terminal into the synaptic cleft

synaptic cell signaling

each neuron may for synapses with hundreds or thousands of other neurons

depolarization

_____ is the rapid increase in membrane potential that occurs along the membrane of

the axon in response to the summed dendritic signal at the axon hillock

what is action potential

Axon hillock sums the inhibitory and excitatory signals received in the dendrites

Balance between the two signals determines whether axon hillock triggers action potential along the axon

Once the axon hillock reaches its threshold point action potential is initiated and continues down the axon

Like dominos falling

depolarizing

Excitatory signals in action potential are….

hyperpolarizing

inhibitory signals in action potential are….

what do glial cells do

they often support neurons

they make up myelin sheaths

are helper cells

what are myelin sheaths

vertebrate animals increase the speed of depolarization along axons by insulating

with these

acts like a plastic insulation around electrical wire

central nervous system (CNS)

is the brain and spinal cord

interneurons-dominant

works together with PNS for physiological homeostasis

peripheral nervous system

is cranial and spinal nerves that branch off from the the CNS

sensory and motor neuron-dominant

Many functions in vertebrate animals are involuntary functions performed by this

works together with CNS for physiological homeostasis

simple reflexes

are direct activation of a motor neuron by a signal from a sensory neuron

Occurs in spinal column without going to brain

no signal goes to brain

sensory cells

present in cells of sensory organs

changed in response to stimulus

transmit signals to adjacent neurons

how sensory cells transmit signals

typically determined by the frequency of the firing rate of neurons

Stronger stimuli cause a higher frequency firing rate

Weaker stimuli cause a lower frequency firing rate

Determined by axon hillock

what senses use Chemoreception

smell and taste

what Chemoreception does

is based on sensory receptors that bind to particular molecules

how smell works

1000 different receptor proteins that recognize odorant

receptors are on chemosensitive hairs that extend from olfactory neurons in our nasal passage

Olfactory neurons send chemical signals to interneurons that process them

how taste works

Taste receptors are present in microvilli extending from sensory cells present in taste buds

These cells depolarize and send a chemical signal to adjacent sensory neurons

high concentration of chemical signals

smell and taste

Input from ____ and ____ neurons are combined in a chemoreception center of the brain

how hearing works

similar to detection of gravity and movement except the signal in vibration of air

Intensity and pitch are detected and a complex signal is processed by the brain

how vision works

detects electromagnetic waves

Vision ranges from simple structures that just detect presence or absence of light with complex structures that provide great detail

membrane channels

acting as the primary mechanism for converting external stimuli into signals that our nervous system can interpret

opsins

light receptor proteins in human eye

react to photons of light and change their shape

humans have one for blue, green, and red light

foveal vison

region of the retina where the sharpest focus of the image will occur

dense in cones

peripheral vison

the ability to see things that are not directly in front of you, or "out of the corner of your eye"

rods are more common

brain

The information from sensory input is huge and requires dedicated regions of the ____ to process it

3 types of muscle tissue

Skeletal-muscles involved in movement

Cardiac-fibrous cells found in heart

Smooth-muscles that perform involuntary and frequent functions

muscle fibers

long cells

Result from fusion of multiple muscle cells called myoblasts

Have multiple nuclei as a result

actin in muscels

muscle fibers contain these specialized contractile myofibrils

__________ microfilaments

myosin in muscle fibers

______ is a molecular motor that makes thick bundles

Contraction is caused by _____ binding to actin and pulling on it

Contraction is caused by _____ binding to actin and pulling on it

cross bridge cycle

myosin heads bind to actin

use chemical energy from the breakdown of ATP to generate a pulling force against actin filaments

detach and prepare to bind again

calcium in muscle cells

Muscle cells typically have very low levels of Ca++ in cytoplasm

High levels outside of cells

Inside the cell large amounts of Ca++ sequestered in sarcoplasmic reticulum

what causes an increase in cytoplasmic Ca++

Neuron signal causes “calcium spark”-dramatic increase

Release of sarcoplasmic Ca++ and influx from outside of cell

Ca++ affects troponin which modifies tropomyosin and this exposes myosin-binding sites on actin

motor neuron

signal from it determines rate of muscle contraction

As frequency increases the strength of the contraction ramps up

Eventually tetanus is reached with near-constant forceful contraction

Antagonist pairs of muscles

on opposite surfaces of bone

perform flexion and extension

how bones grow and mature

begin as cartilage and calcify over time

Growth plate of bones expands cartilage

Bones calcify to harden from center of bone towards ends

During maturation bones will fully calcify

what gases are being exchanged in respiration

obtain oxygen and get rid of Co2

ventilation

the process of air moving in and out of the lungs

Breathing air requires little effort since it has a low density and high concentration of oxygen

Breathing in water requires a greater expenditure of energy to move water and extract a less common molecule from the medium

The three main structures that perform gas exchange

gills, trachea, lungs

gills

Highly vascular structures extending from the body of aquatic animals

ventilated by the animal moving through water or they may deliberately pass water over the gills while they are not moving

There is a system of countercurrent exchange (like in blood heating) in which blood with lowest oxygen pressure is exposed to ventilated water last

Tracheal systems

Network of tubes that branch throughout the body

Relies on multiple exchange structures

Any single area of tissue would be near a gas exchange structure

There may be no need to combine circulation and respiration

Lungs

Large, centralized internal structures for gas exchange

Air enters through nose and mouth into nasopharynx

Passes through the trachea

Single tube

Then enters one of two bronchi

Become bronchioles as they decrease in diameter and branch

Eventually end at small, highly vascularized sac-like structures called alveoli

Capillaries surrounding alveoli carry out gas exchange

Alveoli have strong surface tension for small delicate structure

negative pressure breathing

To inhale the diaphragm, a muscle on the lower end of the lungs, actively moves down expanding the volume of the cavity

Also aided by expansion of rib cage

hemoglobin

In humans the main respiratory pigment is a protein called _____

what is hemoglobin

Hemoglobin is a compound protein comprising four polypeptides

The iron in the heme group can attract and bind to oxygen

Hemoglobin is found in red blood cells

The cell shape increases rate of gas exchange

What is myoglobin

Myoglobin is another respiratory pigment

Typically associated with marine mammals that dive for extended period of time

what is myoglobin used for

Myoglobin in tissue allows them to store and retain oxygen in tissue until released later in dive

How hemoglobin functions in gas exchange and how conditions affect it

In high oxygen pressure in the lungs iron in heme will bind oxygen

once it binds shape changes in the protein increases the binding efficiency of the other 3 sites

it retains oxygen until pressure drops

The accumulation of carbon dioxide in the blood results in the formation of carbonic acid (H2CO3) in red blood cells

Hemoglobin is affected by pH and unloads oxygen at reduced pH

The role of a circulatory system

Drives the bulk flow gas exchange

open circulatory system

Exchange of molecules between hemolymph and cells

Eventually hemolymph drains to collection points called sinuses

Hemolymph in sinuses is syphoned back into circulatory system

Like a straw

fluids used in open circulatory system

hemolymph

Leaks out and acts as fluid surrounding cells-interstitial fluid

closed circulatory system

Blood stays in blood vessels and exchange of molecules occurs by movement across the walls of the blood vessels.

Blood doesn’t just leak out and surround tissue

fluid used in closed circulatory system

blood

The heart and circulation (steps 1-4)

1. Deoxygenated blood (low on oxygen) collects in right atrium

2. Blood is pumped into right ventricle. Passes through one-way valve between the chambers

3. Contraction of right ventricle pumps blood into pulmonary arteries to go to lungs

In the lungs blood travels through capillaries and drops off CO2 and picks up oxygen

4. Newly oxygenated blood travels through pulmonary veins back to heart where it enters the left atrium

the heart and circulation (step 5-8)

5. Blood is pumped into the left ventricle

6. Contraction of the left ventricle pumps blood through the aorta out through the entire body

7. Blood travels through arterial system until it reaches capillary beds

8. Oxygen and CO2 are exchanged and deoxygenated blood travels through veins back to the right atrium

arteries

blood vessels that take blood away from the heart towards capillary beds

veins

blood vessels that take blood from capillary beds towards the heart

capillaries

Most of the exchange of material occurs in thin blood vessel called ______

Coordination of pumping blood

A special group of cells called the sinoatrial node (SA node) produce electrical signals

facilitate contraction of the atria and these same signals are received by the AV node

causes ventricle muscle fibers to contract

Receives signals from other body systems to speed up or slow down

Herbivores

extensively eat plants

Carnivores

extensively eat other animal

Omnivores

eat both plants and animals

Chemical energy

caloric content
Used in cellular respiration to produce ATP

Organic molecules

to provide building blocks of macromolecules
Protein, polysaccharides, nucleic acid, lipids

Essential nutrients

an animal can’t produce these on their own and need to
get them from their diet

vitamins and minerals
Required for optimal function of processes

Essential amino acids

humans can only synthesize 12 of 20 these
Remainder must come from food

Essential fatty acids

serve as precursors for phospholipids and steroids
Found in meat, dairy, eggs, grains, and nuts so easy to obtain

Vitamins

molecules that aid in biological processes

The difference between undernutrition and malnutrition

Undernutrition is the consumption of too few calories

Malnutrition is the consumption of too few essential nutrients

ingestion

eating or feeding

Filter feeding, substrate feeding, bulk feeding, or fluid feeding

digestion

breaking down the food into absorbable molecules

absorption

uptake of small molecules by the animal’s cells

elimination

undigested material passes through digestive system

What is an alimentary canal

an internal tube with openings at “each end”

there may be elaborate, modified chambers along the tube and even some accessory components that branch off from the tube

the mouth

digestion begins immediately

Chewing mechanically breaks food into smaller pieces

salivary gland

Saliva contains enzymes that breakdown starches

Mucus protects mouth and allows food to move through the system more easily

epiglottis and glottis

Food passes from the mouth to the esophagus when swallowed

Entry into the trachea is blocked by the epiglottis

the stomach

digestion continues in the stomach

Gastric juice is secreted by cells that line the stomach

Extremely acidic-pH 2

Enzymes that degrade macromolecules like proteases

Mucus protects stomach tissue from gastric juice

Strong muscles surrounding the stomach keep churning the mix called chyme

the small intestine

much of digestion and almost all of absorption occur here

Digestion of macromolecules occurs with the help from accessory organs

produces digestive enzymes itself

Some molecules are modified with the help of bacteria that live in the small intestine

Absorption of nutrients occurs at the surface area of the small intestine

Large intestine

-primarily involved in reabsorption of water

Colon

most of the length of the organ

As undigested material moves through the ____, the cells remove water

Rectum

-end of large intestine

Appendix

involved in immune function and also archive for flora

Liver

produces bile which aids in utilization of lipids

Stored in gallbladder until secreted into small intestine

Pancreas

produces amylases, proteases, nucleases, and lipases

Also produces bicarbonates which neutralize pH of chyme

Role of the immune system

to distinguish self from not-self and destroy not-self

Not all foreign molecules are considered threat

antigens

Molecules recognized by an immune system are called _____

immunoglobulins

Molecules produced by the immune system that bind to antigens are called