NEW CONTENT FOR FINAL!!!

skeletal muscles

muscles attached to bone + voluntary movement

cardiac muscles

muscles attached to heart + involuntary movement

smooth muscles

muscles on the walls of hollow visceral organs + involuntary movement

sarcomeres

filaments that are arranged into orderly parallel stacks + generates more force

how are sarcomeres visible

as bands in skeletal and cardiac muscles only

muscle fiber

each really big muscle cell

made up of myofibrils that are divided into sarcomere

how do muscles create movement

by contraction or shortening muscles

how is muscle contraction done?

by having filaments with the molecules actin and myosin slide on each other, shortening the

length of the muscle cells (sarcomeres).

Parts of the sarcomere

Sliding filament model

During contraction, the thick and thin filaments slide together lengthwise

what are the steps of Skeletal Muscle Fiber Contraction

1) Neuron has AP, activates neuromuscular junction

2) Muscle has AP, signal propagates to rest of muscle

3) Muscle contracts using cross bridge cycling

neuromuscular junction

the neuron/muscle synapse that functions very similarly to a neuron/neuron synapse

acetylcholine

the nuerotransmitter in skeletal muscles

Acetylcholine release at the nueromuscular junction

1) An action potential in the neuron opens voltage-gated calcium channels.

2) Calcium influx into the neuron causes the release of acetylcholine.

3) Acetylcholine binds to its receptor on the muscle fiber, opening a channel that lets in

sodium.

4) Acetylcholine is broken down in the cleft

When the sodium channels open in the muscle, what happens?

Sodium enters the muscle, effect is depolarizing

what type of receptor is acetylcholine

an acetylcholine-gated cation channel receptor

Signal propagation: From nueromuscular junction to the sarcomere

1) If enough acetylcholine receptors are activated, there will be a muscle action potential.

2) AP travels down the membrane and throughout the fiber in structures called T-tubules.

sarcoplasmic reticulum (SR)

A membrane-bound organelle that uses Ca2+ pumps to accumulate Ca2+ inside itself

how does the sliding filament model work on a molecular level?

the sliding occurs because myosin heads in thick filaments repeatedly grab onto actin in thin filaments and pull

Filaments without calcium

Myosin heads cannot bind to actin because tropomyosin is in the way.

how do changes in actin, troponin, tropomyosin, myosin, or calcium would influence

muscle contraction.

Ca2+ binds to troponin. Troponin moves tropomyosin off the binding sites so the actin and myosin can form cross bridges

Steps of cross bridge cycling

1) Cross bridges form.

2) Working (power) stroke: myosin head turns and pulls thin filament to contract.

3) ATP binding to the myosin detaches the cross bridges.

4) Energy from ATP hydrolysis moves myosin back into the initial state.

What will happen to muscle contraction when the nerve stops firing?

Contraction ends gradually as Ca2+ is pumped back

In rigor mortis, why is the muscle stiff?

There is a lot of calcium but no ATP, so the cross-bridges cannot be released

Contrasting muscle contraction in death and life

LIVING - you always have some ATP around, but the calcium is sequestered in SR

DEATH - membranes break down and calcium is around, but there is no more ATP being made.

how do you get to the sympathetic and parasympathetic nervous systems

through the peripheral nervous system → autonomic nervous syste,

parasympathetic division

“Rest and digest”

• Promotes maintenance functions and conserves body energy

• Promotes low blood pressure, low heartrate, and digestion

sympathetic division

“fight or flight

• Mobilizes the body during activity

• Promotes high blood pressure, high heartrate, and faster and deeper breathing, but inhibits digestion

adrenal gland and stress

When stressed, the adrenal gland both…

• Releases cortisol + is stimulated by the sympathetic division to release epinephrine and norepinephrine.

what are the Two parallel stress pathways

nueral and endocrine

Effects of epinephrine and norepinephrine on the body

they are nuerotransmitters + hormones

Increased heart rate and vasoconstriction → increased blood pressure

Stimulate liver to break down glycogen → Increase blood sugar

cortisol effects on body

acne + getting sick easily

Epinephrine/ norepinephrine effects on body

increased heart rate, stomachaches, headaches

both cortisol and Epinephrine/ norepinephrine effects on body

inability to sleep + fatigue + tiredness

innate behaviors

Instinctive, based on genetics, evolved through natural selection, inborn, unaffected by environment, low variation in population

ex) newborn instincts

learned behaviors

based on experience, trial and error, high variation in population

ex) social skills, tricks in pets

optogenetics

Making neurons express channels that are light-sensitive

How to force a neuron to fire with light

through optogenetics

“fire together, wire together”

mental experiences or actions that occur simultaneously and repeatedly strengthen the connections between neurons, making those pathways stronger and more automatic

how do you test the idea of ‘fire together, wire together’

1) Force neurons to “fire together” that normally wouldn’t.

2) Check to see if they “wired together” to produce a false, composite (mixed) memory that is

associated with the neurons you forced to fire together

hippocampus

nuerons in the hippocampus, the stimulus they respond to best is a particular location,

thing, or event

Different Sets of Neurons Fire in Different Locations or Situations!

what is learning?

a change in synapse

involves both strengthening and weakening synapses

what can a change in synapse be?

Change in number of neurons

Change in number of synapses

Change at the synapses location themselves

strengthening a synapse

when an AP in the presynaptic neuron will cause a bigger response in the postsynaptic neuron

weakening a synapse

when an AP in the presynaptic neuron will cause a smaller response in the postsynaptic neuron

synaptic plasticity

he ability of neural connections (synapses) to strengthen or weaken over time in response to increased or decreased activity

what are the two main ways the immune system protects yourself

Innate Immune System + Adaptive Immune System

main process for immune system

Recognize a pathogen → Activate and mobilize forces to defend against it → Attack it → Control and end the attack

innate Immune System

rapid response, found in all plants/animals, general, only a few signals

adaptive immune system

acquired, slow response, very specific signals, only in vertebraes

what does Innate Immune Protection look like

inflammation, sweat, mucus, tears

cytokines

molecules that signal to other cells to do something

what are the cells of the innate immune system

macrophages, nuetrophils, dendritic cells, eosinophils

macrophages

Engulfs and destroys (phagocytoses) pathogens, dead cells, debris. Secretes cytokines.

talks to the adaptive immune system

dendritic cells

Talks to adaptive immune system

nuetrophils

Phagocytoses pathogens, first responder. Secretes cytokines

eosinophils

Attacks larger pathogens like parasites and cancer cells

which of these consequences will occur if an animal doesn’t make macrophages?

Bacteria will grow more + the adaptive immune system won’t be activated as quickly

pathogens

can be distinguished from the body’s own cells because they: cause damage + have certain characteristics

PAMPs (pathogen-associated molecular patterns)

types of signals that are shared by classes of pathogens

detected by TLR (toll like receptor)

Toll-like receptor (TLR)

a receptor found in all cells of the innate immune system so they can recognize any PAMP

antigen

a substance that triggers the body's immune system to produce antibodies because it can be detected by antibodies in B cells and T-cell receptors in T cells

antibody

made by cells of the adaptive immune system

detect and bind to specific antigens

adaptive immune system steps

A pathogen enters the body

the immune system recognizes a specific antigen (unique marker)

B and T cells that match that antigen are activated

B cells make antibodies, T cells attack infected cells

Some cells become memory cells to remember and fight it in the future

Two arms of the adaptive immune system

Cell-mediated arm + Humoral arm

humoral arm

B-cells divide to make plasma cells, which secrete antibodies

cell mediated arm

Cytotoxic T-cells kill infected body cells (& cancer cells)

why do you need two arms in the adaptive immune system

Sometimes, pathogens are in blood/body fluids, and antibodies can reach them.

– Humoral arm

Sometimes, pathogens are inside body cells (viruses and some bacteria), and you just need to kill those infected body cells

– cell mediated arm

memory B cells and memory T cells

react to the antigens of the pathogen directly and quickly

– So quickly you usually don’t feel sick.

– Memory can last for decades

Traditional Vaccines

Receive an antigen from a source that won’t make you sick

antigen sources: Dead microbe, Weakened microbe, Part of a microbe

mRNA vaccines

inside the dendritic cell, mRNA codes for pathogen protein

antigen source: mRNA from pathogen

If someone has an autoimmune disorder, would you treat it by strengthening or weakening their immune system?

Weakening their immune system!!

People with autoimmune disorders have an immune system attacking their own bodies. If

the immune system is strengthened, it will attack the body better, which is bad

autoimmunity

when the immune system mistakenly attacks the body's own healthy cells, tissues, or organs

self tolerance + how to develop it

Self-tolerance is the ability of the adaptive immune system to recognize the body’s own cells as “self” and avoid attacking them.

develops through central tolerance (self-reactive T and B cells are eliminated during development) and peripheral tolerance (remaining self-reactive cells are inactivated or suppressed, e.g., by regulatory T cells).

muscle weakness

muscle weakness is often caused by issues in nerves.

does acetlycholine enter muscle ?

NO! Acetylcholine is secreted into the synaptic cleft and binds to a receptor on the muscle. It never actually enters the muscle.

Troponin = tropomyosin ?? True or false

FALSE

Troponin and tropomyosin are both in the thin

filaments. Tropomyosin binds to actin, preventing it

from binding to myosin. Troponin detects calcium;

when calcium is present, it moves tropomyosin off

the myosin binding sites

what is ATP required for?

ATP is required for the cross bridge to break.

antibiotics

Antibiotics are drugs given to kill or stop the growth of bacteria.