NPB 10 Midterm 2 ! (copy)

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contraction

contraction

thick filaments (myosins) and thin filaments (actin) SLIDE

calcium

helps in regulation of proteins on thin filaments - > causes them to move out of the way

the sarcomere shortens " sliding" of thick and thin filaments and results in contraction

mechanics of muscle contraction

in smooth and cardiac form, there are contractile proteins -myosin -actin

in skeletal muscle, the myosin is arranged thick filaments and actin is arranged in thin filaments

sarcomere

primary unit of contraction -thousands inside of muscle cells

how does sarcomere shorten in length -> contracts and slides?

-requires ATP which drives the head bending "power stroke" -ATP also allows the head to let go of actin (thin filament) -in relaxed muscles, regulatins protein tropomyosin sits on the actin thin filaments and BLOCKS

what happens when we activate a muscle?

1. calcium enters muscle cell

2. causes the tropomyosin to move out of the way

3. thick filament and the thin filaments will form crossbridge (heads bind)

4. contraction

exciting muscle cells results in....

a rise in calcium levels= muscle contraction

e

xciting muscles requires...

input from a neuron (efferent pathway)

1. AP travels down the alpha- motor neuron

2. AP causes neurotransmitter (acetylcholine) to be released in synapse

3. ACH binds its receptor on muscle and activates the receptor and sodium ions enter the cell

4. causes an AP in muscle

what happens when AP spreads through a muscle?

Calcium enter the cytoplasm of the muscle from the outside and an organelle sarcoplasmic reticulum

how do you stop contraction?

1. remove calcium from the cytoplasm

2. stop having AP in the muscle cell

3. stop signaling between the neuron and the muscle

muscle twitch

most basic simple contraction and it can't do much as it is a fast rise to tension and fast relaxation

contracts when tension accumulates and peaks and then relaxes in a matter of milliseconds

summation of twitches allows us to generate strong force and long lasting contraction

why study twitches?

-a slow twitch generally has more endurance and has metabollic pathways that generate alot of aTP- > consumes oxygen in a type 1 muscle

-a fast twitch generally generates force very quickly. --fatigue resistant - > type 2A muscles --fatiuable_ > type2B

motor unit

1 motor neuron and all the muscle cells it controls

small motor unit

neuron innervate control 10-50 muscle cells

(important for moving light loads and control)

large motor unit

neuron innervate HUNDREDS of muscle cells

recruitment of motor units

progressively activates more and more motor units which generates more force

primary motor cortex

first to elicit commands to do specific motor activities

associative motor cortex

The association cortices include most of the cerebral surface of the human brain and are largely responsible for the complex processing that goes on between the arrival of input in the primary sensory cortices and the generation of behavior.

cerebellum

A large structure of the hindbrain that controls fine motor skills.

basal nuclei

fine control of voluntary activity

spinal cord

mediates myotatic reflexes like a knee jerk and pain withdrawl reflexes

sarcopenia

age related decline in muscle function, causes are multi factoral -inactivity -genetics

exercise early in life = protective effecti

1. builds muscle

2. metabolism

sarcopenia-> leads to weakness -> leads to falls

cardiovascular system

transports stuff throughout body

-gases oxygen and carbon dioxide -fuel glucose, fats/ (free fatty acids) -hormones -wastes -thermal energy- heat

heart

pressure maker \n pressure gradients: differences in pressure drives flow

pathways

vasculature

blood transport medium

can move gases, fuel, signal bacteria, cells, hormones

systemic circulation

-blood comes from the left heart -receives blood from the lungs (to the left atrium)

-delivers oxygenated blood, low CO2

pulmonary circulation

-blood leaves the right ventricles to the lungs ( pulmonary blood vessels) -oxygen poor, CO2 rich -right atrium receives blood from the body organs

1. pressure gradients= blood flow if....

2. pressure gradients= no blood flow

1. Pa > Pb

2. Pa= Pb

gradient of pressure

blood flow= Change in pressure/ resistance to flow

heart

know:

• superior vena cava

• atrium and ventricles ( R and L) -inferior vena cava atrio-ventricular valves -semilunar valves -pulmonary veins

• apex

right ventricle

drives blood to lung ( pulmonary circulation)

left ventricle

drives blood to body (systemic circulation)

-must shove, push blood into aorta

valves

prevents BACKWARDS blood flow

AV valves

prevent backwards flow from ventricles to atria

• close when ventricles contract

semilunar valves

prevent backward flow from arteries back into ventricles

-close when ventricles relax

aorta

The large arterial trunk that carries blood from the heart to be distributed by branch arteries through the body.

fill with blood -> stretches - > recoils -> drive blood flow when ventricles relax - > ventricles contract - > fill with blood

*elastic artery:

pulmonary trunk/ pulmonary arteries

fills with blood when ventricle contracts - > recoils and drives blood into pulmonary circulation

*elastic artery

elastic artery

"store" energy as they fill with blood, then they recoil and drive blood out

arterioles

small vessels that receive blood from the arteries

*resistance vessels: can oppose blood flow

vasodilation

reduces resistance to flow and is caused by metabolytes

capillaries

-exchange blood vessels

-allow molecules to cross

-small diameter -thin walls ( 8- 10 microns in diameters) -close to tissues -very slow blood flow

endothelial cell

makes up walls of capillary

fenestra/ gaps/ pores

allow exchange between endothelial cells

discontinuous capillaries

have gaps between cells; found in bone marrow, liver, and spleen; allow the passage of proteins

fenestrated capillaries

have pores in vessel wall; found in kidneys, intestines, and endocrine glands

continuous capillaries

have a wall where the endothelial cells fit very tightly together.

-found in brain -dont allow everything to leave the blood and then enter the tissue

venules and veins

-drain capillaries -blood pressure is low -drain lower extremities

muscle pump

blood flow is driven up while muscles contract

venous valves

backwards flow is prevented when muscles relax

systolic BP

arterial pressure when ventricles contract

diastolic BP

arterial pressure when the ventricles relax

mean arterial pressure

MAP= (1/3 x SP)+ (2/3 x DP)

-drives our blood flow and homeostatically regulates it

-as MAP increases, it creates after-load on the ventricle so the ventricle must work harder

hypertension

high blood pressure

-imposes a workload on the heart

red blood cell

-no nucleus -lots of hemoglobin -iron binds to oxygen -100 ml of blood and there is approximately 40% volume of RBC -binds to oxygen in pulmonary circulation

in tissues (muscle and brain) hemoglobin________ its affinity to oxygen

loses

in the lungs hemoglobin _______ gains affinity to oxygen

gains

highly metabolic tissues releases metabolytes and its hotter which....

changes the affinity of hemoglobin so that hemoglobin releases the oxygen

why is blood in the fetus very sticky???

it allows for fetal blood to become oxygenated

sickle cell hb

was evolved for places where malaria was prevalent

-imports some type of resistance to malaria -changes the shape of the rbc

(shape is usually circular and it gets changed into a crescent shape, which is not as effective in carrying oxygen and results in sickle cell anemia)

what organs receive constant blood flow?

brain, heart (coronary circulation), kidneys

what receives varied blood flow?

muscle- when activity increases, blood flow increases

what receives little blood flow?

fat and tissue

What is vasoconstriction of the arteriole caused by?

SNS input

where does sns input come from?

CNS (spinal cord)

-SNS activity increases when we are scared or trying to escape something

how to increase blood flow to tissues

a. decreases SNS activity to smooth muscles, this relaxes smooth muscles

b. metabolytes that are released by tissue will cause smooth muscle to relax

respiratory system

moves air into and out of lungs

-gas exchange between the blood and the alveoli

internal respiration

cellular respiration

-mitochondria: uses oxygen to generate ATP

(as we increase rate of ATP synthesis, cellular respiration increases which causes external respiration)

conductive pathways

air movement

-mouth,nose -trachea -branches -bronchi

bronchiole

Airways in the lungs that lead from the bronchi to the alveoli. no cartilage

-warms air as we inspire and wets the air followed by removing dust, pollen, and particulates - > mucus

exchange surfaces

allows gases oxygen and carbon dioxide to move between lungs and blood

Alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood.

-type 2 alveolar cells produce surfactant

respiratory muscles

-diaphragm -intercostal muscles (internal and external) -abdominal muscles -scalene and sternocleidomastoids

what happens during breathing?

inspiration involves increasing the lung volume so air can move in. expiration involves decreasing lung volume so air can move out.

think of a syringe

what happens during inspiration?

contraction of respiratory muscles (diaphragm and external intercostal muscles)

what happens during expiration?

the muscles relax

what happens during forced expiration?

forced expiration -abdominal muscles and internal intercostal muscles (rib muscles) strongly decrease the thoracic volume and lung volume -> increases pressure in lungs

what happens during forced inspiration?

scalene and stemocleidomastoid muscle (neck) strongly increase thoracic volume

What happens to inspired gas?

-move through the conductive pathways ( nose and mouth -> trachea -> bronchi - > bronchioles)

• air velocity is initially really fast _> air slows down

-air is moistened and warmed

• dust, pollen, floating dirt are removed and stick to mucus

what happens when air hits the respiratory/ exchange surfaces of the lung?

it allows for gases to move between the blood and the lung (alveolus)

what do alveoli do?

type 1: cells are thin because it allows for gas exchange

type 2: secrete pulmonary surfactant which make it easier to breathe

premature babies are born with non functional or low functional type 2 cells -> respiratory distress

how are alveoli organized?

in sacs and ducts

what makes up the air?

79%- nitrogen 20%- oxygen 0.03%- CO2

Patm- 760 mmHg Po2- 160 mmHg

when air enters the lungs?

Po2= 100 mmhg Pco2= 40 mmHg

think of these as concentrations