Physiology Exam 2

Lines the walls of the heart

Responsible for the rhythmic contractions of the heart that allow it to function as a pump

lines the walls of most hollow organs, such as the blood vessels and intestines

Responsible for moving contents through these hollow organs

• Slow twitch

• fatigue-resistant
  

• have numerous mitochondria

• small
  
• high myoglobin
  
• 1st to be recruited
  

a protein which makes the tissue dark in appearance

found in Type 1 fibers

• fast twitch
• medium fatigue rate
  
• many mitochondria
  
• medium in diameter

• high myoglobin
  

• 2nd recruited
  

• Fast twitch
• fast fatigue rate
• few mitochondria
• largest diameter
• few myoglobin
• 3rd recruited
  

The force level is constant and higher than that found in a single twitch

due to a relatively sustained intracellular Ca²⁺ level

• conduction failure in T-tubules (build-up of K+ blocks APs)
  
• build-up of H+, ADP, and Pi (slow cross-bridge cycling)
• Central command fatigue
  

muscle contraction without shortening or lengthening

• AP propagates down T-tubule
• DHP changes conformation w/ increased + voltage & tugs on RyR
• Ca²⁺ released from SR via RyR
• Ca²⁺ activates actin
  

dark bands

represent the region where actin and myosin filaments overlap each other

light bands

Represent the regions where only actin filaments are present

located in the center of the I band

where actin filaments are anchored

the unit of contractile function in striated muscle

covers the distance beteewn two Z lines

center of a sarcomere

where myosin filaments are anchored

the sarcomere shortens as a result of the thick and thin filaments sliding past one another

muscle contraction

site deep within the muscle fiber the plasma membrane invaginates at each sarcomere reaching deep into the interior of the contractile apparatus

cross-bridge cycling rate is reduced

-characterized by high force, low shortening velocity and low ATP consumption

have short twitch-like contractions

common in the gastrointestinal tract

long sustained contractions

common in airways and blood vessels

• individual cells are linked together by gap junctions and are electrically coupled (entire sheet of cells contract together)
  

• able to spontaneously generate action potentials (pacemaker activity)
• GI tract, reproductive organs, bladder, sm blood vessels
  

• No gap junctions
  
• independent, uncoupled cells
• activated (or inhibited) by autonomic nerves, hormones
• lungs, lrg blood vessels, eye muscles, hair follicles
  

pituitary

thyroid

adrenals

pancreas

ovaries

testis

thyroid

adrenals

pancreas

ovaries

testis

amine

peptide

steroid

• Steroids and thyroid homrone
• require plasma protein carriers in blood
• receptors found inside the nucleus
  

• proteins and catacholamines
  

• travel freely in blood
• receptors found on plasma membrane
  

• minutes-hours
• hours-days
  

• determine which tissues respond to an endocrine broadcast
• High sensitivity
• huge signal amplification
• Hormone levels influence expression of their own (or can be permissive to others') receptors
  

Neural tissue during development

the smooth muscle of blood vessels where it stimulates constriction

the kidney where it stimulates water retention

adrenocorticotropic hormone (ACTH)

tyroid stimulating (TSH)

follicle stimulating hormone (FSH)

luteinizing hormone (LH)

• GnRH (Protein)
• GHRH (Protein)
• SS (Protein)
• TRH (Protein)
• DA (Amine)
• CRH (protein)
  

number of cells increases

• a goiter due to excess TSH levels that increase size and # of follicles (if no iodine)
  

• A low BMR giving rise to cold intolerance, excessive weight gain, decreased alertness, fatigue
  

secretion of catecholamines: epinephrine and norepinephrine into the blood

*causes vasoconstriction, increased heart rate, increased force or cardiac contraction facilitated breathing and dilated pupils

• caused by: Graves' disease (most common) where TSI stimulates the TSH receptor

• Nervousness & anxiety
• Increased HR
• Insomnia
• Weight loss
• Heat intolerance
• Goiter
  

• Glucorticoids (cortisol)
• Sex steroids (androgens)
• Mineralcorticoids (aldosterone)
• regulates Na⁺ and K⁺ concentrations, and blood volume
  

during stressful situations & normal resting state (basal levels)

targets: skeletal muscles, liver and adipose tissue

• Permissive of adrenergic receptors in cardio system (maintain BP)
• Liver glucose production between meals
• Anti-inflammatory & anti-immune (prevent hyper-response)
• Fetal/neonatal development
  

• Metabolic effects
• Bone resorption
• Support sympathetic response (high BP)
• Stimulates erythropoietin (replace RBCs)
• Anti-inflammatory & anti-immune
• Psychological/analgesic
• Inhibit nonessential functions (e.g. reproduction)
  

• Cause: tuberculosis, tumors, autoimmune destruction
• Symptoms: low BP, low blood sugar, anxiety, fatigue, weight loss, muscle weakness, hyperpigmentation of the skin
  

catabolism exceeds anabolism

GI empty and fuel for ATP symthesis is provided by endogenous stored sources

brain gets top priority for glucose and other tissues switch to metabolizing fatty acids for energy

1. secretion of sex hormones

2. production of gametes (sperm and ova)

secondary sexual characteristics

=> body shape and distribution of hair

mitosis, meiosis and differentiation of germ gells

takes place in the testis in convoluted tubules known as seminiferous tubules

1. with high glycogen content, they provide nutrition for the developing sperm cells

2. they secrete androgen binding protein in response to FSH which helps maintain high levels of testosterone in the seminiferous tubules

3. they form tight juctions through which the sperm cells pass as they develop

when female germ cells are in a state of arrested meiosis

*at birth

• follicle growth and development occur
• LH levels steady & FSH inhibited by high estrogen
• Day 7 => granulosa cells start to have receptors for LH & thus estrogen increases
  

• the ovum is freed from the ovary when the follicle ruptures at about the midpoint of the cycle
• Estrogen levels are high
• LH "surge" occurs just before
  

• the corpus luteum is formed
• actively secretes sex hormones progesterone and estrogen which prepare endometrium for embryo
• High est. & progest. levels neg. inhibit FSH & LH
  

• the proliferation of granulosa cells
  
• secretion of fluid into the enlarging hormone-rich antrum
• conversion of adrogens to estrogen
• Estrogen + feedback on granulosa to produce more estrogen
  

1. Force developed in in single muscle fibers (stimulation frequency; fiber length; fiber type; amt of fatigue)
2. Total # of muscle fibers contracting at once (motor unit size & recruitment)
   

• Rate of myosin ATP hydrolysis (depends on myosin isoform)
• Metabolic pathway used to form ATP (glycolysis or O.P.)
  

• FG fibers will increase in diameter (due to increase in actin and myosin
• increase in synthesis of glycolytic enzymes
  

• Give intention to move
• cortex
  

• "command neurons" create a "motor program" based on input from above (intention) and sensory input from below (position, space)
• sensory/motor cortex, thalamus, basal nuclei, brainstem, cerebellum
  

• Providing sensory input and enacting the "motor program"
• Muscle spindles, golgi tendon organs, spinal/brainstem interneurons, alpha motor neurons
  

1. Temp halts est. secretion & increases progest. secretion
2. restarts meiosis in the oocyte
   
3. production of prostaglandins which causes swelling of follicle & digestion of wall
4. differentiation of granulosa/theca cells into luteal cells
   

• High
• SS
• GHRH
• GH
  

• Acromegaly - too much GH after epiphyseal plates close
• Gigantism - too much GH before epiphyseal plates close
  

• GH
• IGFs
• Insulin
• Thyroid hormone (permissive to GH)
• Testosterone (stimulates GH & IGF secretion @ puberty and protein synthesis & close epi plates)
  
• Estrogens/DHEA (stimulate GH & IGF @ puberty & close epi plates)
  

• Amino Acids
  
• GIP (secreted by GI cells; cause feed-forward response)
• Parasym neurons (feed-forward response)