Physiology Lab Module 3

endocrine system

system of glands in the body that secrete hormones and regulate many body functions

lipid soluble hormones

-enter the cell by passing through cell membrane

-bind to a receptor inside the cell

-hormone + receptor enter the nucleus and activate genes

-released by ovary into blood

water soluble hormones

-cannot pass cell membrane

-hormone binds to receptor on the surface of the cell

-causes activation of enzymes inside of the cell

-released by pancreas into blood

hypothalamus

control center for the endocrine system and homeostasis

-sends hormone to the pituitary gland

pituitary gland

regulates all other endocrine glands

anterior pituitary gland

produces and releases hormones based on the hormone recieved from hypothalamus

anterior pituitary gland hormones

-prolactin

-growth hormone

-thyroid stimulating hormone

-adrenocorticotropic hormone

-gonadotropins

posterior pituitary gland

-hypothalamus produces oxytocin and antidiuretic hormone

-hormones sent to posterior pituitary, which releases these hormones as needed

pineal gland

small gland found in the brain

-produces melatonin

adrenal gland

gland found on top of the kidneys

-zona glomerulosa, zona fasciculata, zona reticularis

zona glomerulosa

produces aldosterone

zona fasciculata

produces cortisol

zona reticularis

produces androgens (sex steroids)

pancreas

gland that regulates glucose levels in the body

-also has a role in digestive system

insulin

decreases blood sugar levels

-made by beta cells of pancreas

glucagon

increases blood sugar levels

-made by alpha cells of pancreas

hypoglycemia

insulin shock (slow movements)

somatostatin

regulates alpha and beta cells

-produces by delta cells of the pancreas

thyroid gland

-found above the trachea

-produces hormones that regulate metabolism and body temperature and regulate calcium levels in blood

thyroid stimulating hormone (TSH)

-produced by anterior pituitary

-sent to thyroid to produce T3 and T4, which increase metabolism and body temperature

hyperthyroidism (Grave’s Disease)

disease caused by overactive thyroid

-high metabolism causes weight loss, rapid heartbeat, sweating, nervousness

sarcolemma

cell membrane of muscle

sarcoplasmic reticulum

stores calcium (Ca²⁺)

sarcomere

where contraction occurs, structural unit of skeletal muscle

myofibril

strands of proteins found in muscle cell

thick filament

contains myosin

thin filament

contains actin, troponin, tropomyosin

muscle contraction

-ACh neurotransmitter binds to muscle cell

-sarcoplasmic reticulum releases Ca²⁺

-Ca²⁺ binds to troponin

-sarcomere contracts

flexion at elbow

agonist is brachialis

antagonist is triceps brachii

extension at elbow

agonist is triceps brachii

antagonist is brachialis

abduction at shoulder

agonist is deltoid

antagonist is pectoralis major

adduction at shoulder

agonist is pectoralis major

antagonist is deltoid

electromyogram (EMG)

measures the action potential from a muscle contraction

-applied force, number of active motor units, frequency of motor units

motor units

a single neuron connects to multiple muscle cells

-low strength = fewer active