Bio 203 Exam 2 Review Guide

Adaptation

can occur with constant stimulation

reduction in sensitivity of constant stimulus

depends on the stimulus

Perception

conscious awareness of the stimulus

Nociceptors

pain (danger) sensors

detect chemicals released by cell damage

2 types of pathways to brain

fast pain: localized, adapts (cut, injection)

slow pain: not localized, does not adapt (burning/aching pain)

Thermoreceptors

temperature changes, separate hot and cold sensors

Mechanoreceptors

physical distortion, touch receptors (different types)

Proprioceptors

in muscles and tendons (position of joints, tension and contraction of muscles)

Olfaction (smell)

chemoreceptors

olfactory epithelium contains olfactory neurons

each neuron responds to one chemical

many different types of receptors

sensations bypass thalamus and go to cerebral cortex (conscious) and limbic system (subconscious)

Gustation(taste)

less diverse

Five types of taste

sweet, salty, bitter, sour, umami

Iris

Iris has circular and radial muscles

Circular muscles constrict pupil

Radial muscles dilate pupil

Pupil dilation is regulated by:

Light intensity

Para/sympathetic activity

Rods

respond to all colors, more sensitive, responds to movement

Cones

respond to red, green, blue

Vestibular system

Semicircular canals detect head movement

Rotational movements of the head

Fluid flows through ampulla, distorts mechanoreceptors on hair cells

Maculae detect head position

Gravity

Linear acceleration

Maculae contain otoliths (CaCo3 crystals) are embedded in gel

Gravity distorts gel, activates mechanoreceptors on hair cells

Cochlea

Cochlea contains 3 canals

Central canal contains Organ of Corti (AKA Spiral Organ)

Sound vibrations cause O of C to vibrate

Hair cells press against tectorial membrane

Mechanoreceptors are opened

Nerve signal sent back to CNS

Nervous system vs. endocrine system

nervous used neurotransmitters across synapses for fast, short-lived effects on single cells; endocrine uses hormone via the bloodstream for slower, longer-lasting effects on many cells

Hypothalamus

links nervous and endocrine systems; produces ADH, oxytocin, and regulatory hormones

Homeostasis

stable internal balance maintained by receptors, a control center, and effectors

Negative feedback

main endocrine mechanism where a hormone's effect counteracts the original stimulus

Pituitary gland

regulated by the hypothalamus; split into anterior and posterior lobes

Anterior pituitary

activated by hypothalamic releasing hormones; releases ACTH, TSH, GH, PRL, FSH, LH, and MSH

Posterior pituitary

activated by neurons; releases ADH and oxytocin

Growth hormone (GH)

causes the liver to release somatomedins to promote overall growth and protein synthesis

Thyroid-stimulating hormone (TSH)

stimulates the thyroid to lease T3 and T4

Adrenocorticotropic hormone (ACTH)

stimulates the adrenal cortex to release glucocorticoids

Follicle-stimulating hormone (FSH)

promotes ovarian follicle development/ estrogen and sperm maturation

Luteinizing hormone (LH)

triggers ovulation, progesterone, and testosterone secretion

Prolactin

stimulates milk production in mammary glands

Antidiuretic hormone (ADH)

causes kidneys to retain water to raise blood volume/pressure

Oxytocin

triggers smooth muscle contractions for labor, milk ejection, orgasm, and bonding

Exocrine pancreas

99% of the organ; secretes digestive enzymes into the intestine

Endocrine pancreas

1% of the organ; contains alpha and beta cells

Insulin

"feasting" hormone from beta cells; lowers blood sugar by storing glucose as glycogen

Glucagon

"fasting" hormone from alpha cells; raises blood sugar by breaking down glycogen and fat

Type 1 diabetes

early-onset, insulin-dependent due to insufficient insulin production

Type 2 diabetes

mature-onset, insulin-independent due to insulin resistance (linked to obesity)

Diabetes mellitus

high blood sugar caused by a lack of insulin or insulin resistance

Thyroid gland

below the larynx; produces T3 and T4 to boost metabolism and heat production

T3

highly active form of thyroid hormone (~10%)

T4

inactive transport form (~70-90%) converted to T3 in the liver and gut

Calcitonin

released by C cells; lowers blood calcium by stimulating bone deposition and kidney excretion

Hyperthyroidism

overactive thyroid causing slow heart rate, weight loss, and heart intolerance

Hypothyroidism

underactive thyroid causing slow heart rate, weight gain, fatigue, and cold tolerance

Parathyroid glands

four small glands on the back of the thyroid

Parathyroid hormone (PTH)

raises blood calcium by dissolving bone and reducing kidney calcium loss

Calcium homeostasis

maintained tightly 8.5-11 mg/dL via calcitonin and PTH

Adrenal glands

composed of the steroid-producing cortex and sympathetic medulla

Adrenal cortex

outer regions split into zona glomerulose, fasciculata, and reticularis

Adrenal medulla

inner core for short-term stress; secretes epinephrine and norepinephrine

Glucocorticoids

cortisol from the fasciculata increases glucose and suppresses inflammation during stress

Aldosterone

mineralocorticoid from the glomerulosa; retains sodium and water in kidneys

Epinephrine

triggers immediate "fight or flight" responses

Cortisol

dominant hormone of the resistance phase of stress; mobilizes fats and conserves glucose

Glucose homeostasis

balanced dynamically by insulin and glucagon

Energy homeostasis

regulated by thyroid hormones, GH, and cortisol

Negative feedback

primary loop where hormonal responses reverse physiological deviations

Growth hormone disorders

gigantism (GH excess before puberty) and acromegaly (GH excess after puberty)

Cortisol disorders

Addison's disease (too little cortisol; low blood pressure, poor stress response) and Cushing's Disease (too high cortisol; truncal obesity, high blood pressure)

Functions of blood

Transport gases, nutrients, hormones, waste

Reservoir in homeostasis; pH regulation, ion levels

Clotting

Defense against infection

Temperature regulation

Plasma

liquid, cell-free part of blood, that has been treated with anti-coagulants

55% of total volume

Water - 92%

Proteins - 7%

Albumins for osmosis, Globulins antibodies and transport proteins, Fibrogen for clotting

Other solutes - 1% (nutrients, ions, waste)

Serum

liquid part of blood after coagulation, therefore devoid of clotting factors as fibrinogen

Formed elements

45% total volume

All cells made in bone marrow

Red blood cells - 99.9%, Carry oxygen

White blood cells <0.1%, Fight infection

Platelets <0.1%, clotting