BIOL - 1260 - exam 3

dynamic equilibrium in the body

homeostasis

allow their internal conditions to become similar to the environment

conformers

what are the components of a homeostatic system?

sensor, integrator, effector

compares sensory info to set point

integrator

behavior that helps restore the internal condition

effector

direct transfer of heat between two bodies in contact with each other

conduction

heat is exchanged between a solid and a moving liquid/gas

convection

transfer of heat between two objects that aren’t in direct contact

radiation

liquid becomes gas

evaporation

heat byproduct of chemical reactions warms the body; ex - mammals, birds

endotherm

heat comes from the environment; ex - amphibians, fish, invertebrates, reptiles

ectotherm

compounds that dissociate into ions when dissolved in water; ex - Na+, Cl-, K+, Ca2+

electrolytes

helps maintain homeostasis by regulating water and solute levels

osmoregulation

higher solute concentration = -

higher osmolarity

in osmotic equilibrium with their environment; ex - sharks, marine invertebrates

osmoconformers

actively maintain a relatively constant blood osmolarity different than the environment

osmoregulators

renal - brings bad blood to the kidney. renal - carries clean blood away

artery; vein

what path does urine take?

kidney → ureter → bladder → urethra

what two parts make up the kidney?

outer cortex and inner medulla

basic functional unit of the kidney

nephron

where are the glomerulus and convoluted tubes located?

cortex

where are the loop of Henle and collecting ducts located?

medulla

what do the excretory organs do?

filtration, reabsorption, secretion

where does filtration occur and what happens?

in Renal corpuscle; glomerulus brings blood, Bowman’s capsule surrounds glomerulus

where does reabsorption occur?

in renal tubule

contain microvilli facing the lumen; functions in active transport of selected molecules out of the filtrate

proximal tubule

what happens in the proximal tubule?

1. Na+ pumped into lumen, creating a gradient

2. cotransporters use gradient to remove ions and nutrients from the filtrate

3. solutes that move into the cell diffuse into nearby blood vessels

   1. water follows ions from proximal tubule into the cell and into blood vessels

describe the limbs of the loop of Henle

descending limb is highly permeable to water, but not solutes; ascending limb is permeable to Na+ and Cl-, but not water

blood vessels surrounding loop of Henle; water and solutes diffuse into vasa recta from loop of Henle

vasa recta

distal tubule and collecting duct, regulated by ADH

secretion

small volume of concentrated urine

ADH present

large volume of dilute urine

no ADH

signal molecule; binds to receptor at ligand binding site

ligand

in cytoplasm, respond to hydrophobic ligands that can cross the plasma membrane

intracellular receptors

membrane anchored proteins that bind to external ligands that function via signal transduction

extracellular receptors

binds to enzyme site when active and triggers release of second messengers

GPCRs

any enzyme that helps phosphorylate a molecule

kinase

triggers phosphorylation cascades that cause a response to be triggered in the cell

RTKs

act on the same cell that secretes them

autocrine signals

diffuse locally and act on nearby cells

paracrine signals

hormones carried between cells by blood or other fluids

endocrine signals d

diffuse a short distance between neurons

neural signals h

hormones released from neurons

neuroendocrine signals

response turns off the signaling pathway

negative feedback o

organs that secrete hormones into the bloodstream

endocrine system

what are the chemical classes of hormones?

1. peptides/polypeptides

2. amino acids

   1. steroids

an enzyme activated in response to epinephrine

phosphorylase

initiates a fight or flight response

epinephrine

work to maintain glucose homeostasis in the blood

insulin and glucagon

diabetes that don’t synthesize enough insulin

type 1

diabetes that makes patients resistant to insulin

type 2

signaling molecule that regulates urine osmolarity

ADH

what pathway does ADH take?

hypothalamus → bloodstream → kidneys

extreme thirst, excessive amount of urine, nighttime urination

diabetes insipidus

what can be used to treat diabetes insipidus?

desmopressin

how do you test the kidney’s ability to reabsorb water?

1. urine density

2. urine osmolarity

3. serum osmolarity

more water = - osmolarity

lower

a temporary state of reduced metabolic activity

dormancy

when do plants experience dormancy?

under conditions of cold and drought

promote plant growth

gibberellins

inhibits plant growth

abscisic acid (ABA)

what does ABA do?

induces stomal closure in response to water stress, promotes root elongation and suppresses branching

what are the types of nerve cells in animals?

1. sensory neurons - receive and transmit

2. interneurons - process info

3. motor neurons - respond

convert chemical signals to electrical signals

dendrites

integrates incoming electrical signals

cell body

conducts electrical signals

axon

what order of neurons do signals travel?

sensory → interneuron → motor

don’t transmit electrical signals

Schwann cells

gaps between Schwann cells

nodes of Ranvier

the charge difference between the inside and outside of a cell due to differences in charged ions

membrane potential

resting membrane potential of a neuron is -

-65 mV

rapid, temporary changes in membrane potential

action potentials

voltage gated ion channels open in response to -

changes in membrane voltage

threshold potential = -

-55 mV

immune system attacks the myelin sheaths; signals can’t jump from node to node

multiple sclerosis

space between cells

synapse

how do neurons communicate?

via fusion of synaptic vesicles and release of neurotransmitters

neurotransmitters result in…

• EPSP

  • IPSP

depolarize

EPSP

hyperpolarize

IPSP

_ can be used to determine whether a signal is responded to or ignored

summation